Written by Sig Silber

HEADLINES (Updated 7:49 PM EDT) –

– Thunderstorms are expected over parts of the central U.S., with severe weather possible in the Northern/Central High Plains through tonight

– Even more rainfall could cause additional flooding and flash flooding for eastern Texas into Louisiana

– Late-season snow will continue across higher elevations of the West, with well over a foot of snow likely in the Northern Rockies

– Critical Risks of fire danger remain in place for portions of the Central Great Basin and Southwest

This article provides continuous updates for a variety of Weather and Weather-Related Threats as well as a general weather forecast. These are “Live” maps that continually update. Please pay attention to the Mesoscale Events maps — Mesoscale Events are potentially life-threatening situations.

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For those interested in longer-term forecasts, we just published the new NOAA Seasonal Outlook and it can be accessed here.

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CONUS Focal Points

Short Range Focal Points

Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 406 PM EDT Thu May 20 2021

Valid 00Z Fri May 21 2021 – 00Z Sun May 23 2021

…Even more rainfall could cause additional flooding and flash flooding for eastern Texas into Louisiana…

…Thunderstorms are expected over parts of the central U.S., with severe weather possible in the Northern/Central High Plains through tonight…

…Late-season snow will continue across higher elevations of the West, with well over a foot of snow likely in the Northern Rockies…

…Critical Risks of fire danger remain in place for portions of the Central Great Basin and Southwest…

Ample moisture from the Gulf of Mexico will continue streaming into the central U.S. over the next few days, and upper-level energy moving from the Plains to the Midwest should continue to trigger showers and thunderstorms over the region. Additional rainfall totals of up to 3 inches are possible for southeastern Texas into parts of Louisiana, which have already seen several days of heavy rain, and flooding is ongoing in some areas. The next rounds of rain should serve to exacerbate ongoing flooding and could lead to numerous instances of flash flooding. A Moderate Risk of excessive rainfall is in place through tonight, and Flash Flood Watches are in effect along the western/central Gulf Coast. Lessening rain totals by Friday, but still some modest rainfall potential, has led to a Slight Risk of excessive rainfall in place for Friday for southeastern Texas and southwestern Louisiana.

A deep upper-level low is forecast to drop slowly southward across the West and persist there over the next couple of days. This feature providing lift combined with a frontal system moving slowly across the north-central U.S. will lead to scattered showers and thunderstorms across the Northern/Central Plains and Midwest.

A Slight Risk of severe thunderstorms is in place through tonight for northern and central parts of the High Plains mainly for wind and hail threats. Isolated strong to severe thunderstorms are possible for the Mississippi Valley as well. Additionally, isolated flash floods are possible for eastern North Dakota/northwestern Minnesota through tonight where locally heavy rain could occur if thunderstorms train over the same area.

Underneath the upper low, temperatures are expected to be substantially below normal over the West. High temperatures are forecast to be more than 30 degrees below average for portions of Montana, with temperature anomalies of 20 degrees below normal common for the Intermountain West. These cold temperatures will support lowering snow levels across the West, so snow is likely for the Cascades, Sierra Nevada, and higher elevations of the Intermountain West. But the greatest snow totals are expected in the Northern Rockies, and Winter Storm Warnings are in effect for portions of Montana where snow totals should be well over a foot.

Meanwhile, the upper-level pattern will support gusty winds across the interior West, and combined with dry conditions, fire danger will continue. Critical Risks of fire weather are delineated for much of the Central Great Basin and Southwest through Saturday, and the interior valleys of California and the Southern High Plains are under Elevated Risks as well.

Elsewhere, the northeastern U.S. can expect increasing chances for showers and thunderstorms for the end of the week along a meandering front. Warmer than average temperatures are forecast to continue for the Great Lakes/Ohio Valley and Northeast/Mid-Atlantic over the next several days, with highs rising well into the 80s and even into the 90s.

We try to keep this up to date but if is not you can find the updated version here.

When you click on this image it takes you to the SPC Fire Warning Page and you get a set of maps for Days 1, 2, 3 – 8, etc. You can then click on those for more detailed information. The map is a bit blurry as I tried to make it a bit larger than the map provided by NOAA but should be able to see where the current wildfire risks are. But if you click on this map, you will get to see three maps that show the risk for different time periods.

