798
FXUS21 KWNC 061930
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST FEBRUARY 06 2025
SYNOPSIS: PREDICTED ENHANCED ONSHORE FLOW LEADS TO AN INCREASED CHANCE OF HEAVY
PRECIPITATION AND HEAVY MOUNTAIN SNOW ACROSS THE WEST. MULTIPLE WEAK LOW
PRESSURE SYSTEMS ARE LIKELY TO TRACK ACROSS THE CENTRAL AND EASTERN CONTIGUOUS
U.S. (CONUS) THROUGH MID-FEBRUARY. HEAVY PRECIPITATION IS MOST LIKELY ACROSS
THE OHIO AND TENNESSEE VALLEYS. ARCTIC HIGH PRESSURE IS FAVORED TO MAINTAIN
MUCH BELOW-NORMAL TEMPERATURES ACROSS THE NORTHERN GREAT PLAINS AND UPPER
MISSISSIPPI VALLEY.
HAZARDS
MODERATE RISK OF HEAVY SNOW FOR THE CASCADES AND SIERRA NEVADA MOUNTAINS,
FRI-SUN, FEB 14-16.
SLIGHT RISK OF HEAVY SNOW FOR THE CASCADES, KLAMATH MOUNTAINS, SIERRA NEVADA
MOUNTAINS, NORTHERN TO CENTRAL ROCKIES, FRI-TUE, FEB 14-18.
SLIGHT RISK OF HEAVY PRECIPITATION FOR SOUTHERN CALIFORNIA, FRI, FEB 14.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF CALIFORNIA AND THE PACIFIC
NORTHWEST, FRI-TUE, FEB 14-18.
MODERATE RISK OF HEAVY PRECIPITATION FOR THE OHIO VALLEY AND TENNESSEE VALLEYS
AND PARTS OF THE SOUTHEAST, FRI-SUN, FEB 14-16.
SLIGHT RISK OF PERIODIC HEAVY PRECIPITATION FOR PARTS OF THE OHIO AND TENNESSEE
VALLEYS, LOWER MISSISSIPPI VALLEY, AND SOUTHEAST, FRI-MON, FEB 14-17.
POSSIBLE FLOODING FOR PARTS OF KENTUCKY, TENNESSEE, AND WEST VIRGINIA.
SLIGHT RISK OF EPISODIC HIGH WINDS FOR THE WEST AND CENTRAL TO SOUTHERN HIGH
PLAINS, FRI-TUE, FEB 14-18.
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR THE NORTHERN GREAT PLAINS,
AND UPPER MISSISSIPPI VALLEY, FRI-SUN, FEB 14-16.
DETAILED SUMMARY
FOR SUNDAY FEBRUARY 09 - THURSDAY FEBRUARY 13:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY FEBRUARY 14 - THURSDAY FEBRUARY 20: ON FEBRUARY 14, AN AMPLIFIED
500-HPA TROUGH ALONG WITH THE GEFS PROBABILISTIC EXTREMES TOOL (PET) AND
24-HOUR PRECIPITATION AMOUNTS FROM THE ECENS SUPPORT A SLIGHT RISK (20-40%
CHANCE) OF HEAVY PRECIPITATION FOR SOUTHERN CALIFORNIA. HEAVY PRECIPITATION MAY
TRIGGER MUDSLIDES AND DEBRIS FLOWS IN THE RECENT BURN SCAR AREAS. BEYOND THE
EARLY PART OF WEEK-2, MODEL SOLUTIONS REMAIN CONSISTENT THAT THE STRONGEST
ONSHORE FLOW AND STORM TRACK SHIFTS NORTHWARD ALONG THE WEST COAST. A MODERATE
RISK (40-60% CHANCE) OF HEAVY SNOW IS POSTED FOR THE CASCADES AND SIERRA NEVADA
MOUNTAINS FROM FEBRUARY 14-16, DUE TO GOOD MODEL AGREEMENT AND CONSISTENCY
ALONG WITH THE GEFS PET DEPICTING AN ELEVATED CHANCE OF 3-DAY SNOWFALL AMOUNTS
OF 1.5-2.0 INCHES, LIQUID EQUIVALENT. A BROADER SLIGHT RISK FOR HEAVY SNOW,
VALID FEBRUARY 14-18, IS HIGHLIGHTED IN THIS REGION AND ALSO INCLUDES MUCH OF
THE ROCKIES.
