945
FXUS21 KWNC 051954
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST MARCH 05 2025
SYNOPSIS: THE MAJOR FEATURE DURING WEEK-2 IS PREDICTED TO BE CONTINUED INLAND
PROPAGATION OF MID-LEVEL LOW PRESSURE INTO THE WESTERN CONTIGUOUS U.S. (CONUS)
EARLY IN THE PERIOD. WHILE PRECIPITATION AMOUNTS ARE FORECAST TO DECREASE
ACROSS THE WESTERN CONUS COMPARED TO LATE WEEK-1, A STRONG SURFACE CYCLONE IS
PREDICTED TO TRACK ACROSS THE GREAT PLAINS AND MIDWEST AROUND THE MAR 14-15
TIMEFRAME, RESULTING IN A VARIETY OF IMPACTS EXPANDING ACROSS THE CENTRAL AND
EASTERN CONUS, SPECIFICALLY HEAVY SNOW AND HIGH WINDS OVER NORTHERN AND CENTRAL
REGIONS, AND POTENTIALLY HEAVY FRONTALLY FOCUSED RAINFALL ACROSS THE EAST. THE
MID-LEVEL LOW MAY RELOAD ACROSS THE WEST COAST LATER IN WEEK-2 FAVORING ONGOING
CHANCES OF HEAVY PRECIPITATION ALONG THE WEST COAST.
HAZARDS
MODERATE RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE TENNESSEE VALLEY
AND SOUTHEAST, FRI-SAT, MAR 14-15.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS MUCH OF THE EASTERN THIRD OF THE
CONUS, FRI-SUN, MAR 14-16.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS COASTAL AREAS OF THE PACIFIC
NORTHWEST AND NORTHERN CALIFORNIA, THU-WED, MAR 13-19.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF SOUTHERN CALIFORNIA AND
SOUTHERN ARIZONA, THU, MAR 13.
MODERATE RISK OF HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY, FRI-SAT, MAR 14-15.
SLIGHT RISK OF HEAVY SNOW ACROSS THE CASCADES, KLAMATH, AND NORTHERN SIERRA
NEVADA MOUNTAINS, THU-WED, MAR 13-19.
SLIGHT RISK OF HEAVY SNOW ACROSS THE SOUTHERN SIERRA NEVADA MOUNTAINS, THU, MAR
13.
SLIGHT RISK OF HEAVY SNOW OVER PORTIONS OF THE GREAT BASIN, INTERMOUNTAIN WEST
AND THE ROCKIES, EXTENDING INTO THE NORTHERN AND CENTRAL PLAINS AND UPPER
MIDWEST, THU-SAT, MAR 13-15.
MODERATE RISK OF HIGH WINDS ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN
ROCKIES, GREAT PLAINS, AND UPPER MIDWEST, THU-SAT, MAR 13-15.
SLIGHT RISK OF HIGH WINDS ACROSS A BROAD REGION EXTENDING FROM THE INTERIOR
WEST TO THE GREAT LAKES AND MISSISSIPPI VALLEY, THU-SUN, MAR 13-16.
SLIGHT RISK OF EPISODIC HIGH WINDS ALONG PORTIONS OF THE WEST COAST, THU-WED,
MAR 13-19.
SLIGHT RISK OF MUCH ABOVE NORMAL TEMPERATURES ACROSS THE RIO GRANDE VALLEY,
THU-FRI, MAR 13-14.
POSSIBLE FLOODING FOR PARTS OF SOUTHWESTERN OREGON AND NORTHERN CALIFORNIA.
