US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
436 PM EDT Wed Oct 07 2020
 
Valid Saturday October 10 2020 - Wednesday October 14 2020
 
Hazards:
- Heavy precipitation across portions of northern Idaho, Sun-Mon, Oct 11-Oct 12.
- Heavy precipitation across portions of northwestern Wyoming, Sun, Oct 11.
- Heavy rain across much of the mid-Mississippi Valley, the Tennessee and Ohio Valleys into the 
central and southern Appalachians and the interior Mid-Atlantic, as well as the Pacific Northwest 
from the Cascades westward, Sat-Sun, Oct 10-Oct 11.
- Flooding possible across portions of the Lower Mississippi Valley to the Louisiana coast.
- Flooding occurring or imminent across portions of the Southeast.
- High winds across the interior portion of the lower Mississippi Valley, Sat, Oct 10.
- Much above normal temperatures across much of the Great Plains into the nearby Rockies and into 
the Upper Midwest, Sat-Sun, Oct 10-Oct 11.
- Much above normal temperatures across much of the northern High Plains and nearby Rockies, Sat, 
Oct 10.
- Heavy precipitation across much of the Alaska Panhandle, Wed, Oct 14.
 
Detailed Summary:

The medium range period will likely begin with Tropical Storm Delta weakening and tracking further 
inland across the interior sections of the lower Mississippi Valley on Saturday, where some high 
winds are still possible early in the day.  Heavy rain is forecast to advance well ahead of the 
tropical storm as it continues to interact with an upper-level trough moving across Texas and 
gradually losing tropical characteristics.  Much of the mid-Mississippi, Tennessee and Ohio Valleys 
into the central and southern Appalachians will likely see heavy rainfall through much of the 
weekend.  Heavy rain is also forecast for the interior sections of the Mid-Atlantic as a large high 
pressure system feeds Atlantic moisture into the area under a persistent east to southeasterly 
flow.  The heavy rain could spread further up the central Appalachians early on Monday.  Models 
continue to show a varying degree of uncertainty regarding how fast the rain will reach New England 
by early next week.  Nevertheless, all models indicate that the system will gradually weaken with 
time.  This will diminish the threat of heavy rain associated with the remnants of Delta moving 
further into the Northeast on Tuesday.  However, a strong cold front will likely approach the 
Northeast by midweek with areas of heavy rain and thunderstorms possible.

Outside of Delta, a major change in the synoptic pattern is in store as a deep upper trough is 
forecast to work its way across the western U.S into the Plains during the medium range period.  A 
large dome of cold air will settle across much of the western U.S. behind a strong cold front.  
This will likely bring a period of mixed precipitation to the higher elevations of northwestern 
Wyoming and northern Idaho Sunday and Monday before tapering off on Tuesday.  There could be some 
meaningful snowfall accumulations at the coldest locations from northern Idaho to northwestern 
Wyoming, and possibly the higher elevations of northern Colorado.

Ahead of the cold front however, much above normal temperatures are forecast for much of the Plains 
into the nearby Rockies into this weekend.  In fact, record high temperatures reaching the upper 
90s to near 100 are possible over the southern High Plains to along the Rio Grande on Saturday.  
Meanwhile, an active weather pattern behind the strong cold front will bring persistent rain, some 
of which heavy, across the Pacific Northwest from the Cascades westward and down into northern 
California during the weekend.  Another surge of Pacific moisture could reach northwestern 
Washington by the middle of next week.

Finally, the synoptic pattern appears to be settling down during much of the medium range period 
for Alaska.  However, there is a fairly good agreement that a Pacific cyclone will impact the 
Alaska Panhandle with heavy precipitation and possibly high winds by the middle of next week.

Kong