Written by Sig Silber

HEADLINES (Updated 8:46 om EDT) –

– There is a Slight Risk of excessive rainfall over parts of the Northeast and Mid-Atlantic

– Temperatures will be 5 to 10 degrees below average over the Northern High Plains in contrast temperatures will be 10 to 20 degrees above average over parts of the interior West Coast and the Great Basin

– Fire weather danger in California to persist through Thursday, dry conditions and record heat along the West Coast

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.

Directory

CONUS Focal Points

Short Range Focal Points

Short Range Forecast Discussion NWS Weather Prediction Center College Park MD – Valid 00Z – 459 PM EDT Tue Sep 29 2020

Valid 00Z Wed Sep 30 2020 – 00Z Fri Oct 02 2020

…There is a Slight Risk of excessive rainfall over parts of the Northeast and Mid-Atlantic…

…Temperatures will be 5 to 10 degrees below average over the Northern High Plains in contrast temperatures will be 10 to 20 degrees above average over parts of the interior West Coast and the Great Basin…

…Fire weather danger in California to persist through Thursday, dry conditions and record heat along the West Coast…

A strong front over the East Coast and tropical moisture will produce heavy rain along the East Coast through roughly Wednesday morning. The WPC has issued a a Slight Risk of excessive rainfall over parts of the Northeast and Mid-Atlantic through Wednesday morning. The heavy rain will aid in producing scattered, mainly localized, areas of flash flooding with urban areas most vulnerable as well as small streams with isolated significant flash flooding possible through Wednesday morning. The front and moisture will move off the East Coast by Wednesday evening.

Meanwhile, another strong front over the Plains will move eastward to Northeast and south to interior Gulf Coast States by Thursday morning. As the boundary passes over the Great Lakes it will produce showers and some of the showers will be rain and snow mixed over the Upper Great Lakes overnight Thursday. Cold high pressure over Western Canada will move southward to the Northern/Central Plains by Thursday evening. In contrast, a strong upper-level high over the West Coast will lead to temperatures being 10 to 20 degrees above average over parts of the interior West Coast and the Great Basin with dry conditions over the region. Additionally, high pressure over the Rockies will aid in producing strong wind over the area with offshore flow over Southern California through Thursday. The SPC has issued an elevated area of fire weather over parts of the Northern High Plains into the Central Plains and over Southern California through Thursday morning. Furthermore, parts of Southern California and the Central Rockies have air quality alerts.

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 Florida Peninsula, Fri-Tue, Oct 2-Oct 6.

– Heavy rain across portions of the Mid-Atlantic coast, Sun-Mon, Oct 4-Oct 5.

– Flooding occurring or imminent across portions of Florida and Louisiana.

– Much above normal temperatures across portions of northern California to southern Oregon, Fri-Tue, Oct 2-Oct 6.

– Much above normal temperatures across portions of central California, Fri, Oct 2.

– Much below normal temperatures across portions of the central Plains to the west of the Middle Mississippi Valley, Fri, Oct 2.

– Heavy precipitation across the Kenai Peninsula Borough, Fri-Sat, Oct 2-Oct 3.

– Heavy precipitation across portions of southern Alaska to the Alaska Panhandle, Sun-Mon, Oct 4-Oct 5.

Detailed Summary:

During the medium range period (Friday, Oct 2 – Tuesday, Oct 6), a deep upper-level trough will remain a dominant feature over the central to eastern U.S., while upper-level ridging should continue to persist across the West. Much of the western U.S. will see warmer than average temperatures through the period. Parts of central California just inland from the Pacific coast will see one more day of high temperatures well into the 90s on Oct. 2. which is more than 12 degrees above normal. The ridge will gradually lose some strength by the weekend into early next week. This will allow the warm temperatures to moderate some but portions of northern California to southern Oregon will continue to experience much above normal temperatures into early next week.

In contrast to the warmth in the West, much of the eastern two-thirds of the country will continue to witness below normal temperatures into early next week under a lingering longwave upper-level trough. The associated chilly conditions over the central Plains should be moderating at the start of the medium range period but temperatures should still be around 12 degrees below normal for parts of the area. Meanwhile, an Alberta clipper is forecast to dip into the central Plainsduring the weekend, bringing a reinforcing shot of chilly air back into the northern Plains. This shot of chilly air will be short-lived however, as warmer than normal temperatures will quickly work their way into the Plains early next week behind a warm front. A note about the Alberta clipper–some of the global models (the ECMWF in particular) have been indicating that the clipper could eventually evolve into a nor’easter for the Northeast. This scenario has not been adopted for this chart for today but the situation will be monitored for the days to come.

Over the eastern U.S., a cold front will stall just off the East Coast and across southern Florida during much of the medium range period. A continued feed of tropical moisture ahead of the front is forecast to keep a good chance of heavy rain for southern to eastern Florida through early next week. The National Hurricane Center is also watching for the potential of a tropical cyclone developing and moving across the western Caribbean for that general time period. In addition, there is increasing model support for a wave of low pressure to form along the front off the southeast U.S. coasts which may lead to further East Coast development as mentioned earlier. Regardless of the potential of East Coast cyclogenesis, heavy rain is likely near the Mid-Atlantic coast on Sunday and Monday.

Over Alaska, an active pattern will lead to fast and frequent energetic oceanic cyclones to push toward the southern part of the state through early next week. Heavy precipitation will be likely across the Kenai Peninsula Borough on Friday and Saturday associated with and first cyclone, spreading eastward into the northern part of the Alaska Panhandle Sunday and Monday associated with the second cyclone. The second cyclone could be potent enough to bring 50-knot winds to the coastal sections of southern Alaska on Sunday but a high wind area has not been depicted on the map at this time. Farther north in interior Alaska, above normal temperatures are forecast, with highs approaching 60 degrees.

(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.

We also include drought information in this section.

New Seasonal Outlook Issued September 17, 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

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

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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