Written by Sig Silber

HEADLINES (Updated 5:13 pm EDT) –

– Record heat eases along parts of the West Coast but remains in the Desert Southwest, while fire danger remains a threat

– Scattered showers and thunderstorms will persist for the coming days across the southeastern quadrant of the country

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 – 354 PM EDT Wed Aug 19 2020

Valid 00Z Thu Aug 20 2020 – 00Z Sat Aug 22 2020

…Record heat eases along parts of the West Coast but remains in the Desert Southwest, while fire danger remains a threat…

…Scattered showers and thunderstorms will persist for the coming days across the southeastern quadrant of the country…

An upper-level high located over the Southwest is forecast to weaken somewhat over the next couple of days, which along with a Pacific cold front should lead to some moderation of temperatures especially for the Northwest and northern California. However, record high temperatures are forecast to be widespread across the Desert Southwest again Thursday and Friday, along with a few potential records in the Central Great Basin, Central/Southern Rockies, and Southern High Plains. Fire danger is also a continued threat in the West with the hot and dry conditions. Elevated to Critical Risks of fire weather are in place from the Storm Prediction Center for portions of California across the Great Basin and Northern Rockies for the next couple of days. Furthermore, scattered dry thunderstorms could produce lightning strikes that could ignite wildfires. Some areas of California and Colorado have Air Quality Alerts in place due to smoke from ongoing fires.

On the other hand, much of the eastern half of the country will experience cooler than normal temperatures due to persistent upper-level troughing. A stalled front interacting with tropical moisture should cause continued chances for showers and thunderstorms for much of the Southeast including Florida as well as the Mid-Atlantic through the end of the workweek. Rainfall totals in most areas should not be significant, but locally heavy rainfall could cause isolated concerns for flooding or flash flooding. A few strong storms containing gusty winds cannot be ruled out either, especially Thursday. Isolated to scattered strong thunderstorms are also a possibility in the Rockies to Plains, particularly each afternoon/evening.

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 Lower Mississippi Valley and the Southern Plains, Mon-Tue, Aug 24-Aug 25.

– Heavy rain across portions of the Southeast and the Lower Mississippi Valley, Sat-Wed, Aug 22-Aug 26.

– Heavy rain across portions of the Southeast, Mon-Wed, Aug 24-Aug 26.

– Excessive heat across portions of the Central Great Basin, California, and the Southwest, Sat-Wed, Aug 22-Aug 26.

– Excessive heat across portions of California and the Southwest, Mon-Wed, Aug 24-Aug 26.

– Excessive heat across portions of the Central Rockies, the Central Great Basin, the Northern Rockies, the Northern Great Basin, and the Southwest, Sat-Mon, Aug 22-Aug 24.

– Heavy rain across portions of mainland Alaska, Mon, Aug 24.

Detailed Summary:

The primary hazards over the lower 48 for the August 22-26 period remain the same as yesterday; excessive heat across many of the western states and the potential for heavy rain with tropical cyclone activity in the Gulf Coast states and Florida.

Starting in the West, the persistent and strong upper level ridge will maintain above normal temperatures across much of the Great Basin, California and the Desert Southwest through the period. However, with the exception of much of Central California the Mojave Desert region, the heat will abate somewhat. Over the Southwest, monsoonal moisture, some associated with Hurricane Genevieve, will stream northward across southern Arizona and southern California. This will bring cloudier conditions with the threat for afternoon and evening thunderstorms during this weekend. Drier conditions are possible next week, so the heat is likely to return, though given the ridge is somewhat weaker, temperatures may not return to levels experienced recently. Across the Great Basin, short wave energy moving in from the Pacific will weaken and flatten out the ridge during the early-mid part of next week. As a result, temperatures will lower, especially across Oregon, Idaho, and northern sections of Nevada and Utah. In addition, there are indications that some monsoonal moisture will push into the Four Corners region, increasing the threat for scattered thundershowers.

Across the Gulf Coast states and Florida,the weather will be unsettled for much of the period. Over the weekend, the focus for potentially heavy rain will likely be along the coast from the central Florida panhandle westward to extreme southeastern parts of Louisiana. This is in response to short wave troughing between the Bermuda ridge and the ridge across the Four Corners region, plenty of Gulf of Mexico moisture and the presence of a dying frontal boundary. Beyond the weekend, attention turns to the tropics. Two systems, one currently in the central Carribean and the second in the mid tropical Atlantic, have the potential to impact the U.S. during the early to middle part of next week. Please see the latest outlooks from the National Hurricane Center for more information about these features. Right now, guidance suggests that the central Carribean system will affect the Texas Gulf Coast, while the system in the central Atlantic impacts Florida and the eastern Gulf Coast region. Confidence at this point is low, but the entire Gulf Coast region will need to monitor the tropics over the coming days.

Elsewhere, a weak upper level disturbance will likely trigger scattered showers and thundershowers in the vicinity of a dying front in the mid-Atlantic states Saturday. While amounts are currently not expected to be particularly heavy, parts of this region have had much above normal rainfall this month, so rain on top of saturated soils could lead to isolated runoff problems.

In Alaska, the pattern will be changing as a rather strong low moving across northeastern Russia pushes a pretty well-defined cold front across much of the mainland this weekend. The models continue to highlight a marginal potential for heavy rainfall (locally around 1-1.5 inches) across the western and central Alaska range on Sunday with the front. Low pressure traversing the Gulf of Alaska will support widespread rainfall over coastal sections of south-central Alaska on Monday, but at this time, amounts don’t look high enough to support a threat area. The other impact of this system will be to knock down temperatures to near or even below normal levels.

(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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