DETAILED SUMMARY
FOR SATURDAY MARCH 08 - WEDNESDAY MARCH 12:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR THURSDAY MARCH 13 - WEDNESDAY MARCH 19: A HIGHLY AMPLIFIED SHORTWAVE TROUGH
IS FORECAST TO PROGRESS ACROSS THE CONUS DURING WEEK-2, WITH THIS FEATURE
SERVING AS THE FOCAL POINT FOR A VARIETY OF HAZARDS ACROSS THE COUNTRY. MUCH OF
THE HEAVY PRECIPITATION IS FORECAST TO OCCUR DURING LATE WEEK-1 OVER SOUTHERN
CALIFORNIA, ALLOWING THE MODERATE AND HIGH RISKS OF HEAVY PRECIPITATION AND
SNOW TO BE REMOVED IN THE UPDATED OUTLOOK. HOWEVER, THE ECENS PROBABILISTIC
EXTREMES TOOL (PET) CONTINUES TO DEPICT VERY HIGH PROBABILITIES (AT LEAST 60
PERCENT) FOR PRECIPITATION TO EXCEED THE 85TH CLIMATOLOGICAL PERCENTILE EARLY
IN THE PERIOD ACROSS THE SOUTHWEST, WITH THE GEFS PROBABILITIES GENERALLY
WEAKER (20-40 PERCENT). THE STRONGER SIGNALS IN THE PETS ARE PARTLY DRIVEN BY
THE LOW PRECIPITATION CLIMATOLOGIES, AND MOST LOCATIONS ARE NOT FORECAST TO
RECEIVE MORE THAN 1-INCH OF PRECIPITATION IN 24-HOURS. GIVEN THAT THERE WILL
LIKELY BE SOME LEFTOVER MOISTURE FOLLOWING THE HEAVIEST PRECIPITATION ON DAY-7
(MAR 12), A SLIGHT RISK OF HEAVY PRECIPITATION IS CONTINUED ACROSS PORTIONS OF
SOUTHERN CALIFORNIA AND THE SOUTHWEST FOR DAY-8 (MAR 13), ALONG WITH AN
ACCOMPANYING SLIGHT RISK OF HEAVY SNOW ACROSS THE SOUTHERN SIERRA NEVADA
MOUNTAINS. FOLLOWING THE PASSAGE OF THIS FIRST TROUGH, THERE IS GOOD AGREEMENT
IN THE ENSEMBLES FAVORING MEAN TROUGHING RELOADING ACROSS THE EASTERN PACIFIC
WHICH IS FAVORED TO BRING A CONTINUED THREAT OF WEATHER RELATED HAZARDS FOR THE
WEST COAST, PERHAPS FOCUSED A BIT MORE TO THE NORTH. THIS SUPPORTS THE
CONTINUATION OF THE SLIGHT RISKS FOR HEAVY PRECIPITATION, HIGH WINDS, AND HIGH
ELEVATION SNOW ACROSS THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA FOR ALL OF
WEEK-2. A FLOODING RISK REMAINS OVER THE MORE SATURATED AREAS OF SOUTHWESTERN
OREGON AND NORTHERN CALIFORNIA.
AS THE AFOREMENTIONED UPSTREAM TROUGH MOVES FARTHER EAST, LEE CYCLOGENESIS IS
FORECAST ACROSS THE PLAINS WITH THE ECENS, GEFS, AND CMCE DYNAMICAL MODELS IN
VERY GOOD AGREEMENT DEPICTING A STRENGTHENING SURFACE LOW PRESSURE SYSTEM
ACROSS THE CENTRAL CONUS DURING THE EARLY TO MIDDLE PART OF THE PERIOD, WITH
SEVERAL OF THE LAST DETERMINISTIC RUNS FROM THE GFS AND ECMWF DEPICTING A SUB
980-HPA LOW. WHILE THE PETS ARE MORE MODEST, THE SYNOPTIC SET-UP LOOKS
FAVORABLE FOR A LARGE-SCALE IMPACTFUL EVENT, WITH INCREASED CHANCES FOR A
SNOWSTORM ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST AND HEAVY RAIN AND
POTENTIALLY THUNDERSTORMS ACROSS THE EAST. A SLIGHT RISK OF HEAVY PRECIPITATION
IS ISSUED FOR MAR 14-16 ACROSS MUCH OF THE EASTERN THIRD OF THE CONUS, WITH AN
