792
FXUS21 KWNC 171917
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MARCH 17 2025
SYNOPSIS: AN ACTIVE AND PROGRESSIVE WEATHER PATTERN IS FAVORED TO BRING A
VARIETY OF POTENTIALLY HAZARDOUS WEATHER TO MANY PARTS OF THE CONTIGUOUS U.S.
(COUNS) DURING THE WEEK-2 PERIOD. AT THE BEGINNING OF WEEK-2 A LOW PRESSURE
SYSTEM IS PREDICTED TO MOVE OVER THE NORTHEAST, INCREASING THE LIKELIHOOD FOR
HIGH WINDS. ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO COME ASHORE OVER THE
PACIFIC NORTHWEST AT THE OUTSET OF WEEK-2 AND MOVE INTO THE CENTRAL CONUS BY
THE MIDDLE OF THE PERIOD, BRINGING POTENTIALLY HEAVY SNOW, HIGH WINDS, AND
HEAVY PRECIPITATION TO PORTIONS OF THE WESTERN AND CENTRAL CONUS.
HAZARDS
SLIGHT RISK OF EPISODIC HIGH WINDS FOR THE NORTHEAST U.S. AND PORTIONS OF THE
MID-ATLANTIC, TUE-THU, MAR 25-27.
SLIGHT RISK OF EPISODIC HIGH WINDS FOR COASTAL PORTIONS OF WASHINGTON AND
OREGON, TUE-SAT, MAR 25-29.
SLIGHT RISK OF EPISODIC HIGH WINDS FOR MUCH OF THE CENTRAL CONUS, THU-SUN, MAR
27-30.
SLIGHT RISK OF PERIODS OF HEAVY PRECIPITATION FOR WESTERN WASHINGTON AND
OREGON, TUE-SAT, MAR 25-29.
SLIGHT RISK OF PERIODS OF HEAVY PRECIPITATION FOR PORTIONS OF THE OHIO,
TENNESSEE, AND LOWER AND MIDDLE MISSISSIPPI VALLEYS, SAT-MON, MAR 29-31.
SLIGHT RISK OF PERIODS OF HEAVY SNOW FOR THE CASCADE MOUNTAINS, TUE-SAT, MAR
25-29.
SLIGHT RISK OF PERIODS OF HEAVY SNOW FOR THE NORTHERN ROCKIES, THU-SAT, MAR
27-29.
SLIGHT RISK OF PERIODS OF HEAVY SNOW FOR PORTIONS OF THE NORTHERN PLAINS AND
UPPER MISSISSIPPI VALLEY, SAT-MON, MAR 29-31.
RISK OF RAPID ONSET DROUGHT FOR PORTIONS OF THE SOUTHERN PLAINS.
DETAILED SUMMARY
FOR THURSDAY MARCH 20 - MONDAY MARCH 24:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY MARCH 25 - MONDAY MARCH 31: ENSEMBLE SOLUTIONS FROM THE GEFS, ECWMF
AND CMCE ARE IN FAIRLY GOOD AGREEMENT WITH REGARD TO THE SYNOPTIC SETUP AS
DEPICTED IN 500-HPA HEIGHTS AND ANOMALIES DURING THE WEEK-2 PERIOD. THESE
MODELS DEPICT MID-LEVEL TROUGHING OVER THE NORTH PACIFIC AND NORTHEAST U.S. AND
RIDGING OVER THE BERING SEA, WEST COAST, AND CANADIAN MARITIMES. THIS HIGH
WAVENUMBER TENDS TO RESULT IN EASTWARD PROPAGATION OF MULTIPLE SHORT-WAVE
TROUGHS EMBEDDED IN THE PREVAILING FLOW, WHICH IS DEPICTED IN MULTIPLE
ENSEMBLES. HOWEVER, MODEL SOLUTIONS DIVERGE QUITE A BIT DURING THE MIDDLE OF
WEEK-2, RESULTING IN LOWER FORECAST CONFIDENCE. NONETHELESS, MODEL SOLUTIONS
ALL DEPICT A FAIRLY ACTIVE PATTERN AND A SIMILAR PROGRESSION OF WEATHER OVER
THE CONUS DURING WEEK-2.
AT THE OUTSET OF WEEK-2 A SURFACE LOW IS FAVORED TO FORM OVER THE GREAT LAKES
REGION. MULTIPLE MODELS DEPICT SIGNIFICANT PRECIPITATION ASSOCIATED WITH THIS
SYSTEM WHICH COULD AFFECT THE EASTERN CONUS DURING WEEK-1, BUT BY DAY-8 (MARCH
25) THE HEAVIEST PRECIPITATION WILL LIKELY HAVE MOVED OFFSHORE. HOWEVER, TIGHT
SURFACE PRESSURE GRADIENTS ASSOCIATED WITH THE SURFACE LOW RESULT IN ENHANCED
PROBABILITIES OF HIGH WINDS FOR PARTS OF THE EAST COAST AS THIS SYSTEM SLOWLY
TRACKS TOWARDS THE CANADIAN MARITIMES. THE GEFS AND ECMWF PROBABILISTIC
EXTREMES TOOLS (PETS) BOTH INDICATE AT LEAST A 20% CHANCE OF MAXIMUM WIND
SPEEDS EXCEEDING THE 85TH PERCENTILE CLIMATOLOGICALLY FOR PORTIONS OF THE
MID-ATLANTIC EARLY IN WEEK-2, THEREFORE A SLIGHT RISK (20-40% PROBABILITY) OF
HIGH WINDS IS POSTED FOR MAR 25-27.
