Written by Sig Silber

HEADLINES (Updated 4:29 pm EDT) –

“- Very hot and humid conditions will continue in the East on Monday

– Severe weather and flash flooding are possible in central and eastern parts of the country along a front”

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 403 PM EDT Sun Jul 19 2020

Valid 00Z Mon Jul 20 2020 – 00Z Wed Jul 22 2020

…Very hot and humid conditions will continue in the East on Monday…

…Severe weather and flash flooding are possible in central and eastern parts of the country along a front...

Hot temperatures combined with high dewpoints are currently causing dangerous heat across the central and eastern U.S. Heat Advisories stretch from the Southern Plains across the Middle Mississippi and Ohio Valleys to the Eastern Seaboard, with Excessive Heat Warnings in effect for the Philadelphia region, parts of the Delmarva peninsula, and far southeastern Virginia/northeastern North Carolina. Temperatures in some areas continue to rise and could set record high temperatures today. Additionally, even the typically hot Phoenix area has an Excessive Heat Warning in effect today. Overnight, temperatures are forecast to stay warm in the East, compounding the heat danger, and widespread warm low temperatures should be set on Monday morning from the Appalachians eastward. A cold front passing through should help drop temperatures at least a few degrees in the Ohio Valley on Monday, but high heat indices will continue for the Eastern Seaboard. The Northeast should see relief from the heat on Tuesday, but the Mid-Atlantic remains hot. Warmer than average temperatures are also forecast for the Great Basin over the next couple days, while cooler temperatures will be present in the Northern/Central Plains to the Midwest.

A cold front is expected to move across the Great Lakes region and Northeast over the next couple of days, providing a focus for thunderstorms. A Slight Risk of severe thunderstorms is in place for the Lower Great Lakes toward portions of the Ohio Valley through the evening, and locally heavy rainfall is possible as well. Farther west, the front will meander over the Plains, Mississippi Valley, and Ohio Valley into Tuesday. With the stalling front, rain and thunderstorms could cause flash flooding over the Central Plains and Middle Mississippi Valley through tonight with rainfall amounts possibly over 2 inches. A Slight Risk of flash flooding is also in place for the Southern High Plains today, while severe weather is more likely farther north over the Central High Plains. Then on Monday, a couple of areas could see rainfall amounts and rates capable of flash flooding: parts of the Northern Plains to Upper Mississippi Valley, and parts of the Central Plains to Middle Mississippi Valley. Severe weather appears most likely in the Northern Plains Monday. Rain and storms should spread up to the Midwest and Great Lakes on Tuesday as the warm front lifts north. Scattered showers and thunderstorms are also possible for Florida and the Gulf Coast through the period.

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 Upper/Middle Mississippi Valley and Central Plains, Mon, Jul 20.

– Flooding possible across portions of the Northern Plains.

– Flooding occurring or imminent across portions of the Upper/Middle Mississippi Valley, the Great Lakes, and the Northern Plains.

– Flooding likely across portions of the Central Plains.

– Excessive heat across portions of the Mid-Atlantic, the Middle/Lower Mississippi Valley, the Central Appalachians, the Tennessee Valley, the Northeast, the Southeast, and the Ohio Valley, Mon-Wed, Jul 20-Jul 22.

– Heavy rain across portions of the Alaska Panhandle, Mon, Jul 20.

Detailed Summary:

The medium range period (Monday, July 20 – Friday, July 24) will continue to feature a summer-like pattern with heat across the Southwest into the Central/Eastern U.S. as high pressure persists south of the jet stream located across the northern states. Hot temperatures combined with high dewpoints will lead to high heat indices over parts of the Middle/Low Mississippi Valley, and the Tennessee/Ohio Valleys early in the week. Warm overnight lows are expected as well, exacerbating the heat threat. Heat indices over 105 could remain across the Lower Mississippi and Tennessee Valleys through Wednesday. Additionally, high heat indices over 110, even approaching 115 in some places, are forecast across the Mid-Atlantic region to the New York City area for the first half of next week, leading to an Excessive Heat area there. The Desert Southwest, southern Texas, and the Florida peninsula should also remain hot, but all those areas are around or just a few degrees above normal for this time of year. The main consistent spot where temperatures could be below normal is the Northern Plains on the cool side of a front.

Rain and thunderstorms are possible in the vicinity of fronts moving through north-central and eastern parts of the country through the period. On Monday an area of organized convection will develop along front that is forecast to stall over the Middle Mississippi Valley and Central Plains. Heavy rain could occur as moisture from the Gulf of Mexico will flow over the boundary. The exact placement of the heavy rainfall amounts will change depending on the positioning of the front. Rain and thunderstorms are also expected along the Eastern Seaboard, but model guidance is not currently consistent on areas where the rain could focus to become heavy. Southwestern Florida could see heavy rainfall on Tuesday, but heavy amounts may remain offshore. Another area to watch for heavy rain potential is eastern North Carolina on Thursday and Friday but model guidance continues to vary.

Over Alaska, moisture streaming into the Panhandle on Monday. Showers are also likely over interior Alaska through the period, but organized heavy rainfall is not expected there. Some rain may also spread into the Aleutians around midweek as another low pressure system moves across. A cold upper-level trough will lead to cooler than normal conditions across much of the state, but especially over the North Slope, where high temperatures could be as much as 30 degrees below average through Tuesday, and low temperatures could be below freezing.

(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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