May 21, 2021 Weather Impacts On Economic Activity – Looking Ahead

Written by Sig Silber

Our focus is the Western Drought but we also take a look at what the longer-range (10 years out) situation might be. It is the time of the month for the World Agricultural Supply and Demand Estimates (WASDE). So that may be of interest to some as it has a big impact on the World Economy. We have an updated Atlantic Hurricane Forecast from NOAA. See our latest video in our weekly education program on sustainable agriculture. It addresses water issues. We have not removed the first video so that readers can see the introduction to this very important topic. Tonight’s article contains all of our regular features and as usual, we include an intermediate-term weather forecast which itself is very interesting.

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Forecasting is a risky proposition but there seems to be a tendency to view climate as changing only in ways that can be described by Decadal Trends when we know there are long cycles that have been major factors in the way climate changes. These cycles may indeed be impacted by Global Warming. But they are not likely to simply disappear. Data supplied by NOAA suggests that these cycles are still impacting our climate. Thus it is reasonable to ask the question how long will the Western Drought persist?. My estimate is that it began in 1998 and it will end soon. In 2015 I predicted that it might end by 2020 and clearly that has not happened but it seems reasonable to me that it will end in this decade. Ending generally means that some other part of CONUS with tend to be less wet than usual. So the economic impact of the transition may in fact be greater than the current drought. That is the topic for another article. Tonight we just examine the case for this drought ending or significantly moderating in terms of its current location. But for now, the West is dealing with a serious drought.

Western Water Supply Forecast.

We will come back to more detail on the Water Availability question but first let’s think about the probably duration of the current Western drought.

Decadal Changes

I try to avoid doing forecasting since that is a no-win exercise. If you get it right…the conclusion is “it was obvious”. And if you get it wrong, that proves just how stupid you are. I forget when but I took a crack at it some time back and it may be useful to take a look at what I came up with then. I forget when I published it but I put it in my repository which you can actually get to from the LIVE article if you know how and have a lot of patience. I took advantage of another paper that made predictions on the AMO and the IPO which is highly correlated with the PDO. Below is what I published.

Recently I Ialked about North America. Although the climate of North American may be influenced by all three ocean cycles as far as I know only the impact of the North Atlantic and the North Pacific has been carefully studied. So that is what I will focus on in this weekly report. But we should not forget that some of the variance observed by McCabe et al in their work might have been explained by the IOBD if it had been included.

The following Graphic from the Luo and Li paper (Joint statistical-dynamical approach to decadal prediction of East Asian surface air temperature LUO FeiFei & LI ShuangLin) is very interesting. [Editors Note:The link I had no longer works but this link will work for those who have a subscription to ResearchGate and if not, just sign up as it is free]

Now I have modified the above to line up some key dates in the graphics namely the beginning of decades starting from the one we are in and looking forward. The decades are numbered across the top as “1”, “2”, “3”, “4”.

The seminal work on the impact of the PDO and AMO on U.S. climate can be found here. The key maps which were presented earlier are repeated below:

You may have to squint but the drought probabilities are shown on the map and also indicated by the color coding with shades of red indicating higher than 25% of the years are drought years (25% or less of average precipitation for that area) and shades of blue indicating less than 25% of the years are drought years. Thus drought is defined as the condition that occurs 25% of the time and this ties in nicely with two combinations of AMO and PDO phases i.e. four combinations.

In reality there are more than four combinations since for example AMO positive can cover years where the index is just barely positive to the years where the index is most positive. That may be possible to deal with using a software package but working with maps averaging the years where the indicated combination occurred makes for a more convenient way to display information but does not reflect that there is a continuum of combinations of two indices.

So combining the work of McCabe et al with the work of Lou and Li , what can we say about these beginning years in the decade which started in 2014 and subsequent decades out into our future?

1. 2010

This was clearly AMO+/PDO-. This is McCabe Condition D and full explains the approximately twice a century severe drought in the Southwest and also in the Great Lakes area.

2. 2020

This might be PDO+/AMO+ to AMO Neutral. This might be somewhere between McCabe A and McCabe C but closer to McCabe C. McCabe C is associated with extreme drought in the Northern Tier west of the Great Lakes. McCabe C also is associated with a high probability of drought in the South Atlantic Coast states extending into the Mid-West.

