Written by Sig Silber

HEADLINES (Updated 6:59 pm EDT) –

…Widespread weather impacts expected across the Western to Central U.S. over the next two days…The early Season Winter Storm to continue into Wednesday across the Central Rockies into the Central High Plains with heavy snows likely… Heavy Rains and isolated Flash Flooding possible across portions of the Southern to Central Plains Wednesday into Thursday… Much Below Average Temperatures expected across the Central to Southern Plains Wednesday and Thursday… An Elevated to Critical Fire Weather Threat will continue into Wednesday across much of the West Coast…

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 – 324 PM EDT Tue Sep 08 2020

Valid 00Z Wed Sep 09 2020 – 00Z Fri Sep 11 2020

…Widespread weather impacts expected across the Western to Central U.S. over the next two days.…

…The early Season Winter Storm to continue into Wednesday across the Central Rockies into the Central High Plains with heavy snows likely…

…Heavy Rains and isolated Flash Flooding possible across portions of the Southern to Central Plains Wednesday into Thursday…

…Much Below Average Temperatures expected across the Central to Southern Plains Wednesday and Thursday…

…An Elevated to Critical Fire Weather Threat will continue into Wednesday across much of the West Coast…

The early season winter storm affecting the Central Rockies into the Central High Plains will move only very slowly tonight through much of Wednesday, spinning in place across the four corners region. Widespread heavy snows are likely across the Central Rockies and extending into the Central High Plains of southeast Wyoming, the Nebraska Panhandle, eastern Colorado into northeast New Mexico. This system will begin to move more to the northeast on Thursday, with a diminishing heavy snow risk for the Central Rockies and Central High Plains.

To the southeast of the Heavy snow region, heavy rains are likely to develop across areas of West to Southwest Texas Tuesday night into Wednesday morning, expanding northward later Wednesday into Thursday into north central Texas, central Oklahoma and Kansas. Rainfall across these regions has been below average over the past two weeks. This will reduce the potential for flash flooding, although there still is the chance of isolated flooding issues over the next two days given the heavy rain potential.

In addition to the heavy snow and rain threat from the Rockies into the Plains, temperatures are expected to be much below average across these areas over the next two days. High temperatures on Wednesday are expected to be 30 to 35 degrees below average across large portions of the Southern to Central Plains from eastern New Mexico/western Texas, across much of Colorado, Kansas, Nebraska and Wyoming. Temperatures will begin to moderate across these areas on Thursday but remain 20 to 25 degrees below average

Strong winds on the western side of the winter storm have brought dangerous and life threatening fire weather conditions to large portions of western U.S. from the desert Southwest, through the Great Basin, much of California into the Pacific Northwest. An elevated to critical fire weather threat will continue across much of these area through Wednesday. Diminishing winds are possible across these area by Thursday, bringing some relief to the ongoing fires and fire weather threat.

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:

– Heavy rain across portions of the Central Appalachians, the Tennessee Valley, the Southern Plains, the Southern Appalachians, the Great Lakes, and the Ohio Valley, Sun-Mon, Sep 13-Sep 14.

– Heavy rain across portions of the Mid-Atlantic, the Northeast, and the Great Lakes, Sun, Sep 13.

– Heavy rain across portions of the Central Plains, the Middle Mississippi Valley, the Upper Mississippi Valley, and the Northern Plains, Fri-Sat, Sep 11-Sep 12.

– Heavy rain across portions of the Southeast, the Mid-Atlantic, and the Southern Appalachians, Sun-Tue, Sep 13-Sep 15.

– Flooding possible across portions of the Southern Plains.

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

– Much above normal temperatures across portions of the Central Great Basin, the Northern Plains, the Northern Rockies, California, the Northern Great Basin, and the Pacific Northwest, Fri-Mon, Sep 11-Sep 14

– Much above normal temperatures across portions of California, the Pacific Northwest, and the Northern Great Basin, Fri-Sat, Sep 11-Sep 12.

– Much above normal temperatures across portions of the Central Plains, the Northern Plains, and the Northern Rockies, Sat-Mon, Sep 12-Sep 14.

– Heavy rain across portions of mainland Alaska and the Aleutians, Sun-Mon, Sep 13-Sep 14.

– High winds across portions of mainland Alaska and the Aleutians, Sun-Mon, Sep 13-Sep 14.

Detailed Summary:

The theme of the medium range period (Fri Sept. 11 – Tues Sept. 15) can be summarized in one word: transition. After the significant cold snap and heavy snow blanketing the Rockies through mid-week, the upper low is forecast to make its way east into the Plains to start the weekend, then open up into a shortwave trough over the Great Lakes by Sunday. Friday will likely still be quite cool in parts of the central Plains and Rockies with moderating temperatures into the weekend. The Pacific Northwest continues to deal with well above normal temperatures into the start of the weekend but a new storm system approaching the region ushers in a welcomed cooler temperature regime early next week. Unfortunately, the warm start to the week also means favorable fire weather conditions with dry and hot conditions expected early in the period. By early next week, upper level ridging returns to the Intermountain West, resulting in the arrival of much above normal temperatures across the northern Rockies and Plains. The East Coast may see a slight reprieve from being at the mercy of a large subtropical high over the northwest Atlantic as a pair of cold fronts swing through the Northeast early next week, but in general, the upper level ridge looks to stick around just offshore, keeping warm and humid conditions in the forecast for most of the period in the Southeast.

Precipitation-wise, a low pressure system swinging through the Midwest may generate heavy rainfall amounts across the region Friday and into early this upcoming weekend. In the Southeast, southeasterly flow tapping into Atlantic and Gulf moisture sets up a scenario where several days worth of precipitation is likely in the southern Appalachians. It is possible rainfall could become excessive at times, which combined with above normal soil moisture content could lead to flooding into early next week. Another area that could experience upslope flow is West Texas where low level winds and elevated moisture levels could lead to persistent periods of rainfall this weekend and into early next week.

For Alaska, a potent low pressure system over the North Pacific will deepen more as the storm moves passes over the Aleutians and into the Bering Sea early next week. The deep low is forecast to produce an area of high winds over parts of the Aleutian Islands and the Alaska Peninsula on Sunday and Monday. In addition, a plume of moisture associated with the storm moves into parts of the the Aleutians and the southwest mainland. The system will produce an area of heavy rain from parts of the Alaska Peninsula and the Southwestern mainland that could extend into the Gulf of Alaska Coast on Monday, but spread in ensemble guidance makes the precipitation amounts uncertain at this time there.

(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.

During the summer we might add some drought information in this section.

New Seasonal Outlook Issued August 20, 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

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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