Written by Sig Silber
HEADLINES (Updated 4:01 PM EDT) –
– Stifling heat and humidity throughout much of the central and eastern United States, dangerous heat returning to the Southwest by Wednesday
– Scattered showers and a few severe thunderstorms possible from the northern and central Plains into the Midwest over the next few days, hit-or-miss showers and storm in the Southeast
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.
Readers can scan through this article or jump to where they want to go via the links to the right. To get back to the Directory, hit the back arrow at the top of the URL bar on your screen. But in many cases, one of my Editors has graciously inserted a Return to Directory link to click so that is even easier. This is so high tech that I hardly believe it. |
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CONUS Focal Points
Short Range Focal Points
Short Range Forecast Discussion NWS Weather Prediction Center College Park MD
335 PM EDT Tue Aug 24 2021
Valid 00Z Wed Aug 25 2021 – 00Z Fri Aug 27 2021
…Stifling heat and humidity throughout much of the central and eastern United States, dangerous heat returning to the Southwest by Wednesday…
…Scattered showers and a few severe thunderstorms possible from the northern and central Plains into the Midwest over the next few days, hit-or-miss showers and storm in the Southeast…
Sizzling temperatures look to bake much of the southern tier and eastern half of the Lower 48 through mid-week thanks to an expansive area of upper level ridging that is forecast to stretch from Southern California to the East Coast. Heat Advisories have been posted from the central High Plains to the Ohio Valley while some have also been issued in parts of the Northeast. The hottest conditions are presently located in the ArkLaMiss portion of the Lower Mississippi Valley where Excessive Heat Warnings remain in place through early thins evening. As ridging aloft over the South Central U.S. bleeds into the Desert Southwest, oppressive heat is set to transpire the second half of the week in southern Arizona and far southern California. In advance of this impending heat wave, an Excessive Heat Watch has been issued for these areas beginning Wednesday morning and lasting into Friday.
Some parts of the country can expect temperatures to exceed the century mark, most notably in the central High Plains and the Desert Southwest. In fact, afternoon high temps may reach up to 115F both Thursday and Friday in southeast California and southwest Arizona. While only a handful of daily high temperature records are at risk of being broken, a plethora of warm minimum temperature records are likely to fall thanks to high humidity levels keeping overnight temperatures very warm. These warm nighttime temperatures in the 70s and even near 80F can be particularly dangerous for those without access to proper air conditioning. Unfortunately, the large dome of upper level high pressure will continue to deflect cold fronts attempting to usher in cooler and more refreshing air-masses to the north for the time being, forcing much of the South and east-central U.S. to stay hot and steamy through the end of the work-week.
Elsewhere, two separate rounds of showers and storms are set to impact the north-central United States over the next few days. The first wave of low pressure and its associated frontal boundaries are already responsible for segments of thunderstorms tracking through the Upper Midwest this afternoon. These thunderstorms may continue to progress east-southeast into the early evening hours and potentially produce damaging wind gusts and tornadoes across the Upper Midwest. A few isolated severe thunderstorms could develop farther south and into the Central Plains as well.
By Wednesday, the same frontal boundary is expected to lift north as a warm front over the central High Plains as an approaching upper level trough over the West Coast (storm system number 2) enters the Northern Rockies. This could spell more chances for spotty severe storms throughout the northern and central High Plains. While heavy rain could cause localized flash flooding, much of this section of the country from the northern High Plains to the Upper Midwest is experiencing severe to exceptional drought and will welcome this rainfall.
By Thursday however, widespread showers and storms are likely to form over the Dakotas and Upper Mississippi Valley. With recent rainfall saturating more of the ground and a better setup for heavy rainfall coming together, a day 3 Slight Risk for Excessive Rainfall has been issued for parts of these regions on Thursday.
Farther south and east, typical widely scattered summer thunderstorms are anticipated across the Southeast and Gulf Coast with the main hazard associated with heavy rain. The slow movement of these pop-up thunderstorms could lead to localized instances of flash flooding.
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 |
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These graphics update and can be clicked on to enlarge. You can see where the weather will be | |
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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 Friday August 27 2021 – Tuesday August 31 2021
Hazards:
– Flooding occurring or imminent across portions of the Mid-Atlantic and the Northeast.
– Flooding likely across portions of the Mid-Atlantic.
– Excessive heat across portions of California and the Southwest, Fri, Aug 27.
– Heavy rain across portions of the Great Lakes, the Upper Mississippi Valley, and the Northern Plains, Fri-Sun, Aug 27-Aug 29.
– Heavy rain across portions of the Lower Mississippi Valley and the Southern Plains, Sun-Tue, Aug 29-Aug 31.
– High winds across portions of mainland Alaska, Fri-Sat, Aug 27-Aug 28.
– Much below normal temperatures across portions of mainland Alaska, Fri-Sat, Aug 27-Aug 28.
