April 17, 2020 Weather Impacts On Economic Activity – New Seasonal Drought Forecast

Written by Sig Silber

We cover a lot of ground tonight. We have the new Seasonal Drought Forecast; the NASS Executive Presentation on Citrus Crops; and an interesting NASS Presentation on the historical highs and lows for crops with respect to various measures. We have the state rankings for March for temperature and precipitation plus a couple of climate studies on Southwest Megadrought that I did not find very impressive. Of course, we have our full set of regular weekly reports that focus on the latest NIDIS Drought Report. The current situation is good but that might start to deteriorate a bit after a couple of weeks of continued wet conditions when it warms up. We provide a 28-day weather forecast where the first 14 days update daily.

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OMG – I should have published the Seasonal Outlook Today. Maybe tomorrow.

Directory

Special Topics for this Week

New Seasonal Drought Outlook

Here is the short discussion released with the updated drought assessment. We may provide the long discussion with the report tomorrow but the shorter discussion is easier to follow.

Latest Seasonal Assessment – As the rainy season draws to a close for the western contiguous U.S., the most likely outcome is for current drought to persist. There is also the potential for new drought development in the Pacific Northwest and Northern Intermountain Region, the Sierras in California, and northwestern Nevada. This is associated with well below normal precipitation since the beginning of the Water Year (Oct 1, 2019) and the expectation of warm, dry conditions in MJJ. Drought removal is favored in eastern Colorado, with the expectation of a continuing wet April and a favorably wet MJJ climatology. For the areas of drought near the Gulf Coast, nearly all official precipitation outlooks from one week to one season in advance favor at least a one-category improvement in drought conditions, resulting in drought removal for most areas. In contrast with the West, the state of Florida is nearing the end of its dry season, which typically transitions to its wet season in May and very early June. Elsewhere across the Lower 48 states, no broad-scale areas of drought are expected to develop. In Hawaii, the rainy season is nearing its end, which will make it much more difficult to mitigate any remaining drought. Therefore drought persistence is the most likely outcome. There is no drought at the current time in either Alaska or Puerto Rico, and there are no convincing indications to the contrary for the May-July season.

NASS Executive Briefing for Citrus

Here is the Crop Production Historical Track Records

And a few of the key slides.

State Temperature and Precipitation Rankings (relative to the 126 years of data).

Climate Change Studies.

This study has been getting some play this week. That is not consistent with the recent record is of no concern to the authors.

Here is another related study. They show up in clusters as grant money becomes available and is spent.

I tried to find an Executive Summary and this is the closest I came to finding something that was at all useful.

Water Supply Issues

It is also useful to look at the last seven days.

Here is a side by side comparison

This is an up to date map of snow depth. It is up-to-date when published but it does not auto-update but you can obtain updates Here.

Current Drought Conditions

Now we take a look at Thursday’s U.S. Drought Monitor Report.

The U.S. Drought Monitor is a comprehensive way of understanding the drought situation for the U.S. It is issued every Thursday and reflects the conditions as of the prior Tuesday. Drought is defined as a moisture deficit bad enough to have social, environmental or economic effects. Thus, more factors than recent precipitation are considered and more information on how it is done is found at the end of this report.

U.S. Affiliated Pacific Islands and the U.S. Virgin Islands.

And this shows the U.S. including Alaska, Puerto Rico, and Hawaii.

Below is the map for just CONUS.

Last Week	This Week

Some might find this animation of twelve weeks of change useful;

The graphic below shows the one-week change in drought intensity. Yellow is bad. Green is good.

Now we show the week to week change information by region. The yellow is where the level of drought has been raised. The green is where the level of drought has been lowered.

Eastern Colorado is degraded.

No Change

No Change

Degradation along the Gulf Coast. South Texas has improved but West Texas has degraded.

Degradation in Central Florida but improvement north of the Florida border in Georgia and Alabama.

Mostly degradation except for the Southern Tier. The Northwest was dry as was Eastern Colorado.

Here is the Discussion that was issued with the Drought Report. The Regional Headings can be clicked on to obtain maps and statistics.

