March 26, 2021 Weather Impacts On Economic Activity - Is This A Megadrought?

Written by Sig Silber

Slightly Updated at 7:15 pm EDT March 29, 2021

Some are calling the current drought in the West a “Megadrought”. I am not convinced that it has risen to that level although the term itself is not well defined. We will discuss this a bit tonight. We provide some updated information on La Nina. We show the state rankings with respect to temperature and precipitation for the three months of meteorological winter. This article contains all of our regular features and as usual, we include an intermediate-term weather forecast.

Please share this article – Go to the very top of the page, right-hand side, for social media buttons. Please feel free to send this article to anyone who you think might benefit from reading it.

First, let us start with a short ENSO Update.

These are the forecasts that NOAA relies on the most. On the left is the forecast used to make the Seasonal Outlook. On the right is the second forecast of the month…there are two each month. The methodology is not identical. The first forecast is based on a survey of meteorologists, the second is based on computer forecasts. If you look at AMJ in both forecasts you can see that the odds of ENSO Neutral have increased a bit for that period of time. Also looking farther out, the odds of a double-dip La Nina seem to have declined a bit.

This is what is called the plume of forecasts. It shows the forecast for many models. Unless you have a favorite model you might want to look at the green, red, and blue lines. They all seem to move above -0.5 meaning out of La Nina but they all stay on the negative side of Neutral. There is not a lot of agreement among the models so if you believe in averages, this is a good way to look at things.

Let’s look at State Rankings for the three-month period Dec – Feb which is meteorological winter.

Two states were much above average but there was a large average to below-average area.

Looking at maximum temperatures the situation is similar.

But looking at minimum temperatures, all of New England was much above average.

We do not usually do it but let us look at the climate divisions with respect to Minimum Temperatures.

We still see New England being much above average but there are some additional northern tier climate divisions where the minimum temperatures were much above average.

And then precipitation

On balance, the overall level of precipitation was below average. North Dakota was much below average. North Carolina and Virginia were much above average.

And precipitation by climate division

We see some climate divisions within states that set records for dryness

Western Drought. Is it a Megadrought?

I could have generated the following myself and it would show better but everything takes time so when I find something useful I do.

Here is that direct source of the above but it is easily generated from the Drought Monitor so that is the ultimate source. One sees rises and declines in the drought levels since 2000. Those who are not familiar with low-frequency cycles like the PDO and AMO attribute everything to Climate Change. Those who are more informed have a more nuanced assessment of the data.

Of course, the low-frequency cycles may themselves be influenced by Global Warming. That also goes for the medium frequency cycles such as ENSO

What we know for sure is that it is drier than normal and warmer than normal. And it is causing problems.

But let us now focus on the Sierra Nevada mountains which are very important for California.

Notice that 2020-2021 is close to but is not the lowest snowpack over the last five years.

II am not sure what period of time is covered. The average showed for withdrawals is either a typo or it covers more than the years shown in the table. The recharge is highly variable suggesting that some draw conclusions that are not valid based on looking out the window to determine current weather. They complicate the work for people who want to address these issues objectively.

California/Nevada Update

You can watch a replay of this webinar here. I did not watch it live. The graphics might have looked better in the live presentation.

But I was very impressed with what saw when I looked at the recorded version of the webinar so I have snipped many of the exhibits and show them here.

I may have gone overboard and included too many of the slides in the presentation. But California is very important.

I probably could find a better map but this does show the regions for Drought Early Warning System Regions. Some may remember the anacronym DEWs from Cold War Days. It is the same idea but a different enemy is involved.

Here the speaker is addressing the perceived severity of this drought. I say perceived because people seem to have short memories. But for sure they are having a rough time in most of California and a lot of Nevada.

Again the quality of the graphics is not great. But here I think the speaker is trying to make the point that drought conditions are very bad but the last three months have if anything been an improvement.

This shows the importance of the January Atmospheric River or California would be in really bad shape.

Sometimes March rescues a dry year. It does not look like it will happen this year but this graphic only goes through March 18 but the speaker had access to the forecast. Colorado got wet. Location: Location: Location

This is a very important graphic. Most of our systems are designed to handle a dry year. But two in a row is a problem. Three in a row is a disaster. Do two years in a row equate to a “megadrought”? I know a lot of people who think so. I avoid reading their articles since I think perhaps incorrectly that I still have some brain cells that work.

This is pretty interesting but the graphic quality is not great. You can think of this as being about Atmospheric Rivers or the Jet Stream or the impact of a Modoki. The point is that we depend on a small number of intense precipitation events. If we do not get them, we have dry years. The La Nina extended far to the west and may have interfered with the development of Atmospheric Rivers. Be careful what you wish for as flooding can be as bad as drought for the West Coast and for flood control dams where I live which is New Mexico.

Here we look at evaporative demand. Again you see that the problem has been mostly the three months prior to the past three months.

I wish the graphics were better but the message is clear, the level of the snowpack was less than usual.

The color of the circles is what counts. The scale is shown on the right. It is all bad but the yellows are less bad and the red circles are worse.