– High significant wave heights for coastal portions of mainland Alaska, Fri-Sat, Aug 27-Aug 28.
– Heavy rain across portions of the Alaska Panhandle, Sat-Sun, Aug 28-Aug 29.
Detailed Summary:
During the medium range (Friday, August 27th – Tuesday, August 31st) the upper-level pattern over the CONUS is forecast to at first be characterized by ridging in the east and troughing over the Northwest before a more zonal regime emerges towards the latter half of the period. Coupled with low pressure/frontal systems at the surface, this troughing aloft will aid in the development in multiple rounds of heavy rain over the Upper Midwest throughout the weekend. Beginning on Friday, a low pressure wave over Nebraska with an eastward extending warm front is expected to lift into the Upper Mississippi Valley. Abundant atmospheric moisture will likely be available in this region, allowing any convective precipitation that forms along and ahead of the northward moving warm front to produce heavy rain with accumulations between 2 and 3 inches in 24 hours from eastern Minnesota to the Michigan Upper Peninsula Friday into Saturday. In spite of relatively dry soils and near normal precipitation throughout the Upper Midwest, these high rainfall totals will make localized flash and urban flooding a concern. Saturday into Sunday the upper-level trough will propagate out of the Northwest and lift over the Northern Plains, ushering an occluded system at the surface from the Northern Plains into the Upper Midwest, bringing the region its second bout of heavy rain. Widespread accumulations of 1+ inches in 24 hours will be likely from the Dakotas to the Michigan Upper Peninsula, putting more stress on the already saturated soils from the previous days’ rain.
The aforementioned high pressure aloft over the eastern US will allow daily highs from the Central Plains to the Mid-Atlantic to sit 5 to 10 degrees above normal throughout the weekend, while daily lows will reach 10 to 15 degrees above average. Conversely, during the same time period upper-level troughing will likely keep high temperatures 5 to 10 degrees below normal in the Northwest. While not a large deviation from normal, highs in extreme southwestern California and the Desert Southwest are forecast to be sweltering, reaching between 110 and 115 degrees on Friday. Residents of these regions, which includes the Phoenix metro area, will be exposed to excessive heat, putting them at risk for heat-related illness. To lessen the impact of extreme heat, residents should stay indoors, seek air-conditioned buildings, avoid prolonged outdoor exposure, and stay hydrated.
Shifting focus to the tropics, the National Hurricane Center is currently keeping an eye on an area of low pressure that could develop into a tropical depression over the weekend either in the northwest Caribbean Sea or southwest Gulf of Mexico. Current guidance suggests that a tropical cyclone may form and bring heavy rain to coastal Texas and Louisiana beginning Sunday night into Monday morning before moving further inland. While there is uncertainty in the models surrounding the exact location of the heavy rain along the western Gulf Coast, there is consensus that wherever the potential tropical cyclone hits there will be a significant amount of rain. At this time a broad heavy rain contour has been drawn in Texas and Louisiana to highlight the areas of potential impact, however, throughout the course of the week this area will likely be refined to match the most up to date guidance.
Over Alaska, the first half of the medium range period is forecast to be active as two systems move in on the state simultaneously from both the north and the south. Focusing on the northwest, on Friday an occluded system is expected to pass north of Alaska over the Beaufort Sea as its trailing cold front propagates west to east through the state. Behind the front and ahead of a shortwave trough over the East Siberian Sea, high winds with gusts up to 30 knots will bring windy conditions to the western Far North and significant waves to the coastline extending from Point Barrow to the Kotzebue Sound on Friday and Saturday. In addition to driving the high winds and significant waves the cold front is forecast to drop temperatures 10 to 15 degrees across the central mainland throughout the weekend, keeping highs generally in the 50s and 60s and lows in the 30s at lower elevations. As the previously mentioned shortwave trough moves out of the East Siberian Sea and into the Far North over the weekend a moderate amount of mixed precipitation will also be possible over the Lisburne Peninsula and Brooks Range, however, it is not expected to be hazardous. To the south, an occluded system is forecast to move through the Gulf of Alaska on Friday before reaching the Alaska Panhandle on Saturday. As the system approaches the region and moves onshore it is expected bring heavy rain in excess of hazardous levels to the Panhandle, with accumulation totals between 2 and 2.5 inches in 24 hours likely throughout the weekend.
(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 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
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And then Precipitation
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For those interested in more detail, there are additional weather maps and information in the MORE WEATHER Addendum. The link to the Addendum is here. |
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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. |
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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
| Current watches, warnings, and advisories issued by the agencies of the National Weather Service. Hazards should show up in the various maps but the below links will take you to all outstanding watches and warnings in each category which may include some categories not covered in the various maps or difficult to find. So if there is a category of interest, click on the appropriate link below. |
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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 | |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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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