3. 2030

PDO-/AMO Neutral. This might be somewhere between McCabe B and McCabe D. Note the IPO (which I am using as a surrogate for the PDO) is forecast by Lou and Li to be less negative at its low point presumably due to the combination of subcycles with different amplitudes within the IPO. Also notice the significant difference between McCabe B and McCabe D. This illustrates the importance of the Atlantic SST’s

4. 2040

PDO+/AMO Neutral. This might be somewhere between McCabe A and McCabe C. McCabe C seems to flip drought in the West from south to north. So McCabe A and McCabe B both spare the Southwest but the condition of the Atlantic may have a big impact on the Northern Tier west of the Great Lakes. McCabe C also is associated with a high probability of drought in the South Atlantic Coast states extending into the Mid-West.

5. And dare we project out to say 2050? This might be PDO?/AMO-. That might result in conditions intermediate to McCabe A and McCabe B. McCabe B would raise the risk for drought in the Southeast including moderate probability of drought in Florida and small areas of extreme drought in other places.

Caveats:

• There is no intention of suggesting that the drought probability for a particular year in a particular geographic area can be predicted accurately with this methodology. It is intended to provided a reasonable scenario of how these probabilities might vary over time. This can be very useful for water planning.
• The IPO is not the PDO but they are highly correlated.
• The authors show signficant confidence intervals around their projections. i.e. the timing of the peaks and valleys of these cycles could fall in the shaded area of the graphic rather than exactly as shown.
• Other authors might project these cycles slightly differently
• I believe the authors have taken Global Warming into account. But RCP 4.5 may be considered by some as being too conservative.
• The McCabe et all maps are maps of drought frequency. I am assumng they are highly inversely correlated with amounts of precipitation.

I have not tried to interpret the implications for each state in the Lower 48. The McCabe et al analysis is a mathematical analysis based on historical data. Underlying the data are climate patterns determined by mountains and interactions with Canada and Mexico. If I better understood all of these patterns I would feel more confident in making predictions state by state. I am hoping that my experiment with combining the emerging information on ocean cycles with the work of McCabe et al and similar will inspire others to undertake more work in this area.

Back to the topic of the new Climate Normals.

The big news is still the climatology reset. The next two graphics are pretty interesting. We presented them last week but they are worth taking another look at.

First Temperature.

Now precipitation.

Overall Conclusion

The Western Drought will end soon. There will be another part of CONUS plagued with Drought. “Soon” does not mean right away. It may be very soon or it may be as much as a decade away. But if history repeats, this Western Drought will end fairly soon. It might shift north first as part of the transition.

Updated Hurricane Forecast

Important News

We might as well show the situation for the California Reservoirs here.

Let’s looks at some other information now.

We update the above map each time we publish but more frequent updates can be obtained here.

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

And here is the water year.

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

Let’s look at the current drought situation.

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

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

This Week’s Drought Summary

Troughing over the western CONUS and ridging over the East resulted in strong southerly flow over the Southern and Central Plains, leading to widespread heavy rainfall (0.5 to 3 inches, and more) over portions of the Great Plains, Lower Mississippi Valley, and into western areas of the Corn Belt this week. The heaviest precipitation fell over southeastern Texas and southern Louisiana, where some locations received over 10 inches of rainfall. The heavy rainfall resulted in widespread removal and improvement in drought conditions from the Front Range eastward to Nebraska and Kansas, and southward to the Mexico border. Unfortunately, the moisture was unable to make it farther north than Nebraska, resulting in continued degradations across the Northern Plains, Upper Midwest, and Great Lakes. The Northeast experienced below normal precipitation, but due to below normal temperatures and near-normal precipitation over the past 30-60 days across much of the region, only minor changes to abnormally dry (D0) areas were warranted in southeastern Pennsylvania. In the Southeast, portions of Virginia and North Carolina have continued to dry out over the past 90 days, warranting D0 expansion. Locally heavy rainfall (2 inches) also fell over areas experiencing abnormally dry and moderate drought (D1) in South Carolina and Florida, leading to some modifications in those locations based on rainfall 7-day rainfall totals. The La Nina signal in the West was evident in the precipitation totals at the end of the climatological wet season in March. The presence of this antecedent dryness has resulted in much below-normal snowpack throughout much of the West, leading to continued drought deterioration since the region began its transition into a climatologically drier time of year during April.

