Written by Sig Silber

HEADLINES (Updated 6:03 pm EDT) –

“– Isaias is forecast to make landfall possibly as a hurricane in the Carolinas tonight, causing severe thunderstorms, dangerous storm surge, and flash flooding for the Eastern Seaboard

– Dangerous heat continues in the Desert Southwest and Intermountain West “

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 Mon Aug 03 2020

Valid 00Z Tue Aug 04 2020 – 00Z Thu Aug 06 2020

…Isaias is forecast to make landfall possibly as a hurricane in the Carolinas tonight, causing severe thunderstorms, dangerous storm surge, and flash flooding for the Eastern Seaboard…

…Dangerous heat continues in the Desert Southwest and Intermountain West…

Tropical Storm Isaias will continue to move northward and could regain hurricane strength before making landfall in the Carolinas Monday night. Regardless of whether Isaias is a strong tropical storm or a hurricane, the impacts should be similar, and Isaias will cause high wind in the Carolinas and potentially in areas under Tropical Storm Watches farther north. Life-threatening storm surge is possible along the coasts of Florida, Georgia, the Carolinas, and up toward the Chesapeake Bay as Isaias moves northward very quickly. Isaias is forecast to move through the Mid-Atlantic on Tuesday and through the Northeast late Tuesday into Wednesday morning. Very heavy rainfall and life-threatening flash and urban flooding are threats along the storm’s track through the Eastern Seaboard, along with minor to moderate river flooding. Moderate Risks of flash flooding is in place for much of the Carolinas and Mid-Atlantic through Tuesday as widespread rainfall totals of 3-6 inches are expected, with isolated maximum totals of 8 inches. A few tornadoes are also possible ahead of Isaias in the Carolinas Monday night. Please see the National Hurricane Center for additional and updated information on Isaias.

Elsewhere, showers and thunderstorms are possible in the Mid-Atlantic north of Isaias as well as back along a frontal system in the Ohio Valley and Great Lakes. There is also potential for scattered thunderstorms in much of the High Plains today and tomorrow, near a quasi-stationary front expected to eventually move eastward late on Tuesday. Marginal to Slight Risks of severe weather are in place there.

Temperatures are expected to remain hot across the Desert Southwest, with temperatures in the 110s prompting Excessive Heat Warnings again in some areas. Heat Advisories also remain in place for portions of the Central Great Basin as above normal temperatures continue. Red Flag Warnings are also in effect on Monday over portions of the Great Basin where there should be favorable conditions for fire weather. Temperatures are expected to be over 100 degrees to near record levels in the Southern High Plains Tuesday and Wednesday. Meanwhile, cooler than average temperatures with highs only in the 70s are expected for the Northern/Central Plains and the Midwest.

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:

– Flooding possible across portions of the central and southern Appalachians, the Mid-Atlantic, the Northeast, as well as the northern Plains.
– Flooding occurring or imminent across portions of the Mid-Mississippi Valley and the northern Plains.
– Flooding likely across portions of the northern Plains.
– Heavy rain across portions of the southern coastal areas of Alaska, Thu-Fri, Aug 6-Aug 7.

Detailed Summary:

With the expected departure of Isaias into eastern Canada, a more tranquil medium-range period is forecast for the entire mainland U.S. Although no general areas of heavy rain are indicated, locally heavy rainfall could impact parts of the northern Plains and the mid-Mississippi Valley during the weekend as a stationary front drapping across the Plains returns as a warm front. Rain associated with a frontal wave should slowly move off the Mid-Atlantic states during the weekend. Meanwhile, afternoon and early evening thunderstorms can be expected across the Florida peninsula through the medium-range period. Temperatures are not expected to stray too far from normal across the country through next Monday as a Pacific cold front moves through the northwestern U.S. into the northern Plains.

Meanwhile, a relatively active pattern is expected to continue for Alaska. A large occluded cyclone is forecast to make landfall across southwestern Alaska on Thursday–likely bringing heavy rain into much of the Kenai Peninsula Borough in southern Alaska on Thursday and Friday, together with some strong gusty winds and rough seas near the coast across the Alaska Peninsula. The occluded cyclone is not expected to bring heavy rain into much of Alaska as the cyclone gradually weakens and dissipates over land. Meanwhile, persistent rain and cool conditions are foreacst along the Alaska Panhandle. Considerable clouds and areas of rain will keep afternoon high temperatures cooler than normal across much of Alaska (especially the Panhandle) but overnight lows are expected to be near normal (slighty above normal for the interior).

(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.

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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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