US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
438 PM EDT Mon Oct 12 2020
 
Valid Thursday October 15 2020 - Monday October 19 2020
 
Hazards:
- Heavy precipitation across portions of the Northern Rockies, Sun, Oct 18.
- Heavy rain across portions of the Mid-Atlantic, the Northeast, and the Great Lakes, Fri, Oct 16.
- Flooding possible across portions of the Southeast and the Southern Appalachians.
- Flooding occurring or imminent across portions of the Lower Mississippi Valley and the Southern 
Appalachians.
- Flooding likely across portions of the Southeast and the Southern Appalachians.
- High winds across portions of the Central Plains and the Southern Plains, Thu, Oct 15 and Sat, 
Oct 17.
- Much above normal temperatures across portions of the Central Great Basin and California, 
Thu-Sat, Oct 15-Oct 17.
- Much below normal temperatures across portions of the Upper/Middle Mississippi Valley, the 
Northern/Central Plains, and the Northern Rockies, Sun-Mon, Oct 18-Oct 19.
- Heavy precipitation across portions of the Alaska Panhandle, Thu, Oct 15.
 
Detailed Summary:

High pressure building over the Pacific Northwest and low pressure over Texas and the Four Corners 
Region into California will aid in developing high wind over some of the area but there is still 
uncertainty if the winds will meet the 34 mph or gust of greater than 58 mph criteria over the 
entire area.  At this time WPC is issuing High Winds over parts of Southern High Plains on Thursday 
where we feel the criteria has the greatest chance of being met.  Low pressure moving into Western 
Canada on Thursday into Friday will move into the Northern Plains on Saturday.  High pressure over 
the Southern High Plains on Friday will move southeastward to the Tennessee Valley by Saturday.  
The developing pressure gradient over the Southern High Plains, on Saturday, will bring high winds 
to the same part of the Southern Plains that had High Winds on Thursday.  As the high moves 
eastward off the Mid-Atlantic Coast on Sunday and low pressure moves into the Great Lakes, a 
pressure gradient could develop over parts of the Great Lakes and the Ohio Valley on Saturday and 
Sunday that might meet the High Wind criteria but there is not enough agreement between the models 
to put an area of High Wind with confidants.   

Meanwhile, a developing upper-level ridge over Pacific close to the West Coast will move into the 
West Coast that will allow temperatures to become 12 or greater above normal over parts of Central 
California on Thursday into Saturday.  In addition, a front over the Great Lakes extending 
southwestward to the Southern Plains, on Thursday, will move eastward to the East Coast by Friday.  
The front will aid in producing rain along and ahead of the boundary over parts of the Northeast 
that will meet the criteria of one inch in twenty four hours for heavy rain.   

Cold high pressure over Western Canada on Saturday will move southeastward to the Northern High 
Plains by Monday. The temperatures associated with the high will be cold enough to meet the 
criteria of 12 or great below normal over parts of the Northern High Plains into the Upper 
Mississippi Valley on Sunday and Monday.  Some of the temperatures will be in the teens overnight 
Sunday into Monday over the Northern High Plains.  Upslope flow associated with the high will aid 
in producing higher elevation snow and lower elevation rain over parts of the Northern Rockies on 
Sunday.   

Over Alaska, low pressure over the North Pacific/Gulf of Alaska, on Thursday, will move into 
Western Canada on Friday.   Moisture associated with the system will produce heavy precipitation 
over the southeastern portion of the Alaska Panhandle on Thursday.  High pressure will build in 
over much of the mainland on Friday moving out of Alaska by Sunday.  Low pressure will move into 
the Aleutians on Sunday and Monday.   i

Ziegenfelder