Thunderstorm Risk

This should play out something like shown in this 60 Hour Forecast Animation

Here is a national animation of weather fronts and precipitation forecasts with four 6-hour projections of the conditions that will apply covering the next 24 hours and a second day of two 12-hour projections the second of which is the forecast for 48 hours out and to the extent it applies for 12 hours, this animation is intended to provide coverage out to 60 hours. Beyond 60 hours, additional maps are available at links provided below. The explanation for the coding used in these maps, i.e. the full legend, can be found here although it includes some symbols that are no longer shown in the graphic because they are implemented by color-coding.

The two maps below break it down by day and may be easier to read.

Now, the Day One and Two CONUS Forecasts: These Maps Update Daily.

Day One CONUS Forecast	Day Two CONUS Forecast
These graphics update and can be clicked on to enlarge. You can see where the weather will be

During the winter much of our weather originates in the Pacific. That is why we pay attention to the near-term history of storms arriving.

Temperature

A version that shows a 40 hour animation and some other views can be found here

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Day 3 – 7 Hazards

Valid Sunday May 23 2021 – Thursday May 27 2021

Hazards:

– Heavy rain across portions of the Northern High Plains, Sun-Mon, May 23-May 24.

– Flooding possible across portions of the Central Plains, the Middle Mississippi Valley, the Lower Mississippi Valley, and the Southern Plains.

– Flooding occurring or imminent across portions of the Middle Mississippi Valley, the Lower Mississippi Valley, and the Southern Plains.

– Flooding likely across portions of the Central Plains, the Middle Mississippi Valley, the Lower Mississippi Valley, and the Southern Plains.

– Much above normal temperatures across portions of the Upper Ohio Valley and Great Lakes, Sun-Tue, May 23-May 25.

– Much above normal temperatures across portions of the Southeast, Sun-Wed, May 23-May 26.

Detailed Summary:

A strong upper level low initially over the Great Basin to begin the medium range period on Sunday will lift into the Northern Rockies/High Plains. Moderate to heavy precipitation is expected to accompany this system on Sunday into Monday across portions of the Northern Rockies and High Plains. Accumulating snowfall appears likely in the higher terrain, but does not look heavy enough to reach criteria for an area on the outlook for today. Did go ahead though and introduce a heavy rain area for the lower elevation areas of central into eastern Montana where several pieces of guidance are indicating rainfall in excess of an inch each day. The attendant cold front with this system will shift into the Central Plains and Upper Midwest early next week, with convection likely to break out ahead of and along the front. Heavy rainfall is possible, especially within mesoscale convective complexes, but there remains enough uncertainty on exactly where any MCSs may form so it’s difficult to pinpoint an outlook heavy rain area at this time.

The only other mention for heavy rainfall across the CONUS next week is along portions of the already very saturated central Texas Gulf Coast. Gulf of Mexico moisture will be funneled into the region this weekend in between Western U.S. troughing and Eastern U.S. ridging, but rainfall amounts are marginal for reaching criteria and the area of concern is too localized. As a result, the small area highlighted on yesterdays forecast was removed today.

In terms of temperatures across the nation during the extended range, there are two regions of concern for consecutive days of much above normal temperatures. The first is across portions of the upper Ohio Valley/Great Lakes where daytime highs approaching 90 degrees (10 to 20 degrees above average) will continue from this weekend into early next week with near record highs possible for some locations, especially Sunday. Into the East, parts of the interior Southeast (from Georgia to South Carolina) will also be much above normal through most of next week, where the first heat wave of the season will bring temperatures into the upper 90s, with many locations forecast to reach or exceed record highs for this time of the year. Above normal temperatures may expand into parts of the Mid-Atlantic as well, but a back door cold front should keep values in check early into the week. As warmer air moves in Wednesday, a brief period of temperatures 10-20 degrees above normal are possible, but should cool back towards normal by Thursday so for this reason a hazards area was excluded for the Mid-Atlantic region (but continued from yesterday for the Southeast).

Finally in Alaska, a system is expected to affect the Aleutians into the Alaskan peninsula this weekend into next week, but any associated wind and rainfall hazards should remain below criteria. As such, no significant hazards were added in Alaska.

