566
FXUS21 KWNC 031929
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST FEBRUARY 03 2025
SYNOPSIS: ARCTIC HIGH PRESSURE INCREASES THE CHANCE OF MUCH BELOW-NORMAL
TEMPERATURES FROM THE WEST COAST TO THE GREAT PLAINS AND UPPER MISSISSIPPI
VALLEY. MULTIPLE LOW PRESSURE SYSTEMS ARE FORECAST TO BRING AN INCREASED RISK
OF HEAVY SNOW TO THE OHIO VALLEY, MID-ATLANTIC, AND NORTHEAST DURING
MID-FEBRUARY. PERIODS OF RAIN ARE LIKELY TO OCCUR ACROSS THE SOUTHEAST WITH THE
HEAVIEST AMOUNTS FOCUSED ON THE TENNESSEE VALLEY.
HAZARDS
HIGH RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PARTS OF THE NORTHERN GREAT
PLAINS, TUE-WED, FEB 11-12.
MODERATE RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PARTS OF THE PACIFIC
NORTHWEST, NORTHERN ROCKIES, AND NORTHERN GREAT PLAINS, TUE-THU, FEB 11-13.
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PARTS OF THE WESTERN AND
CENTRAL U.S., TUE-MON, FEB 11-17.
SLIGHT RISK OF HEAVY SNOW FOR THE OZARKS, OHIO AND TENNESSEE VALLEYS,
MID-ATLANTIC, AND NORTHEAST, TUE-SAT, FEB 11-15.
SLIGHT RISK OF HEAVY SNOW FOR THE CASCADES AND NORTHERN ROCKIES, TUE-MON, FEB
11-17.
MODERATE RISK OF HEAVY PRECIPITATION FOR THE TENNESSEE VALLEY AND SOUTHERN
APPALACHIANS, TUE-THU, FEB 11-13.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE SOUTHEAST, LOWER
MISSISSIPPI VALLEY, EASTERN OKLAHOMA, AND EASTERN TEXAS, TUE-SAT, FEB 11-15.
DETAILED SUMMARY
FOR THURSDAY FEBRUARY 06 - MONDAY FEBRUARY 10:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY FEBRUARY 11 - MONDAY FEBRUARY 17: EARLY IN WEEK-2, THE GEFS DEPICTS
A BRIDGING BETWEEN ANOMALOUS 500-HPA RIDGES OVER ALASKA AND SCANDINAVIA AS HIGH
LATITUDE BLOCKING BECOMES ESTABLISHED OVER THE NORTHERN HEMISPHERE. CONSISTENT
WITH THIS PATTERN CHANGE, NEARLY ALL OF THE GEFS ENSEMBLE MEMBERS FEATURE A
TRANSITION TO A NEGATIVE ARCTIC OSCILLATION BY FEBRUARY 11. PRIOR TO WEEK-2,
ARCTIC HIGH PRESSURE IS FORECAST TO SHIFT SOUTH INTO THE LOWER 48 STATES AND
THE HIGH LATITUDE BLOCKING IS LIKELY TO RESULT IN ADDITIONAL ARCTIC HIGHS
EXPANDING SOUTH FROM CANADA. BASED ON GEFS AND ECMWF PROBABILISTIC EXTREMES
TOOL (PET) AND UNCALIBRATED ECMWF MODEL OUTPUT, A HIGH RISK OF MUCH BELOW
NORMAL TEMPERATURES (FEB 11 AND 12) IS POSTED FOR THE NORTHERN GREAT PLAINS
WHERE THERE IS NEAR OR MORE THAN A 60 PERCENT CHANCE OF MINIMUM TEMPERATURES
FALLING BELOW THE 15TH PERCENTILE AND -10 DEGREES F. ANY ENHANCED WINDS COULD
RESULT IN WIND CHILL VALUES BELOW -25 OR -30 DEGREES F, THE COLD ADVISORY
CRITERIA. A BROADER MODERATE RISK, THROUGH FEBRUARY 13, EXTENDS WEST TO INCLUDE
THE PACIFIC NORTHWEST. THE UNCALIBRATED ECMWF MODEL FEATURES MINIMUM
TEMPERATURES NEAR 25 DEGREES IN PORTLAND, OREGON ON FEBRUARY 11 AND 12.
