Written by Sig Silber

HEADLINES (Updated 6:25 pm EDT) –

“- Relief from the heat for portions of the Northeast Tuesday and Wednesday while hot and humid conditions continue across the remainder of the East and Northwest

– Severe weather and flash flood threats from portions of the northern and central U.S. into the Ohio Valley and Mid-Atlantic into mid-week”

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 400 PM EDT Mon Jul 20 2020

Valid 00Z Tue Jul 21 2020 – 00Z Thu Jul 23 2020

…Relief from the heat for portions of the Northeast Tuesday and Wednesday while hot and humid conditions continue across the remainder of the East and Northwest…

…Severe weather and flash flood threats from portions of the northern and central U.S. into the Ohio Valley and Mid-Atlantic into mid-week...

Summer heat and humidity will be taking a temporary break across the Northeast as a cold front moves through the region tonight. High temperatures on Tuesday and Wednesday will be dipping back into the 70s (northern New England) and 80s (southern New England/New York). Subtle relief will also be seen farther south into the Mid-Atlantic region where high temperatures will be a few degrees cooler on Tuesday and Wednesday than what was seen Sunday and Monday, but highs well into the 90s will continue for at least another few days along with high humidity.

The cold front to pass through the Northeast will stall from the Mid-Atlantic Coast into the Central Plains on Tuesday. This front and another frontal system moving through the north-central U.S. will serve as foci for showers and thunderstorms, some of which will be severe and contain locally heavy flash flooding rainfall.

Farther south across Texas, an area of low pressure drifting westward through the Gulf of Mexico will continue produce showers and thunderstorms to its north and west as it tracks toward the middle Texas coast while weakening. National Hurricane Center is watching this disturbance for organized tropical development, but believes the chances are low given the system will be moving over land soon.

Across the western U.S., above average heat will continue in Washington/Oregon as well as into the Intermountain West on Tuesday. For Wednesday, highs in the mid-upper 90s are expected to shift east into portions of Montana into Wyoming but a cold front will bring cooler weather to the Pacific Northwest for Wednesday.

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

This loop showing the prior 40-hours provides perspective. We have not yet figured out how to make this loop update but it is still useful for a few days. An updated version and some other views can be found here.

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Day 3 – 7 Hazards

Hazards:

– Heavy rain across portions of the Southwest, the Central Great Basin, the Central/Southern Rockies, the Plains, the Upper Mississippi Valley, and the Great Lakes, Thu-Mon, Jul 23-Jul 27.

– Heavy rain across portions of the Southeast, the Mid-Atlantic, the Lower Mississippi Valley, and the Southern Plains, Thu-Fri, Jul 23-Jul 24.

– Flooding occurring or imminent across portions of the Upper Mississippi Valley and the Northern Plains.

– Flooding likely across portions of the Central Plains.

– Excessive heat across portions of the Central/Northern Plains and the Upper Mississippi Valley, Fri-Sat, Jul 24-Jul 25.

– Excessive heat across portions of the Southeast and the Mid-Atlantic, Thu, Jul 23.

– Excessive heat across portions of the Southeast and the Mid-Atlantic, Mon, Jul 27.

– Much above normal temperatures across portions of the central/Northern Plains, the Upper Mississippi Valley, and the Great Lakes, Fri-Mon, Jul 24-Jul 27.

Detailed Summary:

The medium range period (Thursday, July 23 – Monday, July 27) will be characterized by upper-level high pressure centered over the Middle Mississippi Valley, creating a “ring of fire” summertime weather pattern, in which temperatures underneath the high are hot and thunderstorms form around the edges of the upper-level high’s influence. High temperatures are forecast to be in the 90s most everywhere from the High Plains eastward to the Atlantic coast at least at some point from Friday to Monday, with the exceptions of New England and higher elevations of the Appalachians. The most abnormally high temperatures are expected for north-central parts of the country, slowly migrating
eastward from the Plains into the Midwest and the Great Lakes region. Heat indices could be over 100 degrees, even over 105, for the end of the week in parts of the Northern Plains and Upper Mississippi Valley, necessitating an Excessive Heat hazard area. Additionally, hot temperatures with high dewpoints will combine to create high heat indices for the Southeast and Mid-Atlantic on Thursday, as well as again next Tuesday as the warmth drifts eastward.

To the west of the upper-level high, anomalously moist southerly flow from the Pacific and Gulf of Mexico will begin monsoon season in the Southwest and Four Corners region, ramping up late this week and continuing into early next week. Scattered to widespread thunderstorms could cause locally heavy rain. Temperatures a few degrees below normal are also forecast there. Then along the northern side of the high, an active jet stream could lead to multiple rounds of rain and thunderstorms across the Northern Plains to the Upper Midwest through the period. Farther south, a trough of low pressure with tropical moisture should move toward the western/central Gulf Coast late this week, which could cause heavy rainfall along the coast, but there is uncertainty with how far inland heavy rainfall will occur. Lastly, heavy rain could occur for the southeastern Mid-Atlantic region into South Carolina as moisture streams in south of a front.

In Alaska, no hazards are currently delineated. One item to watch is a low pressure system moving through the Gulf of Alaska early next week. Onshore flow with that system should increase rain chances over south-central and southeastern Alaska, but at this point, model guidance varies with the timing and depth of this low, which leads to uncertainty in how heavy the precipitation totals will be. A cool pattern is expected to persist through the period underneath lower than normal upper-level heights, with below normal temperatures, especially highs, for much of the state.

(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.

We will update the above map weekly but more frequent updates can be obtained here.

There is not much snow left.

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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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