Written by Sig Silber

HEADLINES (Updated 6:05 pm EDT) –

“–Thunderstorms with heavy rain are possible across much of the central and eastern U.S., with severe weather expected in the Northern Plains to Upper Mississippi Valley

– Record heat will be widespread across the West Coast to the Southern Plains

– Fire danger is expected for the Great Basin into the Rockies”

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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CONUS Focal Points

Short Range Focal Points

Short Range Forecast Discussion NWS Weather Prediction Center College Park MD – 413 PM EDT Thu Aug 13 2020

Valid 00Z Fri Aug 14 2020 – 00Z Sun Aug 16 2020

…Thunderstorms with heavy rain are possible across much of the central and eastern U.S., with severe weather expected in the Northern Plains to Upper Mississippi Valley…

…Record heat will be widespread across the West Coast to the Southern Plains…

…Fire danger is expected for the Great Basin into the Rockies…

Over the next couple of days, a frontal system moving across the Dakotas into the Midwest will help cause thunderstorms in those areas. The Storm Prediction Center has delineated Enhanced Risks of severe weather through tonight for portions of the Northern High Plains and northern Minnesota, and across much of Minnesota tomorrow. Strong winds and hail are the main threats, but tornadoes cannot be ruled out. Additionally, rainfall totals of 1 to 3 inches are expected, with locally higher amounts possible. This could lead to flash flooding, and Slight Risks of excessive rainfall are in place for north-central parts of the country.

Scattered thunderstorm activity is also forecast for the Lower/Middle Mississippi, Tennessee, and Ohio Valleys, as well as the Southeast and Mid-Atlantic through Saturday. While these storms are not expected to be severe, flash flooding could be a threat with locally heavy rain. Slight Risks of flash flooding as well as Flash Flood Watches are in effect for western portions of the Ohio Valley and across much of the Mid-Atlantic through tonight. Locally higher rainfall totals could also occur for eastern Oklahoma/western Arkansas. On Friday and into Saturday, the Central and Southern Appalachians eastward have Slight Risks of flash flooding in place as upslope flow could enhance rainfall totals in the mountains, and much of the Carolinas/Mid-Atlantic have seen heavy rainfall recently so the ground is saturated.

Meanwhile farther west, hot and mainly dry conditions are expected, though afternoon isolated storms could occur in the Southwest to the Southern/Central High Plains. Excessive Heat Warnings and Heat Advisories stretch from California through the Desert Southwest and into the Southern Plains, as temperatures above 100 degrees will be widespread, with temperatures over 110 degrees in the Desert Southwest. Dozens of record high minimum and maximum temperatures should be tied or set for those areas through the weekend (and beyond). After a cool day today in the northwestern U.S., the upper-level ridge building will mean hot temperatures spread to the Pacific Northwest especially by Saturday. Another threat expected is fire danger, and Elevated to Critical Risks have been outlooked by the Storm Prediction Center for portions of the Great Basin into much of Wyoming through Friday. Red Flag Warnings are also in effect.

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 Southeast, the Mid-Atlantic, and the Southern Appalachians, Tue-Wed, Aug 18-Aug 19.

– Heavy rain across portions of the Mid-Atlantic, Sun, Aug 16.

– Flooding possible across portions of the Upper Mississippi Valley.

– Excessive heat across portions of California, the Lower Mississippi Valley, the Pacific Northwest, the Northern Great Basin, and the Southern Plains, Sun, Aug 16.

– Excessive heat across portions of the Central Great Basin, California, and the Southwest, Sun-Thu, Aug 16-Aug 20.

– Excessive heat across portions of the Lower Mississippi Valley and the Southern Plains, Sun-Mon, Aug 16-Aug 17.

– Much above normal temperatures across portions of the Central Great Basin, the Northern Plains, the Northern Rockies, the Central Rockies, California, the Northern Great Basin, and the Pacific Northwest, Sun-Tue, Aug 16-Aug 18.

– Much above normal temperatures across portions of the Central Rockies and the Central Great Basin, Sun-Wed, Aug 16-Aug 19.

– Heavy rain across portions of the Alaska Panhandle, Sun-Mon, Aug 16-Aug 17.

Detailed Summary:

The expected jet stream pattern during the medium range period (Sun, Aug. 16 – Thurs, Aug. 20) features an amplified regime with a strong ridge across the West and a corresponding trough setting up over the East. The most commonly observed hazard is stifling heat in the Southwest and much above normal temperatures in the Northwest. In fact, Sunday could be a scorcher in parts of the Pacific NW with some guidance suggesting upper 90s around the Seattle metro area and near 100 in Portland. Daily record high temps could be broken in parts of the region and thus an Excessive Heat area was added for this Sunday. Sunday and Monday will also remain quite hot in the South Central U.S. where heat indices look to range between 105-115 degrees. The ridge will give way to some weak troughing in the Pacific NW early next week, but the dome of upper level high pressure remains a fixture over the Southwest. Daytime highs exceeding 110 degrees are likely from the Great Valley of California on south into the Desert Southwest. Sweltering conditions will also be experienced in portions of the Intermountain West much of the period. One region’s excessive heat typically means another is much cooler; in this case, the Central Plains and Mississippi Valley where daily temperature anomalies may range between 10 and 15 degrees below normal next week.

Precipitation-wise, the corridor with the wettest areas versus normal are most likely to occur in the Southeast and Mid-Atlantic. Early in the period, a departing frontal system may generate areas of moderate-to-heavy rainfall in the Mid-Atlantic. Given the antecedent rainfall and overly saturated soil across the region, rainfall rates around 1″ could lead to flash flooding. It is worth noting there remains a considerable amount of model spread on positioning of the rainfall axis, how much rain is observed, and timing of the storm system’s departure. Meanwhile, the longwave trough set-up across the east-central U.S. will promote a stalled front over the Southeast and rich Gulf moisture funneling over the region. By Tues. Aug 18th, a wave of low pressure is forecast to develop over the Southeast and promote heavy showers and storms across the region. Portions of the Carolinas and Georgia are currently most at risk for receiving heavy rainfall in forecast days 5-6. An upper trough may dig as far south as the Gulf Coast by days 6-7. Should this occur, the threat for heavy rainfall could expand farther west into the Deep South and deeper into Florida.

In Alaska, a low pressure system is forecast to spin offshore of the Panhandle this weekend. Moisture inflow with this cyclone could lead to heavy rain particularly in the Panhandle where a couple inches of rainfall are possible. Another low pressure system is currently forecast to track through the Bering Sea next week, while another front drops southward across the northern part of the state. There is some potential for gusty wind and heavy rain with these features in southwestern Alaska, but large variability in model guidance persists, thus drawing hazard areas there are low confidence at this time. Additionally, another large upper low is forecast to track through the Gulf of Alaska by days 6-7, potentially leading to more heavy rainfall towards the middle of next week in the Panhandle. Temperatures are expected to be warmer than average across western regions and interior Alaska through early next week, with highs in the 70s and even nearing 80 degrees. Far northern Alaska may begin to cool to slightly below normal levels by mid-week.

(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.

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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

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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