Northeast

Despite below-normal precipitation this week across most of the Northeast, excluding northeastern Maine which received 1 to 2 inches of rainfall, 7-day average temperatures were below-normal, with the largest negative anomalies (6°F to 10°F) across western Pennsylvania. Rainfall has also been near-normal in the region over the past 30-60 days. However, D0 was expanded southwestward into southeastern Pennsylvania, as there has been a drying trend over the past 30-90 days, culminating in D2 30-day SPIs. Additionally, USGS 7-day stream flows have fallen below the 24th percentile, with a couple of stations falling below the 10th percentile.

Southeast

Over the past 60 to 90 days, Virginia and the Carolinas have continued to dry out. With D3-D4 equivalent 30-day SPIs, USGS 7-day average stream flows falling below normal (10th to 24th percentile), and with having received 25 to 50 percent of normal precipitation (per AHPS), D0 was expanded into the mountains of southwestern Virginia and northwestern North Carolina, and northward across northeastern North Carolina into the Tidewater. In South Carolina, some minor retractions and expansions of D0 (abnormally dry) and D1 (moderate drought) areas was warranted, based on 7-day rainfall totals and 30-60 day rainfall deficits. D0 and D1 areas were also modified in a similar manner across the southern Florida Peninsula for similar reasoning. Elsewhere in the Southeast, sufficient 30 to 90-day rainfall totals and widespread below-normal 7-day average temperatures (more than 5°F negative departures) warranted a status quo depiction this week.

South

Heavy rainfall and flooding was the main concern in many areas of the Southern Region. Across eastern Texas, the Ark-La-Tex, and southern Louisiana, many areas received in excess of 3 inches of rainfall. Southeastern Texas and southern Louisiana were the hardest hit areas, with several locations receiving up to, and exceeding, 10 inches of rainfall. On Monday, the National Weather Service issued flood warnings in the Lake Charles, Louisiana area, where 11 inches of rain fell in a 6-hour period. Near Baton Rouge, Louisiana, locations east, southeast, and south of the city picked up nearly 12 inches of rainfall Monday night into Tuesday. Farther west in Texas, large reduction in drought coverage was warranted in areas receiving over 2 inches of rainfall. Some locations in southern Texas picked up 5 to 10 inches of rain, warranting 2 to 3-category improvements and removal in the drought depiction. From northern Mississippi to central Tennessee, 30-day rainfall deficits are beginning to increase. This area remains drought free this week, but bears watching if deficits continue to increase.

Midwest

In the Midwest, the heaviest rain (1.5 to 3 inches, and more) fell across central Illinois, southwestern Iowa, and central Missouri, extending to west-central Indiana. Most of this rainfall occurred in drought-free areas, but some D0 (abnormally dry) removal was warranted in east-central Illinois and west-central Indiana. In areas that received little to no precipitation across central Illinois, short-term (30-60 day) SPIs and USGS 7-day average stream flows tipping below normal warranted expansion of D0. In the Chicago area, extending across Lake Michigan into southwestern Michigan, D2 (severe drought) was introduced, as CPC soil moisture percentiles have fallen into the bottom 1% (corroborated by NASA SPoRT), D3 to D4 equivalent 30-day to 6 month SPIs, and USGS average stream flows below the 10th percentile. D0 and D1 were expanded northward in southern Minnesota and D0 into north-central Wisconsin, associated with CPC soil moisture falling below the 10th percentile, below to much below-normal USGS 7-day average stream flows (below the 24th percentile), and D0 to D1 30-90 day SPIs in D0 (abnormally dry) areas and D3-D4 SPIs in D1 (moderate drought) areas over the same periods. D0 was also expanded eastward across northern Minnesota, as 30-day SPIs have shown sharp declines and vegetation has become increasingly stressed. The Minnesota Department of Natural Resources indicates an extreme fire danger extending from Koochiching County southeast to Saint Louis County, where there is an ongoing wildfire sparked by lightning that has burned more than 1,600 acres.