It is difficult to read the time scale but these are daily readings and as the comment in the graphic shows, one storm provided almost half the snowpack. I work with cloud seeding and I have noticed that when I look at studies of cloudseeding in the Rocky Mountains. The major impact of cloud seeding is for a few storms during the winter. I am not sure if it is enhancing major storms or turning storms that would be a dud into productive storms.

This is a disturbing slide. Again I apologize for the graphic quality but you can see the black line setting a record for soil dryness. This seems to me to be a continual problem due to Global Warming. Early snowmelt may make trees happy but that water typically does not enter into the water budget. Generally speaking, the water budget is based on streamflow and what is provided by pumping from groundwater. Early snowmelt may to some extent recharge groundwater. But it will reduce the streamflow from a given amount of SWE. I believe that is our major problem and will get worse but it is an ongoing problem. When it is combined with periods of time when precipitation is down or if temperatures spike the combination of events leads to a reduction in the water budget of a state.

It should be no surprise that streamflow is down.

We have shown the graphic on the left before and what is on the right is a this year last year comparison.

I have slipped in a more readable current reservoir storage.

There are quite a few reservoirs that are below average.

Below is a larger version of the table. It shows for six important reservoirs their current levels relative to the ten year average. It also shows that 2014 was bad year also.

I am now going to enlarge the graph on the right.

I think the dark blue line is the current year. There are dates across the bottom but they are hard to read. I assume the shaded blue area is the average pattern of rise and fall of the lake level. I am guessing that the light blue line is the worst ever in recent times but that is just a guess. The speaker did not explain this graph. I tried to find it at https://cdec.water.ca.gov/reservoir.html and there is a lot of information there but I could not find this graph. It may be there somewhere. There is a lot of information at that URL. I wish the legend was readable. But what you can see is that the lake level has not risen very much this winter. The dates start with the beginning of the water year at the start of October. We are close to what the peak will be if not there. As we move into the summer the lake level will fall. I hope this helps.

So this is how that speaker summarized the situation. Now we move on to the second speaker at that webinar and subsequent speakers.

This is a forecast and not a very encouraging one.

I already presented this information.

This just shows that temperatures are expected to be warmed than normal. But it is difficult to interpret what this means given that we are having Global Warming and the definition of “normal” will be redefined to be the mean of the three decades 1991-2020. This IMO should already have happened. If you listen to the whole presentation you will hear a discussion about the many microclimates in Nevada and how Northern Nevada and Southern Nevada are very different so this graphic may not fully capture that.

We have seen something similar to or identical to this earlier in the presentation but this shows that the southern Sierras are in worst shape than the northern Sierras.

We have seen a slide like this before and it just confirms that California is not going to have a good run-off season. Nevada is shown also.

I have listened to the explanation of the graphic on the right and still do not understand it. But I think that red line near the bottom is key. I will listen a third time and perhaps be able to explain it.

This was a promo for the USDA Climate Hubs Program. I will provide more information on it next week.

I left the image of the speaker in when I sniped the slides being presented at this webinar. I think we would take any of those conditions here in NM and be very happy. So drought is relative.

Here they are talking about cattle and the way cattle are moved to higher allegations during the summer. Here in NM, the Navajo do that also and it is called Sheep Camp. It is good for the sheep and good for the mental health of those who need to get away.

Here we get into drought mitigation and based on surveys you can see the strategies and the percentage of use and the self-reported effectiveness of each of the strategies. The animals might have a different perspective on the strategies. They might not see the appropriateness of the early culling which was described but does not show on this chat other than by identification of the animals to sell.

I guess this is just to point out that the situation for farmers has gotten worse.

That is the end of the California-Nevada DEWs report. They will have another webinar on May 24, 2021, and a drought status update in early April.

Southern Plains Update

I am presenting some of the slides in the presentation. The full presentation can be found here.

These graphs show climatology by month and the January and February data for this year.

Oklahoma also does appear to be in bad shape as of the first two months of the year.

It is not clear why Texas is in trouble. February was not a good month.

New Mexico is off to a bad start in January and February, but like California, the problem in New Mexico started last year.

It is a nice format for showing information

You can really see the north/south divide here.

Intermountain West Update

The Rocky Mountains seem to be the dividing line between dry and wet.

For the full webinar click here.

But not every part of the U.S. is in drought.

You can access the full report here.

Drought Free

No drought but possibly severe weather.

But we are not going to ignore the drought or the poor prospects of an adequate Spring runoff. So that’s where we start:

Last Week	This Week

There is some snow. But looking ahead to Spring runoff it does not look great but it had been looking better than it has recently. But you can see the change in one week and you can find updates here.

Last Week	This Week

The second set of maps is a bit out of date but I like them as they are easier to interpret and they show the winter wheat growing area and snow is helpful to winter wheat during cold spells especially when the seedlings are immature. In one week there has been a lot of snowmelt.

Recent Events.

Track this by our LIVE article. To find the latest version you go to the Directory and click on the LIVE article that is shown on the top of the stack

Here is what the SNOTEL data is telling us about Spring runoff.

Purple and blue is better than red or orange.

And here is the water year.

You can definitely see the north/south divide.

And it is always useful to look at the last seven days.

You can see where the green is.

Let’s look at the current drought situation.