This Week’s Drought Summary

An active pattern brought snow, rain, thunderstorms and severe weather over much of the United States. Most of the precipitation was east of the Missouri River valley and the greatest amounts were centered over Tennessee, Arkansas, Kentucky, western Virginia and the northern portions of Mississippi, Alabama, and Georgia, where more than 3 inches of rain was widespread. Southern California also had record-breaking rains continue, while snow was recorded in portions of the northern Plains and Midwest. Temperatures were generally warmer than normal over the country with just the Southwest and northern Plains being below normal. The greatest departures were in Florida where temperatures were 6-8 degrees above normal for the week and in Montana and southern California where temperatures were more than 10 degrees below normal.

Northeast

Temperatures were warm over most of the region, with departures of 4-6 degrees above normal over the Mid-Atlantic to up to 2-3 degrees below normal in Maine and New Hampshire as well as portions of southern New York. Most of the region recorded precipitation for the week with areas of the Mid-Atlantic at more than 300 percent of normal, while in New England, areas of New York were below normal. Overall, pockets of dryness have been developing through the region, but timely precipitation has prevented the introduction of abnormally dry conditions up to this point. The area remains drought free for this week.

Southeast

Temperatures were above normal throughout the region this week with departures of 4-8 degrees above normal. South Florida had the warmest temperatures, with departures of 8-10 degrees above normal. Most all of the region was above normal to well above normal for precipitation as a significant storm system moved through the region Saturday through Monday. Much of region recorded 130-175 percent of normal precipitation. With the weekend rains, some areas of abnormally dry conditions were improved in Georgia and Alabama. The outlier was most of Florida and the Gulf Coast of Alabama and the outer banks of North Carolina. These areas were drier than normal, with some areas only seeing 50 percent of normal rain for the week and some parts of central Florida receiving less than 5 percent of normal for the week. Short-term dryness has plagued the Gulf coast areas and Florida; over the last 90 days, this area is running precipitation deficits of 4-8 inches below normal. With many of the drought indices and indicators paving the way for degradation this week, a large area of severe drought was introduced over portions of central and northern Florida. Without rain, further degradation is anticipated in the coming weeks.

Midwest

Most of the region had above-normal temperatures for the week with departures of 2-4 degrees above normal. Areas of Wisconsin, Iowa, and Minnesota were cooler than normal for the week with temperatures of 3-5 degrees below normal. The eastern extent of the region recorded above-normal precipitation for the week with 200-400 percent of normal over Ohio and Kentucky. Dryness was widespread over Indiana, Illinois, Missouri, western Iowa and into Minnesota with less than 75 percent of normal precipitation for the week. Overall, the region has been drier than normal the last few weeks, but for agricultural purposes, this has been welcomed, especially after the last few years where the region had an abundance of spring moisture. Even with some areas drying out, there was no need to introduce abnormally dry conditions for this week and the region remains drought free.

High Plains

It was mostly dry over much of the region this week with just areas of northern Wyoming, southwest South Dakota, and north-central Nebraska recording above-normal precipitation. Temperatures were below normal in the Dakotas, northern Nebraska, and Wyoming with departures of up to 8 degrees below normal. Areas of Colorado, Kansas and southwest Nebraska were above normal with departures of 2-4 degrees above normal. There are some pockets of dryness developing in portions of Nebraska and Kansas, but no changes were made there this week, although the area of south-central Nebraska and central Kansas is trending toward the introduction of abnormally dry conditions. Eastern Colorado and southwest Kansas remain the driest portion of the High Plains. Severe drought was expanded over southeast Colorado this week and moderate drought and abnormally dry conditions were pushed eastward. This area will need to be watched for further degradation in the weeks ahead.

South

Warmer than normal temperatures were widespread throughout the region with departures of 6-8 degrees above normal along the Gulf Coast. Precipitation was mixed over the area with portions of southeast Oklahoma, central to southern Texas, Arkansas and northern Louisiana and Mississippi all recording well above normal precipitation with readings of 150-400 percent of normal. Conditions remained dry over the Gulf Coast as well as west Texas. In west Texas, moderate drought was introduced and abnormally dry conditions were expanded this week. In central and south Texas, there was a mix of degradations and improvements as some areas were still realizing the impact of previous rains that allowed for some areas of extreme and severe drought to improve. A new area of severe drought was introduced in far southeast Louisiana and some improvements were made to the abnormally dry conditions in Mississippi. There is a very tight gradient setting up going inland from the Gulf Coast as these coastal areas continue to miss out on any precipitation and have had above-normal temperatures too.

