Written by Sig Silber

HEADLINES (Updated 4:57 PM EDT) –

– Snow is expected to spread quickly from the Central U.S. to the Midwest today, and then across northern New England on Wednesday into Thursday

– Subfreezing record cold temperatures expected across much of the south-central U.S. Wednesday morning, shifting to parts of the eastern U.S. Thursday morning

– Critical fire weather threat over Arizona through Friday

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.

Please share this article – Go to the very top of the page, right-hand side for social media buttons. Also, feel free to send this email to anyone you feel will benefit from it.

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 408 PM EDT Tue Apr 20 2021

Valid 00Z Wed Apr 21 2021 – 00Z Fri Apr 23 2021

…Snow is expected to spread quickly from the Central U.S. to the Midwest today, and then across northern New England on Wednesday into Thursday…

…Subfreezing record cold temperatures expected across much of the south-central U.S. Wednesday morning, shifting to parts of the eastern U.S. Thursday morning…

…Critical fire weather threat over Arizona through Friday…

Late season snow event continues to spread eastward across the Ozarks into the Ohio Valley as a developing area of low pressure is forecast to race along the Alleghenies into the Northeast later today into tomorrow morning. As the low pressure system progresses northeastward, rain and mixed precipitation will continue to envelop the Midwest, before a swath of wet snow falls along the Canadian border from New York into Northern New England beginning Wednesday morning through Friday. 6 to locally 8 inches is possible along the border through Friday. As such, “Moderate” impacts are expected in these locations from snow-load, per the Weather Prediction Center Winter Storm Severity Index, and Winter Weather Advisories are in effect for the region. Further south in the Mid-Atlantic, some rain and a few rumbles of thunder are possible as the storm moves through.

In the wake of the developing storm system, a bout of unseasonably cold air is forecast to spill into the Central U.S. today and tomorrow, leading to widespread freeze and frost concerns tonight across the central/southern Plains and the Midwest. Freeze Watches and Warnings extend continuously from north-central Michigan into central Texas. Numerous daily record low temperatures are forecast to be tied or broken on Wednesday morning as temperatures dip to below freezing, around 20-25 degrees below average for late April. Residents in these areas are encouraged to take preventative measures to mitigate the impacts of sub-freezing temperatures on vulnerable vegetation if possible. By Friday, the frigid airmass will moderate as it drifts east, although low temperatures will remain around 10 degrees below normal in the Central U.S., with lows hovering in the mid-30’s to 40’s.

Meanwhile, active weather across Florida has been edging very slowly southward into southern Florida ahead of a slow-moving front. A low pressure wave forming on the front could bring additional heavy showers and thunderstorms today across central Florida. Improving conditions should begin Wednesday morning as the wave moves off into the Atlantic and rain chances decrease across southern Florida.

While excessive rain may be problematic in Florida, dry, windy conditions will set the stage for a fire weather threat in Arizona over the next three days as low pressure deepens in the region. Accordingly, the Storm Prediction Center has issued an Elevated Risk of fire weather today, and a Critical Risk tomorrow, with the potential for additional impactful fire weather also highlighted on Friday.

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 Friday April 23 2021 – Tuesday April 27 2021

Hazards:

– Heavy precipitation across portions of the Central Great Basin, California, and the Southwest, Sun-Mon, Apr 25-Apr 26.

– Heavy rain across portions of the Lower Mississippi Valley, the Tennessee Valley, the Mid-Atlantic, the Southern Appalachians, the Southeast, and the Southern Plains, Fri-Sat, Apr 23-Apr 24.

– Heavy rain across portions of the Central Plains, the Lower Mississippi Valley, the Northern Plains, the Upper/Middle Mississippi Valley, and the Southern Plains, Tue, Apr 27.

– Severe weather across portions of the Southeast, the Lower Mississippi Valley, and the Southern Plains, Fri, Apr 23.

– Severe weather across portions of the Southeast and the Lower Mississippi Valley, Sat, Apr 24.

– Flooding occurring or imminent across portions of the Lower Mississippi Valley.

– High winds across portions of the Great Lakes, the Mid-Atlantic, the Northeast, the Central Appalachians, and the Ohio Valley, Fri, Apr 23.

