Valid Friday February 03, 2023 to Thursday February 09, 2023
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EST January 26 2023Synopsis
: Surface high pressure, with
anomalously cold temperatures, is likely to shift eastward from the Great
Plains and Midwest to the Northeast late next week. Enhanced onshore flow
increases the risks of heavy precipitation, heavy snow, and high winds across
the Pacific Northwest, northern California, and the northern to central Rockies
from February 3 to 6. Later in week-2, a more zonal flow pattern is expected
across the mid-latitudes which leads to higher forecast uncertainty.
- Moderate risk of much below-normal temperatures
for the Upper Mississippi Valley and Great Lakes, Fri, Feb 3.
- Slight risk of much below-normal temperatures for the Great Plains and
Midwest, Fri-Sat, Feb 3-4.
- Moderate risk of much below-normal temperatures for parts of the Northeast,
Fri-Sat, Feb 3-4.
- Slight risk of much below-normal temperatures for the Northeast and
Mid-Atlantic, Fri-Sun, Feb 3-5.
- Slight risk of heavy precipitation for portions of California, Oregon, and
Washington, Fri-Mon, Feb 3-6.
- Slight risk of heavy snow for northern Coastal Range, Cascade Range, Sierra
Nevada Mountains, and Northern Rockies, Fri-Mon, Feb 3-6.
- Slight risk of high winds for portions of California, Oregon, and
Washington, Fri-Mon, Feb 3-6.
Sunday January 29 - Thursday February 02: WPC Days 3-7 U.S.
Hazards For Friday February 03 -
Thursday February 09:
The Arctic air outbreak across the Great Plains and
Midwest is likely to peak prior to week-2, on Feb 1 and 2. However, the GEFS
and ECMWF reforecast tools support a continuation of a slight (20%) and
moderate (40%) risk of much-below normal temperatures (minimum temperatures
reaching the lowest 15th percentile) for these areas through the beginning of
week-2. As 500-hPa heights increase and the core of the Arctic air shifts
northeastward beyond that time, moderating temperatures are forecast across the
central U.S. by Feb 5.
A short-lived and transient outbreak of Arctic air is forecast for the
Northeast early in week-2 with a deep anomalous 500-hPa trough rotating through
southeastern Canada. On Feb 3 and 4, a moderate risk of much below-normal
temperatures is posted for northern New York and New England where the
reforecast tools depict minimum temperatures having a 40 percent chance of
falling below the 15th percentile. Uncalibrated model solutions feature minimum
temperatures below -10 degrees F in the outlined area for a moderate risk. A
broader slight risk of much below-normal temperatures extends south to the
Mid-Atlantic through Feb 4. Due to large model differences on how far south the
anomalous cold spreads, the Southeast is not included in the slight risk.
Recent deterministic model runs, such as the ECMWF (0Z/Jan 26), have shown
a wave of low pressure developing across the lower Mississippi Valley late next
week with an eastward track to the Mid-Atlantic. This could occur with a
shortwave trough separating from the full-latitude trough over the east-central
CONUS. If this were to happen, accumulating snow may affect the central
Appalachians and Mid-Atlantic. However, forecast confidence is low due to the
lack of good model agreement/consistency and this type of winter weather event
is difficult to predict at the week-2 time scale.
The GFS and ECMWF ensemble means remain consistent that a shortwave trough
progresses eastward from the northeastern Pacific to the Pacific Northwest and
northern Rockies early in week-2. This shortwave trough, reforecast tools, and
uncalibrated model output support a slight risk of heavy precipitation and snow
across the Pacific Northwest, northern California, and the northern Rockies
from Feb 3-6. The integrated vapor transport tool for the GEFS and ECMWF
ensemble indicate the most likely area for heavy precipitation to be from
40-45N along the West Coast. The enhanced onshore flow, associated with the
shortwave trough, also results in a slight risk of high winds for the Pacific
Northwest and northern California. Although model spread increases by the
second week of February, the consensus is for the storm track to shift
northward with the ECMWF and Canadian ensemble means predicting the development
of a mean 500-hPa ridge near the West Coast.
The GEFS and ECMWF ensemble means are in poor agreement with the longwave
pattern over Alaska. The GEFS is most bullish with anomalous cold, while the
ECMWF reforecast tool favors near to above-normal temperatures during week-2.
Therefore, no temperature hazards are posted. Above-normal precipitation is
slightly favored for the Alaska Panhandle, but hazardous precipitation is
Forecaster: Brad Pugh
Please consult local NWS Forecast Offices for short range forecasts and region-specific information.
Week-2 Probabilistic Extremes Tool
GFS Ensemble Forecasts