And the week to week change

There was some slight improvement this week. More information can be found here.

Here we look at four-time periods: one week, one month, six months, and a full year.

You kind of have to look at this 4-Plex in reverse. The lower right map shows the situation today as compared to a year ago. This set of graphics shows that this drought has materialized over the past year.

It is easy to get confused by this graphic. The map in the lower right does not show that the drought was worse a year ago but the change from a year ago to today. So the drought now is much worse than a year ago.

Drought Discussion (The Regional links are live and will take you to the drought map for that Region)

A couple of low pressure systems resulted in widespread precipitation (0.5 to 3 inches, locally more) across the central and southern Plains, Ohio and Tennessee Valleys, Southeast, and Mid-Atlantic from March 16 to 22. However, mostly dry weather persisted across southern Texas, the Florida Peninsula, northern New England, the Great Lakes, and northern Plains. Periods of rain and high-elevation snow occurred across the Pacific Northwest, northern California, and the central Rockies, but the Southwest remained mostly dry. As of March 23, 7-day maximum temperatures averaged above normal across the northern Plains and Upper Mississippi Valley.
Northeast
Following below normal precipitation during the first half of March, widespread precipitation (0.5 to 1.5 inches) overspread the northern Mid-Atlantic and southern New England. However, much of Maine, northern New Hampshire and Vermont, Upstate New York, and parts of Massachusetts remained mostly dry. Therefore, a slight increase in D0 (abnormal dryness) and D1 (moderate drought) was made. Although 28-day streamflows generally are running average, soil moisture and SPI values at various time scales support the ongoing D0 and D1. Also, areas east of Lake Erie (northeast Pennsylvania and western New York) had an expansion of D0 this week.
Southeast
On March 17 and 18, a severe weather outbreak occurred with numerous tornado reports across Alabama, Georgia, Florida, North Carolina, and southeast Virginia. In addition to the severe weather, widespread rainfall (0.5 to 2 inches, locally more) soaked much of the Southeast which prompted a 1-category improvement to ongoing D0 (abnormal dryness) and D1 (moderate drought). 28-day streamflows and 60 day SPI values continue to support lingering areas of D0-D1 across Alabama. Parts of northern and central Georgia received less rainfall this past week which prompted an increase in abnormal dryness (D0) based largely on 60-day SPI. The Florida Peninsula remained mostly dry this past week and the D0 (abnormal dryness) was expanded. D1 (short-term moderate drought) was added to mainland areas of Monroe County in south Florida where less than 2 inches of rainfall has occurred during the past 90 days and fire danger is very high.
South
The severe weather outbreak that affected the Southeast Region began across the Lower Mississippi Valley on March 17 and local rainfall amounts exceeded 2 inches across parts of Arkansas, Louisiana, and Mississippi where 1-category improvements were made. More widespread rainfall amounts of more than 1.5 inches increased soil moisture throughout nearly all of Tennessee. Based on this past week’s rainfall of 1 to 3 inches and improving soil moisture conditions, improvements were made to much of Oklahoma and parts of northern to central Texas. Small 2-category improvements were justified for the northeast Texas Panhandle and northwest Oklahoma where the heaviest rainfall occurred. Periods of above normal temperatures, enhanced surface winds, and below normal precipitation this month supported a continued worsening of drought conditions throughout southern Texas. Soil moisture declines rapidly from central to west Texas where indicators support D3 (extreme) to D4 (exceptional) drought categories.
Midwest
Widespread precipitation (0.5 to 2 inches) fell from Missouri east to Kentucky, Illinois, Indiana, and Ohio on March 17 and 18. This recent precipitation maintained saturated soils, high streamflows, and minor to moderate river flooding across the Middle Mississippi Valley and Lower Ohio Valley. In areas that were drier preceding this precipitation, extending from northeast Missouri east to Ohio, a large decrease in D0 (abnormal dryness) and D1 (moderate drought) coverage was warranted. However, this recent rainfall had to be balanced with longer term SPIs. There was a sharp northward cutoff to this precipitation and D0-D1 coverage was increased across lower Michigan, extreme northern Indiana, and southern Wisconsin based on soil moisture and SPI values at various time scales.
High Plains
Frequent precipitation during the past two weeks continues to result in additional improvements to parts of the central Plains and central Rockies. 7-day total amounts (March 16-22) ranged from 1 to 3 inches, locally more, across a broad region including south-central Nebraska and much of Kansas. As of March 22, Grand Island Nebraska has received 6.95″ so far this month which makes it the wettest March on record. The drought amelioration extends west to the central Rockies where numerous improvements were made including a two-category change from D3 to D1 in southwest El Paso County and southeast Teller County as SPIs are now D1 at all timescales. The removal of D3 in southeast Colorado and southwest Kansas was based on: SPIs are either neutral or positive dating back to 6 months and improving soil moisture conditions. In contrast to the major improvements across the central Rockies and central Plains during the past two weeks, persistent dryness continues to support additional expansion of D2 (severe) and D3 (extreme) drought across parts of North Dakota.