(This is updated only during the week) Note the first list is weather highlights, this list is hazards. Not sure there is that much of a difference but they come from two different parts of NOAA. The Day 3 – 7 Hazards List does not update on weekends. But it is still useful as it remains valid for the period of time it covers. Of course, all forecasts are subject to change. Later we show a map of the hazards. Perhaps we should show them together.

Click here for the latest complete Day 3 -7 Hazards forecast which updates only on weekdays. It includes the full discussion which I do not update in this article but only present the highlights.

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Ski Snow Reports

New Feature – Ski Reports. (We may be a tad premature but not by much). It is difficult to find reports that auto-update on-screen (and they are very long) but these links will get you to them – If you have additional suggestions make them in the comments section after every GEI Article and we may add those links. We will try to not have too much overlap as that can add to the confusion.

We will update the above map (or maps) weekly (or more often when the situation is changing rapidly) but more frequent updates can be obtained here.

Snow Forecasts.

Day 1

Day 2

Additional snow information can be found here and here.

We also include drought information in this section.

More information can be found here. Normally the map in the upper left at this site is the two maps I normally show. You have to toggle between the current situation and the one-week change. That seems to be working now at the alternative site. I think the University of Nebraska – Lincoln will be working soon. But for those who want that information now, it is available at the alternative site that I have provided. But I think that what we show in the article is correct…but I am not positive about it. No date is shown so it may not be current as I think it is.

May Drought Outlook.

Seasonal Outlook Issued May 20, 2021

Here is the short version of the NOAA discussion released with this forecast.

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.

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.

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Tropical Events

I am replacing the large with three small maps but you can click on them to get larger versions. Even though they are small maps you should be able to tell if there is activity and If I see activity I will make the map where there is activity full size and when available add other related maps. Sorry for any confusion but the NHC maps do not update during the Winter except if there is activity. We leave them in simply because if there is a storm NOAA will start to update the relevant map even though it is not normally updated during the off season. The maps are a bit small but if you click the map you can see the date and time when it was updated.

the Central Pacific.	the Eastern Pacific	the Atlantic and the Gulf of Mexico

Atlantic and Gulf of Mexico

Nothing to report

The Eastern Pacific

NA

The Central Pacific

NA

Updates on individual named storms can be obtained here.

And the Western Pacific

Weekly Tropical Forecast

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Intermediate-Term Weather Forecast

And shifting to the Alaska and CONUS 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, there are larger versions in the Addendum (More Weather the link is shown at the end of this section, and there are larger versions of these maps in the Addendum. 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

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Mesoscale Events

The following map shows where mesoscale events are occurring or forecast. If you do not see any areas highlight on this map than there are no mesoscale events taking place or forecast. A mesoscale event is a very serious situation for a very small area and detailed information is provided for these events when they occur or are forecast. If a mesoscale event is shown, click on the map and more detail on the event will be shown.

Two different parts of the NWS issue this map and they are not always in agreement although they are pretty close. They (Norman Oklahoma and College Park Maryland) issue the alerts when they realize the need, so it is best to look on both maps and click one or both if you see areas highlighted.

This next map showing where “Headlines” have been issued for convection (and an animation of the recent movement of storms) should update and you should be able to click on to get additional details but if it does not update when you click on it, click here.

There is a slight difference between convection and thunderstorms. The below map shows where “Headlines” have been issued for Thunderstorms. You should be able to click on the map to get additional details but if it does not update, you can click here.

The map below shows the current wildfire risk which becomes more significant as we move into Summer. When you click on this image it takes you to the SPC Fire Warning Page and you get a set of maps for Days 1, 2, 3 – 8, etc. You can then click on those for more detailed information. The map is a bit blurry as I tried to make it a bit larger than the map provided by NOAA but should be able to see where the current wildfire risks are. But if you click on this map, you will get to see three maps that show the risk for different time periods.

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Now the Day 3 – 7 Hazards Outlook Maps

The orange and red outlined areas are what is most concerning of the forecasted Day 3 – 7 Hazards. This graphic does not update during the weekend. There is a discussion that goes with this graphic and you can access that discussion here.

The following is provided to help the reader relate the maps to how NWS will describe an area of the U.S.

