Written by Sig Silber

Updated at 6:23 pm EDT Wednesday, May 20, 2020 – “…There is a high risk of excessive rainfall over the Southern Appalachians, heavy rain to drench the southern Mid-Atlantic……Daily episodes of severe weather to transpire in the High Plains, critical fire weather conditions linger across portions of the Southwest and Four Corners Region……Showers, mountain snow, and below normal temperatures in the Northwest…“

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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CONUS Focal Points

Short Range Focal Points

Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 353 PM EDT Wed May 20 2020 Valid 00Z Thu May 21 2020 – 00Z Sat May 23 2020

…There is a high risk of excessive rainfall over the Southern Appalachians, heavy rain to drench the southern Mid-Atlantic…

…Daily episodes of severe weather to transpire in the High Plains, critical fire weather conditions linger across portions of the Southwest and Four Corners Region…

…Showers, mountain snow, and below normal temperatures in the Northwest…

A stalled upper-level low over the Mid-South continues its onslaught of heavy rain over the southern Appalachians and Mid-Atlantic. Rainfall rates will become excessive within bands of embedded thunderstorms. The storm’s seemingly endless supply of moisture, its slow movement, and the region’s overly saturated soil are a recipe for significant flooding tonight and into Thursday. Flash Flood Watches remain in effect for parts of the eastern Ohio Valley, southwest Virginia, and much of the western Carolinas. High risks for excessive rainfall are forecast for the Southern Appalachians of North Carolina and southwest Virginia through Thursday morning where widespread flash flooding is likely. Landslides and debris flows are possible within steeper terrain. Storm total rainfall amounts could exceed ten inches in parts of the southern Appalachians. A few severe storms are possible along the coastal Carolinas and into southern Georgia this evening and into Thursday. In addition, brisk onshore winds responsible for coastal flooding in the Virginia Tidewater, the lower DelMarVa Peninsula, and North Carolina Outer Banks will gradually weaken overnight.

In the Heartland, rounds of severe storms are expected to develop up and down the Great Plains this evening and through Friday. This is due to the  combination of a slow progressing frontal boundary to the north and the dry line to the south acting as triggers for thunderstorms up and down the High Plains this evening and again on Thursday. The front’s slow progression could also lead to flash flooding concerns in areas impacted by heavy thunderstorms. To the south, dry and windy conditions will prevail across the Southwest, promoting elevated to critical fire weather conditions across much of the Southwest through through Friday.

In the West, an upper level trough is swinging through the northern Rockies this afternoon with scattered heavy showers and thunderstorms dotting parts of the Northwest. Rainfall rates could be heavy enough to cause flash flooding this evening. As a result, a slight risk for excessive rainfall is in place for parts of eastern Oregon and Washington, northern Idaho, and northwest Montana through early Thursday morning. As this upper low heads north into the Canadian Prairies, another upper low will track into the Pacific Northwest on Thursday. This next storm system will be responsible for ushering in considerably cooler temperatures, numerous showers, and even some mountain snow for both Thursday and Friday.

Click here for the latest complete NWS/WPC Short Range Discussion. (Sometimes we provide part of or even the full discussion above and you can tell because it goes beyond the bullet points. We do that when we think the bullet points do not provide enough information. But the link just provided always takes you to the full discussion with updates twice a day and sometimes we are a bit late updating the bullet points so that link will get you there. You can tell if we are late by the time of the stamped update. This time of the year, NOAA does the updates at around 3 a.m. and 3 p.m. EST. We try to do the updates in our article as close to that as possible but it is not always possible.)

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.

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

Water Vapor.

This view of the past 24 hours provides a lot of insight as to what is happening.

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Day 3 – 7 Hazards

– Heavy rain across portions of the central Plains, Sat-Sun, May 23-May 24. – Heavy rain across portions of central to northern Texas, Mon-Tue, May 25-May 26. – Severe weather across portions of South Dakota and much of Nebraska, Sat, May 23. – Flooding possible across portions of the Southeast into the central and southern Appalachians, the interior Mid-Atlantic and the lower Great Lakes.

– Flooding occurring or imminent across portions of the Lower Mississippi Valley, northeastern South Dakota, northern Washington, the Midwest, the lower Great Lakes, and the Ohio Valley.

– Flooding likely across portions of the northern Intermountain region, the southern Appalachians, the lower Great Lakes, and the Ohio Valley.

– Much above normal temperatures across portions of California into the central Great Basin, Tue-Wed, May 26-May 27.

– Enhanced wildfire risk across portions of the the southern High Plains, Sat, May 23.

– Heavy precipitation across portions of southern Alaska, Sat-Sun, May 23-May 24.

Detailed Summary:

The highly amplified synoptic pattern currently across the U.S. is expected to return to a more typical configuration by the medium range period (Saturday 5/23 – Wednesday 5/27). The cutoff upper-level low over the eastern U.S. should continue to gradually weaken and then move off the East Coast, ending the rainfall across the Mid-Atlantic by the weekend.

Over the Pacific Northwest, the arrival of the next upper-level trough will usher in colder air through the northern Rockies behind a cold front, likely bringing a period of wet snow for the higher elevations of northwestern Wyoming into Saturday morning as a result. Severe thunderstorms are possible on Saturday across parts of the northern Plains although moisture ahead of the front appears to support only modest amounts of rainfall. As the cold front pushes further down the Plains, returning moisture from the Gulf of Mexico should raise the threat of heavy rainfall later on Saturday through Memorial Day across the central to northern Texas. The front is forecast to become nearly stationary early next week across the southern High Plains as the highest threat of heavy rain shifts farther to the south into Texas by Tuesday.

Cooler than normal conditions are expected to spread across the northwestern U.S. toward the southern Plains behind the Pacific cold front in contrast with above normal temperatures across the Plains toward the Great Lakes ahead of the front. By next Tuesday into Wednesday, a warming trend is expected for a good portion of California into Nevada under a building ridge of high pressure where temperatures of about 15 degrees above normal are forecast.

As for Alaska, a weakening occluded cyclone is forecast to bring heavy rain across the lower elevations of southern coastal sections including the Kenai Peninsula through Sunday. Snow is expected for the higher elevations. Above normal temperatures are forecast to persist across central Alaska, gradually spreading into the North Slope by the weekend but they do not necessitate a temperature hazardous area at this time. Ice jam flooding will be a concern over the North Slope as rivers have not yet broken up, while minor snowmelt flooding is a possibility in central and southern parts of the mainland.-

(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. 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 weekly but more frequent updates can be obtained here.

There is not much snow left.

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Tropical Events

This is now beyond the time of the year we pay special attention to Tropical Events other than the Western Pacific.

So 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.

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

Updates on individual named storms can be obtained here.

And the Western Pacific

Week 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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