Written by Sig Silber
HEADLINES –
– Severe thunderstorms and numerous instances of flash flooding possible across the Northeast today
– Excessive heat found throughout the Northern Plains and Intermountain West
– Potential for dry lightning over central and northern California on Sunday could lead to conditions capable of producing new wildfires
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
334 AM EDT Sat Jul 17 2021
Valid 12Z Sat Jul 17 2021 – 12Z Mon Jul 19 2021
…Severe thunderstorms and numerous instances of flash flooding possible across the Northeast today…
…Excessive heat found throughout the Northern Plains and Intermountain West…
…Potential for dry lightning over central and northern California on Sunday could lead to conditions capable of producing new wildfires…
A slow moving cold front is continuing to meander eastward between the Lower Great Lakes and Southern Plains this morning, while producing scattered showers and thunderstorms. As it reaches the Northeast today it is expected to run into a very warm and humid airmass, sparking numerous thunderstorms. Much of the Northeast has experienced a waterlogged first half of July, leaving many low-lying areas extremely susceptible to flash flooding. Thunderstorms will be capable of producing 1 to 3 inches of rain, with locally higher amounts across areas that have seen triple their normal rainfall so far this month. A Moderate Risk (level 3/4) of Excessive Rainfall has been issued for portions of southern New England and the Northeast, where the combination of wet soil and heavy rain is most likely to cause flash flooding.
Additionally, a few storms may turn severe between western Connecticut and northeast Maryland with damaging wind gusts and isolated tornadoes possible. For the most part, the heavy rain threat is expected to come to an end on Sunday for the Northeast as the system reaches the coastline. Isolated downpours and flash flooding are expected to remain possible further south across the Southeast, Lower Mississippi Valley, and Southern Plains through the end of the weekend.
For the Southwest, additional showers and thunderstorms associated with the summer monsoon could produce an isolated flash flood threat this weekend, but activity is forecast to be slightly weaker than earlier this week.
A building upper-level ridge over the western U.S. will lead to temperatures soaring well above average across the Northern Plains and Northern Great Basin for the next several days. Highs into the triple digits can be expected throughout eastern Montana and lower elevations of the Intermountain West. Excessive Heat Warnings/Watches and Heat Advisories have been issued. Meanwhile, high temperatures into the low-to-mid 90s are forecast throughout the Northern Plains and into parts of northern/central Minnesota. This heat wave will exacerbate the severe to exceptional drought currently found across the region, which in combination can make for an environment ripe for wildfires to spread uncontrollably.
Speaking of wildfires, dry lightning could be a concern for parts of northern and central California on Sunday as monsoonal moisture enters from the south, but produces very little rain. If thunderstorms do form, extremely dry fuels struck by lightning could produce new fires. Fire Weather Watches have been issued.
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
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Day 3 – 7 Hazards
Valid Monday July 19 2021 – Friday July 23 2021
Hazards:
– Heavy rain across portions of the Central Plains, the Middle Mississippi Valley, the Lower Mississippi Valley, and the Southern Plains, Mon, Jul 19.
– Heavy rain across portions of the Southern Plains, Tue-Wed, Jul 20-Jul 21.
– Heavy rain across portions of the Lower Mississippi Valley and the Southern Plains, Tue, Jul 20.
– Heavy rain across portions of the Southwest, Mon-Thu, Jul 19-Jul 22.
– Flooding possible across portions of the Central Plains, the Middle Mississippi Valley, the Great Lakes, and the Ohio Valley.
– Flooding possible across portions of the Middle Mississippi Valley, the Great Lakes, and the Ohio Valley.
– Flooding occurring or imminent across portions of the Central Plains, the Southeast, and the Middle Mississippi Valley.
– Flooding occurring or imminent across portions of the Southeast and the Middle Mississippi Valley.
– Flooding likely across portions of the Central Plains, the Middle Mississippi Valley, and the Southern Plains.
