US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
332 PM EST Fri Jan 11 2019
 
Valid Monday January 14 2019 - Friday January 18 2019
 
Hazards:
Heavy precipitation across portions of California, the Pacific Northwest, and the Northern Great 
Basin, Fri, Jan 18.
Heavy precipitation across portions of California, the Pacific Northwest, and the Southwest, 
Mon-Thu, Jan 14-Jan 17.
Heavy precipitation across portions of the Southern Rockies, the Central Rockies, the Central Great 
Basin, the Northern Rockies, and the Southwest, Thu-Fri, Jan 17-Jan 18.
Heavy rain across portions of the Southeast, the Lower Mississippi Valley, and the Southern Plains, 
Thu-Fri, Jan 17-Jan 18.
Heavy snow across portions of the Central Great Basin, California, and the Southwest, Tue-Thu, Jan 
15-Jan 17.
Flooding occurring or imminent across portions of the Lower Mississippi Valley, the Middle 
Mississippi Valley, the Mid-Atlantic, the Southeast, the Southern Plains, and the Ohio Valley.
Flooding likely across portions of the Southeast.
High winds across portions of California and the Pacific Northwest, Fri, Jan 18.
High winds across portions of California, Mon-Thu, Jan 14-Jan 17.
High winds across portions of the Mid-Atlantic, Mon, Jan 14.
High significant wave heights for coastal portions of California and the Pacific Northwest, Thu, 
Jan 17.
Heavy precipitation across portions of mainland Alaska, Mon-Wed, Jan 14-Jan 16.
High winds across portions of mainland Alaska, Mon, Jan 14.
 
Detailed Summary:

The medium range period will be very active for the western U.S., particularly for the West Coast 
as a trough digs across California. The 12Z GFS, 12Z ECMWF and their ensemble means are all 
signaling heavy precipitation for California from Monday, January 14 through Thursday, January 17. 
This includes both heavy rainfall and higher elevation snowfall. Additionally, guidance is also 
showing very good agreement for the Sierra Nevada mountain range receiving heavy snowfall through 
this time period also. By Friday, January 18, heavy precipitation will begin to wind down for most 
of California--although lighter precipitation could occur. However, another upper trough will 
approach the Pacific Northwest. Consequently, another round of heavy rain and higher elevation 
snowfall, especially along the Washington Cascades, is expected on the 18th. These systems 
impacting the West Coast will also bring the additional hazard of high winds along the coastline 
during the week along with the possibility of significant waves in northern California on the 17th 
as an occluded front approaches California. 

As the digging trough slides eastward on the 17th and 18th, precipitation will begin to increase 
across the Great Basin. Guidance from overnight along with the 12Z run continue to signal areas in 
the Four Corners to receive heavy snowfall in the higher mountain tops. Heavy rain may also impact 
isolated areas in favorable terrain. 

An upper level disturbance will slide across the southern Plains and enter the lower Mississippi 
Valley on January 17-18. This may bring heavy rainfall to these regions; however, the last few runs 
of the GFS and ECMWF have not come to a consensus on exactly where the axis of heavy rainfall will 
set up. In the coming days, this area of heavy precipitation could shift. Furthermore, the ECMWF 
and GFS are indicating a winter weather event possibly setting up in the central Plains/middle 
Mississippi Valley by January 18. However, confidence remains low on where the wintry precipitation 
sets up--with the GFS being faster than the ECMWF. 

Alaska remains active as a trough sets up along south-central region of the state. This will bring 
heavy precipitation to this area--with heavy rainfall and higher elevation snow. Some models also 
indicate high winds will impact southwest Alaska on Monday, January 14.


Reinhart