Written by Sig Silber

Updated at 7:07 pm Wednesday May 13, 2020 – “…Severe thunderstorms and flash flooding possible from the Southern Plains to the Lower Great Lakes over the next few days……Warmer temperatures finally return to the Ohio Valley and Mid-Atlantic by the end of the week…”

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 343 PM EDT Wed May 13 2020 Valid 00Z Thu May 14 2020 – 00Z Sat May 16 2020

…Severe thunderstorms and flash flooding possible from the Southern Plains to the Lower Great Lakes over the next few days…

…Warmer temperatures finally return to the Ohio Valley and Mid-Atlantic by the end of the week…

The extended stretch of abnormally cold conditions from the Ohio Valley to the Northeast is on the verge of ending. As cold Canadian high pressure remains entrenched over these regions, Freeze Warnings and Frost Advisories extend from the shores of Lake Erie to the New England coast tonight. As a warm front to the south begins its trek north, temperatures will soar to much warmer levels by Thursday with parts of the Ohio Valley making a run at 80 degrees on Thursday. It will be the Mid-Atlantic’s and Northeast’s turn to welcome a surge of warmer than normal temperatures by Friday.

The pattern change across the Lower 48 also refers to a more active storm track across the central U.S. today and into the second half of the week. A pair of upper-level troughs out West will work in tandem with a strengthening high pressure system over the Southeast to funnel Gulf of Mexico moisture northward into the Nation’s Heartland. Episodes of severe weather are likely from the southern and central Plains to the lower Great Lakes, highlighted with an Enhanced Risk from the Storm Prediction Center today in northwest Texas and western Oklahoma. Excessive rainfall is also on the table from the southern Plains to the Great Lakes, with a Slight Risk in place for Thursday and Friday. Rainfall totals could range between 1 to 2 inches with locally higher amounts possible.

Elsewhere across the CONUS, rounds of showers are likely from far northwest California to western Washington as steady onshore flow brings beneficial rainfall to drought stricken areas of the Pacific Northwest. Speaking of “drought stricken”, dry and warm conditions continue for the southwestern quadrant of the U.S. that support elevated and critical fire weather conditions in the Four Corners region and southern High Plains. Dry conditions are also anticipated throughout much of the Southeast as high pressure dominates the region the rest of the week. The lone exception to this dry pattern is in South Florida and the Florida Keys, where a stalled frontal boundary and forming low pressure system is likely to keep scattered showers and storms in the forecast through the week’s end.

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 Great Lakes into the central Appalachians, the eastern portion of the southern Plains, as well as from northern California to the Cascades and the Olympic Peninsula, Sat-Sun, May 16-May 17.

– Heavy precipitation along portions of the Sierra Nevada, Mon-Tue, May 18-May 19.

– Heavy rain across portions of Montana, Wed, May 20.

– Heavy rain across portions of the central Appalachians into southern New England, Mon-Tue, May 18-May 19.

– Flooding possible across portions of the central Plains, the Mid-Mississippi Valley, and the Great Lakes.

– Flooding occurring or imminent across portions of the Great Plains into the Midwest, as well as the lower Mississippi Valley.

– Much above normal temperatures across portions of the central Rockies eastward into the central and northern Plains, Mon-Wed, May 18-May 20.

– Heavy precipitation across portions of southern coastal areas of Alaska, Tue, May 19.

Detailed Summary:

A major change in the synoptic pattern will be the theme during the medium range period (Saturday 5/16 to Wednesday 5/20). Models are in excellent agreement that a relatively flat upper-level pattern across the U.S. during the weekend will evolve to a highly amplified omega block by the middle of next week. Prior to this pattern change, moisture streaming northward from the Gulf of Mexico will interact with a well-developed warm front to result in a threat of heavy rain across the lower Great Lakes into the central Appalachians during the weekend. By early next week, the threat of heavy rain should shift eastward across the central Appalachians into southern New England as a major upper-level trough is forecast to form along the East Coast. This will be in stark contrast with a major ridge of high pressure forecast to develop over the Great Plains. The current WPC forecast calls for the trough/cyclone to move slowly off the East Coast. However, uncertainty is quite high with this rapidly evolving synoptic pattern. The ECMWF is now indicating the possibility of mutual interaction of the East Coast trough with a subtropical/tropical low pressure system off the East Coast that could result in a lingering upper low centered near the Mid-Atlantic coast by the middle of next week.

Models have been indicating the formation of a low pressure system near or east of Florida this weekend as it generally heads northeastward into the Atlantic. The National Hurricane Center continues to monitor this area for the potential of subtropical cyclogenesis. Impacts associated with this system are expected to remain largely offshore, although models have been showing a trend for a better-defined system to track closer to the Southeast U.S. this weekend. As mentioned in the last paragraph, there is a possibility for this system to mutually interact with the rapidly deepening trough forecast to develop along the East Coast by early to the middle of next week.

Over the West Coast, a deepening upper-level trough is forecast to approach from the Pacific during the weekend. Moisture ahead of this system is forecast to bring a potential for heavy rain across portions of northern California into southwestern Oregon through the weekend. By next Monday into Tuesday, heavy wet snow could spread into the Sierra Nevada as the upper trough digs further into California.

While major troughing develops along either side of the country, a pronounced ridge of high pressure is forecast to develop over the Rockies during the weekend before moving east into the Great Plains early next week. This will ensure a significant warming trend across the northern and central Plains for early to middle of next week with afternoon temperatures likely reaching well up into the 80s to near 90.

Underneath this strengthening upper ridge over the Plains, a noteworthy mesoscale vortex could linger in the vicinity of eastern Texas as a piece of upper-level energy may become trapped underneath the upper ridge and begin interacting with moisture from the Gulf of Mexico. The GFS

shows the system spinning closer to the Texas coast and result in a better-defined system along with heavier rainfall amounts. On the other hand, the ECMWF tends to send the system farther to the northeast. The predictability regarding a mesoscale system of this nature is generally rather low for the medium-range. However, the potential for heavy rainfall cannot be ruled out especially if the system meanders closer to the Gulf Coast, which could lead to the possibility of subtropical/tropical development as suggested by the GFS.

Over the Pacific Northwest, a frontal system moving onshore is expected to bring localized areas of heavy rainfall this coming weekend for the terrain-favored areas along the Cascades as well as for the Olympic Peninsula.

Over Alaska, a low pressure system moving across the southern portion of the state could result in heavy precipitation along the southern coastal areas later on Monday into Tuesday. Above normal temperatures are forecast to continue over the western and much of the southern portions of the state, in contrast with colder than normal temperatures over the north and northeast portions of the state.

(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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