– Excessive heat across portions of the Central Great Basin, the Northern Rockies, and the Northern Great Basin, Mon, Jul 19.
– Excessive heat across portions of the Northern Plains, Mon-Thu, Jul 19-Jul 22.
– Excessive heat across portions of the Upper Mississippi Valley and the Northern Plains, Wed-Fri, Jul 21-Jul 23.
– Much above normal temperatures across portions of the Central Plains, the Central Great Basin, the Northern Plains, the Northern Rockies, the Central Rockies, the Northern Great Basin, and the Upper Mississippi Valley, Mon-Fri, Jul 19-Jul 23.
– Much above normal temperatures across portions of the Central Rockies, the Central Plains, the Upper Mississippi Valley, and the Northern Plains, Wed-Fri, Jul 21-Jul 23.
– Heavy rain across portions of mainland Alaska, Mon-Wed, Jul 19-Jul 21.
Detailed Summary:
During the medium range forecast period (Monday, July 19th to Thursday, July 23rd), an upper-level trough settling into the Northeast will inch a slow moving cold front southward across the Mid-Atlantic, Tennessee Valley, and Southern Plains. On Monday, heavy rain is possible over southern Kansas into the Ozarks as the front initiates additional rounds of storms in addition to any lingering convection from the day prior.
Beginning Tuesday, the front is forecast to stall over northeast Texas, across the South, and into the Carolinas. Model guidance continues to indicate the likelihood of moderate rainfall ahead of the stalled front but with a fair amount of uncertainty regarding if and where low pressure waves will form and develop along the front. The development of these frontal waves will be important in determining if and where heavier rainfall and thunderstorms will be triggered. The highest chance for heavy rain resides over Southeast Oklahoma, ArkLaTex, and South-Central Texas Tuesday through Wednesday. Deterministic and ensemble guidance is in reasonable agreement regarding a lobe of vorticity cutting off from the main upper-trough over the region, which combined with frontal forcing would support locally higher rainfall totals over the highlighted Heavy Rain areas.
Over the southern Rockies into the Desert Southwest, monsoonal moisture will keep a good chance of showers and afternoon/early evening thunderstorms through the medium-range period. Most areas should see rainfall below hazard levels but the upslope portion west of the Mogollon Rim to the Gila Mountains in Arizona appears to be under the highest threat of heavy rain through the middle of next week when models indicate an influx of monsoonal moisture from the south.
Meanwhile, the heatwave is expected to continue from the central and northern Great Basin eastward across the northern Plains and into the upper Midwest under a persistent upper ridge through much of the medium range period. The highest temperature anomalies are expected over the northern High Plains, where high temperatures into the triple digits are forecast through midweek next week. The Excessive Heat area over Montana into the Dakotas was extended until next Thursday to reflect lingering highs over 100 concurrent with very high heat risk areas per NWS HeatRisk guidance. In Idaho on Monday, the Excessive Heat was trimmed to the eastern Snake River Valley where the hottest high temperatures are expected and an Excessive Heat Watch resides.
Moreover, a new Excessive Heat area was introduced beginning Wednesday across the Dakotas and West Minnesota where several days in a row of triple digit heat indices are forecast. In addition, much of the Dakotas, northeast Wyoming, and the western half of Minnesota are experiencing severe to exceptional drought that will likely worsen due to the persistent heat and lack of rain.
Alaska will likely enter an extended period of wet weather toward the middle of next week as a series of occluded cyclones is forecast to steadily move across the Bering Sea toward Mainland. Only a small area of heavy rain is indicated over portions of northwestern Alaska Tuesday to Wednesday ahead of the arrival of the first cyclone. However, widespread moderate rainfall can be expected to make steady progress across much of Alaska through the middle of next week. Areas toward the Kanai Peninsula could see higher rainfall amounts from the 21st-22nd, but there are discrepancies as to if the totals reach hazard values. As such, did not include a Heavy Rain area
(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.
July Drought Outlook.
Seasonal Outlook Issued May 20, 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
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. |
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 |
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 |