West

Most of the region was dry this week outside of a few areas in Montana and western Wyoming while in the Southwest, record-setting rains continued in southern California and into Arizona. Over the last 6 weeks, areas in and around Kern County, California have gone from significant precipitation deficits to well above normal readings accompanied by flooding in the region. Most of southern California recorded 800 percent of normal precipitation just in the last week and 200-400 percent of normal over the last 30 days. Temperatures were cooler than normal over the southwest areas of the west and Montana while most of the rest of the region was 2-4 degrees above normal and northern California was 6-8 degrees above normal. The current water year has been dry over much of the region and this has allowed further degradations to be shown in portions of northern California up to Washington. In western Oregon, the current conditions are similar to 2000-2001 and 2004-2005 with the exception of the near-normal snowpack. Some counties in southwest Oregon are reporting the earliest start to the irrigation season since 2000-2001 with several counties preparing to file drought declarations with the state of Oregon. Severe drought was expanded over much of northwest California northward into Oregon. Severe drought was also expanded in the interior of Washington. Abnormally dry conditions and moderate drought were also expanded over eastern and western portions of Oregon and Washington this week as well as western Montana and northern Idaho. In southern California, moderate drought and abnormally dry conditions were removed from Kern County and vicinities in response to the record-breaking precipitation. Improvements were also made to areas of severe and moderate drought in northeast Arizona and to abnormally dry areas of northeast and north central Arizona.

Alaska, Hawaii, and Puerto Rico

There were no changes in Alaska and Puerto Rico this week. In Hawaii, more abnormally dry conditions were added to the Big Island while on Lanai, most of the abnormally dry conditions were improved outside of the northernmost extent of the island.

Pacific Islands

The weather conditions across the U.S.-Affiliated Pacific Islands (USAPI) during this USDM week (4/8/20-4/14/20) consisted of a fragmented Inter-Tropical Convergence Zone (ITCZ) continuing across southern portions of Micronesia, especially in the east, and a dry trade-wind regime dominating northern and western Micronesia. A near-equatorial trough extended from the ITCZ across western Micronesia for much of the week. Smaller surface troughs, trade-wind disturbances, and weak circulations migrated westward across Micronesia within and near the ITCZ and near-equatorial trough, with trade-wind convergence frequently occurring in the east and upper-level divergence occasionally enhancing showers in the eastern Federated States of Micronesia (FSM). The surface convergence, upper-level divergence, and circulations brought abundant rainfall over portions of eastern FSM, while the dry trade-wind pattern inhibited circulations and disturbances as they moved over the Marianas and western FSM. South of the equator, weather over the Samoan Islands was influenced by an elongated surface trough associated with Tropical Cyclone Harold. The tropical cyclone stayed south of the islands, but its associated trough lingered and was enhanced by an extremely moist and unstable air mass, bringing heavy rainfall and flash flooding to American Samoa.

Satellite-based estimates of 7-day precipitation (QPE) showed patchy bands of rainfall extending northwest to southeast from Micronesia to the Samoan Islands and beyond. A distorted band of 1+ inches of rain extended across the Marshall Islands (RMI) and eastern half of the FSM, with areas of 2+ inches over Kosrae State and parts of the southern RMI. Isolated patches of 1+ inches were over the northern RMI and near Yap and Koror. The satellite QPE generally showed little to no rainfall over most of the western half of the FSM and over the Marianas. A broad band of 2+ inches of rain stretched northwest to southeast across the Samoan region. Within this band, an area of 4+ inches was over and south of American Samoa.

