LIVE ALL WEEK: Severe Weather Events Week Of 23 Sept 2019

Written by Sig Silber

Updated at 5:30 p.m. EDT September 28, 2019 to focus on potenially historical early winter storm.

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 and continually update. Please pay attention to the Mesoscale Events maps — Mesoscale Events are potentially life-threatening situations.

Focal Points

Short Range

…Major winter storm to bring heavy snow and high winds to parts of the Northern Rockies…
…Much below average temperatures across the Northwest, with much above average temperatures east of the Rockies…
…Heavy rainfall and severe weather possible across parts of the north and central U.S. through Monday..

Click here for the latest complete NWS/WPC Short Range Discussion. From today’s afternoon discussion:

A major to potentially historic early season winter storm is ongoing today across parts of the Northern Rockies as an anomalous upper level low pressure system rotates aloft. Heavy snowfall, strong winds, and potential blizzard conditions will continue across the Northern Rockies through Sunday. Widespread winter storm warnings and advisories are in effect from the interior Pacific Northwest through western Montana and northwest Wyoming. As much as 1 to 3 feet (locally more) of snowfall is possible, especially across western Montana which would create dangerous to impossible travel conditions across the region. This system will also usher in a very cold airmass, at least for September standards, with daytime highs 20 to 30+ degrees below average across much of the Northwest. Many daily record low maximum temperature records are possible through Monday, especially across the Northern Great Basin/Rockies, and California.

Day 3 – 7 Hazards. (will not update until Monday)

– Heavy rain across portions of the Plains, the Upper/Middle Mississippi Valley, the Great Lakes, the Southern Rockies, and the Southwest, Mon-Thu, Sep 30-Oct 3.
– Flooding possible across portions of the Central Plains, the Upper/Middle Mississippi Valley, and the Great Lakes.
– Flooding occurring or imminent across portions of the Northern/Central Plains and the Upper/Middle Mississippi Valley.
– Much above normal temperatures across portions of the Northern/Central Plains, the Upper/Middle Mississippi Valley, and the Great Lakes, Mon, Sep 30.
– Much above normal temperatures across portions of the Middle/Lower Mississippi Valley, the Great Lakes, the Ohio Valley, the Tennessee Valley, the Central/Southern Appalachians, the Mid-Atlantic, and the Southeast, Mon-Fri, Sep 30-Oct 4.
– Much below normal temperatures across portions of the Northern/Central Plains, the Central Great Basin, the Northern/Central Rockies, California, the Northern Great Basin, and the Pacific Northwest, Mon-Thu, Sep 30-Oct 3.
– Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Mon-Tue, Sep 30-Oct 1.

Click here for the latest complete Day 3 -7 Hazards forecast which updates only on weekdays.

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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

This is the time of the year we pay special attention to Tropical Events

Here is a different look at the overall situation but it is a Google Product, not a NHC Product, so it is unofficial and may not always be totally accurate. The advantage of this product is you can zoom in to see the land areas that may be impacted:

You can use the + and – to zoom in or out and you can scroll the map. I recommend that you first look at the bottom of the map for where you can click to see the full map meaning a large version of the map and then use the “+” to zoom in to areas along the track where you have an interest.

First looking at the Atlantic and the Gulf of Mexico

Switching to the Eastern Pacific

And the Central Pacific.

Updates on individual named storms can be obtained here.

And the Western Pacific

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 part 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.

For the Day 2 Outlook click here. For Day 3, click here. For Days 4 – 8 click here. An explanation of the risk codes used can be found 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.

Or for the Day 2 Fire Outlook click here. For the Day 3 – 8 Fire Outlook click here.

Now the Day 3 – 7 Hazards Outlook

The orange and red outlined areas are what is of 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.

Now to our More Detailed 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.

In and of itself Atmospheric Rivers are not a definitive predictor of extreme weather but it shows where concentrated “rivers” of moist air are forecast to be impacting North America and that is part of the equation for severe weather.

This view provides a better view of the Northeast, the Antilles and also Europe.

Here are two satellite images.

This is a little different than the AR as it shows all Liquid Water not just thick streams of moisture. Thus it shows more activity than the AR graphic. But if you try to line the two up, you will easily be able to see where the AR is on this graphic. The gray areas are where different satellite images are pieced together to provide a wide view.

And the East Coast

These are a little different then the AR imagery as this shows clouds and AR shows streams of moisture in the atmosphere.

You have to really study this graphic to see the outline of CONUS.

Here is the web site where this set of images can be found.

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.

As of this evening, we see for Day 7 a clear North/South Divide. It will be Hot south of that boundary.

Day 3 Above, 6 Below	Day 4 Above,7 Below	Day 5 Above.

The above is an advanced look. Our most recent 25 Day Intermediate-Term Forecast might provide additional information. The URL for that report changes each Monday so you can find it on the Econintersect.com website or consult the Directory which can be accessed here.

Here are the precipitation forecasts. First the cumulative for Days 1 – 3

This pretty much corresponds to the discussion above.

Then cumulative for Days 1 – 5

This represents five days of precipitation rather than three days as shown in the earlier graphic.

Then cumulative for Days 1 – 7

The areas that have cumulative seven-day precipitation increase. You can see where QPF is accumulating.

Remember the commentary is generally as of last Night unless updated which is indicated in the lede paragraph. The graphics auto-update so the commentary may not be up-to-date beyond the initial date of publication.

Heat continues being a hazard.

Looking ahead to next week.

Usually, nothing shows in this graphic for the following week as it is usually too far out to be forecasting severe weather. But this graphic auto-updates.

Current watches, warnings, and advisories issued by the agencies of the National Weather Service. Hazards should show up in the various maps but the below links will take you to all outstanding watches and warnings in each category which may include some categories not covered in the various maps or difficult to find. So if there is a category of interest, click on the appropriate link below.

Below you will see a number of different maps which 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 are 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.

Convective Outlooks
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.
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 thunderstorm 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