High Plains

The High Plains Region was a tail of two extremes. From Nebraska southward, and westward to the Front Range saw widespread heavy precipitation (0.5 to 3 inches, with locally higher amounts of greater than 5 inches stretching from west to east across Kansas), leading to large reductions in D0 (abnormally dry) to D2 (severe drought) coverage in Colorado, Nebraska, and Kansas, with some D3 (extreme) reduction in southeastern Colorado. Some moderate precipitation also fell across portions of the Front Range of Wyoming also, further improving SWE across the Big Horn Basin. This warranted some improvements from D2 (severe drought) to D1 (moderate drought) along the east-facing slopes of the Absaroka and Wind River Ranges, and D1 was also improved to D0 for interior parts of the basin. In addition, AHPS percent of normal precipitation exceeds 150% for all periods going back at least 90 days, SPIs indicate near to abnormally dry conditions going back 180 days, and USGS 7-day and 28-day average stream flows are near normal. NASA SPoRT and NASA GRACE also show improvements in soil moisture and groundwater, respectively. Across the Dakotas, near to above normal temperatures and below normal precipitation this week warranted some further degradations. Targeted expansions of D1 and D2 drought occurred in South Dakota, as the state continues to fall behind during a climatologically wetter time of year, which are depicted in the 30-90 day SPIs. There are also continued reports of poor water quality in livestock water sources in northwestern parts of the state. In North Dakota, warm (2°F to 4°F positive average temperature anomalies), dry, and windy conditions continued. CPC soil moisture ranks in the bottom 1% across much of the state, USGS 7-day average stream flows are much below normal, and VegDRI and VHI indicate extreme stress on vegetation. As such, D4 (exceptional drought) was introduced for parts of north-central North Dakota. Furthermore, many farmers have been forced to plant in dry soils this year, but erosion and lack of rainfall have resulted in poor and/or a lack of germination. Fire also continues to remain a high risk across the state and most counties have imposed burn restrictions. Since the beginning of the year, there have been more than 1,000 fires reported across North Dakota, with over 100,000 acres burned.

West

Most basin snow water equivalent (SWE) percentiles across the Western Region are well below normal for the period of record (near and below the 65th percentile), especially in the Four Corners region (below the 5th percentile in Arizona and New Mexico). Only parts of the Pacific Northwest and areas of central Montana experienced near and above-normal seasonal snowfall. However, above-normal temperatures over much of the West over the past 60 days has resulted in rapid snowmelt and, due to dry topsoil, much of the melt water has not made it into the rivers, lakes, and reservoirs. In California, the water level in Lake Tahoe is 2.5 feet lower than this time last year. USGS 7-day average stream flows across the coastal ranges near the Bay Area have dropped below the 2nd percentile. In addition, CPC soil moisture ranks below the 1st percentile, NASA GRACE indicates severely depleted groundwater, and vegetation indices (VegDRI and VHI) indicate severe vegetation stress. There are increasing reports of reduced pasture forage, livestock requiring supplemental feed and/or being sold off, and some reports of livestock mortality. Additionally, stock ponds are running dry and farmers have been forced to haul water in some locations. Given the worsening conditions, drought was deteriorated from D3 (extreme) to D4 (exceptional) in areas along the coastal ranges near the Bay Area. Targeted degradations were also made in portions of Idaho as a result of deteriorating soil moisture conditions (NASA SPoRT 0-10 cm and 0-40 cm depths and CPC soil moisture below the 5th percentile state-wide), supported by widespread D1-D3 30-90 day SPIs. New Mexico was the only state in the Western Region where improvements were warranted, as severe weather along the Front Range of the Rockies resulted in some small improvements in areas experiencing D3 and D4 drought conditions in northern and eastern parts of the state.

Caribbean

D1 (moderate drought) was expanded northeastward to southern Rio Grande County in Puerto Rico. This area has experienced less than 50 percent of normal precipitation in the last 30 days and USGS 7-day average stream flows have fallen below the 10th percentile.