In the Republic of the Marshall Islands (RMI), the southern islands of Jaluit and Mili remained free of dryness. Mili was especially wet, with well over 4 inches of rain reported during the drought-monitoring period. Jaluit received 2 to 6 inches of rain each of the previous 4 weeks, but reported less than an inch during the week ending April 14. Majuro retained an abnormally dry (D0-S) status due to lower-than-optimal reservoir storage, despite April 1-14 rainfall totaling 5.79 inches (138% of normal). Majuro’s April 14 storage of 26.577 million gallons (73.8% of capacity) was down from 28.631 million gallons (79.5%) on April 8. On Ailinglapalap, where moderate drought (D1-S) was introduced a week ago, less than an inch of rain fell for the fourth consecutive week; further drought intensification may occur unless appreciable rain soon arrives. Kwajalein experienced a slightly wetter week, with 2.21 inches reported from April 8-14. The week’s wettest day on Kwajalein was the 14th, when 1.36 inches fell; however, severe drought (D2-S) was retained, as March was very dry (total of 1.54 inches) and drought impacts have worsened in recent weeks. Similarly, extreme drought (D3-S) was retained for Utirik, despite a weekly rainfall of 2.38 inches (with one day missing). Previously, Utirik had experienced 10 consecutive weeks with less than an inch of rain. Data from Wotje was missing; thus, no drought assessment was made.

In the Federated States of Micronesia (FSM), the eastern islands of Kosrae and Pohnpei remained free of dryness. Weekly rainfall was particularly heavy, in excess of 12 inches, on Kosrae. Pingelap received more than 4 inches of rain for the second consecutive week, resulting in elimination of abnormal dryness (D0-S). In the south, Kapingamarangi remained free of dryness. Abnormal dryness (D0-S) was retained for Lukunor and Nukuoro, despite periods of beneficial rainfall in recent weeks; both islands received above-normal March rainfall but also report lingering agricultural impacts related to earlier dryness. Conditions worsen to the north and west, with moderate drought (D1-S) continuing a Chuuk Lagoon. At the end of the drought-monitoring period, 2.16 inches of rain fell at Chuuk Lagoon on April 14; however, month-to-date rainfall remains slightly below normal and year-to-date rainfall is nearly 5 inches below normal. Chuuk Lagoon will be monitored for possible improvement if beneficial rainfall continues. Serious drought persisted in western sections of the FSM, including Ulithi (D2-S), Woleai (D2-S), and Yap (D3-S). Ulithi reported a tenth consecutive week with less than an inch of rain. Woleai received 2.89 inches of rain (with one day missing), but continued to experience significant drought impacts. Likewise, Yap reported increased rainfall, but continued to note agricultural impacts and water-supply concerns. Despite rainfall totaling 0.99 inch on April 14, Yap’s month-to-date total stood at 2.14 inches (86% of normal). Further, Yap’s January 1 – April 14 rainfall totaled just 8.02 inches (38% of normal).

In the Republic of Palau, drought impacts are similar to those reported across western sections and the FSM and include water-supply shortages, agricultural damage, and an enhanced threat of wildfires. At the international airport, April 1-14 rainfall totaled 0.92 inch (25% of normal), while year-to-date rainfall stood at 18.08 inches (56%). Like last week, Palau is considered to be in moderate drought (D1-S). According to a National Weather Service meteorologist, the Palau Public Utilities Corporation (PPUC) reported during the first week of April a Water Shortage Alert for Aimeliik, Airai and Ngerchelong. By April 7, mandatory conservation was implemented, limiting water use to essential purposes (e.g. car washing prohibited). By April 13, water levels were reported to have declined substantially for the Ngerikiil water source and slightly for Ngerimel Dam, leading to water rationing from 11 pm to 5 am local time until further notice.

In the Commonwealth of the Northern Mariana Islands (CNMI), drought continued to gradually intensify. For Rota and Guam, drought intensity was changed from moderate to severe drought (from D1-S to D2-S). Many reporting sites in the CNMI have received less than an inch of rain for 10 consecutive weeks. According to the National Weather Service, the Keetch-Byram Drought Index, indicative of fire danger and reported on a scale from 0 to 800, was noted on Guam to be 721 (in the extreme category) on April 14. To the north, Saipan’s drought intensity (extreme drought, or D3-S) remained unchanged.

American Samoa is experiencing neither dryness nor drought, and in fact remains very wet, courtesy of recent tropical moisture. During the first 12 days of April, rainfall at the Pago Pago International Airport totaled 11.32 inches.