– High winds across portions of the Northeast, Mon, Apr 26.

– Much above normal temperatures across portions of mainland Alaska, Fri-Mon, Apr 23-Apr 26.

Detailed Summary:

In the medium-range forecast period, a front and wave of low pressure over the Southern Plains on Friday moving slowly across the Gulf Coast States to the Mid-Atlantic by Sunday. The low will move northeastward to the Canadian Maritime Provinces by Monday and Tuesday. Moisture from the Gulf of Mexico will move northward and pool along the boundary producing showers and thunderstorms over the Southern Plains into the Lower Mississippi Valley on Friday. Severe thunderstorms are likely with these thunderstorms over that region on Friday. The showers and thunderstorms will move eastward with the boundary over the Central Gulf Coast and the Southeast on Saturday. The region of severe thunderstorms will move eastward on Saturday. The rain associated with these thunderstorms will be heavy; therefore, an area of heavy rain is depicted on the Hazards Chart from parts of the Southern Plains/Lower Mississippi Valley to the Southeast/southern Mid-Atlantic on Friday and Saturday.

Moreover, the associated area of low pressure will deepen as the system pulls away from the Northeast on Sunday and Monday. On Monday, the pressure gradient associated with the low will produce high wind over the Northeast Coast. While not depicted on the Hazards Chart, an area of strong wind will develop over parts of the Great Lakes on Sunday. Another area of low pressure over Southeastern Canada will produce high wind over the Northeast. The strong spring sunshine will help the momentum of faster medium and upper-level wind to mix down to the surface on Friday.

A front over the Eastern Pacific will move onshore over the West Coast on Saturday into Sunday. The front will continue to move eastward to the Plains by Tuesday. A plume of moisture will accompany the boundary onshore, streaming moisture into the Sierra Nevada Mountains in California, producing an area of heavy precipitation on Sunday and Monday. There will be rain and higher elevation snow associated with the heavy precipitation.

As the front moves eastward, there is a little uncertainty of exactly where the heavy rain will be with the system over the Plains and Mississippi Valley on Tuesday. Some models have heavier rain over the Lower Mississippi Valley, while others have heavy rain over northern Minnesota. WPC decided that the uncertainty was not so great. Yet, WPC feels confident enough to have two regions of heavy rain. One over the Central/Northern Plains into parts of the Upper Mississippi Valley associated with the surface and upper-level low. The second area will be over parts of the Middle/Lower Mississippi Valley in the warm sector ahead of the cold front.

For Alaska, upper-level ridging over the southern mainland to the Far North will remain in place from Friday into Monday. Upper-level troughing will move in from the east on Monday. The upper-level ridging will allow temperatures to become above freezing for a good portion of the day through Monday over the North Slope region. A low just south of the Aleutians/Alaska Peninsula will produce precipitation but will not reach our criteria for a hazard. However, another low will move near the Aleutians/Alaska Peninsula Sunday through Monday, strengthening the area of low pressure. This system will have strong low-level flow pulling moisture off the Gulf of Alaska for a short time on Sunday afternoon into early Monday. Yet again, the precipitation will not exceed the criteria for a hazard, but at this time. The hazard may be introduced over the next several days if the models suggest it.

For Alaska, an upper-level ridging over the southern mainland to the Far North will remain in place from Thursday into Monday when upper-level troughing will move in from the east. The upper-level ridging will allow temperatures to become above freezing for a good portion of the day through Monday. A low just south of the Aleutians/Alaska Peninsula will produce precipitation but will not reach our criteria for a hazard. However, another low will move near the Aleutians/Alaska Peninsula Saturday through Monday. This system will have strong low-level flow pulling moisture off the Gulf of Alaska for a short time on Sunday afternoon. Yet again, the precipitation will be close or may even begin to exceed the criteria for a hazard, but at this time, WPC will leave this hazard off the chart. The hazard may be introduced over the next several days if the models suggest it.

(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.

April Drought Outlook..

Seasonal Outlook Issued April 15, 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 Eastern Pacific

NA

The Central Pacific

NA

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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