The U.S. Virgin Islands remained dry for another week, with all three islands remaining at D2. The NWS’s quantitative precipitation estimates for the past 7 days indicated that none of St. Thomas or St. John received more than a quarter of an inch. St. Croix was similarly dry with the southwest part of the island receiving a quarter of an inch or less while the eastern tip remained dry.

Vegetation remained stressed across all islands. Precautions such as ordering hay and water deliveries were being taken to get through the dry season. Forests and grasslands were at risk for fire.

St. Thomas remained at D2-SL. Precipitation at Cyril E. King AP was 0.05 inches, or much below normal. The CoCoRaHS stations reported from 0.03 to 0.11 inches. The SPI values for the King Airport indicated drought-free conditions at 1, 3 and 12 months, moderate drought at 6 months, and abnormal dryness at 9 months. The Grade School 3 well was 14.752 feet below land surface and has not been so low since 2017.

St. John remained at D2-S. The Windswept Beach CoCoRaHS station reported 0.10 inches. Other CoCoRaHS stations reported from 0.10 to 0.44 inches. The SPI values for Windswept Beach indicated abnormal dryness at 1, 9 and 12 months, moderate drought at 3 months and severe drought at 6 months. The Susannaberg DPW 3 well was at 16.91 feet below land surface, the water level steadily falling since late 2020, when the water level was more than 7 feet below the land surface.

St. Croix remained at D2-SL. Precipitation at Henry Rohlsen AP amounted to 0.22 inches. The CoCoRaHS stations reported from 0.06 to 0.12 inches. The SPI values for Henry Rohlsen AP indicated moderate drought at 1, 3, 9 and 12 months and extreme drought at 6 months. The water level in Adventure 28 well was at 23.71 feet below land surface, the water at its lowest level since late 2016.

Pacific

Abnormal dryness (D0) continues for northern and eastern Mainland Alaska with no changes this week. Temperatures have verified above-normal over the past 30 days, but with near and above-normal snowpack across much of the state, no changes to the depiction were warranted this week

In Hawaii, persistent trade winds over the past couple of weeks have resulted in sufficient rainfall along the windward slopes and USGS stream flows to remain near-normal. USGS stream flows are mixed in the leeside streams of Oahu and NDVI supports a continued D0 depiction there as well. As such, no changes warranted this week in Hawaii.

The weather features across the U.S.-Affiliated Pacific Islands (USAPI) during this USDM week (05/12/21-05/18/21) included several surface troughs which migrated westward across Micronesia; trade-wind convergence associated with a developing Inter-Tropical Convergence Zone (ITCZ) over the Federated States of Micronesia (FSM) and Marshall Islands (RMI); weak circulations which developed over Yap State and Palau waters; and an old frontal boundary, with convergent trade-wind flow to its south, which lingered near the northern Marianas. One of the circulations developed into Tropical Depression 03W west of Palau. The surface convergence associated with these features was enhanced by divergence aloft associated with an upper-level trough and upper-level lows that stretched the length of Micronesia mainly north of 10 degrees North latitude. South of the equator, a high pressure ridge dominated the weather over the Samoan Islands, with scattered trade-wind showers bringing light rain to American Samoa.

Satellite-based estimates of 7-day precipitation (QPE) showed a band of precipitation stretching from Indonesia and the Philippines eastward across Micronesia and beyond, associated with the climatological ITCZ, and patchy areas of precipitation south of the equator bracketing the Samoan Islands. A continuous band of 1+ inches of rain ran from Palau, across the FSM, to the RMI, with embedded 4+ inch areas. Wisps of half an inch or less of rain were evident on the QPE over the Marianas. The Marianas showers were likely shallow and warm-topped, and precipitation from events like this is hard to detect by this satellite QPE tool. The QPE showed an area of 2+ inches of rain east of American Samoa, but little precipitation was detected over the Samoan Islands.

Rainfall for the Republic of Palau was above normal with Palau IAP receiving 5.45 inches and Koror COOP reporting 5.11 inches for the week. The area remained free of dryness.