Virgin Islands

For the third consecutive week, mostly dry conditions dominated the U.S. Virgin Islands. From March 24 – April 13, a volunteer observer at Windswept Beach on St. John reported rainfall totaling just 0.07 inch. During the same 21-day period, rainfall totaled 0.31 inch at King Airport on St. Thomas and 0.55 inch at Rohlsen Airport on St. Croix. However, the recent dry spell was immediately preceded by unusually wet weather in early to mid-March. Short-term (1-month) SPI values do net yet indicate significant dryness, and USGS well data suggests that depth to water has only recently begun to increase in response to the short-term dryness. As a result, St. John and St. Thomas remain free of dryness and drought, while abnormal dryness (D0-L) is retained for St. Croix due to much longer-term precipitation deficits and chronically low groundwater levels.

Looking Ahead

Over the next 5-7 days, it is anticipated that the eastern half of the United States will stay quite wet, with the Southeast projected to record the most precipitation. Some relief may come to the Gulf Coast region as well. The Northern Plains and upper Midwest look to be dry while the central and southern Plains will see up to an inch of precipitation. Precipitation looks to be scattered through the West with some upper elevations seeing the most precipitation. Temperatures during this time are expected to be cooler than normal over most of the United States with departures of 9-12 degrees below normal over the Midwest to New England.

The 6-10 day outlooks show much of the central U.S., West, Southeast, and Alaska having a greater than normal probability of above-normal temperatures while the Midwest and Northeast show a higher than normal probability of below-normal temperatures. The greatest probabilities of recording above-normal precipitation are over the Four Corners into the south to the Southeast and interior Alaska.

And shifting to the Alaska and CONUS Intermediate-Term Weather Forecast

And then Precipitation

Here is the discussion that was released with the Week 3 – 4 forecast today. We do this because we believe that when considering the economic impacts of weather one needs to look ahead more than 14 days.

Prognostic Discussion for Week 3-4 Temperature and Experimental Precipitation Outlooks NWS Climate Prediction Center College Park MD 300PM EDT Fri Apr 17 2020

Week 3-4 Forecast Discussion Valid Sat May 02 2020-Fri May 15 2020

A highly amplified upper-level trough expanded east from the western U.S. during early to mid-April, while a strong subtropical ridge aloft remained anchored over the southern Gulf of Mexico and south Florida. Week-2 model solutions depict anomalous upper-level ridging over the southwestern U.S. with an upper-level trough persisting across the mid to high latitudes of eastern North America. Neither ENSO (which is neutral) nor the Madden-Julian Oscillation (MJO) can be utilized in the Weeks 3-4 outlook. Since the beginning of April, a Kelvin wave has propagated eastward from the Maritime Continent to the Western Hemisphere. An equatorial Rossby wave has recently interfered with this Kelvin Wave as it approached Africa. Although a few of the dynamical model solutions indicate an increase in enhanced convection over the Indian Ocean by the beginning of May with perhaps a developing MJO, it is unlikely that even a more organized MJO would influence the mid-latitude circulation pattern during May. Therefore, the temperature and precipitation outlooks are based on dynamical model forecasts from the NCEP CFS, ECMWF, and JMA, and SubX multi-model ensemble (MME) of experimental and operational ensemble prediction systems. Soil moisture conditions and anomalously warm sea surface temperatures (SSTs) in the Gulf of Mexico were also factors.

The ECMWF and JMA models are in good agreement with an upper-level ridge along the West Coast and the persistence of the anomalous subtropical ridge over the Gulf of Mexico and Florida. Although both of these dynamical models feature an amplified upper-level trough over the mid to high latitudes of central and eastern North America, the orientation of the trough axis and the amplitude are different. The JMA model depicts a full-latitude trough extending from northern Canada south into the Great Plains and Mississippi Valley, while the ECMWF model has the upper-level trough centered across the Great Lakes, southeast Canada, and the Northeast. Either solution is plausible based on the Week-2 circulation pattern. The predicted pattern by the CFS model seems to be the least likely outcome as its large positive 500-hPa height anomalies are out of phase with the ECMWF and JMA models at the higher latitudes of the Northern Hemisphere. Based on the expectation of upper-level ridging with above-normal 500-hPa heights, above normal temperatures are favored across much of the western CONUS. The largest probabilities (above 60 percent) of above normal temperatures are forecast across the Southwest as this region is strongly favored to have above normal temperatures leading into Week-3. Increased chances of above normal temperatures also include the southern Great Plains, Gulf Coast, and Florida. Low soil moisture and much above normal SST anomalies in the Gulf of Mexico elevate probabilities to above 60 percent across south Texas and the Florida Peninsula. The SubX MME generally supports the spatial coverage of increased chances of above normal temperatures. A consensus approach using the preferred ECMWF and JMA models, that feature an amplified upper-level trough over the east-central CONUS, favors below normal temperatures across the northern Great Plains, Great Lakes, Corn Belt, and parts of the Northeast.