West
A slight expansion of severe drought (D2) was made to northeast Montana, based on 90-day SPI and soil moisture below the 10th percentile. These low soil moisture conditions are related to the lack of snowfall this winter. In contrast to the northern high Plains, snow water content is running close to average for late March and led to the elimination of abnormal dryness (D0) across south-central Montana. Since parts of western Arizona and southeast California have received little to no precipitation during the past two month, D3 (extreme) and D4 (exceptional) drought were slightly increased. This expansion of D3-D4 was supported by 9-month SPI values which covers the failed 2020 monsoon and this past winter. An expansion of D2 (severe) and extreme (D3) drought across parts of southern California was based on large water year to date precipitation deficits and 6-month SPI values. No other changes were made at this time to the remainder of California as 6 to 12 month SPIs generally support the current depiction and snow water content is running near two-thirds of average for the Sierra Nevada Mountains. During subsequent weeks, the drought depiction will be reassessed across California. Although much of the precipitation this past week fell along the coast or over the Cascades, a reassessment of longer term SPIs dating back 6 to 12 months supported removal of the D2 (severe) drought in southwest Oregon. Due in part to recent high-elevation snow and rainfall during the past two weeks, a slight decrease in D3 (extreme) and D4 (exceptional) drought was made to northern and northeast New Mexico. However, widespread D4 persists across southeast New Mexico where dust storms have been quite frequent this month and soil moisture remains in the lowest one percentile.
Alaska, Hawaii, and Puerto Rico
Abnormal dryness continues for northern and eastern Mainland Alaska with no changes this week. As of mid-March the water year precipitation remains below 70 percent for northeast parts of Alaska.
Numerous preliminary reports of 6-day totals, ending on March 13, exceeded 10 inches across parts of these islands and maximum amounts of more than 20 inches were reported. Based on this heavy rainfall during mid-March, a broad 1-category improvement was made to Hawaii which results in limiting long-term drought (D1) to only Maui.
After above normal precipitation resulted in a decrease of abnormal dryness (D0) and short-term moderate drought (D1) during the previous week, drier weather returned and no changes were made to Puerto Rico.
Pacific Islands
The weather features across the U.S.-Affiliated Pacific Islands (USAPI) during this USDM week (03/17/21-03/23/21) included near-equatorial troughs which persisted across Palau and Yap State, accompanied early in the week by a weak circulation; an Inter-Tropical Convergence Zone (ITCZ) across the central to eastern Federated States of Micronesia (FSM) and southern Marshall Islands (RMI), fed by wind-speed convergence and interlaced with surface troughs; and a dry trade-wind regime across the Marianas with minor interference from weak shear lines or surface troughs. South of the equator, American Samoa encountered a surface trough, mid- to upper-level low pressure, and nearby surface low early in the week, with a high pressure ridge taking control later in the week.
Satellite-based estimates of 7-day precipitation (QPE) showed a band of precipitation stretching east-west across Micronesia (the ITCZ), with areas of 2+ inches over Palau and Yap State, and areas of 4+ inches further east. The areas with the heaviest precipitation were between the equator and 5 degrees North latitude over central FSM, and southern portions of the RMI. Patchy areas of up to 1 inch of rain were detected by this tool near and over parts of the Marianas, but mostly no rain was indicated for the northern parts of the USAPI. A large area of 4+ inches of rain, with embedded 10+ inches, was indicated south of the Samoan Islands, with 2+ inches sweeping across American Samoa.
Both Palau and American Samoa were wet (more than the 2-inch and 1-inch, respectively, weekly minimum precipitation needed to meet most water needs) this week. Weekly rainfall totals in Palau included 2.48 inches at the Palau IAP and 3.40 inches at Koror COOP/ROR, and, in American Samoa, 1.94 inches at Pago Pago, 2.11 inches at the automated station at Toa Ridge, and 3.12 inches at the automated station at Siufaga Ridge. With monthly totals above the corresponding monthly minimums through March 23, D-Nothing continued at Palau and Tutuila.
