Written by Sig Silber

HEADLINES (Updated 5:54 pm EDT) –

– Sally to pose a life-threatening flood threat along the central Gulf Coast, High Risk for flash flooding on Tuesday

– Cold front sparks showers and thunderstorms from the Tennessee Valley to the Northeast this evening, cooler and drier conditions arrive across the Great Lakes and Northeast early week

– Hot temperatures in the northern Plains on Monday; wildfires and poor air quality continue over parts of the interior Pacific Northwest/Northern California and the Great Basin

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 – 414 PM EDT Sun Sep 13 2020

Valid 00Z Mon Sep 14 2020 – 00Z Wed Sep 16 2020

…Sally to pose a life-threatening flood threat along the central Gulf Coast, High Risk for flash flooding on Tuesday…

…Cold front sparks showers and thunderstorms from the Tennessee Valley to the Northeast this evening, cooler and drier conditions arrive across the Great Lakes and Northeast early week…

…Hot temperatures in the northern Plains on Monday; wildfires and poor air quality continue over parts of the interior Pacific Northwest/Northern California and the Great Basin…

Tropical Storm Sally is in the eastern Gulf of Mexico this afternoon and has its sights on the central Gulf Coast where it is forecast to make landfall Monday night. No matter whether Sally makes landfall as a tropical storm or a hurricane, the water-related hazards are expected to be biggest threats to life and property. The latest Excessive Rainfall Outlook for Monday shows a Moderate Risk for flash flooding from the mouth of the Mississippi River extending east along the coast to the Alabama/Florida border. Tuesday features a rare Day 3 High Risk area in eastern Louisiana, southern Mississippi, and far southwest Alabama. The latest precipitation forecasts calls 10-20 inches of rain over the central Gulf Coast through Wednesday night with locally high amounts possible where the heaviest rain bands set up. Locations just outside of the High Risk area are also at risk for prolific rainfall rates to could lead to life threatening flooding. Other hazards Sally looks to produce include life threatening storm surge, battering surf, tropical storm force winds, and a chance for tornadoes. Please see the latest advisory from the National Hurricane Center for additional and updated information across this area. Residents within Sally’s reach should monitor the storm’s progress and follow the advice of local officials.

Meanwhile, showers and thunderstorms are forming single file along a long cold front that extends from New England to the Mid-South. There remains a Slight Risk for excessive rainfall in the Tennessee Valley as thunderstorms could cause localized areas of flash flooding this evening. The front will usher in cooler and drier conditions across the Great Lakes and Northeast on Monday as high pressure builds in overhead. The front will inch south across the Southeast on Monday with part of the front becoming stationary over the Deep South through Tuesday. By Tuesday, almost the entire Eastern Seaboard is forecast to experience below normal high temperatures (the exception being the Florida Peninsula). The cold front does push through the Southern Plains providing west Texas with below normal temperatures through Tuesday.

Out West, an upper-level ridge over the Intermountain Region continues to support the ongoing wildfires and poor air quality. As a result, dense smoke advisories and air quality alerts are posted over the Pacific Northwest, parts of California, and parts of the Great Basin. As the ridge moves east on Monday, so does the the dome of above normal temperatures as the Northern Plains get the brunt of the heat. Highs in parts of eastern Montana could reach the mid 90s. Lastly, the fire weather forecast for Sunday evening remains at critical to elevated levels in portions of the West. An approaching Pacific system will bring with it an increase in humidity levels and a chance for beneficial rainfall to the Pacific Northwest late Monday into Tuesday, but much of California and the Great Basin will remain dry and breezy. This has led to yet another elevated risk for fire weather across the Great Basin and northern Rockies on Monday.

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 Southeast, the Lower Mississippi Valley, the Southern Plains,

and the Tennessee Valley, Wed-Fri, Sep 16-Sep 18.

– Heavy rain across portions of the Lower Mississippi Valley and the Southern Plains, Mon-Tue, Sep

14-Sep 15 and Thu-Fri, Sep 17-Sep 18.

