Valid Wednesday March 04, 2020 to Tuesday March 10, 2020
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EST February 25 2020Synopsis
: Mid-level low pressure is
predicted over much of northern and eastern Alaska, and most of the western and
central contiguous U.S. (CONUS) during week-2. Mid-level high pressure is
forecast from the north-central and northeast Pacific into southwestern Alaska,
and over the eastern CONUS. Colder-than-normal temperatures are favored across
most of Alaska during week-2, though there may be a brief moderation in
temperatures during the middle of the forecast period. Heavy precipitation is
favored across a large portion of the southeastern CONUS during the first
several days of week-2. Hazards
- Moderate risk of much
below normal temperatures for southwestern, south-central, and central Alaska,
Wed-Thu, Mar 4-5.
- Slight risk of much below normal temperatures for most of Alaska south of
the Brooks Range, Wed-Tue, Mar 4-10.
- Moderate risk of heavy precipitation for Tennessee and much of the
east-central Gulf Coast region, Wed-Fri, Mar 4-6.
- Slight risk of heavy precipitation for the southern Ohio Valley, the
Tennessee Valley, the central and eastern Gulf Coast region, and parts of
adjacent states, Wed-Fri, Mar 4-6.
- Continued flood risk across the interior Gulf Coast states.
For Friday February 28 - Tuesday March
WPC Days 3-7 U.S. Hazards For Wednesday March 04 - Tuesday
Mid-level low pressure is predicted over most of the Arctic
Circle basin during week-2, extending southward over northern and eastern
Alaska. Mid-level high pressure is forecast from the north-central and
northeastern Pacific into southwestern Alaska. This pattern is conducive for
anomalously cold air across most of the 49th state. Accordingly, a slight risk
(>=20%) of much below normal minimum temperatures (15th percentile or less) is
depicted for Alaska, with the exceptions of the North Slope and the western
Aleutians, Mar 4-10. A moderate chance (>=40%) of much below normal
temperatures is specified for southwestern, south-central, and central portions
of Alaska, Mar 4-5. The probabilistic extremes temperature tool indicates the
ECMWF and GFS ensembles support a 60% chance of subzero minimum temperatures
for nearly all of the state, except the immediate southern coast. The ensembles
also predict at least a 20% chance for minimum temperatures to reach/exceed -40
deg F over northern and eastern portions of the Central Interior. Over the
CONUS, there is considerable discrepancy between models as to the exact
placement and magnitude of the anomalous cold; therefore no hazardous
temperature region has been specified on the map for the Lower 48 states.
As a surface high moves out over the western Atlantic early in week-2,
return flow on its western side favors the increase of low-level Gulf moisture
across the eastern CONUS. A slight risk of heavy precipitation (>1" in a
24-hour period) is indicated for the southern Ohio Valley, the Tennessee
Valley, the central and eastern Gulf Coast region, and parts of adjacent
states, Mar 4-6. A moderate risk of heavy precipitation is posted for
Tennessee and much of the east-central Gulf Coast region, Mar 4-6, where the
GFS and ECMWF-based tools were in best agreement. The 12z GEFS predicts surface
low pressure will track across the eastern third of the CONUS during the first
few days of week-2. With a 500-hPa trough predicted upstream of the highlighted
heavy precipitation area and accompanying southwest flow aloft, combined with
southerly flow near the surface, there is a significant chance that severe
weather could develop. This region and time of year only adds to those odds,
especially over the central Gulf Coast region. There are enhanced odds of
flooding across portions of this region which have already reported very heavy
rainfall in recent weeks. This includes much of the interior Gulf Coast states,
where monthly precipitation anomalies range between 3-6 inches above normal,
and 30-day accumulations range from 200%-400% of normal (or greater).
The ECMWF and GFS ensemble mean precipitation forecasts depict subtropical
moisture coming into the southwestern/south-central CONUS late in week-2. No
precipitation hazard area has been posted today for this region due to
substantial uncertainty this far out in time regarding the spatial extent and
amount of the precipitation. The possibility of this subtropical moisture
entering the country associated with an atmospheric river will be monitored in
the days ahead.
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