With the exception of the NPS automated station at Saipan (1.13 inches), this week was dry (below the 1-inch weekly minimum needed to meet most water needs) in the Marianas. Based on data received for the week, a third of an inch or less was recorded at Guam (0.39 inch), Rota (0.11), Tinian (0.17), Saipan ASOS (0.22), and Saipan IAP (0.03). Guam (2.51 inches) and Rota (2.76 inches) had more than 2 inches for the month so far, but that was still below the corresponding monthly minimum. The Saipan stations had about an inch or less (1.30 at NPS, 0.60 at ASOS, and 0.21 at IAP). Abnormal dryness (D0-S) continued at Guam and Rota and moderate drought (D1-S) continued at Saipan.
The ITCZ gave eastern and southern portions of the FSM a wet week, with rainfall totals in the east ranging from 2.11 inches at Pohnpei to 3.27 inches at Kosrae, and in the south ranging from 1.98 inches at Kapingamarangi to 3.25 inches at Nukuoro, based on data through March 22 or 23. It was a dry week (less than the 2-inch weekly minimum) at stations in the western FSM and at Pingelap (1.34 inches) in the east. Weekly totals at the western stations ranged from 1.17 inches at Fananu to 1.45 inches at Yap. Ulithi reported 0.26 inch but with 3 days missing. Monthly totals were below the monthly minimum (for this point in March) at Nukuoro (5.31 inches) and Lukunor (5.70), but wet at the other FSM stations. D0-S continued this week at Fananu due to the dry week, but with 7.67 inches of rain for the month so far, improvement may be made next week if sufficient rain falls. D3-SL continued at Kapingamarangi, but with 6.07 inches so far this month, improvement may be made next week if sufficient rain falls to improve conditions on the ground. D-Nothing continued at the rest of the FSM stations.
In the Marshall Islands, no data was received from Utirik this week so an analysis could not be made for this station. The ITCZ soaked parts of the southern RMI while northern portions were dry. Mili recorded 8.67 inches of rain this week, Ailinglaplap 4.36 inches, Jaluit 3.01 inches, and Majuro 2.33 inches. On the dry side, Kwajalein reported 0.91 inch and Wotje 0.45 inch. With the month-to-date total (9.32 inches) now well above the 8-inch monthly minimum, Jaluit was improved from D0-S to D-Nothing. D1-S continued at Kwajalein, where the monthly total rainfall so far was 5.33 inches, and D3-S continued at Wotje where only 0.45 inch of rain has been reported for the month. The reservoir level at Majuro on March 22 was 25.2 million gallons, or 70% of maximum which was below the 80% threshold for concern, but sufficient rain has been falling to keep the status D-Nothing. D-Nothing continued at the rest of the RMI stations.
Virgin Islands
The weather conditions across the U.S. Virgin Islands (USVI) during this USDM week (03/17/21-03/23/21) were dominated by upper-level ridging and surface high pressure. Patchy shallow moisture fed spotty light showers triggered by weak trade-wind perturbations, but dry stable air was the rule.
Radar-based estimates of rainfall (QPE) for the 7 days ending at 12z on Tuesday showed a fourth of an inch or less of precipitation across western portions of St. Croix and St. Thomas, with less than a tenth of an inch to no precipitation further east. USGS data showed groundwater levels continuing to decline across all three islands. Reports indicated browning of vegetation across St. John.
Weekly rainfall totals on St. Croix ranged from no measurable rain at East Hill to 0.30 inch at the CoCoRaHS station at Frederiksted 0.5 N, on St. Thomas ranged from 0.06 inch at Anna’s Retreat 2.5 ESE to 0.22 inch at Charlotte Amalie West 4.2 WNW, and on St. John from 0.12 inch at Cruz Bay 1.6 E to 0.23 inch at Windswept Beach and 0.65 inch at Cruz Bay 0.8 NE. Weekly normal rainfall is about a third of an inch at the airport stations. Monthly rainfall totals (through March 23) ranged from 0.23 inch (Rohlsen AP) to 1.53 inches (Frederiksted 0.5 N) on St. Croix, from 0.07 inch (Anna’s Retreat 2.5 ESE) to 0.81 inch (Charlotte Amalie 1.4 NE) on St. Thomas, and from 0.44 inch (Cruz Bay 1.6 E) to 0.79 inch (Cruz Bay 0.8 NE) on St. John. Rohlsen AP had the fifth driest March so far (out of 62 years) while King AP ranked 13th driest out of 58 years and East Hill 22nd driest out of 48 years. Both King AP and East Hill had the seventh driest year-to-date. With the continued dryness, D1-SL continued on St. Croix and D2-S continued on St. Thomas and St. John.
Looking Ahead
During the next 5 days (March 25 to 29), a pair of low pressure systems are forecast to bring widespread precipitation (0.5 to 2 inches, locally more) to the Lower and Middle Mississippi Valley, Ohio and Tennessee Valleys, and Northeast. Farther to the south across the Florida Peninsula and southern Texas, dry weather is likely to persist. Little to no precipitation is also forecast for the northern Great Plains. Additional snow is expected throughout the Rockies, Intermountain West, and Cascades.
The CPC 6-10 day extended range outlook (valid from March 30 to April 3) favors near normal temperatures for much of the lower 48 in a variable pattern. Probabilities of above normal temperatures are elevated for the northern Plains, Florida, and California. Below normal temperatures are most likely across Alaska. Above normal precipitation is favored for the Northeast, Mid-Atlantic, western Gulf Coast, Rio Grande Valley, and Alaska. Increased chances of below normal precipitation are forecast across the Upper Mississippi Valley, much of the Plains, and throughout the West.