The Mariana Islands remained at D0. Rainfall was above normal for Guam where 2.62 inches fell. The island was receiving frequent showers, greening the vegetation. Conditions were drier on Rota and Saipan. Rota received 0.99 inches, while Saipan received from 0.39 to 0.70 inches. Saipan was receiving just enough rain to turn vegetation green here and there.

The Federal States of Micronesia were mixed in terms of precipitation for the week, with some locations receiving less than the 2 inches needed for minimum weekly water needs. Ulithi has been dry, so D0 was introduced as rainfall was 0.51 inches, following three weeks of below normal precipitation. Kapingamarangi remained at D0 and received 1.36 inches. Rainfall was also below normal for Nukuoro, 0.59 inches; Pohnpei, 1.83 inches; and Yap with 1.40 inches. Chuuk and Fananu reported 4.01 and 6.78 inches, respectively.

The Marshall Islands were mostly wet for the week, apart from Ailinglaplap which received 0.50 inches, far below the weekly minimum of 2 inches to meet most water needs. All other locations all reported more than 2 inches for the week. Wotje remained at D2 and received 2.25 inches. Water was being rationed, and some crops were dying. Kwajalein continued at D1 and benefited from 2.74 inches of rain. Vegetation was recovering on Kwajalein island; on northern atolls, vegetation was not green or particularly lush. Residents of the northern Marshall Islands continue to conserve water, especially atolls with limited water resources and catchment tanks. Mili, Majuro and Jaluit received considerably more rain, reporting 6.90, 9.97, and 5.21 inches, respectively.

American Samoa was on the dry side for the past week, but remained free of dryness overall, as the previous week was wet, leaving the islands in good standing. Pago Pago received 0.77 inches, Siufaga Ridge reported 0.64 inches, and Toa Ridge received 0.38 inches.

Looking Ahead

During the next 5 days (May 20 to 24), the Southern and Central Plains, much of the Corn Belt, and Northern Tier states are favored to remain wet. Temperatures are also forecast to remain below-normal for much of the period across the Northern Tier. High pressure is expected to dominate over the eastern U.S., coinciding with little to no rainfall and above-normal temperatures. The Southwest and Coastal California will likely remain dry also. However, temperatures are favored to remain below-normal, moderating to near-normal as the week progresses toward Tuesday.

The CPC 6-10 day extended range outlook (valid from May 25 to 29) favors above normal temperatures across the eastern U.S. and Central and Southern Plains, with enhanced probabilities in the Southeast. Above normal temperatures are also favored over northern and western Mainland Alaska, with above-normal probabilities extending to the eastern Aleutians. Below-normal temperatures are favored from the Pacific Northwest eastward to the Dakotas. Above-normal precipitation is predicted across the Southern and Central Plains, Corn Belt, and Lower Great Lakes. In Alaska, odds tilt toward above-normal precipitation for the Southwest Mainland, Eastern Aleutians, and along the South Coast to the Northwest Panhandle. Below-normal precipitation is favored in the Southeast U.S. and along the East Coast, with enhanced probabilities in the Deep South and Florida. Below-normal precipitation is also favored for the Central Pacific Coast, Great Basin, and Eastern Rockies to the High Plains.

Regional Reports

Soil Conditions

The result of the drought is very dry soil conditions

Soil Dryness in More Depth.

Surface Soil

Subsurface

April Drought Outlook

Here is the short version of the NOAA Discussion released with the forecast. We provided the long version in the article we published last night on the new NOAA Four-Season Outlook.

Latest Seasonal Assessment – Drought improved across parts of Texas, northeastern Colorado, central Wyoming and the Northeast in the past month due to heavy rainfall, while drought developed or intensified in many parts of California, the Pacific Northwest, Northern Intermountain West, Northern Rockies, and the Carolinas due to increasing precipitation deficits. Drought persistence or development is favored for most of the West and High Plains, based on elevated probabilities of below normal precipitation and above normal temperatures for June-July-August. Drought removal or improvement is expected across east-central Texas along with most of Oklahoma due to heavy recent rainfall and additional heavy rainfall forecast for the rest of May.Lack of a rainfall signal from monthly and seasonal precipitation outlooks supports drought persistence across the Midwest. The Great Plains and Corn Belt will be closely monitored in the monthly drought outlooks through the summer. The wet monthly and seasonal outlooks along with the onset of the convective season strongly support removal across the small drought areas in southern Florida. The persistence forecast for the Northeast is based on a weak rainfall signal and likelihood of above normal temperatures during June-July-August along with a favorable time for soil moisture discharge.

