Written by Sig Silber

HEADLINES (Updated 5:27 pm EDT) –

“– Hurricane Isaias is currently passing over the Bahamas and should impact the U.S. East Coast with dangerous storm surge and flash flooding regardless of landfall

– There is a slight risk of severe thunderstorms and a slight risk of excessive rainfall over parts of the Ohio Valley into the Mid-Atlantic

– Excessive heat continues in the Desert Southwest with warm temperatures across the 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 349 PM EDT Sat Aug 01 2020

Valid 00Z Sun Aug 02 2020 – 00Z Tue Aug 04 2020

…Hurricane Isaias is currently passing over the Bahamas and should impact the U.S. East Coast with dangerous storm surge and flash flooding regardless of landfall…

…There is a slight risk of severe thunderstorms and a slight risk of excessive rainfall over parts of the Ohio Valley into the Mid-Atlantic…

…Excessive heat continues in the Desert Southwest with warm temperatures across the Intermountain West…

Hurricane Isaias will continue to batter the Bahamas with hurricane conditions and dangerous storm surge. The hurricane is forecast to move northwestward and skirt near the Florida east coast Saturday night and Sunday, and Hurricane Warnings have been issued there for high winds. While it is uncertain if Isaias will make landfall in Florida, dangerous storm surge and potentially life-threatening flash flooding could occur regardless, and small shifts in the track could lead to different impacts, so preparation for hazardous weather is necessary. Isaias is currently forecast to turn northward and then northeastward Sunday and Monday, and could impact the Carolinas with heavy rain and wind. Please consult the National Hurricane Center for further and updated information on Isaias.

A low pressure system is expected to lift northeastward across the Ohio Valley and Lower Great Lakes through tonight, causing potentially heavy rain along it. A Slight Risk of flash flooding is in place for those areas toward portions of the Mid-Atlantic, and a Slight Risk of severe weather is also forecast for eastern portions of the Ohio Valley into the Central Appalachians. Then on Sunday, the lead frontal system should shift toward the Eastern Seaboard, leading to thunderstorms there. A Slight Risk of severe weather is in place for the northern Mid-Atlantic to Northeast, and there is a Slight Risk of flash flooding over the Southern/Central Appalachians. Showers and thunderstorms are also possible with a secondary frontal system moving through the Midwest, but rainfall totals are expected to remain light. Additionally, Marginal Risks of flash flooding are in place for the Southern Rockies to Southern High Plains with some monsoonal moisture.

Across the West, above normal temperatures will remain underneath an upper-level ridge. Temperatures in the 110s are forecast to persist in the Desert Southwest, leading to continued Excessive Heat Warnings, and an Elevated Risk of fire weather has been delineated from the Storm Prediction Center through Sunday morning. Heat Advisories stretch northward into the Intermountain West as temperatures over 100 are possible and record highs could be set. Meanwhile, cooler than average temperatures are expected for much of the Plains toward 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:

– Heavy rain across portions of the Southeast, the Mid-Atlantic, the Northeast, and the Central Appalachians, Mon-Tue, Aug 3-Aug 4.

– Heavy rain across portions of the Mid-Atlantic and the Northeast, Tue-Wed, Aug 4-Aug 5.

– Flooding possible across portions of the Northern Plains.

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

– High winds across portions of the Southeast, the Mid-Atlantic, and the Northeast, Mon-Tue, Aug 3-Aug 4.

– High winds across portions of the Northeast, Tue-Wed, Aug 4-Aug 5.

– High significant wave heights for coastal portions of the Southeast and the Mid-Atlantic, Mon, Aug 3.

– High significant wave heights for coastal portions of the Mid-Atlantic and the Northeast, Tue, Aug 4.

– Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Mon-Tue, Aug 3-Aug 4.

Detailed Summary:

Isaias impacting much of the East Coast (starting in Florida this weekend) is the headliner for potential weather hazards the first week of August. First off, the eventual track and intensity of the storm, even as the weekend begins, remains unclear. It will track over the very warm waters surrounding the Bahamas, but also experience lingering mid-upper level wind shear that is attempting to keep the storm disorganized internally. That said, the Bermuda ridge and the upper level trough over the east-central U.S. dictates the steering flow, ultimately forcing Isaias to track northeast along the Eastern Seaboard the first half of the week. Heavy rain and thunderstorms, some of which could produce torrential rainfall rates, is anticipated from the Southeast to the Mid-Atlantic with localized flash flooding and even river flooding possible Monday into Tuesday. The axis of heavy rainfall is reliant upon storm track: closer to or just off the coast means more rain along the coast (less inland) while a more inland track brings heavy rainfall deeper into the Southeast and Mid-Atlantic mainland. One common threat for these regions coastlines are battering waves and the potential for tropical storm force winds. As a result, beaches and inlets could contend with some coastal flooding and beach erosion. By Tuesday, Isaias is forecast to make its way up the Northeast coast with the aforementioned hazards (heavy rain, high waves, strong winds) accompanying the system. Similar to the southern regions, whether the storm tracks along the coast or slightly farther inland determines where the most rainfall takes shape. The heavy rain threat in the Northeast is aided by the region’s placement under the right-entrance region of a jet streak located over the St. Lawrence River Valley, supporting the potential for a predecessor rainfall event (PRE) over the Northeast. The storm could still be making its way off the coast of New England on Wednesday but more tranquil conditions will return the second half of the week.

Meanwhile, an upper-level ridge will remain a commanding feature over the western U.S. much of the week. Temperatures should range between 5 to 10 degrees above normal across much of the interior western U.S. before an upper trough ushers cooler air into the Pacific Northwest and the northern Rockies by early next week. High temperatures are expected to top 115 degrees for the hottest locations in Desert Southwest on Monday before moderating very gradually toward the middle of next week. The hottest high temp anomalies may be centered over eastern New Mexico and West Texas. Over the northern Plains and Midwest, much cooler than normal temperatures will remain in place behind the slow-moving upper trough entrenched across the east-central U.S..

Over Alaska, the pattern appears to get more active as a pair of significant occluded cyclones are forecast to impact the southern periphery of the state. This appears to be more of a prolonged rain event than heavy rain falling in a short time-frame. A heavy rain area is indicated on the map from the southern coastal sections of Alaska down along the Panhandle from the first half of the week. The second occluded cyclone late week is currently expected to bring additional heavy rainfall to the Panhandle during that span, but there is still some uncertainty in the track and timing of this storm system that could make for wetter conditions along the south-central coast 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.

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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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