Written by Sig Silber

HEADLINES (Updated 5:07 PM EDT) –

– Several rounds of showers and thunderstorms likely across northern/central Florida through Monday

– Strong cold front to bring another spring snow event to the Northern Rockies and northern High Plains beginning Sunday afternoon

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 323 PM EDT Sat Apr 17 2021

Valid 00Z Sun Apr 18 2021 – 00Z Tue Apr 20 2021

…Several rounds of showers and thunderstorms likely across northern/central Florida through Monday…

…Strong cold front to bring another spring snow event to the Northern Rockies and northern High Plains beginning Sunday afternoon…

The active weather currently found across the central Gulf Coast is forecast to slowly move eastward and into the Sunshine State this evening and linger through Monday. A slow moving cold front will be responsible for multiple rounds of showers and thunderstorms. A few storms could turn severe from the central Gulf Coast to northern Florida, with much of the activity shifting into Florida by tomorrow. The Storm Prediction Center has issued a Marginal Risk for severe thunderstorms through Monday morning for the region. Additionally, flash flooding will be a concern due to upwards of 5 inches of rain forecast to fall across northern/central Florida. A Marginal Risk of Excessive Rainfall has been issued to highlight the potential hazard.

Meanwhile, light snow found throughout the Southern Rockies will come to an end early Sunday morning as a more significant system drops into the Northern Rockies from Canada. A strong cold front will enter the Northern High Plains by Sunday afternoon and quickly sink southward before reaching the Central Rockies and Central Plains by Monday evening. In its wake, below average temperatures and wintry precipiation will be found across the region. The highest snowfall amounts are forecast to occur along the Bighorn Mountains of north-central Wyoming, where over a foot of snow is possible. Other mountain peaks from northwest Montana to Wyoming, as well as the Black Hills of Wyoming and South Dakota, could see snowfall accumulations over 6 inches. Winter Storm Watches and Winter Weather Advisories have been issued. Light snow could extend as far east as northwest Iowa by late Monday evening as cold temperatures enter the Upper Midwest.

Speaking of temperatures, much of the lower 48 will experience below average temperatures over the next few days. The only exceptions will be found across southern Florida and the Western U.S., where above normal temperatures remain locked in place. A few new daily high temperature records are not out of the question for these areas on Sunday.

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 Monday April 19 2021 – Friday April 23 2021

Hazards:

– Heavy rain across portions of the Southeast, Mon-Tue, Apr 19-Apr 20.

– Heavy rain across portions of the Lower Mississippi Valley and the Southern Plains, Fri, Apr 23.

– Flooding possible across portions of the Southeast and the Lower Mississippi Valley.

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

– Much below normal temperatures across portions of the Plains, Tue-Wed, Apr 20-Apr 21.

– Much below normal temperatures across portions of the Central/Southern Plains and the Middle/Lower Mississippi Valley, Wed, Apr 21.

Detailed Summary:

There are multiple hazard areas for heavy rain and below normal temperatures during the medium range forecast period (Monday, April 19 – Friday, April 23). The first area of concern will be across portions of Florida as multiple low pressure disturbances traverse a quasi-stationary front draped across the the central Florida Peninsula. Heavy rain is expected on Monday and Tuesday for the northern and central Florida Peninsula as the front first retreats northward on Tuesday and then drifts slowly southward. Widespread rainfall totals over 3-4 inches are likely. Some lingering heavy rain is also possible during the day Wednesday before a second, stronger cold front pushes in from the northwest bringing drier, continental air southward across the Peninsula by Thursday morning.

The second area of concern is in the central U.S. A shortwave trough will sweep through the Rockies and Plains beginning Sunday. The associated surface cold front may produce some accumulating snowfall in the Northern and Central Rockies on Monday. The heaviest snow totals are not expected to be particularly high and should remain isolated to the peaks of the Wind River Range, Big Horn Mountains, and Front Range. Some snow is also possible eastward into the Central High Plains and Kansas Tuesday morning, but this snow will likely be mixed with rain and any accumulations should remain light.

However, as this system progresses across the central and eastern U.S. on Tuesday and Wednesday, a strong area of high pressure will fill in across the central U.S. This will contribute to much below normal minimum temperatures across most of the Central High Plains Tuesday morning and expand southward to include northern portions of the Southern High Plains and Texas as well as eastward into the Central Plains and Oklahoma for Wednesday morning. Widespread freezing temperatures are likely for northern portions of this area, and vegetation may be sensitive to these temperatures, particularly across central and eastern Kansas as well as southeastern Nebraska.

By Friday, rain chances in the Central and Southern Plains as well as the Middle and Lower Mississippi Valley will rapidly increase as a shortwave approaches from the west and a surface low pressure center develops in the lee of the Rockies. Gulf moisture will return northward behind a lifting warm front and contribute to the development of widespread storms. Current forecasts indicate that portions of eastern Texas and most of Louisiana could receive heavy rain with totals of 1-2+ inches possible, but the area of heaviest rainfall remains uncertain.

Elsewhere, strong ridging along the Pacific coast will lead to above normal highs, particularly for portions of central and southern California on Monday, but the departure from normal and duration is not considered to be hazardous. Some snow showers are possible for eastern portions of the Great Lakes region, New York, and interior New England as the storm system and associated cold front in the central U.S. moves to the east Wednesday and Thursday. Cooler temperatures are expected behind the cold front from the Appalachians northward into the Northeast, but these temperatures should not be well below normal. Cooler temperatures and some mountain snow are are also forecast for Montana on Thursday and Friday as a cold front pushes southeast from Canada, but the temperatures and snow amounts are not expected to be particularly significant at this time.

For Alaska, no weather hazards are currently expected during this forecast period. Above normal temperatures will continue across the North Slope, but are not considered hazardous. Periods of rain and gusty winds are likely for the Aleutian Islands, Alaskan Peninsula, and Kodiak Island Monday through Friday due to the passage of back to back low pressure systems over the Pacific. There is a possibility of more significant rainfall around Wednesday, but there is not currently enough model consensus on coverage or amounts to introduce a hazard area at this time.

(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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