Written by Sig Silber

HEADLINES (Updated 6:43 pm EDT) –

– Winter weather from Northern Rockies to Upper Midwest through Thursday; rain and thunderstorms across Mississippi/Tennessee/Ohio Valleys through Friday

– Cold air dives south through Plains while warm air lingers in the east over next two

– Fire weather threat continues for northern California while Critical Fire Risk develops over Southern Plains

– New system brings heavy snowfall threat to Pacific Northwest and Northern Rockies on 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.

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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.

Directory

CONUS Focal Points

Short Range Focal Points

Short Range Forecast Discussion NWS Weather Prediction Center College Park MD – 415 PM EDT Wed Oct 21 2020

Valid 00Z Thu Oct 22 2020 – 00Z Sat Oct 24 2020

…Winter weather from Northern Rockies to Upper Midwest through Thursday; rain and thunderstorms across Mississippi/Tennessee/Ohio Valleys through Friday…

…Cold air dives south through Plains while warm air lingers in the east over next two days…

…Fire weather threat continues for northern California while Critical Fire Risk develops over Southern Plains…

…New system brings heavy snowfall threat to Pacific Northwest and Northern Rockies on Friday…

A deepening upper-level trough will generate much of the weather that occurs within the CONUS over the next couple of days. An area of low pressure currently stationed over the Front Range will organize and begin moving east tomorrow. In the meantime, it will continue producing heavy snow across the Northern Rockies of Montana and the Dakotas. Winter Storm Watches and Warnings are in effect for those areas. Moderate rainfall and scattered to isolated thunderstorms are expected along the associated warm front as it lifts into the Middle to Upper Mississippi Valley/Great Lakes. Snow will shift eastward into the Northern Plains and Upper Midwest tomorrow as the low pressure system moves into the Mississippi Valley. Rain and thunderstorms will follow the cold front as it tracks across the Midwest and Ohio/Tennessee Valleys on Friday.

A strong area of high pressure will build over the Rockies behind the aforementioned low pressure system. This will filter in cold continental Canadian air into the Plains over the next two days with high temperatures reaching 15-25 degrees below average. Meanwhile warm air will remain to the south of the warm front draped along the midsection of the country and will raise temperatures to 15-20 degrees above average from the Southern Plains to parts of the interior Northeast Thursday and Friday respectively. The threat for fire weather continues over northern California as dry/windy conditions are forecast to persist over the next few days. The above average temperatures over the Southern Plains tomorrow will contribute to the Critical Fire Risk for parts of eastern New Mexico and the Texas panhandle through Friday.

Another low pressure system will enter the Pacific Northwest on Friday. It will bring with it the threat of low-elevation rainfall and heavy snowfall to the Cascades and Northern Rockies. Persistent rain and thunderstorms across Florida may lead to Flash Flooding across the Miami/Ft. Lauderdale area tonight.

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 20 hour animation and some other views can be found here OR SIMPLY CLICK ON THE IMAGE.

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Day 3 – 7 Hazards

Hazards:

Hazards:

– Heavy precipitation across portions of the Northeast, Mon, Oct 26.

– Heavy rain across portions of the Central Plains, the Mid-Atlantic, the Lower Mississippi Valley, the Central Appalachians, the Tennessee Valley, the Great Lakes, the Middle Mississippi Valley, the Northeast, the Southern Plains, and the Ohio Valley, Sun-Mon, Oct 25-Oct 26.

– Heavy snow across portions of the Central Plains, the Central Rockies, the Central Great Basin, the Southern Rockies, the Southern Plains, and the Southwest, Sun-Mon, Oct 25-Oct 26.

– Heavy snow across portions of the Central Plains, the Northern Plains, and the Northern Rockies, Sat, Oct 24.

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

– Much below normal temperatures across portions of the Central Plains, the Great Lakes, the Central Great Basin, the Northern Plains, the Southern Plains, the Northern Rockies, the Central Rockies, the Middle Mississippi Valley, California, the Northern Great Basin, the Upper Mississippi Valley, and the Pacific Northwest, Sat-Wed, Oct 24-Oct 28.

– Much below normal temperatures across portions of the Central Plains, the Central Rockies, the Lower Mississippi Valley, the Central Great Basin, the Southern Rockies, the Middle Mississippi Valley, California, the Upper Mississippi Valley, the Southern Plains, and the Southwest, Mon-Wed, Oct 26-Oct 28.

– Enhanced wildfire risk across portions of California, Sun, Oct 25.

– Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun-Mon, Oct 25-Oct 26.

Detailed Summary:

Early season arctic air is expected to bring record to near record breaking cold temperatures to much of the western and central U.S late this weekend through early next week. The core of the coldest air over the weekend will extend eastward from the Pacific Northwest through the northern Rockies and northern and central Plains states. Temperatures will range from 20-40 degrees below normal, resulting in lows below zero and highs in the teens for parts of the northern high Plains and northern Rockies. The cold weather will not spare the Pacific Northwest, where eastern Washington and Oregon will experience single digit lows in the coldest locations. Needless to say, this will equal or break multiple low temperature records this weekend. Along with the cold temperatures, an upper level disturbance will bring the potential for heavy snowfall to the higher elevations in Montana and Wyoming, with marginally heavy amounts extending eastward into North and South Dakota on Saturday. The heaviest snow potential then drops into the central Rockies on Sunday as the trough deepens and cold air progresses southward.

Much below normal temperatures will continue to advance south and eastward early next week, essentially affecting all of western two-thirds of the country. The air mass will only slowly moderate; widespread temperatures 15-30 degrees normal across much of the western and central U.S. This will likely bring the first freeze of the season to many locations of the south/central Plains. There’s some uncertainty regarding the upper troughing in the Rockies during this period, but the potential exists for heavy snowfall across central and southern Colorado into northern New Mexico on Monday. Another concern, though not specifically depicted on the chart, will be the potential for strong gusty winds late this weekend and early next week, particularly over northern and central California; this could exacerbate the spread of ongoing wildfires.

Deep moisture will pool along the boundary separating the arctic air mass from relatively balmy conditions over the eastern states. Low pressure riding along the front will support a broad area of moderate to heavy rainfall Sunday into Tuesday from the central Plains northeastward through the upper Ohio Valley and northern mid-Atlantic states. Rainfall amounts over this region may range upwards of 1-3 inches and locally higher. As precipitation spreads into New England, there may be enough cold air remaining to support a period of snow over northern/central Maine, but this should change to rain as warm air from the south overspreads the region.

Across Alaska, an area of low pressure lifting into western sections of the mainland will be preceded by a southwesterly flow of very moist Pacific air. Expect heavy precipitation from southeastern portions of the mainland (Prince William Sound eastward) through Yakutat beginning late in the weekend and continuing through Monday. The heaviest precipitation will then spread southward across nearly the entire Panhandle during Monday into Tuesday. Heaviest rainfall will generally be along the coast, with snow over higher elevations.

(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 weekly 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.

New Seasonal Outlook Issued September 17, 2020

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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.

the Central Pacific.	the Eastern Pacific	the Atlantic and the Gulf of Mexico

Atlantic and Gulf of Mexico

And the Eastern 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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