Written by Sig Silber

HEADLINES (Updated 4:47 PM EDT) –

– An intense low pressure system is expected to bring widespread thunderstorms across the Deep South with dangerous severe weather likely through Thursday

– Threat of excessive rainfall will expand into the Southeast tonight

– Critical fire weather threat along the Rio Grande River Valley tonight

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 352 PM EDT Wed Mar 17 2021

Valid 00Z Thu Mar 18 2021 – 00Z Sat Mar 20 2021

…An intense low pressure system is expected to bring widespread thunderstorms across the Deep South with dangerous severe weather likely through Thursday…

…Threat of excessive rainfall will expand into the Southeast tonight…

…Critical fire weather threat along the Rio Grande River Valley tonight…

A low pressure system currently moving through Oklahoma will be the impetus for flash flooding and severe weather concerns across the Deep South over the next 24 hours. This area of low pressure will continue pulling moisture from the Gulf of Mexico and spreading it over the the Lower Mississippi Valley and Southeast tonight and tomorrow. This will contribute to continued atmospheric destabilization and an increased threat of widespread severe thunderstorms and tornado outbreaks across the region. Increased moisture flow into the area has also lead to a heightened risk of flash flooding across the Middle/Lower Mississippi Valley, Tennessee Valley and Southeast tonight. The low pressure system will expand into the east coast tomorrow as it continues to generate thunderstorms and potential severe weather activity in the Southeast, Mid-Atlantic and Ohio Valley. This system, and most of its impacts, should move off into the Atlantic by Friday afternoon leaving behind light snow and windy conditions in its wake across much of the Northeast.

Elsewhere, a new system will enter the Northwest on Thursday and produce some measurable mountain snow for the Olympic and Sierra. Coastal and lower elevation areas will experience rain. This same dynamic will continue across the intermountain west as the system redevelops over the region on Friday morning. Temperatures will cool down across the eastern half of the country, as the storm system moves through. The Northern Plains will experience a gradual warm-up heading into the weekend as a warm front lifts through the region. Much of the Rio Grande Valley is under an Elevated or Critical Fire Weather area for tonight as dry and windy conditions are expected to fuel potential fire activity.

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 Saturday March 20 2021 – Wednesday March 24 2021

Hazards:

– Heavy rain across portions of the Northern/Central Plains, and the Upper/Middle Mississippi Valley, Mon-Tue, Mar 22-Mar 23.

– Heavy snow across portions of the Pacific Northwest and the Northern Great Basin, Sun-Mon, Mar 21-Mar 22.

– Heavy snow across portions of the Northern Rockies and the Northern Great Basin, Mon, Mar 22.

– Heavy snow across portions of the Northern Plains and the Northern Rockies, Sat, Mar 20.

– Heavy snow across portions of the Central Rockies and the Central Plains, Sun, Mar 21.

– Flooding possible across portions of the Central Plains, the Tennessee Valley, the Upper/Middle Mississippi Valley, the Great Lakes, and the Ohio Valley.

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

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

– High winds across portions of the Southeast and the Mid-Atlantic, Sat, Mar 20.

– Heavy precipitation across portions of the Alaska Panhandle, Tue, Mar 23.

Detailed Summary:

The medium-range forecast period (Saturday, March 20th to Wednesday, March 24th) features an area of low pressure off the southeastern tip of Florida and an area of strong high pressure over the Great Lakes and the northern Mid-Atlantic on Saturday. The pressure gradient between the high and low will produce a strong wind along the Mid-Atlantic and the Southeast Coast on Saturday.

Meanwhile, an upper-level trough over the West Coast will split with part of the energy moving northeastward into South-Central Canada by Monday. The second part of the energy will move southeastward to the Texas Panhandle by Tuesday and then move northeastward to Upper Mississippi Valley/Upper Great Lakes by Wednesday. The upper-level energy and weak onshore flow will help produce heavy snow over the Absaroka Range and the Wind River Range on Saturday. The associated front, extending from the Northern High Plains southwestward to Southern California, will move eastward to the Upper Midwest to the Central/Southern High Plains by Sunday, with a wave of low pressure the Central High Plains. The front and an associated wave of low pressure will help produce an area of heavy snow over parts of the Central Rockies on Sunday. Additionally, the upper-level trough and weak onshore flow will help produce heavy snow over parts of the Cascades and parts of the Bitterroot Range/Salmon Range on Sunday into Monday.

Ahead of the front, temperatures will be about 12 degrees above average over the Upper Midwest on Saturday into Tuesday and expand into parts of the Northeast/Ohio Valley by Wednesday. Moisture will pool along the boundary over the Middle Missouri Valley, aiding in heavy rain development on Monday and Tuesday. As the front moves southeastward, the rain will develop over parts of the Lower Mississippi Valley and Southern Plains, but there is some uncertainty if the rain will be heavy enough to depict an area of heavy rain on the Hazards Chart.

For Alaska, low pressure over the Bering Sea will move eastward across the Alaska Peninsula and into the Gulf of Alaska by Sunday. The low will move into the Alaska Panhandle and dissipate by Monday. The system will have light precipitation associated with the storm. A second area of low pressure will develop over the North Pacific on Sunday. The area of low pressure will strengthen on Monday and move into the Gulf of Alaska later on Monday. By Tuesday, a plume of moisture will stream into the Alaska Panhandle, producing an area of heavy precipitation to the panhandle.

(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.

March Drought Outlook..

Seasonal Outlook Issued February 18, 2021

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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

The Central Pacific

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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