The result of the drought is very dry soil conditions

Fire risk is high in some areas and there are and will be environmental negative impacts.

March Drought Outlook

The forecast is for dry. But not all La Nina’s are dry. There is a lot of variation.

The Seasonal Drought Outlook is actually a bit better than the prior forecast last month

That situation is worse than last week and we may see it get much worse soon.

Since we are entering fire season it is time to start showing the wildland fire potential outlook. These will update automatically shortly after the month changes.

Red is bad, green is good.

I live in NM so this is a big concern here.

It just gets worse. Florida enters the picture.

Flooding remains a problem.

Crop Conditions

We will probably be showing this graphic now each week.

NASS Reports.

You can read the full report here. I can’t tell if the drought has led to ranchers reducing their herds and sending a larger portion of their herd to market.

I thought the definitions were interesting especially “disappearance”. I suspect there is some history behind that term.

Let us take a look at energy

Exports equaled the difference between production and consumption.

Intermediate-Term Weather Forecast

Showing from left to right, Days 1- 5, 6 – 10, 8 – 14, and Weeks 3 – 4 You can click on these maps to have them enlarge. Also, the discussions that go with these forecast maps can be found here (first two weeks) and here (Weeks 3 and 4).

First Temperature

And then Precipitation

One sees a lot of wet in the Day 1 – 5 forecast for the East Coast. But then it goes back to being mostly dry.

The Week 3-4 Discussion is always interesting.

Week 3-4 Forecast Discussion Valid Sat Apr 10 2021-Fri Apr 23 2021
La Nina conditions persist over the tropical Pacific. However, the weekly Nino 3.4 sea surface temperature (SST) anomaly was observed to be about -0.5 degree C, and conditions are likely to transition to ENSO-neutral during spring. The Madden Julian Oscillation (MJO) is active over the Indian Ocean as determined by the RMM indices, and forecast by dynamical models to progress into the Western Pacific in the next couple weeks. The impacts of the current MJO and ENSO states and the decadal trends over the CONUS are mostly consistent with current dynamical model forecasts for temperature.

The Week 3-4 temperature and precipitation outlooks are based primarily on dynamical model forecasts from the NCEP CFS, ECMWF, and JMA, and the Subseasonal Experiment (SubX) multi-model ensemble (MME) of experimental and operational ensemble prediction systems. Additional considerations were given to La Nina conditions and decadal trends, as well as the predicted evolution of the pattern from Week-2 forecasts.

There is overall good agreement among dynamical model forecasts of the 500-hPa height pattern for week 3-4, which indicates general persistence of the pattern forecast for week 2 with some increased uncertainty and deamplification. A ridge and positive 500-hPa height anomalies are forecast over the North Pacific and parts of the Aleutian Islands. Troughing is predicted to the west of the Alaska Mainland in the manual blend of dynamical and statistical model 500-hPa heights. Near zero 500-hPa height anomalies and troughing are predicted over western North America, including parts of the northwestern CONUS. Some models, such as the ECCC Canadian ensemble predict greater magnitude negative 500-hPa height anomalies over Alaska, western Canada, and parts of the northwestern CONUS. However, greater weight was given to the ECMWF ensemble model forecast, which depicts only weak negative 500-hPa anomalies over parts of the Northern Rockies, and an amplified ridge and positive 500-hPa height anomalies over the Northeast region. The GEFS and SubX MME mean forecasts are generally consistent with the ECMWF 500-hPa height forecast.

IElevated probabilities of above normal temperatures are indicated across much of the CONUS from the Rocky Mountains eastward to the Atlantic coast, under a ridge and predicted positive 500-hPa height anomalies. Equal chances (EC) of above and below normal temperatures are forecast for most areas of the Pacifc Coast states, under near average 500-hPa heights. Below normal temperatures are favored for western areas of Washington and Oregon, supported by dynamical model forecasts and consistent with lingering La Nina conditions. The highest confidence of above normal temperatures is indicated for the Southern Plains and the eastern half of the CONUS, with probabilities exceeding 70 percent over much of the region and exceeding 80 percent over the Northeast region and much of Texas, supported by dynamical model forecasts from the ECMWF and NCEP GEFS.

Predicted anomalous northerly flow results in increased probabilities of below normal temperatures for southern Mainland Alaska, while decadal trends lead to predicted above normal temperatures for northern Mainland Alaska, consistent with dynamical model forecasts from the GEFS and ECMWF and with the manual blend of models.

The dynamical model guidance is in reasonably good agreement on the spatial pattern of anomalous precipitation during the week 3-4 period. Below median precipitation is favored throughout much of the CONUS from the Central Rockies eastward into the Central Plains and for most of the eastern half of the CONUS, under a predicted ridge and mostly positive 500-hPa height anomalies. However, above median precipitation is predicted from northeastern North Dakota into the western Great Lakes region by the ECMWF and GEFS dynamical model precipitation forecasts. Probabilities exceed 60 percent for below median precipitation over much of the Southeast and parts of the Mid-Atlantic, under positive 500-hPa height anomalies. Above median precipitation is forecast for parts of southeastern New Mexico and western Texas, with the northward flow of surface moisture predicted by the GEFS and the SubX MME means. Above median precipitation is favored for the central western coast of Mainland Alaska into the Alaska Interior, associated with enhanced westerly flow.

Above normal temperatures are favored over Hawaii, shifting to equal chances from the northwest to the southeast, given decreasing sea surface temperature anomalies oriented similarly. The SubX MME anomaly forecast indicates likely above median precipitation over northwestern islands of Hawaii for the week 3-4 period.

International

Australia was too wet.

This week fortunately we do have a map.

In the box are shown the major resources we use. We will not be using them all each week but the reader is welcome to refer to these resources.

Double Dip La Nina Continued

I want to attempt to present a paper that explains why we have more La Ninas than El Ninos. I think you can read the full paper here. I am not positive of that because I am registered with ResearchGate but they did not ask me to log in so I think you can access the full article but hopefully I will present enough for readers to understand the concept.

