Written by Sig Silber
HEADLINES (Updated 6:57 pm EDT) –
– Sally rapidly intensified to a hurricane this afternoon…prolonged threat of hurricane conditions and life-threatening flooding are expected along the central Gulf Coast due to Sally’s slow forward motion
– Welcome rainfall moving into coastal Pacific Northwest but wildfires and poor air quality continue for the interior down into northern California
– Temperatures will be 10 to 25 degrees above average over parts of the Great Basin/Northern Rockies/High Plains
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 – 400 PM EDT Mon Sep 14 2020
Valid 00Z Tue Sep 15 2020 – 00Z Thu Sep 17 2020
…Sally rapidly intensified to a hurricane this afternoon…prolonged threat of hurricane conditions and life-threatening flooding are expected along the central Gulf Coast due to Sally’s slow forward motion…
…Welcome rainfall moving into coastal Pacific Northwest but wildfires and poor air quality continue for the interior down into northern California…
…Temperatures will be 10 to 25 degrees above average over parts of the Great Basin/Northern Rockies/High Plains…
Sally rapidly intensified from a tropical storm to a hurricane earlier today over the northeastern Gulf of Mexico, now packing winds up to 90 mph near the eye. Parts of the eastern Gulf Coast, especially the Florida Panhandle are being impacted by the outer rainbands of Sally. The slow forward motion of Sally will likely prolong the threat of hurricane conditions and life-threatening flooding along the central Gulf Coast. The slow motion of Sally will also increase the uncertainty as to when the hurricane will make a turn toward to north and where on the Gulf Coast will be most severely impacted. Our current forecast calls for 8 to 16 inches of rainfall with isolated amounts of 24 inches over portions of the central Gulf Coast from the western Florida Panhandle to far southeast Louisiana through the middle of the week. Life-threatening flash flooding and hurricane conditions are most likely later on Tuesday into early Wednesday from the Mississippi Delta eastward along the coast of Mississippi and possibly Alabama depending on the eventual track of Sally. Please see the latest advisory from the National Hurricane Center for additional and updated information across this area. Residents within Sally’s reach should continue to monitor the storm’s progress and follow the advice of local officials.
Besides Sally, the tropical air along the Gulf Coast will produce showers and thunderstorms over the region through Wednesday. In contrast, high pressure builds in over the Great Lakes into the Northeast producing cooler and drier conditions across the region with below average temperatures.
Outside of Sally conditions are rather tranquil for the rest of the U.S. Tropical moisture is expected to gradually advance toward the interior Southeast, possibly reaching the Mid-Mississippi Valley late on Wednesday with a few showers and thunderstorms. A chance of thunderstorms will also continue along the western Gulf Coast near a stationary front. In contrast, high pressure builds in over the Great Lakes into the Northeast producing cooler and drier conditions across the region with below average temperatures.
Out West, an upper-level ridge over the Intermountain Region continues to support the ongoing poor air quality. As a result, dense smoke advisories and air quality alerts are posted over the Pacific Northwest, parts of California, and parts of the Great Basin. The fire weather forecast for Tuesday has critical to elevated levels in portions of the Northwest into the Northern Rockies/High Plains.
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 Southern Appalachians, and the Tennessee Valley, Thu-Fri, Sep 17-Sep 18.
– Flooding possible across portions of the Southeast, the Lower Mississippi Valley, and the Tennessee Valley.
– Flooding likely across portions of the Southeast.
– Much above normal temperatures across portions of the Central Rockies, the Central Great Basin,the Northern Rockies, and the Northern Great Basin, Thu, Sep 17.
– Much below normal temperatures across portions of the Great Lakes, the Ohio Valley, and the Upper Mississippi Valley, Fri-Sat, Sep 18-Sep 19.
– Much below normal temperatures across portions of the Great Lakes, the Mid-Atlantic, the Northeast, the Central Appalachians, and the Ohio Valley, Sat-Sun, Sep 19-Sep 20.
– Heavy precipitation across portions of mainland Alaska, Thu-Fri, Sep 17-Sep 18.
– Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Thu-Sat, Sep 17-Sep 19.
– Heavy rain across portions of the Alaska Panhandle, Sat-Sun, Sep 19-Sep 20.
– High winds across portions of mainland Alaska, Thu-Fri, Sep 17-Sep 18.
Detailed Summary:
The remnants of Hurricane Sally will be among the hazards of note across the Lower 48 during the medium range period (Thurs. Sept 17 – Mon. Sept 21). Model guidance remains in different camps as to how progressive Sally is through the Southeast (the GFS & Canadian models have Sally in central Alabama 12Z Thurs; Euro near Mobile, AL; UKMET in southwest Georgia). All guidance agrees upon a swath of heavy rainfall, but the axis extends as far south as southern Georgia and the central Carolinas to as far north as the Tennessee Valley and southern Mid-Atlantic. Regardless, the mid-level center track with ensemble means does support upslope flow along the southern Appalachians does suggest the opportunity is there for copious amounts of rain. The current precipitation forecast suggests totals exceeding six inches are possible where the heaviest bands set up from central Alabama to North Carolina. Please see the latest advisory from the National Hurricane Center for additional and updated information. Resident’s within Sally’s reach should continue to monitor the its progress and follow the advice of local officials. Eventually the storm will be ushered into the northwest Atlantic as a large longwave trough over southeastern Canada steers the storm east this weekend.
Temperature-wise, the aforementioned upper trough swinging through southeast Canada late week will also send a fresh injection of cool Canadian air into the Great Lakes Thursday and Friday, then into the Northeast for the upcoming weekend. Temperatures look cold enough Friday and Saturday morning to develop frost and perhaps a freeze in parts of the Upper Great Lakes has high pressure moves overhead, leading to light winds, clear skies, and maximizing radiational cooling. The same chilly dome of high pressure slides over the Northeast this weekend and much of the northern Appalachians and interior New England could be looking at a widespread frost and/or freeze each morning this weekend and potentially into next Monday morning. Farther west, one day of much above normal temperatures is likely to transpire over the interior Northwest as high temps soar into the 90s. A Pacific storm system should begin to cool things down in the Northwest and northern Rockies on Friday, allowing for seasonally cooler conditions to take shape by the weekend.
In Alaska, a powerful occluded storm system looks to slam into the Gulf Coast on Thursday. The moisture source out ahead of this storm extends all the way into the subtropics, and will result in heavy precipitation from the Kenai Peninsula on east to the upper Panhandle. This is also the case for the Alaska Range extending up towards Denali. Coastal areas and valleys can expect heavy rainfall while the higher elevations pickup heavy snow accumulations. In addition, strong winds are likely to occur across the northern Gulf of Alaska, along the Gulf coast, and as far west as Kodiak Island. A second storm system trailing behind the lead storm and heads for the Panhandle this weekend. The heavy rain threat is expected to extend down the Panhandle this where several inches of rain are possible.
(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
New Feature – Ski Reports. (We may be a tad premature but not by much). It is difficult to find reports that auto-update on-screen (and they are very long) but these links will get you to them – If you have additional suggestions make them in the comments section after every GEI Article and we may add those links. We will try to not have too much overlap as that can add to the confusion.
We will update the above map weekly but more frequent updates can be obtained here.
Snow Forecasts.
Day 1
Day 2
Additional snow information can be found here and here.
During the summer we might add some drought information in this section.
New Seasonal Outlook Issued August 20, 2020
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Tropical Events
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 and when available add other related maps.
the Central Pacific. | the Eastern Pacific | the Atlantic and the Gulf of Mexico |
Atlantic and Gulf of Mexico
And the Eastern Pacific
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
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
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
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 |