Written by Sig Silber

HEADLINES (Updated 7:32 pm) –

– Remnants of tropical cyclone Laura will track eastward through the lower Ohio Valley and Mid-Atlantic states with heavy rainfall, gusty winds, and severe weather possible Friday night and Saturday

– Severe storms and flash flooding possible from the Upper Midwest to the Great Lakes late Friday

– Triple digit heat likely across Texas, with a wildfire threat continuing for parts of the West

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 – 353 PM EDT Fri Aug 28 2020

Valid 00Z Sat Aug 29 2020 – 00Z Mon Aug 31 2020

…Remnants of tropical cyclone Laura will track eastward through the lower Ohio Valley and Mid-Atlantic states with heavy rainfall, gusty winds, and severe weather possible Friday night and Saturday…

…Severe storms and flash flooding possible from the Upper Midwest to the Great Lakes late Friday…

…Triple digit heat likely across Texas, with a wildfire threat continuing for parts of the West…

Severe storms and flash flooding possible from the Upper Midwest to the Great Lakes late Friday

Severe weather and flash flooding will not only be confined to Hurricane Laura as a pair of frontal boundaries trigger strong thunderstorms and heavy rainfall. Today, a Slight Risk for severe weather extends from the northern High Plains and Great Lakes to the Northeast. An Enhanced Risk for severe storms are located over western South Dakota and the Northeast. There is also an opportunity for excessive rainfall as Slight Risks are located over portions of the Midwest and eastern Ohio Valley. By Friday, the severe threat shifts slightly farther south through the eastern Corn Belt while the potential for flash flooding encompasses much of the Great Lakes.

Meanwhile, a frontal system moving to the north is expected to produce showers and thunderstorm as it moves across the northern Great Lakes/Upper Midwest Friday night. Some of these storms are expected to become strong to severe and may produce periods of heavy rain. This system is expected to move across the Northeast on Saturday and help move the remnants of Laura out into the western Atlantic by early Sunday.

The trailing end of this boundary is expected to stall near the Ozark region and Oklahoma, where it is forecast to help produce showers and thunderstorm through the weekend. Some of the these storms are forecast to become strong to severe and produce periods of heavy rain, resulting in localized flooding concerns.

South of the front, above-normal temperatures are expected to persist, with daytime temperatures reaching near or above 100 degrees across much of Texas through the weekend. Heat advisories are in effect across much of Texas, as well as portions of southern Oklahoma and the ArkLaTex region, where heat indices are expected to climb well above 100 — resulting in dangerous conditions.

The potential for showers and thunderstorms is expected to increase through the weekend across portions of Arizona into the lower Colorado Basin. While this will likely bring welcome rains to the dry conditions across the Southwest, these storms may also bring localized flash flooding concerns as well.

A cold front is expected to offer little relief to the dry conditions further to the north as it moves across the Pacific Northwest into the northern Rockies, and Northern California on Saturday. Gusty winds, with little to no precipitation, are expected to contribute to elevated to critical fire weather conditions from western Washington and Oregon into the northern Rockies on Saturday.

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 Lower Mississippi Valley, the Tennessee Valley, the Middle Mississippi Valley, the Southern Plains, and the Ohio Valley, Sun-Tue, Aug 30-Sep 1.

– Heavy rain across portions of the Great Lakes, the Northeast, and the Southern Plains, Wed-Thu, Sep 2-Sep 3.

– Flooding possible across portions of the Southern Appalachians, the Mid-Atlantic, and the Central Appalachians.

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

– Excessive heat across portions of the Southern Plains, Mon-Fri, Aug 31-Sep 4.

– Much below normal temperatures across portions of the Central Rockies, the Central Great Basin, the Northern Rockies, the Northern Great Basin, and the Northern Plains, Mon, Aug 31.

– Much below normal temperatures across portions of the Northern/Central Great Basin, the Northern Plains, and the Northern/Central Rockies, Sun-Mon, Aug 30-Aug 31.

– Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Mon, Aug 31.

– Heavy rain across portions of the Alaska Panhandle, Mon-Tue, Aug 31-Sep 1.

Detailed Summary:

Canadian air will bring a brief cool down to parts of the Northern Rockies as an upper-level trough tracks across the Rockies this weekend. Temperatures will rebound to near normal by beginning of the week; while South Texas will continue to have heat and humidity- heat indices could exceed 110 degrees through the medium-range period. Portions of Louisiana impacted by tropical cyclone Laura will continue to have flooding. A frontal boundary lifting into the central U.S. will provide a focus for heavy rain Monday and Tuesday from northern Texas to Middle Mississippi Valley/Midwest. Further north, a cold front will sweep across the northern tier states into the Great Lakes/Northeast region. Heavy rain will develop near the lower lakes and New York Wednesday and Thursday.

A deep plume of tropical moisture from the remains of the tropical cyclone Bavi will be drawn into a strong low pressure system tracking across the Gulf of Alaska. Heavy rain will spread along and north of the low track, impacting the southern Mainland on Monday and the panhandle Monday and Tuesday. A few light showers may linger into Wednesday across the Southeast.

(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

This is now beyond the time of the year we pay special attention to Tropical Events other than the Western Pacific.

So 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.

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

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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