US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
228 PM EST Mon Jan 14 2019
 
Valid Thursday January 17 2019 - Monday January 21 2019
 
Hazards:
Heavy precipitation (rain and/or snow) from portions of the Middle Mississippi Valley to the 
Mid-Atlantic and southern New England, Fri-Sun, Jan 18-Jan 20.
Heavy rain across portions of California and the Pacific Northwest, Thu, Jan 17.
Heavy rain across the Lower Mississippi and Tennessee Valleys, and portions of the Southeast and 
Mid-Atlantic, Sat-Sun, Jan 19-Jan 20.
Heavy snow (higher terrain) across portions of the California, Thu, Jan 17.
Heavy snow (higher terrain) across portions of the northern Rockies, Central Great Basin and 
Central Rockies, Thu-Fri, Jan 17-Jan 18.
Heavy snow from portions of the Central Plains to the Ohio Valley and the Northeast, Fri-Sun, Jan 
18-Jan 20.
Flooding occurring or imminent across portions of the Southeast, the Lower Mississippi Valley, and 
the Southern Plains.
Flooding likely across portions of the Southeast.
High winds across portions of California and the Pacific Northwest, Thu, Jan 17.
High winds across portions of the Mid-Atlantic and the Northeast, Sun-Mon, Jan 20-Jan 21.
Much below normal temperatures across portions of the Central Plains, the Middle Mississippi 
Valley, the Southern Plains, the Upper Mississippi Valley, and the Northern Plains, Fri-Sun, Jan 
18-Jan 20.
Much below normal temperatures across portions of the Middle Mississippi Valley to the Ohio Valley 
and Northeast, Sun-Mon, Jan 20-Jan 21.
High significant wave heights for coastal portions of California and the Pacific Northwest, Thu, 
Jan 17.
Heavy precipitation across portions of the Alaska Panhandle, Sat-Mon, Jan 19-Jan 21.
High winds across portions of the Alaska Panhandle, Sat, Jan 19.
High significant wave heights for coastal portions of the Alaska Panhandle, Sat, Jan 19.
 
Detailed Summary:

The WPC hazards period (1/17-1/21 -- Thurs to Mon) begins with ongoing precipitation along much of 
the West Coast Day 3 (Thursday) as a deep surface low weakens off the Pacific Northwest Coast. The 
best chance for heavy rainfall will be along the Coast from Washington to southern California with 
heavy snow likely in the Sierra Nevada mountains. The significant precipitation along the West 
Coast should come to an end by Friday as the upper level system digs inland, but heavy snowfall 
will continue to be possible in the higher terrain of the Intermountain West and Northern/Central 
Rockies through Friday. In addition to precipitation hazards, significant waves and high winds are 
possible along much of the coast.

By the end of the week and this weekend (days 4-6), attention shifts towards the central and 
eastern U.S. states with the potential for another winter storm from the Midwest to the Northeast. 
Heavy snowfall is expected to the north (hazard area was drawn from roughly eastern Nebraska to 
northern New England, with heavy rainfall across the Southern States. Somewhere in between (lower 
Ohio Valley and Mid-Atlantic), there is likely to be a transition zone which may include some mixed 
precipitation or ice. There continues to be plenty of uncertainty on the details of where the 
heaviest snow and/or ice will occur so refinements to these areas are likely as the event gets 
closer in time. High Winds are also likely along the Mid-Atlantic and Northeast Coast Sunday and 
Monday as the surface low intensifies and moves away from the Coast.

Temperature hazards across the CONUS include an expansive much below normal temperatures (anomalies 
on the order of -12 to -20F) across the northern and central Plains eastward to the Northeast. A 
secondary much below normal temperatures area was also drawn farther south across eastern Texas 
into northern and western Louisiana.

In Alaska, heavy precipitation, significant waves, and high winds are possible across mainly the 
Alaskan panhandle as a storm moves through the Gulf Fri-Sun. Another storm near/south of the 
Aleutians later in the period is likely to generate a period of significant waves as well, but 
uncertainty in placement, track, and intensity of this system remains high and so a hazard area was 
not included on the chart this time.

Santorelli