Written by Sig Silber

HEADLINES (Updated 4:41 pm EDT) –

– There is an enhanced risk of severe thunderstorms and a slight risk of excessive rainfall over parts of the Upper/Middle Mississippi Valley

– Potentially record breaking heat in the West

– Critical conditions for wildfires persist across the West, Northern/Central Rockies/Plains

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 – 356 PM EDT Sat Sep 05 2020

Valid 00Z Sun Sep 06 2020 – 00Z Tue Sep 08 2020

…There is an enhanced risk of severe thunderstorms and a slight risk of excessive rainfall over parts of the Upper/Middle Mississippi Valley…

…Potentially record breaking heat in the West.…

…Critical conditions for wildfires persist across the West, Northern/Central Rockies/Plains…

A developing strong storm over the Northern Plains will produce showers and thunderstorms overnight Saturday and continue into the Great Lakes on Sunday into Monday morning. The SPC has issued an enhanced risk of severe thunderstorms over Upper/Middle Mississippi Valley through Sunday morning with a slight risk surrounding the area. The main hazards associated with the severe thunderstorms are strong thunderstorm wind gust, large hail with a 10 % probability of two inches or greater. The WPC has issued a slight risk of excessive rainfall over the most of the same area through Sunday morning. The heavy rain associated with the severe thunderstorms will produce mainly localized scattered areas of flash flooding.

Strong high pressure over Western Canada begin to move over the Northern High Plains on Sunday into Monday. Upslope flow associated with the high pressure will aid in producing rain over the Northern High Plains expanding into the Northern Rockies and the Northern High Plains on Monday that will expand into the Upper Midwest by Monday evening. Cold air will move over the Upper Midwest bringing much below average temperatures for the next several days.

Meanwhile, scattered showers and thunderstorms will be possible through the weekend along the Gulf Coast and across parts of Texas and Florida as the front slowly descends from the north and slows. Across the West, hot and dry conditions will persist thanks to the ridge parked over the western states. Daily temperatures for some locations may reach 20 to 30 degrees above average, which would be daily highs in the upper 90s to triple digits. These values may tie or establish new daily records. Lows will be in the upper 70s in Florida this weekend which may break records across the state. Overnight low temperatures will struggle to cool down, relative humidity/dewpoints will likely not be able to recover. These means that fuels (grass, trees, shrubs, dried leaves etc) will be very dry and slightest of sparks could cause a wildfire that quickly spreads out of control. The fire risk remains elevated as dry and windy conditions will continue for the region through the weekend. A vast portion of California, Great Basin, Intermountain West and the Northern/Central High Plains have Excessive Heat Warnings, Heat Advisories and Red Flag Warnings in effect. Several large wildfires across the region are also causing areas to have hazy skies and reduced/poor air quality.

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 Plains, the Upper/Middle Mississippi Valley, the Great Lakes, and the Ohio Valley, Mon, Sep 7.

– Heavy rain across portions of the Central/Southern Plains, and the Middle/Lower Mississippi Valley, Tue, Sep 8.

– Heavy rain across portions of the Great Lakes and the Southern Plains, Wed, Sep 9.

– Heavy snow across portions of the Northern/Central Plains, the Rockies, and the Central Great Basin, Mon-Wed, Sep 7-Sep 9.

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

– High winds across portions of the Central/Southern Plains, the Central Great Basin, the Central/Southern Rockies, California, and the Southwest, Tue-Wed, Sep 8-Sep 9.

– Much above normal temperatures across portions of California, the Central Great Basin, the Pacific Northwest, and the Southwest, Mon-Tue, Sep 7-Sep 8.

– Much below normal temperatures across portions of the Plains, the Rockies, the Mississippi Valley, the Central Great Basin, the Great Lakes, the Northern Great Basin, and the Southwest, Mon-Thu, Sep 7-Sep 10.

– Heavy rain across portions of mainland Alaska, Mon, Sep 7.

– Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Tue-Wed, Sep 8-Sep 9.

– High winds across portions of mainland Alaska, Mon-Tue, Sep 7-Sep 8.

Detailed Summary:

Upper-level high over the over the West Coast will weaken as an upper-level low dives southward out of Western Canada on Monday into Tuesday to the four corners region. The upper-level high will allow temperatures to become 12 degrees or greater above normal over parts of the Great Basin into the Northwest and most of California on Monday.

In contrast, as the upper-level low digs southward to the four corners region by Tuesday and Wednesday. The associated front will race southward to Northeastern Mexico by Wednesday. Cold air behind the front will aid in allowing temperatures to become 12 degrees or greater below normal over parts of the Northern High Plains on Monday expanding into the Northern/Central Plains and the Central Rockies by Tuesday. The below normal temperatures will continue to expand southward into the Southern Plains/Rockies by Wednesday into Thursday as the temperatures will start to moderate by Friday. The temperatures will be cold enough to bring snow to the highest elevations of the Northern/Central Rockies into parts of the Southern Rockies on Monday into Wednesday.

Furthermore, heavy rain will develop along the cold front while moving southward over the Great Lakes into the Middle Mississippi Valley on Monday. On Tuesday, the heavy rain will move to, mainly, the Southern Plains as the front continues to settle southward. By Wednesday, the heavy rain will settle to parts of the Southern Plains/South-Central Texas. In addition on Wednesday, heavy rain will return to the Great Lakes near the boundary. On Thursday into Friday there is too much uncertainty where or if there will be heavy rain over the CONUS.

High pressure at the surface over Northwest Canada will settle over the Norther High Plain/Northern Rockies on Tuesday and into the Central Plains on Wednesday and Thursday before beginning to weaken on Friday. The strong high pressure will aid in producing strong wind over the Central/Southern Plain and Rockies and extending into parts of the Southwest and Southern California through Wednesday.

For Alaska, deep low pressure over the Bering Sea on Monday will move northward into the Far Northwestern mainland by Tuesday. The deep low will bring strong wind to the Southwestern portion of the mainland on Monday and Tuesday when the wind will be 35 knots or greater. The low will aid in producing an area of heavy rain over parts of Southwestern mainland on Monday. In addition, the storm will bring a plume of moisture into parts of the Gulf of Alaska Coast producing an area of heavy rain over parts of the Northeast Gulf of Alaska Coast eastward to near Yakutat from Tuesday into Wednesday. After Tuesday high pressure will build over the Bering Sea and expand onto the mainland through Friday.

(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

We will resume more detailed coverage when the summer is over. 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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