Written by Sig Silber

Updated at 8:20 pm EDT Tuesday May 12, 2020 – “…Pattern change across much of the nation with warmer weather for the eastern U.S. and unsettled conditions from the southern Plains to the Great Lakes…”

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 357 PM EDT Tue May 12 2020 Valid 00Z Wed May 13 2020 – 00Z Fri May 15 2020

…Pattern change across much of the nation with warmer weather for the eastern U.S. and unsettled conditions from the southern Plains to the Great Lakes…

The deep upper level trough that has been anchored over the eastern U.S. and much of Canada has resulted in a late season freeze for many areas, especially from the Ohio Valley to the Northeast states.  Temperatures have been running a good 10 to 20 degrees below normal over the past couple of days, and another night of unseasonably cold temperatures is expected for this same general area along with some record lows.  With Canadian high pressure overhead and calm to light winds, frost and freeze advisories/warnings are in effect from Wisconsin to Maine, and extending south to the central Appalachians and northern portions of the Mid-Atlantic.  These cold conditions will be a thing of the past by the end of the week as a strong warm front lifts through the region ahead of the next storm system, and this will herald the arrival of above normal temperatures by Friday as an upper level ridge builds in.

With the Pacific front crossing the Intermountain West and then emerging across the Plains by Thursday, a corridor of enhanced moisture from the Gulf of Mexico will surge northward ahead of the front and on the western periphery of the surface high that will establish residence over the Southeastern U.S.  Multiple disturbances along the front and shortwaves aloft will provide multiple rounds of showers and storms going through the middle of the week, and some of these storms could be severe, particularly across parts of western Texas and Oklahoma where an Enhanced Risk of severe weather exists on Wednesday near the dryline.  Flooding may also be a concern across portions of the Midwest by Thursday with widespread 1 to 2 inch rainfall amounts likely.

Elsewhere across the continental U.S., heavy showers are likely from northwest California to western Washington near the Coastal Ranges and the foothills of the Cascades with a steady onshore flow through midweek.  Dry and warm conditions are expected to continue for the southwestern quadrant of the U.S., and this also holds true for much of the Southeast states. With the exception of some heavier showers and storms for South Florida, most of the Sunshine State should live up to its nickname with high  pressure governing the overall weather pattern.

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 and southern Plains, across the Mid- Mississippi Valley into the Ohio Valley, Fri-Sat, May 15-May 16.

– Heavy rain across portions of northern New England, as well as northern California into southwestern Oregon, Sun-Mon, May 17-May 18.

– Heavy rain across portions of southeastern Texas, Sun-Tue, May 17-May 19.

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

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

– Flooding occurring or imminent across portions of the lower and middle Mississippi Valley, and the northern Plains.

– Much above normal temperatures across portions of the central Rockies eastward into the northern and central Plains, Mon-Tue, May 18-May 19.

Detailed Summary:

It appears that a gradual change in the synoptic pattern will take place during the medium range period (Friday 5/15 to Tuesday 5/19) across the U.S. Model guidance agrees that a strong ridge of high pressure will be establishing across the High Plains by early next week as a deep trough/closed low approaches the West Coast. Prior to this pattern change, moisture streaming northward from the Gulf of Mexico will likely interact with a stationary front to result in a threat of heavy rain from the eastern portion of the central and southern Plains, across the Mid-Mississippi Valley into the Ohio Valley Friday into Saturday. A low pressure system is forecast to develop along the front and then move toward the Great Lakes on Saturday. Moisture ahead of this system will interact with a well-developed warm front to result in a threat of heavy rain across northern New England Sunday and Monday.

Meanwhile, a deepening upper-level trough is forecast to approach the West Coast 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 from Sunday into Monday. By next Tuesday, heavy wet snow could spread into the Sierra Nevada as the upper trough digs further toward California.

While the upper-level trough deepens over the West Coast, a ridge of high pressure is forecast to strengthen over the Rockies before moving east into the Great Plains early next week. This will  bring a warming trend across the northern and central Plains early next week with afternoon temperatures likely to soar well up into the 80s.

Underneath this strengthening upper ridge, a couple of atmospheric disturbances are of note during the medium-range period. One noteworthy feature would be 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 sends the system farther to the northeast before the strong upper ridge in the central Plains pushes it back into eastern Texas. 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 as suggested by the GFS.

Another noteworthy feature is a low pressure system that is forecast to form to the east of Florida this weekend. This system is being monitored by the National Hurricane Center for the potential of tropical/subtropical cyclogenesis. It appears that this system will move further out to sea at  this point in time.

Over the Pacific Northwest, a frontal system moving onshore could bring localized areas of heavy precipitation this coming weekend.

Over Alaska, low pressure system moving across the southern portion of the state should result in weather impacts below hazards criteria. Above normal temperatures are forecast to continue over 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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