ALTHOUGH THE CENTRAL VALLEY OF CALIFORNIA IS NOT INCLUDED IN THE MODERATE RISK
AT THIS TIME, THERE IS AN ELEVATED CHANCE OF A FREEZE FOR THAT AREA. SINCE THE
GEFS FAVORS A PERSISTENCE OF THE AMPLIFIED 500-HPA TROUGH OVER THE WEST-CENTRAL
U.S., A SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURE IS VALID THROUGH FEBRUARY
17 FOR PORTIONS OF THE WEST, GREAT PLAINS, AND UPPER MIDWEST.
THE GEFS CONTINUES TO DEPICT AN AMPLIFIED 500-HPA TROUGH EXTENDING FROM HUDSON
BAY SOUTHWESTWARD TO THE ROCKIES. DOWNSTREAM OF THIS ANOMALOUS TROUGH, THE GEFS
DEPICTS MULTIPLE WAVES OF LOW PRESSURE TRACKING EASTWARD FROM THE OHIO AND
TENNESSEE VALLEY TO THE MID-ATLANTIC. BASED ON THE GEFS SNOW WATER EQUIVALENT
PROBABILISTIC EXTREMES TOOL (PET) ALONG WITH GEFS AND ECMWF ENSEMBLE MEAN
SNOWFALL AMOUNTS, A SLIGHT RISK OF HEAVY SNOW IS POSTED ACROSS THE OZARKS, OHIO
VALLEY, MID-ATLANTIC, AND NORTHEAST THROUGH FEBRUARY 15. DUE TO UNCERTAINTY ON
THE TIMING AND TRACK OF EACH WAVE OF LOW PRESSURE ALONG WITH PRECIPITATION
TYPE, A MODERATE RISK IS NOT POSTED AT THIS TIME.
FARTHER TO THE SOUTH, A SLIGHT RISK OF HEAVY PRECIPITATION IS VALID THROUGH THE
SAME TIME PERIOD AND EXTENDS SOUTH TO THE GULF COAST. THE GEFS AND ECENS DEPICT
7-DAY AMOUNTS OF 2 TO 4 INCHES ACROSS THE TENNESSEE VALLEY. BASED ON 24-HOUR
AMOUNTS FROM RECENT GEFS MODEL RUNS, A MODERATE RISK OF HEAVY PRECIPITATION IS
POSTED FOR THE TENNESSEE VALLEY AND SOUTHERN APPALACHIANS FROM FEB 11-13. MANY
OF THE 28-DAY AVERAGE STREAMFLOWS ARE BELOW NORMAL ACROSS NORTHERN PARTS OF
ALABAMA AND GEORGIA ALONG WITH EASTERN TENNESSEE WHICH IS EXPECTED TO LIMIT THE
FLOODING RISK THROUGH MID-FEBRUARY. HOWEVER, IF THIS WET PATTERN CONTINUES,
THEN THE FLOODING RISK WOULD INCREASE LATER IN THE MONTH.
AN ANOMALOUS 500-HPA TROUGH ALONG WITH THE GEFS SWE PET SUPPORTS A SLIGHT RISK
OF HEAVY SNOW FOR THE CASCADES AND NORTHERN ROCKIES THROUGH THE ENTIRETY OF
WEEK-2. ALTHOUGH ABOVE-NORMAL PRECIPITATION IS FAVORED FOR THE COASTAL PACIFIC
NORTHWEST, 3-DAY PRECIPITATION AMOUNTS ARE EXPECTED TO REMAIN BELOW HAZARDOUS
THRESHOLDS. IN ADDITION, 28-DAY AVERAGE STREAMFLOWS ARE BELOW NORMAL ACROSS
NORTHWESTERN OREGON AND WESTERN WASHINGTON WHICH WOULD LIMIT ANY FLOODING RISK.
AN AMPLIFIED TROUGH AND ONSHORE FLOW FAVOR ABOVE-NORMAL PRECIPITATION ACROSS
COASTAL SOUTHWESTERN ALASKA. HOWEVER, PRECIPITATION AMOUNTS ARE EXPECTED TO
REMAIN BELOW HAZARDOUS THRESHOLDS.
FORECASTER: BRAD PUGH
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