US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
351 PM EDT Thu Oct 14 2021
 
Valid Sunday October 17 2021 - Thursday October 21 2021
 
Hazards:
- Flooding possible across portions of the Southern Plains.
- Flooding occurring or imminent across portions of the Southeast.
- Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon-Wed, Oct 
18-Oct 20.
- Heavy precipitation across portions of mainland Alaska, Sun, Oct 17.
- High winds across portions of mainland Alaska and the Aleutians, Sun, Oct 17.
 
Detailed Summary:

On Sunday, the parent low associated with a front that moved off the East Coast on Saturday evening 
will have a good pressure gradient associated with the low over the Great Lakes.  The pressure 
gradient produces strong wind over parts of the Lake Huron into Sunday evening. On Sunday, a front 
moving onshore over the Pacific Northwest will advance eastward to the Great Lakes to the 
Central/Western Gulf Coast by Thursday. The system will produce rain over parts of the Pacific 
Northwest/Northern California late Sunday, with some light snow at the highest elevations over 
parts of Northern/Central California overnight Sunday.  Scattered rain and highest elevation snow 
develop over parts of the Great Basin/Northern Rockies overnight Monday into Tuesday morning.  On 
Wednesday, the boundary will intersect moisture flowing northward out of the Western Gulf of 
Mexico, producing scattered showers and thunderstorms over Central/Southern Plains into the Middle 
Mississippi Valley.

Overnight Wednesday, the showers and thunderstorms move into parts of the Ohio Valley while 
continuing into the Lower Mississippi Valley and Southern Plains.  There is uncertainty whether the 
rain will be heavy enough to produce any hazards over the region. However, WPC will continue to 
monitor the situation to see if hazardous rainfall develops.  No hazardous weather develops over 
the lower 48 states during the forecast period.

Over Alaska, the story is different.  On Sunday, a deep area of low pressure moving from the 
Aleutians into the Gulf of Alaska moves eastward to near the Panhandle by Tuesday and stalling out. 
 On Sunday, a second area of low pressure moving off the Asian continent moves across the Bering 
Sea on Tuesday, moving into the Gulf of Alaska by Wednesday.  The lead low has a very strong 
pressure gradient associated with the surface low that produces high winds across the Aleutians on 
Sunday.  Also, on Sunday, the system will produce heavy precipitation across the southern and 
western parts of Kodiak Island and the Kenai Peninsula. Moreover, as the low moves into the Gulf of 
Alaska, heavy precipitation will develop over parts of the Panhandle to just east of Valdez on 
Monday into Wednesday. On Monday, high wind will develop offshore from the Panhandle, but at this 
time does not look like a hazard. 

Ziegenfelder