Written by Sig Silber

HEADLINES (Updated 4:18 PM and 5:59 PM EDT) –

– Hurricane Ida is forecast to intensify into a major hurricane as it approaches the Central Gulf Coast with landfall likely on Sunday evening, bringing heavy rain to the region and a Moderate Risk of Excessive Rainfall

– Severe thunderstorms and flash flooding will be possible across parts of the Northern Plains and Upper Midwest through Sunday morning

– Parts of the Mid-Atlantic may experience flash flooding and severe weather this evening

– Excessive and dangerous heat likely throughout much of the Southwest over the weekend

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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For those interested in longer-term forecasts, we just published the new NOAA Seasonal Outlook and it can be accessed here.

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CONUS Focal Points

Short Range Focal Points

Short Range Forecast Discussion NWS Weather Prediction Center College Park MD

404 PM EDT Fri Aug 27 2021

Valid 00Z Sat Aug 28 2021 – 00Z Mon Aug 30 2021

…Severe thunderstorms and flash flooding will be possible across parts of the Northern Plains and Upper Midwest through Sunday morning…

…Parts of the Mid-Atlantic may experience flash flooding and severe weather this evening…

…Excessive and dangerous heat likely throughout much of the Southwest over the weekend…

…Hurricane Ida is forecast to intensify into a major hurricane as it approaches the Central Gulf Coast with landfall likely on Sunday evening, bringing heavy rain to the region and a Moderate Risk of Excessive Rainfall…

For a majority of the short-range period one long frontal boundary is expected to remain quasi-stationary as it drapes over the Northeast, Great Lakes, Plains, and central Rockies/Great Basin through Sunday morning. A majority of the activity for the next couple of days along this boundary will be focused on the Upper Midwest and Mid-Atlantic regions. This evening a pair of surface lows over Nebraska and Minnesota are expected to lift northeast into the Upper Midwest along with an associated warm front. As storms develop along the front favorable wind shear and rising dewpoints are expected to be in place to support some of these storms becoming severe with the potential to produce high winds, large hail, and a few tornadoes. Furthermore, high atmospheric moisture will allow for heavy rain rates that could possibility lead to flash flooding. As such, the Storm Prediction Center has issued a Slight Risk of Severe Thunderstorms for portions of Iowa, Minnesota, and Wisconsin, while the Weather Prediction Center has issued a Slight Risk of Excessive Rainfall for a similar area, but extended east to include parts of western Michigan. Both issuances are valid through Saturday morning.

With the help of an upper-level trough an occluded boundary is forecast to propagate along the quasi-stationary boundary from the Northern Plains into the Upper Midwest on Saturday. As the upper trough and occlusion interact with parts of the quasi-stationary boundary as they move through these regions, heavy rain and severe weather are expected to impact both the Central Plains and Upper Midwest. Similar to the previous day, strong surface instability, high atmospheric moisture values, and favorable wind shear will create conditions within which flooding, high winds, large hail, and a few tornadoes will be possible. To account for this the Storm Prediction Center has issued an Enhanced Risk of Severe Thunderstorms for portions of southern Minnesota and western Wisconsin within a larger Slight Risk Area extending from Nebraska to the Michigan Upper Peninsula, effective Saturday morning through Sunday morning. Additionally, the Weather Prediction Center has issued a Slight Risk of Excessive Rainfall for portions of northern Iowa, southern Minnesota, and western Wisconsin, valid for the same time period.

On top of the activity in the Upper Midwest, severe weather is also expected this evening ahead of a cold front passing through the Mid-Atlantic and the aforementioned occluded boundary in the Northern Plains. In the Mid-Atlantic a well defined Mesoscale Convective Vortice moving slowly through southwest Pennsylvania/western Maryland will encounter an unstable surface layer that will allow for the development of severe thunderstorms that may produce damaging winds. Additionally, high atmospheric moisture values fueling heavy rainfall and wet soils due to the recent passing of Henri earlier this week will make flash flooding possible. These conditions have prompted the Storm Prediction Center to issue a Slight Risk of Severe Thunderstorms and the Weather Prediction Center to issue a Slight Risk of Excessive Rainfall for portions of the Mid-Atlantic through tomorrow morning.

Meanwhile, storms capable of producing high winds and large hail will also be possible over the Northern Plains due to modest low-level moisture and strong deep-layer shear, prompting the issuance of a Slight Risk of Severe Thunderstorms for portions of eastern Montana and the western Dakotas through tomorrow morning. Along the central Gulf Coast, high precipitable water values will allow showers and thunderstorms that develop due to shortwave energy at the surface to produce high rain rates with accumulation totals of 3 to 6 inches in isolated areas. These high totals have prompted the Weather Prediction Center to issue a Slight Risk of Excessive Rainfall for parts of eastern Louisiana and extreme southern Mississippi through tomorrow morning.

Dangerously hot conditions are forecast to persist in the Desert Southwest throughout the weekend, prompting the issuance of Excessive Heat Warnings for much of south/western Arizona, extreme southeast California, and southern Nevada. With temperatures hitting triple digits and the mid to high 110s in some areas, residents are urged to take precautions to avoid the onset of heat-related illness. Such precautions include: drinking plenty of fluids, staying out of the midday sun, seeking air-conditioned locations, and avoiding outdoor activities. Heat Advisories are also in effect for portions of the Middle Mississippi and Western Ohio Valleys, where high temperatures are forecast to be in the upper 90s and low 100s on Saturday.