I have not made any progress on this since last week but I am leaving it in the article for those who may want to think about the issue and I will try to expand the discussion below next week.

Notice this paper comes from South Korea with some Chinese participation. Like Japan, South Korea is a nation that is on the western side of the Pacific Ocean. The Japanese may not have discovered the Modoki variant of El Nino and La Nina but they gave it a name and recognized the importance of this variation. And here we have scientists from South Korea exploring another aspect of the ENSO Cycle which it turns out may well be related to the Modoki aspect. What we do not know is if this is an aspect of Climate Change. It may well be. On the other hand, it may simply provide new information on ENSO and the PDO. I have not made up my mind on that.

The rest of the discussion is later on in the article. And consider this an introduction because some of my readers may be familiar with this but for me, it is uncharted territory. So I need to do a lot more research. But what caught my interest was the part of the discussion not shown here but in the slides that are presented later in this article which suggests that the Pacific Decadal Oscillation or PDO does not explain as much about weather cycles (what I call low-frequency weather cycles) as I have assumed and that there are other factors now that need to be included in the analysis. One of the two is the Pacific Meridional Model or PMM mentioned in the Abstract. If that is the case, and I can come across some other references to this it is very important – let me just say it that way.

I have moved the other slides I made to somewhere close to the end of this article. I will be coming back to this topic very soon. I am not sure yet if this theory if you want to call it that explains why we may have a two-year La Nina this time around. It is not clear that we will but some of the models suggest it. Not all La Nina’s are dry for the Southwest but most are. So if the ratio of two-year La Ninas to one-year La Ninas is increasing, that is very important. I could have held back all this information until was read to fully discuss it but that did not seem to be proper. Some of my readers may know more about this and can leave me messages in the comment section that follows every article I publish.

I also see the possible connection of what is discussed in this paper with the storm we just had. In the article I posted last night on the NOAA four-season forecast I provided some snapshots of the Equatorial Pacific which showed a lack of movement of the cool and warm anomalies. I showed four snapshots which basically covered three months but I could have gone back many more months and it would have looked similar. You can see that set of graphics here. The importance of that is this La Nina is not decaying rapidly. So it could last into next winter or fade for a short period of time and later regain La Nina Status. I am not making any predictions here but I am raising the question of has something fundamentally changed?

I am certainly familiar with the deliveries to Elephant Butte the major reservoir on the Rio Grande and I am familiar with the deliveries to the three beneficiaries of that project namely an irrigation district in New Mexico, a similar irritation district in El Paso County Texas, and Mexico. Shortly after the MegaNino of 1997 and the subsequent La Nina of 1998 deliveries declined to Elephant Butte Reservoir and to the three (there is actually a fourth in good years when there is surplus water available to Hudspeth County Tx under a Warren Act Contract). I concluded that this was a normal change of phase of the PDO but perhaps there is more to it. So that explains my interest in the topic and although I frame the issue in a New Mexico context it impacts essentially all of the U.S.

Here is where the authors indicate that the PMM phase and the NPGO phase are important. And that is what triggered my interest.

Here they group single-year and multiyear La Ninas and show the PMM Index.

Just what is the Pacific Meridional Mode?

This may help a bit. It is a second reference to the issue and this time an NOAA article. BTW, the fish are never wrong. We create indices on observed fish behavior. If their behavior deviates from what our indices suggest their behavior should be, it is not because the fish are confused it is because our indices or models no longer are accurate.

This graphic also might help

Source I think I have the wrong link to this graphic so I have to work on that. But this is a good graphic.

and here for more information on the PMM.

Here we see that the PMM index is now higher. What is not clear is whether or not the PMM is highly correlated with any other index in which case it tells us nothing. I do not automatically accept what I read. So I have some work to do which is why this presentation is called Part I. It introduces the topic.

I have a lot of work to do to understand the above.

I understand this graphic but I am not sure that it fits the current situation.