EMBEDDED MODERATE RISK ACROSS PARTS OF THE TENNESSEE VALLEY AND SOUTHEAST, MAR
14-15, CONSISTENT WITH STRONGER SIGNALS IN THE UNCALIBRATED PRECIPITATION
GUIDANCE. THERE IS INCREASED SUPPORT FOR DEWPOINT TEMPERATURES EXCEEDING 60
DEGREES F OVER THE LOWER MISSISSIPPI AND TENNESSEE VALLEYS, SOUTHEAST, AND
MID-ATLANTIC WHERE THUNDERSTORM ACTIVITY IS POSSIBLE. DUE TO THE INCREASED
PRECIPITATION RISK AND ANTECEDENT SATURATED CONDITIONS OVER PORTIONS OF THE
MISSISSIPPI VALLEY ASSOCIATED WITH ENHANCED PRECIPITATION FAVORED DURING WEEK-1
(BASED ON WPC QPF), LOCALIZED FLOODING IS POSSIBLE WITHIN THE HIGHLIGHTED
REGION. ON THE BACKSIDE OF THE SURFACE LOW, HEAVY SNOW IS POSSIBLE ACROSS THE
NORTHERN PERIPHERY OF THIS SYSTEM, WITH THE UNCALIBRATED 0Z ECENS DEPICTING
SOME AREAS OF THE NORTH-CENTRAL CONUS WITH AT LEAST A 30 PERCENT CHANCE FOR
SNOWFALL TOTALS EXCEEDING 4 INCHES. AS IN THE PRECIPITATION FORECAST, THE SNOW
FORECAST LEANS MORE BULLISH DUE TO THE IMPRESSIVE AGREEMENT IN THE MODELS
REGARDING SURFACE LOW PLACEMENT AND STRENGTH, WITH A MODERATE RISK OF HEAVY
SNOW HIGHLIGHTED OVER PORTIONS OF THE NORTHERN PLAINS AND UPPER MIDWEST, MAR
14-15. A BROADER SLIGHT RISK FOR HEAVY SNOW EXTENDS BACK INTO PORTIONS OF THE
ROCKIES AND GREAT BASIN AND IS VALID MAR 13-15.
DUE TO POTENTIALLY STRONG SURFACE LOW PRESSURE AND STRENGTHENING PRESSURE
GRADIENTS, A BROAD SLIGHT RISK OF HIGH WINDS REMAINS ISSUED, COVERING MUCH OF
THE INTERIOR WESTERN AND CENTRAL CONUS AND EXTENDING EASTWARD INTO THE OHIO AND
TENNESSEE VALLEYS, AND THE SOUTHEAST, MAR 13-16. WITHIN THIS SLIGHT RISK AREA,
THE PETS DEPICT AT LEAST A 20 PERCENT CHANCE FOR WIND SPEEDS TO EXCEED THE 85TH
PERCENTILE AND 20-MPH OVER SOME LOCATIONS. A MODERATE RISK OF HIGH WINDS IS
ALSO POSTED (MAR 13-15) OVER MUCH OF THE CENTRAL AND SOUTHERN ROCKIES, GREAT
PLAINS, AND UPPER MIDWEST TIED TO THE FORECAST TRACK OF THE SURFACE LOW. A
PERIOD OF ANOMALOUSLY WARM TEMPERATURES IS POSSIBLE ACROSS THE RIO GRANDE
VALLEY EARLY IN WEEK-2, WITH THE UNCALIBRATED 0Z ECENS SHOWING SOME AREAS WITH
MAXIMUM TEMPERATURES EXCEEDING 95 DEG F (CLOSER TO 90 DEG F IN THE GEFS) ALONG
WITH INCREASING SIGNALS IN THE CORRESPONDING PETS. A SLIGHT RISK OF MUCH ABOVE
NORMAL TEMPERATURE IS POSTED ACROSS THE REGION, MAR 13-14, AND IN COMBINATION
WITH THE HIGH WINDS, MAY INCREASE THE WILDFIRE RISK, WHERE BELOW-NORMAL
PRECIPITATION IS PREDOMINATELY FAVORED AND DROUGHT CONDITIONS RANGING FROM D0
TO D4 ARE BEING REGISTERED.
NO HAZARDS ARE POSTED OVER ALASKA. BELOW-NORMAL TEMPERATURES ARE GENERALLY
FAVORED FOR MUCH OF THE MAINLAND WITH NEAR TO ABOVE-NORMAL PRECIPITATION
FORECAST ACROSS THE SOUTHERN MAINLAND AND THE SOUTHEAST.
FORECASTER: THOMAS COLLOW
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