US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
422 PM EDT Tue Oct 26 2021
 
Valid Friday October 29 2021 - Tuesday November 02 2021
 
Hazards:
- Heavy rain across portions of the Mid-Atlantic, the Northeast, and the Great Lakes, Fri, Oct 29.
- Heavy rain across portions of New England, Sat, Oct 30.
- Flooding possible across portions of the Central Plains, the Mid-Atlantic, and the Northeast.
- Flooding likely across portions of the Middle Mississippi Valley, the Great Lakes, and the Ohio 
Valley.
- Much below normal temperatures across portions of the Central Plains and Midwest, Tue, Nov 2.
- Heavy precipitation across portions of mainland Alaska, Fri-Mon, Oct 29-Nov 1.
- High winds across portions of mainland Alaska and the Aleutians, Fri-Sat, Oct 29-Oct 30.
 
Detailed Summary:

Heavy rain in the East and a windy, wet, and snowy period of weather in Alaska highlight the 
Hazards Outlook for the medium range forecast period (Friday, October 29 - Tuesday, November 2). At 
the beginning of the period, a deep, upper-level low will be in place over the eastern half of the 
CONUS. An anomalously strong, occluding low pressure system will move northeastward across the Ohio 
Valley and into the Northeast Friday (October 29) and Saturday (October 30). Widespread showers are 
expected to be ongoing ahead of the occluded front as moisture streams in from the Atlantic ahead 
of and around the northern side of the system. Heavy rainfall greater than an inch is likely from 
the Mid-Atlantic northwest through the interior Northeast and the eastern Great Lakes on Friday. In 
addition, many of these areas have recently seen heavy rain, particularly from the greater New York 
City region west through northern Pennsylvania and southern New York, leading to more saturated 
soils and increased streamflows that may exacerbate the flood threat. The widespread heavy rain 
will move into New England on Saturday with locally higher rainfall totals of 2 + inches possible. 

As the system in the East moves out, the next cold front will progress southward across the Midwest 
and Plains. Storm chances will be low given limited moisture ahead of the front. However, cooler, 
Canadian air behind the front will result in morning lows at or below freezing for areas from the 
Central Plains to the Midwest on Tuesday (November 2), roughly from southwest Kansas northeast to 
northern Illinois. Given the potential for this to be the first freeze for this region, with 
susceptible vegetation remaining sensitive to freezing temperatures, a Much Below Normal 
Temperatures outlook area has been introduced to highlight this forecast first freeze. 
Additionally, as this cold front moves southward, it will likely slow as a wave of low pressure 
moves across the Southern Plains. Moisture returning northward from the Gulf with southerly flow 
ahead of the wave of low pressure will lead to increased lift and convergence across the boundary 
producing showers and storms with the potential for heavy rain. However, given model differences in 
the location of storm coverage and borderline forecast rain amounts, an outlook area will not be 
introduced at this time. 

In Alaska, a wet and windy period of weather is expected for the Aleutians and southern portions of 
the Mainland throughout much of the forecast period as a strong low pressure system moves 
northeastward from the Pacific towards the Gulf of Alaska. The tight pressure gradient around the 
deep low will result in high winds on Friday and Saturday from the Aleutians east along the coast 
to Prince William Sound. The high winds may continue into Sunday (October 31), but the system is 
forecast to weaken and the higher winds will likely begin to subside. Additionally, continuous 
increased moisture ahead of the system as it slows approaching the Gulf of Alaska will lead to 
several days of heavy rain and snow at lower elevations and significant mountains snows from 
Thursday through at least Monday (November 1) from the Alaskan Peninsula east to Southcentral. This 
will include eastern portions of the Aleutian Range, western portions of the Alaska Range and 
Chugach Mountains, and the Kenai Mountains. Several feet of snow is likely, particularly from very 
heavy accumulations expected on Saturday. The exact amount of rain and snow is difficult to predict 
at the lower elevations, but the precipitation is forecast to be heavy regardless. The heavier 
precipitation amounts may wane for eastern portions of the outlook area on Sunday as the system 
stalls and weakens some, but should continue for western portions of the outlook area and resume on 
Monday for the entire outlook area as the system moves further northeastward again. The heavy 
precipitation may also continue into Tuesday. However, given the lack of larger scale influences as 
the current system weakens and another storm system remains further south into the Pacific, will 
defer an extension of the outlook area until there is more confidence in the forecast.
 
Putnam