The dynamical model guidance is in reasonably good agreement with the spatial pattern of anomalous precipitation during early to mid-May. Above normal precipitation is most likely across the Gulf Coast States, lower Mississippi Valley, and Southeast. Farther to the north, below normal precipitation is favored for the northern to central Great Plains northeast to the Great Lakes which are forecast to be north of a mean frontal position during the outlook period. A change from above to below normal precipitation, compared to last week’s forecast, across the northern tier of the CONUS was necessary since a prevalent anomalous northerly flow is forecast. The dipole of anomalous precipitation across the central and eastern CONUS is consistent with an expected southward displaced storm track and increasing likelihood that cold fronts progress south towards the Gulf Coast during this two week period. An upper-level ridge aloft supports increased chances of below normal precipitation across the Pacific Northwest and northern California.

Near to above normal 500-hPa heights along with long-term trends support increased chances of above normal temperatures for the Aleutians, southern mainland Alaska, and the Alaska Panhandle. Equal chances, of above or below normal temperatures forecast across northern mainland Alaska, are related to a moderating effect associated with a deep snowpack. Increased chances of below normal precipitation forecast for the Aleutians and southwest mainland Alaska is supported by nearly all tools and consistent with a weak ridge extending north from the Aleutians to the Bering Strait.

Positive sea surface temperature anomalies support increased chances of above normal temperatures throughout the Hawaiian Islands. Model guidance supports slightly elevated probabilities of below normal precipitation for Hawaii.

Some may find the below way of looking at things useful and I hope these graphics are not too small to read. I did not make them so you could click on them individually but you can click on the whole graphic and it may enlarge. But I think you get the picture. It has been a rapid onset and demise. When you read these graphics, remember that the older graphics are not the drought conditions that existed then but the change from then until now.

Let’s focus on the change between March 17, 2020 and April 14, 2020, i.e. one month.

Focusing on the Intermountain West

Drought Forecasts

These two forecasts (Monthly and Season) are issued by the same agency but to obtain them you need to access two different links here and here.

Here is the Three-Month Forecast which was issued on March 19, 2020

Here is the Monthly Drought Outlook which was updated on March 30, 2020.

Floods

Floods remain a concern.

Last Week	Current Week

Wildfires

Our usual graphic is not updating so we have deleted it. Bu updates from this source can be found here.

Current Wildfire Risk. This is a new model that updates daily by NOAA (but not automatically in this article) to show the short-term risk.

Click here to update. Red is high risk, blue is low risk. This graphic updates daily but you have to click on the link provided to get the updates More information can be found here.

This explains the model a bit.

The below graphics are monthly risk estimates for Wildland Fire Potential. They update monthly.

Looking out another month.

Surface soil conditions

Subsurface Soil Conditions

Crop and Animal Husbandry Progress. USDA Executive Briefings can be found here (there was an Executive Briefing this week and we presented it). NASS reports can be found here. Foreign Intelligence reports can be found here.

There were a lot of NASS reports this week and we did not have time to prepare them for publication. This shows the major reports scheduled. Most are NASS Reports. We reported on one of them.

It is the time that NOAA starts showing crop progress. The data is pretty thin at this point.

International

A map helps and is not always available but fortunately, it was available this week.

Major Sources of Information

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.

Background Information

The sequence of drought occurrence and impacts for commonly accepted drought types. All droughts originate from a deficiency of precipitation or meteorological drought but other types of drought and impacts cascade from this deficiency. (Source: NDMC)

Source: National Drought Mitigation Center, University of Nebraska-Lincoln