– Heavy rain across portions of the Southeast and the Lower Mississippi Valley, Mon-Fri, Sep 14-Sep 18.

– Heavy rain across portions of the Southeast, Mon-Tue, Sep 14-Sep 15.

– Much above normal temperatures across portions of the Central Plains and the Northern Plains, Mon-Tue, Sep 14-Sep 15.

– Much above normal temperatures across portions of the Central Plains, the Upper Mississippi Valley, and the Northern Plains, Tue-Wed, Sep 15-Sep 16.

– Heavy rain across portions of mainland Alaska and the Aleutians, Mon-Tue, Sep 14-Sep 15.

– Heavy rain across portions of mainland Alaska, Tue-Wed, Sep 15-Sep 16.

Detailed Summary:

The spotlight during the medium range (Mon Sept. 14 – Fri Sept. 18) will be on the Gulf Coast as Tropical Depression Nineteen is expected to track into the eastern Gulf of Mexico. As of this afternoon, the NHC currently has T.D. Nineteen becoming a tropical storm as it approaches the Gulf Coast. Environmental conditions are favorable (abnormally warm sea surface temperatures/upper level anticyclone overhead) for this disturbance to organize and strengthen before it reaches the central Gulf Coast. While impacts such as winds and surf are unclear given the uncertainty of development, intensity, and track, an abundance of tropical moisture will be available with this feature. The concerning aspect of this tropical wave is it becomes caught in a weak steering flow pattern as a ridge develops over the west-central U.S. and a weak ridge sits over the Southeast. This could lead to several days of showers and thunderstorms containing torrential downpours and the potential for the training of convection from the Florida Panhandle on west to southern Louisiana. Copious amounts of rainfall are possible as a result with totals in excess of 10″ possible in areas where training convection occurs. Eventually, an upper trough passing through the Great Lakes pushes a cold front south and finally allows a path for the storm to head north into the Tennessee Valley late week. The axis of heavy precipitation by late next week will be dependent upon the exact timing of the front, but it should force the tropical moisture north and lead to the opportunity for soaking rains into the Mid-South and perhaps the southern Appalachians as well.

Elsewhere, temperatures will remain hot for a couple days across the northern and central High Plains due to upper level high pressure over the Rockies and the Great Plains. The heat does not last long, however, as a second injection (in as many weeks) of below normal temperatures returns to these regions. Compared to the most recent cold blast, this will seem more like a pleasant shot of October-like temperatures rather than the frigid and snowy regime from earlier this week. In addition, soaking rainfall may develop in parts of South Texas both at the start period as a weak mid-level circulation center over the western Gulf of Mexico funnels tropical moisture ahead of an approaching cold front. The front should then become stationary and trigger additional showers and thunderstorms the second half of the week. In the West, guidance continues to indicate an upper-level trough ushers in beneficial moisture and precipitation to the wildfire-ravaged portions of the Northwest early next week. The amounts will need to be closely monitored, because while precipitation is certainty welcomed, too much in a short time span could give way to some localized debris flows in burn scarred areas.

In Alaska, the model trends continue to support a more amplified and slower pattern, especially through the first half of the week. The result is guidance holding the large upper low back in the Aleutians through early week and a strong ridge forming along the southern coast. The storm system is likely to produce plenty of precipitation, rough seas, and gusty winds most notably throughout the Aleutians and into far western Alaska. Precipitable water levels are likely to be roughly 2-3 standard deviations above normal as the front swings through early next week and rainfall rates could be excessive in spots. There is still plenty of spread in ensemble guidance making for a low confidence forecast beyond day 5, but guidance does suggest the potential for a new frontal system to swing south of the Aleutians and could introduce a wetter pattern along the Gulf Coast the second half of the week. Ensemble guidance spread remains high however, and thus no hazards have been posted at this time.

(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

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

– Return to Directory

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

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