Written by Sig Silber

Updated at 7:18 pm EDT Monday May 11, 2020 – “…There is a slight risk of severe thunderstorms over the Southern High Plains……Temperatures will be 10 to 25 degrees below average from the Northern High Plains and the Rockies eastward to the East Coast southward to the Carolinas……Low pressure system may spark thunderstorms in New England today with a light wintry mix or snow on the backside…”

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 400 PM EDT Mon May 11 2020 Valid 00Z Tue May 12 2020 – 00Z Thu May 14 2020

…There is a slight risk of severe thunderstorms over the Southern High Plains…

…Temperatures will be 10 to 25 degrees below average from the Northern High Plains and the Rockies eastward to the East Coast southward to the Carolinas…

…Low pressure system may spark thunderstorms in New England today with a light wintry mix or snow on the backside…

Much of the Central and Eastern U.S. will remain in a prolonged stretch of colder than average temperatures.  Record cold minimum and maximum temperatures should be set from the Plains all the way to the Eastern Seaboard Through Wednesday evening.  Freeze Warnings/Frost Advisories and Wind Advisories are in effect across parts of the Midwest and to parts of the Carolinas, with additional Freeze Warnings and Watches across the Appalachians into parts of the Northeast.  Meanwhile, warm and windy conditions are a recipe for fire weather concerns in the Southwest, resulting in the issuance of a Critical Risk by the Storm Prediction Center through Wednesday morning.  Temperatures along the West Coast are forecast to trend cooler on Tuesday as a Pacific storm system advances inland.

The upper-level low coming into the West will also lead to increasing chances for rainfall in the Pacific Northwest and Northern California on through Wednesday, with the heaviest rainfall amounts along the Northern California and Southern Oregon coast.  Higher elevations of the Cascades, Sierra Nevada, and then into the Northern Rockies could see some light snow from this storm system. The Northern High Plains may also see a couple of rounds of wintry weather on the cold side of a front draped across the Intermountain West through Wednesday.  As upper-level energy moves eastward, scattered showers and thunderstorms will ramp up over the Central and Southern Plains through Wednesday.  Rainfall totals between 1-2 inches with locally higher amounts could lead to isolated areas of flash flooding.

Farther east, a low pressure system has its sights set on the Northeast today.  Thunderstorms are forecast ahead of this low, some of which could be strong to severe in Southern New England where a Marginal Risk has been posted by the Storm Prediction Center.  Another round of light wintry mixed precipitation or snow is also possible for the Central Appalachians and parts of the interior Northeast behind the low.  Drier conditions will take hold of the Northeast by Wednesday morning as high pressure centered over the Great Lakes begins to build in overhead.

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 precipitation across portions of California, Sat-Mon, May 16-May 18.

– Heavy rain across portions of California and the Pacific Northwest, Sat-Mon, May 16-May 18.

– Heavy rain across portions of the Central/Southern Plains, the Mississippi Valley, the Great Lakes, the Ohio Valley, and the Northeast, Thu-Sun, May 14-May 17.

– Heavy rain across portions of the Lower Mississippi Valley and the Southern Plains, Fri-Sat, May 15-May 16.

– Heavy rain across portions of the Southeast, Thu-Fri, May 14-May 15.

– Flooding occurring or imminent across portions of the Middle/Lower Mississippi Valley, the Great Lakes, and the Northern Plains.

– Much above normal temperatures across portions of the Central/Southern Rockies and the Central/Southern Plains, Mon, May 18.

Detailed Summary:

The main threat over the medium range period (Thursday 5/14 to Monday 5/18) will be the potential for multiple rounds of heavy rainfall across portions of the central and eastern U.S. A frontal boundary is expected to meander across the Central Plains, Middle Mississippi Valley, and Ohio Valley through the weekend, and moisture flowing into the vicinity of the front plus support from upper-level energy will combine to create the heavy rainfall potential. Portions of the Plains to the Ohio Valley and Great Lakes can expect rain events from Thursday through Sunday before the front finally moves eastward on Monday, while the Southern Plains and western parts of the Lower Mississippi Valley region appear to see the bulk its rain on Friday and Saturday. Severe weather may be a possibility with thunderstorms that occur.

A persistent stationary front near southern Florida could lead to heavy rain there through Friday, before a low develops and moves northeastward away from the state. This low could have tropical characteristics and is being monitored by the National Hurricane Center.

Precipitation is forecast across the Northwest Thursday into Friday, and the Northern Rockies and Wind River Mountains/Tetons could see a few inches of snow. Then as a deep upper-level low approaches, precipitation is expected to increase across the Pacific Northwest and northern California over the weekend and into Monday. Once again northern California and southwestern Oregon can expect the highest precipitation totals, in the form of rain along the coast and some snow in higher elevations of the Shasta/Sierra Nevada. Rain which could be heavy is also possible along the Pacific Northwest coast and into the Cascades (with snow possible in the highest elevations).

Temperature anomalies are not expected to be significant through the weekend, though Thursday morning could be cool across the Northeast before a warmup Friday and Saturday. As the upper-level low approaches the West, temperatures there are forecast to be below average by Sunday and Monday. But east of the upper low, a strengthening upper-level ridge is expected to cause much above average temperatures across the High Plains on Monday, and this warmth will likely move eastward through next week.

Over Alaska, above normal temperatures are forecast to continue over western portions of the state, but areas with anomalies over 20 degrees above normal should be pretty localized. Meanwhile, Arctic surface high pressure should keep northern areas cool. Ice jam and snowmelt flooding will continue to be threats across some central and northern areas of the mainland where rivers have not yet opened up.

(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.

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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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