DURING THE PAST SEVERAL DAYS, MODEL GUIDANCE CONVERGED ON A PAIR OF LOW
PRESSURE SYSTEMS AFFECTING THE WEST COAST WITH AN INITIAL ONE OVER CALIFORNIA
AT THE BEGINNING OF WEEK-2 AND THEN A SECOND ONE TRACKING MORE ACROSS THE
PACIFIC NORTHWEST AROUND DAYS 10-12, FEBRUARY 16-18. BASED ON THESE TWO LOW
PRESSURE SYSTEMS AND SUPPORT FROM THE GEFS PET, A SLIGHT RISK OF HEAVY
PRECIPITATION IS DESIGNATED FOR THE NORTHERN TWO-THIRDS OF CALIFORNIA AND THE
PACIFIC NORTHWEST FROM FEBRUARY 14-18. DUE TO EXPECTED FLUCTUATIONS IN MODELED
TRACKS OF THESE LOW PRESSURE SYSTEMS AT THIS TIME RANGE, A MODERATE RISK OF
HEAVY PRECIPITATION IS NOT DESIGNATED AT THIS TIME. MOST OF CALIFORNIA AND THE
PACIFIC NORTHWEST AVERAGED BELOW-NORMAL PRECIPITATION DURING THE PAST 30 DAYS
WHICH WOULD LIMIT THE RISK OF WIDESPREAD FLOODING. THE ENHANCED PACIFIC FLOW
AND A MEAN 500-HPA TROUGH SUPPORT A SLIGHT RISK OF EPISODIC HIGH WINDS ACROSS
THE WEST FROM FEBRUARY 14-18. THIS WIND HAZARD EXTENDS EASTWARD TO THE CENTRAL
AND SOUTHERN HIGH PLAINS AS THE GEFS AND ECENS DEPICT LEE-SIDE CYCLOGENESIS
ACROSS EASTERN COLORADO.
THE UPSTREAM 500-HPA TROUGH IS LIKELY TO MAINTAIN AN ACTIVE PATTERN ACROSS THE
EAST-CENTRAL CONUS THROUGH MID-FEBRUARY. BASED ON 24-HOUR PRECIPITATION AMOUNTS
FROM THE GEFS AND ECENS, A MODERATE RISK OF HEAVY PRECIPITATION IS POSTED FOR
THE TENNESSEE VALLEY AND INTERIOR SOUTHEAST FROM FEBRUARY 14-16. A SOMEWHAT
BROADER REGION OF SLIGHT RISK IS VALID FROM FEBRUARY 14 TO 17. A POSSIBLE
FLOODING HAZARD CONTINUES FOR PARTS OF KENTUCKY, TENNESSEE, WEST VIRGINIA, AND
INTERIOR PARTS OF THE SOUTHEAST DUE TO FREQUENT RAINFALL DURING THE NEXT WEEK
TO TEN DAYS. 28-DAY AVERAGE STREAM FLOWS ARE RUNNING ABOVE THE 80TH PERCENTILE
ACROSS EASTERN KENTUCKY AND SOUTHERN WEST VIRGINIA.
THE WINTER STORM RISK HAS TIMED OFF ACROSS THE NORTHEAST, WITH REMAINING LIGHT
SNOW FORECAST TO MOVE ACROSS NEW ENGLAND AND OFF THE COAST. ANOTHER WEAK WAVE
OF LOW PRESSURE MAY MOVE THROUGH THE NORTHEAST ON DAYS 10-11 (FEB 16-17), BUT
SNOWFALL ACCUMULATIONS ARE FORECAST TO BE ON THE LIGHT SIDE.
ARCTIC SURFACE HIGH PRESSURE IS FORECAST TO REMAIN ENTRENCHED FROM CANADA
SOUTHWARD INTO THE NORTH-CENTRAL U.S. THROUGH THE EARLY PART OF WEEK-2. BASED
ON THE GEFS PET, A SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES IS POSTED FOR
THE NORTHERN GREAT PLAINS AND MINNESOTA, FEB 14-16, WHERE THERE IS AT LEAST A
20 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. TEMPERATURES ARE PREDICTED TO
SLOWLY MODERATE WITH TIME, RELATED TO A WEAKENING OF THE FULL-LATITUDE RIDGE
OVER ALASKA AND A TRANSITION TO MORE ZONAL FLOW ACROSS CANADA. ALTHOUGH
BELOW-NORMAL TEMPERATURES ARE FAVORED FOR NORTHERN NEW ENGLAND, TEMPERATURES
ARE EXPECTED TO REMAIN ABOVE COLD ADVISORY CRITERIA.
NO HAZARDOUS WEATHER IS EXPECTED THROUGHOUT ALASKA DURING WEEK-2 AS SURFACE LOW
PRESSURE REMAINS SUFFICIENTLY SOUTH AND WEST OF THE STATE. ONLY A SLIGHT LEAN
TOWARDS BELOW-NORMAL TEMPERATURES IS FORECAST ACROSS SOUTHEASTERN PARTS OF THE
STATE.
FORECASTER: ANTHONY ARTUSA
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