Valid Tuesday February 04, 2020 to Monday February 10, 2020
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EST January 27 2020Synopsis
: A very broad area of mid-level low
pressure is predicted over much of Alaska and the CONUS during week-2, with the
exception of southern Alaska and the far western CONUS where mid-level high
pressure is forecast. There is significant uncertainty among the various
computer models regarding the predicted movement and intensity of individual
storm systems during the week-2 period. Hazards
chance of much below normal temperatures over northern Alaska, Tue-Sat, Feb 4-8.
- Slight chance of much below normal temperatures over the vicinity of the
Upper Mississippi Valley and Upper Great Lakes region, Tue-Wed, Feb 4-5.
- Slight chance of heavy precipitation from the eastern part of the southern
Plains to the southern Appalachians and Southeast, Tue-Thu, Feb 4-6, and
Sun-Mon, Feb 9-10.
- Slight chance of heavy snow along the southern coast of Alaska from about
Kodiak Island to the southern tip of the Panhandle, Tue-Mon, Feb 4-10.
- Slight chance of high winds for the northern and central Great Plains,
Tue-Sat, Feb 4-8.
- Slight chance of high winds for the southern coast of Alaska, Tue-Mon, Feb
For Thursday January 30 - Monday
February 03: WPC Days 3-7 U.S.
Hazards For Tuesday February 04 - Monday
A slight risk (20% or greater) for much below normal minimum
temperatures (falling to or below the 15th percentile) exists for two areas
during portions of week-2; northern Alaska (Feb 4-8), and the Upper Mississippi
Valley/Upper Great Lakes region (Feb 4-5). For the first region, the GFS and
ECMWF ensembles predict a subsiding of the cold snap over Alaska, in terms of
its magnitude and spatial coverage, with the best odds for much below normal
temperatures confined to the northern half of the state (Feb 4-8). This is
associated with a predicted 500-hPa trough and below normal heights. This
trough is actually one (minor) lobe of the expansive polar vortex, with another
(major) lobe extending across Canada and most of the CONUS east of the
Continental Divide. This second lobe of the polar vortex, and accompanying well
below-normal heights, is responsible for the second slight risk area across the
Upper Mississippi Valley/Upper Great Lakes region on Feb 4-5.
Multiple surface low pressure systems are forecast to bring widespread
precipitation from the eastern part of the southern Plains eastward to the
vicinity of the southern Appalachians and Southeast, from Feb 4-6 and from Feb
9-10. Between 1.0-1.5 inches of rain are forecast for each event by the GFS and
ECMWF ensemble probabilistic extremes tools. Towards the end of week-2,
temperatures along the northern edge of this precipitation area may be cold
enough to support freezing or frozen precipitation, but confidence this far out
in time is low.
The rear-side of the trough is expected to be located over the eastern
CONUS, supporting a slight risk of high winds (values at or exceeding the 85th
percentile, and 25 mph or greater) across the northern and central Great
Plains, Feb 4-8. This is due to several disturbances forecast to move
southeastward out of the Canadian Prairies and accompanying upslope flow.
Several cyclonic systems are expected to affect the southern coast of
Alaska during week-2. Therefore, a slight risk for heavy snowfall (18 inches
or more in orographically favored regions) is warranted from about Kodiak
Island eastward to the southern tip of the Panhandle region. Low-level
(850-hPa) temperatures from the ECMWF model are forecast to be subfreezing even
for immediate coastal areas, which would be supportive of snow. A slight risk
for high winds (35 mph or greater) is posted for the entire southern coast
during this period.
Forecaster: Anthony Artusa
Please consult local NWS Forecast Offices for short range forecasts and region-specific information.
Week-2 Probabilistic Extremes Tool
GFS Ensemble Forecasts