US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
244 PM EST Fri Dec 14 2018
 
Valid Monday December 17 2018 - Friday December 21 2018
 
Hazards:
Heavy precipitation across portions of California, the Pacific Northwest, and the Northern Great 
Basin, Mon-Fri, Dec 17-Dec 21.
Heavy precipitation across portions of the Northern Rockies and the Northern Great Basin, Mon-Wed, 
Dec 17-Dec 19.
Heavy rain across portions of the Pacific Northwest, Wed-Thu, Dec 19-Dec 20.
Flooding possible across portions of the Southeast, the Middle Mississippi Valley, the 
Mid-Atlantic, and the Ohio Valley.
Flooding occurring or imminent across portions of the Southeast, the Mid-Atlantic, and the Southern 
Plains.
Flooding likely across portions of the Southeast.
High winds across portions of California, the Pacific Northwest, and the Northern Great Basin, 
Mon-Tue, Dec 17-Dec 18.
High winds across portions of the Northeast, Tue, Dec 18.
High significant wave heights for coastal portions of California and the Pacific Northwest, Mon, 
Dec 17.
High significant wave heights for coastal portions of the Pacific Northwest, Mon-Wed, Dec 17-Dec 19.
High winds across portions of mainland Alaska, Fri, Dec 21.
Much below normal temperatures across portions of mainland Alaska, Mon-Thu, Dec 17-Dec 20.
Much below normal temperatures across portions of mainland Alaska, Fri, Dec 21.
 
Detailed Summary:

Fast-moving low pressure systems and associated fronts are forecast to impact the Pacific Northwest 
through much of the medium range hazards period.  Periods of organized moderate to locally heavy 
precipitation along with high winds can be expected from coastal Pacific Northwest into the 
Cascades and down into northern California through much of next week.  Significant waves emanating 
from these large-scale cyclones will batter the Pacific Northwest coastline and nearby offshore 
waters through 12/19, and even down into coastal California on 12/17.  Models show 5-day totals of 
multiple inches of rainfall possible along the coast and snow measured in feet in the highest 
terrain, particularly in the Washington Cascades.

A strong high pressure system building in behind a strengthening low pressure system moving away 
from the northeastern U.S. will result in blustery northwesterly winds across New England next 
Tuesday (12/18) and Wednesday (12/19).  Sustained winds could reach gale force over parts of 
southeastern New England on 12/18.

Flooding will be a lingering concern for a few more days across certain locations of southeastern 
Texas, parts of the Southeast and possibly across the interior sections of the Carolinas into 
southern Virginia where a significant snowfall event has recently occurred.  Flooding is also 
possible from eastern Missouri to southwestern Illinois.

With a constant intrusion of marine air from the Pacific, warmer than normal temperatures will 
spread from west to east across the country.  The most significant temperature anomalies will be 
found across the northern Plains where temperatures are forecast to be more than 20 degrees above 
normal through next Friday.  Watch out for refreezing of cold surfaces overnight as temperatures 
are forecast to dip below freezing each night.

Over Alaska, an occluded cyclone should gradually weakened as it moves northwest into the Gulf of 
Alaska early next week.  This will bring a general improvement of weather conditions across 
southern and southeastern Alaska into midweek.  Another cyclone is forecast to approach the Gulf of 
Alaska from the southwest by the end of the week.  Temperatures will be much colder than normal 
over southwest Alaska through much of next week with a moderating trending expected to start next 
Friday 12/21.

Kong