At the end of the period all eyes will be on the Gulf Coast as Hurricane Ida moves northwestward through the Gulf of Mexico towards its projected landfall location of Louisiana, intensifying into a major hurricane along its way. According to the latest forecast from the National Hurricane Center, Ida is expected to make landfall Sunday evening, bringing extremely heavy rainfall and dangerous maximum sustained winds around 120 miles per hour to coastal Louisiana and the surrounding area. Hurricane and Storm Surge Watches are currently in effect for much of southern Louisiana and extreme southern Mississippi.The Weather Prediction Center has also issued a Moderate Risk of Excessive Rainfall for southeast Louisiana and extreme southern Mississippi effective Sunday morning. Widespread life-threatening flash and urban flooding will be very likely. For the latest information on Hurricane Ida, visit nhc.noaa.gov.

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 40 hour animation and some other views can be found here

The below does not update and is a still rather than the 40-hour animation of the recent past. But if you click on it you will get the upadated animattion. If it does not upload completely you need to hit the refresh button.

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Day 3 – 7 Hazards

Valid Monday August 30 2021 – Friday September 03 2021

Hazards:

– Heavy rain across portions of the northern Plains as well as from the central Gulf Coast northward through the Tennessee Valley into the Ohio Valley, Mon-Tue, Aug 30-Aug 31.

– Heavy rain from portions of the Tennessee Valley, across the central/southern Appalachians, and into the Mid-Atlantic states; and from the northern Plains to the upper Midwest; as well as much of Arizona, Wed-Thu, Sep 1-Sep 2.

– Heavy rain across southwestern Colorado, Thu-Fri, Sep 2-Sep 3.

– Heavy rain across portions of the upper Midwest, Fri, Sep 3.

– Flooding possible across portions of the central Gulf Coast states.

– Flooding likely across portions of central Wisconsin.

– High winds across much of the central Gulf Coast and into the lower Mississippi Valley, Mon, Aug
30.

– Much above normal temperatures across much of the central High Plains, Mon-Wed, Aug 30-Sep 1.

– Much above normal temperatures for a good portions of North Carolina and into South Carolina, Mon-Tue, Aug 30-Aug 31.

– High significant wave heights for coastal portions of Louisiana into Mississippi, Mon, Aug 30.

– Heavy rain across portions of southern Alaska, Wed-Thu, Sep 1-Sep 2.

Detailed Summary:

Hurricane Ida will likely be the top weather story as we begin the medium range period (from Monday, Aug 30 to Friday, Sept 3). The latest projection from the National Hurricane Center places he eye of Ida over south-central Louisiana shortly after making landfall on the coast of southeastern Louisiana as a major hurricane around midnight early on Monday. Torrential rain driven by destructive hurricane-force winds can be expected to push further inland on Monday. Model guidance shows above normal agreement on a relatively slow recurvature of the hurricane into the lower Mississippi Valley Monday into Tuesday. This could prolong the impacts of high winds along the central Gulf Coast and possibly farther inland across southern Louisiana into Mississippi as the hurricane at such intensity at landfall will likely take extra time to spin down over land. In addition to the prolonged threat of high winds, the relative slow motion of the hurricane will likely increase the chance for more prolific rainfall to bring life-threatening flash flooding across Louisiana into the lower Mississippi Valley. There is also a chance for isolated tornadoes to develop over land on the northeastern quadrant of Ida.

Following recurvature, Ida is forecast weaken further as it continues to track northeastward across the Tennessee Valley on Wednesday. Thereafter, models begin to diverge on how fast the tropical moisture is carried downstream across the eastern U.S. from the middle to late next week. Nevertheless, heavy rain can be expected to overspread the central/southern Appalachians and into the Mid-Atlantic Wednesday into Thursday as the tropical moisture interacts with a frontal system dipping south from New England. By Friday, the faster model guidance favors pushing the tropical moisture off the East Coast while the slower guidance is in the process of pushing the post-tropical circulation of Ida toward the Mid-Atlantic coast.

In addition to Ida, tropical cyclone Nora in the eastern Pacific is forecast to make its impact across the western U.S. next week. Latest projection from the National Hurricane Center brings the eye of Hurricane Nora into the Gulf of California early next week. Nora is then forecast to track further northwest towards the southwestern U.S. midweek. Tropical moisture ahead of Nora is expected to surge northward and reach the southwestern U.S. due to the presence of an upper-level low to the west of Baja California. Showers and locally heavy downpours are forecast to reach southern Arizona later on Monday, spreading further north on Tuesday. The bulk of the heaviest rainfall is now forecast to overspread much of Arizona on Wednesday into Thursday. In addition, the moisture plume is forecast to stream further northeast across the central Rockies bringing an increasing threat of heavy rain into the region especially southwestern Colorado late next week.

Outside of the tropics, the northern Plains into the upper Midwest will be under a threat of heavy rainfall as well–first ahead of a warm front early next week, followed by the next frontal system moving into the region later next week when some of the upper-level moisture from Nora could be injected into the system. In addition, much above normal temperatures are forecast early next week over the central High Plains as well as across portions of the Carolinas (along with high humidity).

Over Alaska, the start of September looks stormy as another occluded cyclone is expected to impact the state, this time generating moderate to heavy rainfall over the Aleutians, east towards the upper Peninsula, and along the west-central Gulf coast, together with some gusty winds. Conditions should improve late week as the system moves further off to the east.

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 snow coverage in the Fall

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Drought Coverage

We include drought information in this section.

More information can be found here.

August Drought Outlook.

Seasonal Outlook Issued August 19, 2021

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Tropical Events

Atlantic and Gulf of Mexico

The Eastern Pacific

The Central Pacific

Updates on individual named storms can be obtained here.

And the Western Pacific

Weekly 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

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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