Alaska is forecast to remain drought-free through the end of August. Drought is favored to persist across Puerto Rico during the next few months. Drought development and persistence is forecast across the leeward sides of the Hawaiian Islands.

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.

Crop Progress Reports

Additional Information can be found here.

Crop Highlights

Introduction

Episode 7 Water Management

News

Nothing to report tonight.

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

The Week 3-4 Discussion is always interesting so we include it in the article. Similar discussions for the 6 -10 Day and 8 – 14 Day Forecasts are available here.

Week 3-4 Forecast Discussion Valid Sat Jun 05 2021-Fri Jun 18 2021

Neutral El Nino Southern Oscillation (ENSO) conditions prevail in the tropical Pacific, leaving an active Madden Julian Oscillation (MJO) and an atmospheric Kelvin wave as the main features of tropical variability. Current RMM indices indicate active convection over the Maritime Continent (Phase 4) and the dynamical models consistently propagate the MJO convective signal farther into the West Pacific in the coming days before weakening. However, the associated teleconnections to the extratropics, and thus the attendant impacts on North American temperature and precipitation, tend to be weaker during the summer months. With this in mind, MJO influences factor less into this week’s forecast which relies more on dynamical model blends as well as considerations from decadal trends.

The forecast large-scale atmospheric circulation, as indicated by anomalous 500-hPa anomalous height fields, exhibits good agreement among the dynamical model guidance (CFS, ECMWF, JMA, GEFS and the SubX multi-model ensemble). These models consistently feature ridging across the Gulf of Alaska as well over Nova Scotia and Newfoundland. The majority of the models also suggest weak height anomalies over much of CONUS, though the GEFS favors a more amplified pattern relative to the other models with troughing over the Great Lakes.

Due to the strong model agreement regarding the ridging over the Pacific and the Northeast, the temperature forecast tilts toward above normal probabilities for much of the eastern and western portions of CONUS with highest probabilities centered over the Southwest. While some of the models also indicate a warm solution from the Northern Plains down to the Texas/Louisiana coast, the aforementioned weak troughing indicated by the GEFS as well as increased soil moisture along the Gulf Coast would suggest a cool solution. Therefore, equal chances are carved out for those regions. Equal chances are also forecast over eastern Alaska due to conflicting signals from model guidance, while above normal temperature probabilities are consistently indicated over the western part of the state.

Despite the strong model agreement regarding the large-scale circulation patterns, the precipitation forecast is more uncertain due to conflicting solutions among the guidance. Thus equal chances are favored over much of CONUS. While the aforementioned ridging over the Northeast could potentially bring moisture and increased precipitation probabilities into the Northern Plains, the models disagree on placement of the wet signal, resulting in equal chances forecast throughout the region. Equal chances are also favored across the Gulf Coast region due to higher uncertainty, with the models indicating drier conditions but soil moisture is above normal in this region and could be further enhanced by a potential tropical disturbance that the National Hurricane Center is currently monitoring. Beyond the Texas coast into Oklahoma panhandle and the Southern Rockies, the models consistently tilt toward below normal precipitation probabilities. Model uncertainty yields an equal chances precipitation forecast over much of Alaska but drier conditions are consistently indicated over the Alaska panhandle and southern coast.

Surrounding Hawaii, sea surface temperatures are near-normal to slightly above average, elevating the chances for above normal temperatures during the forecast period. Dynamical model guidance from the SubX suite indicates a tilt toward below normal precipitation in the northwestern part of the state with probabilities decreasing to equal chances in the southeast.

International

Monthly WASDE Report

One can access the full report here.

Energy Analysis

No Report This Week

Major Sources of Information Used in this Weekly Report. We will not be using them all each week but the reader is welcome to refer to these resources.

Science Feature

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 am removing the article from what I am publishing tonight since I have not made any progress on this topic but it is of great importance so I will be coming back to it.