Written by Sig Silber

HEADLINES (Updated 4:45 pm EDT) –

– Hurricane Laura continues north through the Lower Mississippi Valley tonight, and into the Mid-South on Friday

– Severe storms and flash flooding possible from the Northern Plains and Great Lakes into the Northeast tonight and Friday

– Summer sizzle continues across much of the country, raging wildfires continue in 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.

Please share this article – Go to the very top of the page, right-hand side for social media buttons. Also, feel free to send this email to anyone you feel will benefit from it.

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 – 409 PM EDT Thu Aug 27 2020

Valid 00Z Fri Aug 28 2020 – 00Z Sun Aug 30 2020

…Hurricane Laura continues north through the Lower Mississippi Valley tonight, and into the Mid-South on Friday…

…Severe storms and flash flooding possible from the Northern Plains and Great Lakes into the Northeast tonight and Friday…

…Summer sizzle continues across much of the country, raging wildfires continue in the West…

Laura made landfall last night as a dangerous category 4 hurricane packing maximum sustained winds of 150 mph. Laura will continue its trek north and northeast tonight with tropical storm force winds and torrential rainfall spreading across the Middle Mississippi/Tennessee Valley. Additional power outages and tree damage is likely to occur farther north across Arkansas. Also, there are a pair of Moderate Risks for flash flooding; one over much of Arkansas, and another over southeast Louisiana. A Slight Risk for flash flooding stretches up the Mississippi River from New Orleans into southern Missouri. The threat for severe weather and flash flooding continue tonight through Saturday along Laura’s path from the Lower/Middle Mississippi Valley through the Tennessee/Ohio Valley and into the Mid-Atlantic. Laura will quickly weaken to a tropical depression and then a post-tropical storm Friday night into Saturday morning. It will still generate heavy showers and storms across the Appalachians and eventually into parts of the Mid-Atlantic.

Severe weather and flash flooding will not only be confined to Hurricane Laura, but also to the northern tier states as a pair of frontal boundaries trigger strong thunderstorms and heavy rainfall. Tonight, a Slight Risk for severe weather extends from the Northern Plains and Great Lakes to the Northeast. An Enhanced Risk for severe storms was issued for South Dakota and the Northeast. There is also an opportunity for excessive rainfall as Slight Risks are located over portions of the Northern Plains, Great Lakes and Appalachian plateau. 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.

Temperature-wise, a late season heat wave in the Midwest will stick around for at least one more day (Friday) with high temperatures in the mid-upper 90s. The heat wave will soon come to an end as a cold front ushers in a refreshing shot of Canadian air this weekend. Abnormally hot conditions will also materialize over the Southwest, central High Plains and Mid-Atlantic where a handful of daily record highs could be broken. Excessive Heat Warnings remain in effect along the southern Colorado River Basin and across much of southern Arizona. Friday’s hottest temperatures will occur in west Texas as daily max temps reach the triple digits and even challenge daily record highs. Through Saturday, record warm lows will be common across the Southeast and Mid-Atlantic. The western U.S. wildfires look to continue with slightly less dry thunderstorm activity then recent days; a welcome development for so many in the West.

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.

– Return to Directory

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 Central Plains, the Lower Mississippi Valley, the Tennessee Valley, the Middle Mississippi Valley, the Southern Plains, and the Ohio Valley, Tue-Wed, Sep 1-Sep 2.

– Heavy rain across portions of the Southern Appalachians, the Mid-Atlantic, the Central Appalachians, the Upper Mississippi Valley, and the Tennessee Valley, Sun-Mon, Aug 30-Aug 31.

– Heavy rain across portions of the Northeast, the Central Appalachians, the Mid-Atlantic, the Southern Appalachians, the Great Lakes, and the Ohio Valley, Mon-Wed, Aug 31-Sep 2.

– Flooding possible across portions of the Lower Mississippi Valley, the Central Appalachians, the Middle Mississippi Valley, the Mid-Atlantic, the Southern Appalachians, and the Southern Plains.

– Flooding likely across portions of the Lower Mississippi Valley and the Southern Plains.

– 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.

– Excessive heat across portions of the Southern Plains, Sun-Wed, Aug 30-Sep 2.

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

– Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Sun-Mon, Aug 30-Aug 31.

– Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Mon-Wed, Aug 31-Sep 2.

– High winds across portions of mainland Alaska and the Aleutians, Sun-Mon, Aug 30-Aug 31.

Detailed Summary:

Laura made landfall as a high-end category 4 hurricane early this morning (Aug 27th) in southwest Louisiana and is forecast to eventually curve to the northeast on Friday. Flooding will persist in Laura’s wake through at least Monday along the Lower/Middle Mississippi Valley while heavy rain spreads along its track across parts of the Tennessee Valley and Mid-Atlantic regions Sunday and Monday. If Laura is able to maintain a well-defined circulation while traversing the interior Deep South toward the Mid-Atlantic, a period of gusty winds and heavy rainfall could impact parts of the Mid-Atlantic on Saturday. In addition to Laura, a low pressure system is expected to develop along a nearly stationary front draped across the northern states. This may provide a focus for heavy rainfall, especially for parts of the Upper Mississippi Valley. For more information about Tropical Cyclone Laura visit the National Hurricane Center’s website: www.nhc.noaa.gov.

Cool, Canadian air will settle into the Northern Rockies and adjacent High Plains as an upper-level trough tracks across the Rockies this weekend. Much below normal temperatures can be expected Sunday into Monday, before moderating back to near normal. South Texas will have persistent heat and humidity- heat indices could exceed 110 degrees through the medium-range period.

High winds and heavy rain will impact portions of the Aleutians, southwest, south-central and southeast Alaska as a potent low pressure system draws in moisture from Tropical Storm Bavi in the Western Pacific. This system will produce gale to possibly storm-force winds across the eastern Aleutians and southwestern mainland Alaska on Sunday and Monday. Although the exact track of the center low is not certain, it will likely favor a southern track across the region. This would spread heavy rainfall along the southern mainland coast around Anchorage on Saturday and Sunday and then to the panhandle Monday and Tuesday with lingering rain into Wednesday.

(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.

– Return to Directory

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

– Return to Directory

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

– Return to Directory

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

– Return to Directory

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.

– Return to Directory

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.

– Return to Directory

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.

– Return to Directory

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

– Return to Directory