Valid Saturday February 11, 2023 to Friday February 17, 2023
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EST February 03 2023Synopsis
: Mid-level low pressure with one or
more surface storm systems could bring below (above)-normal temperatures
(precipitation) to much of the West, with heavy precipitation possible across
central and southern California, and heavy snowfall possible in the Sierra
Nevada and some higher elevations in the Great Basin and Four Corners region.
It should be noted that while surplus precipitation is anticipated in much of
California, an extreme event like the ones seen earlier this winter appears
unlikely at this time. Meanwhile, the storm systems have the potential to
generate high winds at times over much of the central and western Contiguous
United States (CONUS). To the east, one or more storm systems ejecting out of
the Southwest and through the Great Lakes region could drop heavy snow on
portions of the Upper Midwest and heavy rains across parts of the Southeast and
the Mississippi, Ohio, and Tennessee Valleys. Hazards
- Slight risk of heavy precipitation for parts of the Lower Mississippi,
Ohio, and Tennessee Valleys and the Southeast, Mon-Fri, Feb 13-17.
- Slight risk of heavy precipitation for portions of California and adjacent
Nevada, Sat-Wed, Feb 11-15.
- Slight risk of high winds for parts western CONUS and the central Plains,
Sat-Fri, Feb 11-17.
- Slight risk of heavy snow for the higher elevations of the Sierra Nevada in
California, Sat-Fri, Feb 11-17.
- Slight risk of heavy snow for parts of the higher elevations in the Four
Corners and Great Basin, Sun-Thu, Feb 12-16.
- Slight risk of heavy snow in the Upper Midwest, Tue-Fri, Feb 14-17.
For Monday February 06 - Friday
February 10: WPC Days 3-7 U.S.
Hazards For Saturday February 11 -
Friday February 17:
Tools are in better agreement than yesterday on the
evolution of the mid-level pattern through week-2 as all ensemble means settle
into a pattern featuring a strong anomalous ridge in the central North Pacific,
a mid-level trough with its axis in the western CONUS, and another 500-hPa
ridge over the eastern CONUS. The main area of disagreement is in eastern
Canada. The European ensemble mean keeps above-normal 500-hPa heights in this
region while the Canadian ensemble mean shows near- to below-normal heights in
the region, especially toward the Davis Strait. The GEFS is a compromise of the
other two ensemble means. This could impact temperatures in the eastern CONUS
later week-2. If temperatures are high enough, snowmelt and ice jam flooding is
possible across parts of New England, but confidence is not sufficient to post
a hazard at this time. In any case, this pattern favors generally unsettled
weather in much of the West through at least the middle of week-2, and a
potential storm track from the southern High Plains through the Great Lakes
could trigger hazards for wind, rain, and snow over parts of the interior CONUS.
Timing is uncertain, but for the middle and later part of week-2, the
mid-level trough has the potential to trigger several hazards, particularly in
central and southern sections of the western CONUS. Heavy precipitation is
possible over central and southern California and adjacent Nevada, although an
extreme event like those experienced earlier this winter seems unlikely at this
time. With continued support in the reforecast tools, a slight risk of heavy
precipitation remains posted for California for Feb 11-15, as well as a slight
risk of heavy snow for the higher elevations of the State Feb 11-17. The same
features bring a slight risk of heavy snow to the higher elevations of the
Great Basin and western Four Corners Region for most of week-2 (Feb 12-16), and
any individual surface impulses has the potential to bring high winds to parts
of the central Plains and western CONUS. Therefore, a slight risk of high winds
remains posted for this part of the country for the entirety of week-2 to
capture the uncertainty in the timing of individual storm systems in the
Southwest and their ejection northeastward across the central CONUS during the
After early week-2, most tools take a high surface pressure center from the
eastern CONUS into the western North Atlantic. The resulting southerly surface
winds to the west of the high pressure are expected to pull moist air from the
Gulf of Mexico into much of the southeastern CONUS. Models are in better
agreement today indicating this may be enhanced by a surface low pressure
center or two tracking from southwestern Plains through the Great Lakes region
during mid to late week-2. Regardless, the flow of moist, mild air over a weak
surface front draped across the southeastern CONUS to the south of the storm
track increases the chances for heavy precipitation from the lower Mississippi
Valley across the interior Southeast and southern Appalachians. The GEFS and
Canadian ensemble means drop about twice as much precipitation there as the
European ensemble mean, although totals in the two wetter model means were
slightly lower than yesterday, in the 1.5 to 2.0 inch range from central
Mississippi through northern Georgia and the Tennessee Valley. The GEFS and
European ensemble reforecast tools are more robust than yesterday with the
chances for precipitation exceeding the 85th percentile over the lower
Mississippi Valley and Southeast, but still appear lower than indicated by the
raw ensemble mean precipitation outputs. But the anticipated southerly flow and
the agreement on heavier precipitation in the Canadian ensemble mean prompts
the slight chance for heavy precipitation later in week-2 (Feb 13-17). This is
consistent with the slightly cyclonic mid-level flow expected from the trough
centered farther to the west. Confidence is tempered by the inconsistency on
the precipitation intensity among the tools, but there is somewhat better
agreement than yesterday.
The increased potential for one or more storms tracking from the Southwest
through the Great Lakes Region increases the risk for heavy snow to the north
of the storm track through the Upper Midwest during the middle and later part
of week-2, and for high winds farther west in the wake of these storms. The
reforecast GEFS snow water equivalent tools and the raw precipitation output
from many of the tools increases confidence in this development, but the
uncertainty in the strength and timing of the storms tracking through the
region tempers confidence somewhat for any particular location and time, and a
slight risk of heavy snow is posted for Feb 14-17. .
Over Alaska, a strong storm system west of the Mainland early week-2 could
produce heavy precipitation and high winds along parts of the southern tier
near the Pacific Coast before the low pressure weakens, reducing the pressure
gradient and therefore the high winds and moist Pacific inflow as well by the
middle of week-2.
Forecaster: Rich Tinker
Please consult local NWS Forecast Offices for short range forecasts and region-specific information.
Week-2 Probabilistic Extremes Tool
GFS Ensemble Forecasts