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Now to our More Detailed Weather Report

This graphic is about Atmospheric Rivers i.e. thick concentrated movements of water moisture. More explanation on Atmospheric Rivers can be found by clicking here or if you want more theoretical information by clicking here. The idea is that we have now concluded that moisture often moves via narrow but deep channels in the atmosphere (especially when the source of the moisture is over water) rather than being very spread out. This raises the potential for extreme precipitation events.

500 MB Mid-Atmosphere View

The map below is the mid-atmosphere 3-Day chart rather than the surface highs and lows and weather features. In some cases, it provides a clearer less confusing picture as it shows only the major pressure gradients. This graphic auto-updates so when you look at it you will see NOAA’s latest thinking. The speed at which these troughs and ridges travel across the nation will determine the timing of weather impacts. This graphic auto-updates I think every six hours and it changes a lot. Thinking about clockwise movements around High-Pressure Systems and counterclockwise movements around Low-Pressure Systems provides a lot of information.

Day 3 Above, 6 Below	Day 4 Above,7 Below	Day 5 Above.

Here are the precipitation forecasts. First the cumulative for Days 1 – 3

Then cumulative for Days 1 – 5

Then cumulative for Days 1 – 7

Now we look at the forecast for the Maximum Temperature three days out.

Looking ahead to next week.

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Additional Tools to Obtain Watches and Warnings

Below you will see a number of different maps that are updated in real-time, making this a “live” report. If a part of one or more of the maps shows an area that is highlighted, you can click on it and get the full current report. By having the reader click on these active situations rather than having GEI do so, you will not miss any events in which you might have an interest and which we had not noticed and the page will not get cluttered with warnings, etc that have since expired.

Our focus here is events that are likely to last in the range of six hours but there can be longer or shorter events that are addressed by the Storm Prediction Center which is the main source of the information in this article. Long-term major events like a Hurricane are more likely to be in a separate article. But that may not always be the case. Since in general, all the links on this page transfer you into the NOAA system, in order to get back into this article you need to either close the tab to which you were transferred or click back on the tab that has this article.

Live Warning Maps which If Severe Weather is Shown can be Clicked on to get more detail about these events. If there is a current warning shown on the map, click on the map for additional information related to the event.	These maps are updated as risks are identified.
This is the current graphic showing any mesoscale discussions (MD’s) which are in effect over the contiguous United States. Please read the description of the purpose of our MD’s for further information. Details on all valid MD’s may be found on our Current Mesoscale Discussions page.
Convective Outlooks
This is today’s forecast for organized severe thunderstorms over the contiguous United States. Please read the description of the risk categories for further information. You may find the latest Day 1 Outlook available as well as all Outlooks issued today online.	Today’s Outlook
This is tomorrow’s forecast for organized severe thunderstorms over the contiguous United States. Please read the description of the risk categories for further information. The latest Day 2 Outlook is available as well as all Outlooks that have been issued today.	Tomorrow’s Outlook
This is the day after tomorrow’s (day 3) forecast for organized severe thunderstorms over the contiguous United States. Please read the description of the risk categories for further information. The latest Day 3 Outlook is available as well as all Outlooks that have been issued today.	Day 3 Outlook
This is the day 4-8 forecast for organized severe thunderstorms over the contiguous United States. The latest Day 4-8 Outlook is available as well as all Outlooks that have been issued today. Note: A severe weather area depicted in the Day 4-8 period indicates a 30% or higher probability for severe thunderstorms (e.g. a 30% chance that a severe thunderstorm will occur within 25 miles of any point).	Day 4-8 Outlook
The Thunderstorm Outlooks depict the probability of thunderstorms across the contiguous United States in 4 or 8 hour time periods. The probabilistic forecast directly expresses the best estimate of a thunderstorm occurring within 12 miles of a point. The three probabilistic forecast thresholds are 10, 40, and 70 percent.	Thunderstorm Outlook
Fire Weather Outlooks
This is today’s forecast for organized wildfires over the contiguous United States. Please read the description of the risk categories for further information about this product.	Today’s Outlook
This is tomorrow’s forecast for organized wildfires over the contiguous United States. Please read the description of the risk categories for further information about this product.	Tomorrow’s Outlook
This is day 3-8 forecast for organized wildfires over the contiguous United States. Please read the description of the risk categories for further information about this product.	Day 3-8 Outlook

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