4 | DISCUSSION AND SUMMARY
From the present study, it is necessary to discuss two possible factors responsible for modulating La Niña persistence. The first is the preceding El Niño amplitude. From a linear perspective, the discharging amount is proportional to the El Niño amplitude. With strong discharging, significant SSTA cooling could last more than 2 years. The preceding El Niño amplitude also affects the intensity of the interbasin SSTA gradient by influencing the adjustment time of the Indian and tropical Atlantic Oceans to the Pacific SSTA (Wu et al., 2019). More specifically, the delayed response of SST cooling over the Indian and tropical Atlantic Oceans, in comparison with the Pacific cooling, allows the easterly wind anomaly over the western Pacific to be dominated even after the La Niña decaying phase. This initiates a La Niña that tends to persist up to 2 years. However, the role of the Indian Ocean capacitor effect on western Pacific wind anomalies has been questioned by Chen et al. (2016). Using data analysis and numerical experiment, the authors claim that the Indian Ocean basin warming during mature El Niño wintertime events has little effect on the easterly anomalies in the equatorial western Pacific, and the local process over the western Pacific has more influence over the Indian Ocean capacitor effect. Further numerical experiments may provide quantitative insight in to the importance of these factors, which is beyond the scope of this study. The second factor is a recharging/discharging efficiency with respect to anomalous wind-stress/WSC relevant to SSTA patterns, which contributes to ENSO phase transition. This was the focus of this study. An EP-type El Niño preceding a La Niña leads to strong discharge by positive WSC (0 – 15N) that is widely spread over the Pacific basin, which induces a strong and long-lasting La Niña. When a La Niña develops through the mid-latitude connection (PMM or NPO), SSTA cooling and a tropical easterly wind anomaly expand to the North Pacific. In this case, an anomalous negative WSC is weak and, thus, the recharging efficiency by equatorial Rossby waves is low. Consequently, to understand La Niña persistence, it is reasonable to consider both the preceding El Niño amplitude and recharging/discharging efficiency by anomalous SST/wind-stress patterns as the La Niña evolves. In this study, we investigated how the evolution of single- and multi-year La Niña events differs from their onset phase by analysing both observational and climate model data sets. Our analyses showed that there was a significant difference in the evolution between the two types of La Niña events, even from their initial development associated with a mid-latitude connection. These differences are described as follows (Figure 10).
1. A weak CP-type (Niño-4 > Niño-3) El Niño tends to exist one year prior to a single-year La Niña event, whereas a strong EP-type (Niño-3 > Niño-4) El Niño tends to exist prior to a multi-year La Niña event.
2. For single-year La Niña events, negative WSC, associated with CP-type El Niño and confined to the western Pacific, induces weak discharge that leads to a weak La Niña. In contrast, a widely extended negative WSC of a multi-year La Niña in the Pacific basin causes efficient discharge, resulting in a strong La Niña.
3. From the decay of an El Niño to a La Niña developing period, SSTA cooling is initiated by anomalous easterly wind in the eastern Pacific for single-year La Niña. However, for multi-year La Niña events, SSTA cooling is triggered by a mid-latitudinal influence (i.e., PMM/NPO). Such a difference in initiation of a La Niña explains why the meridional width of multi-year La Niña events exceeds that of single-year La Niña events.
4. During a La Niña peak period, single-year La Niña events have an equatorially confined SST cooling structure; however, multi-year La Niña events have intensified SSTA cooling and meridionally expanded easterly wind anomalies. In addition, the overall structure of multi-year La Niña events is shifted westward. Comprehensively, the SST structure of multi-year La Niña events is similar to Mega-ENSO. Thus, the recharging process of a singleyear La Niña is strong due to equatorially confined SST cooling/strong WSC, whereas that of a multi-year La Niña is relatively weak due to meridionally expanded SST cooling/weak WSC.
5. During a La Niña decaying period, the SSTA cooling of a single-year La Niña disappears with strong recharging, resulting in the termination of the La Niña. For multi-year La Niña, the SSTA cooling persists with a weak recharge. Because of the insufficient recharge, the surface cooling in the equatorial Pacific persists until the following summer. Bjerknes feedback is then initiated, resulting in the development of a second La Niña in boreal winter (Chen et al. 2016).
6. The iteration of processes 3 through 5 for a multiyear La Niña may lead to the development of another La Niña in the subsequent winter.
In summary, by analysing the statistically significant differences in precursory signals between single- and multi-year La Niña events, we observed that a midlatitude connection associated with the PMM/NPO, such as the meridional expansion of anomalous SST and wind stress fields, is critical for La Niña persistence. This indicates that there is similar dynamics operating during mega-ENSO and multi-year La Niña events. These results have important implications for improved ENSO prediction and provide an appropriate alternative interpretation to the state-of-the-art climate models in predicting multiyear La Niña events.

Major Sources of Information Used in this Weekly Report

The U.S. Drought Monitor (the full report can be accessed here)
Selected graphics from our other Weather and Climate Reports are repeated in this report. These reports can be accessed by referencing the Directory here
Selections from the Tuesday USD Weather and Crop Bulletin (the full report can be accessed here). Selections from the USDA Office of the Chief Economist can be found here. NASS Executive Briefings can be found here. A wide range of NASS Reports can be found here. USDA Foreign Agriculture Service Briefs can be found here and here. Other useful sources of information that I regularly utilize are the National Integrated Drought Information System (NIDIS) which can be accessed here and the USDA NRCS Weekly and Weather Climate Update which can be accessed here. A glossary of terms can be found here.

March 26, 2021 Weather Impacts On Economic Activity – Is This A Megadrought?

Jobless Claims Drop To Pandemic Low

The No. 1 Sector To Buy Into Right Now

Related Posts

FBI Warns Investors Of Crypto-Stealing Play-to-Earn Games

Maersk Almost Completing Russia Exit After The Sale Of Logistics Sites

Why Is ‘Staking’ At The Center Of Crypto’s Latest Regulation Scuffle

Mexico’s Pemex Dismantled Resources Worth $342M From Two Top Fields

Oil Giant Schlumberger Rebrands Itself As SLB For Low-Carbon Future

Final August 2021 Michigan Consumer Sentiment Shows A Stunning Loss Of Confidence

답글 남기기 응답 취소

Browse by Category

Categories