MULTIPLE MODEL SOLUTIONS DEPICT PERSISTENT TROUGHING AT THE SURFACE AND ALOFT
OVER THE NORTH PACIFIC RESULTING IN A STEADY MOIST ONSHORE FLOW PREVAILING OVER
THE PACIFIC NORTHWEST. THE INTEGRATED VAPOR TRANSPORT (IVT) TOOL INDICATES VERY
HIGH PROBABILITIES OF IVT TO EXCEED 150 KG/M S FROM BOTH THE ECMWF AND GEFS
THROUGH MARCH 28, AFTER WHICH THE SIGNAL FADES RAPIDLY. CURIOUSLY, THE
PRECIPITATION PETS SHOW A RATHER WEAK SIGNAL WITH REGARD TO HEAVY PRECIPITATION
POTENTIAL OVER THE PACIFIC NORTHWEST. HOWEVER, GIVEN GOOD MODEL AGREEMENT
REGARDING AN ONSHORE FLOW PATTERN THAT FAVORS HEAVY PRECIPITATION, A SLIGHT
RISK OF PERIODS OF HEAVY PRECIPITATION IS POSTED FOR WESTERN OREGON AND
WASHINGTON FOR MARCH 25-29. A SLIGHT RISK OF HEAVY SNOW IS ALSO POSTED FOR THE
CASCADE MOUNTAINS FOR THE SAME PERIOD, AS WELL AS A SLIGHT RISK OF HIGH WINDS
ALONG THE NORTHWEST COAST.
A SHORTWAVE TROUGH IS ANTICIPATED TO MOVE OVER THE WEST COAST AND THE
INTERMOUNTAIN WEST AND INTO THE CENTRAL CONUS OVER THE COURSE OF WEEK-2. THIS
IS ANTICIPATED TO RESULT IN THE AFOREMENTIONED PACIFIC MOISTURE GETTING PUSHED
FURTHER INLAND, FAVORING ENHANCED SNOW FOR THE NORTHERN ROCKIES. THE
UNCALIBRATED ECMWF ENSEMBLE INDICATES ENHANCED PROBABILITIES OF 3-DAY SNOWFALL
EXCEEDING 6 INCHES FOR MAR 27-29, THUS A SLIGHT RISK OF HEAVY SNOW IS POSTED
THESE DATES FOR MUCH OF THE NORTHERN ROCKIES. AS THIS SYSTEM PUSHES FURTHER
EASTWARD, ENSEMBLES DEPICT ANOTHER ROUND OF STRONG LEE CYCLOGENESIS OVER THE
GREAT PLAINS DURING THE SECOND HALF OF THE WEEK-2 PERIOD. MODEL DEPICTIONS OF
MSLP ANOMALIES INDICATE A STRONG PRESSURE GRADIENT SETTING UP OVER THE GREAT
PLAINS BY MARCH 27, RESULTING IN STRONG SOUTHERLY FLOW AND THE ENHANCED
POTENTIAL FOR HIGH WINDS AT THE SURFACE. ONCE AGAIN, THE PETS FOR MAXIMUM WIND
SPEED ARE A LITTLE MIXED WITH REGARD TO THE POTENTIAL FOR EXTREMES IN WIND
SPEED, BUT THE SYNOPTIC SETUP, COUPLED WITH GOOD AGREEMENT FROM MODELS ON
SYSTEM INTENSITY AND EVOLUTION SUPPORTS A SLIGHT RISK OF HIGH WINDS POSTED FOR
MUCH OF THE CENTRAL CONUS FOR MAR 27-30. MULTIPLE ENSEMBLE SOLUTIONS ALSO
INDICATE THE POSSIBILITY OF HEAVY PRECIPITATION DEVELOPING AHEAD OF THIS SYSTEM
AS IT WINDS UP AND DRAWS IN GULF MOISTURE. THERE IS MODEST SUPPORT FROM THE
PETS INDICATING AT LEAST A 20% CHANCE OF 3-DAY PRECIPITATION TOTALS EXCEEDING
THE 85TH PERCENTILE FOR MAR 29-31, WITH THE ECMWF BEING MORE BULLISH THAN THE
GEFS. HOWEVER, THE GEFS PET FOR SNOW WATER EQUIVALENT (SWE) INDICATES AT LEAST
A 20% CHANCE OF 3-DAY SWE EXCEEDING THE 85TH PERCENTILE FOR PORTIONS OF THE
NORTHERN CONUS. WHILE THERE IS SOME SPREAD AMONG MODEL SOLUTIONS REGARDING THE
DETAILS, ONCE AGAIN THE OVERALL GOOD AGREEMENT ON A FAVORABLE SYNOPTIC PATTERN
WARRANTS THE ISSUANCE OF A SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF
THE OHIO, TENNESSEE, AND LOWER AND MIDDLE MISSISSIPPI VALLEYS FOR MAR 29-31, AS
WELL AS A SLIGHT RISK OF HEAVY SNOW FOR PORTIONS OF THE NORTHERN PLAINS AND
UPPER MISSISSIPPI VALLEY FOR THE SAME PERIOD.
MUCH OF THE SOUTHERN AND SOUTHWESTERN CONUS HAS BEEN EXPERIENCING BELOW-NORMAL
PRECIPITATION FOR SOME TIME NOW, A TREND THAT IS UNFORTUNATELY FAVORED TO
CONTINUE THROUGH THE WEEK-2 PERIOD. THERE ARE INSUFFICIENT INDICATIONS AMONG
THE FORECAST TOOLS TO WARRANT A RISK OF MUCH ABOVE-NORMAL TEMPERATURES ON
TODAY’S WEEK-2 HAZARDS OUTLOOK, BUT NONETHELESS VERY ANOMALOUSLY WARM
TEMPERATURES ARE LIKELY FOR PORTIONS OF THE RIO GRANDE VALLEY AND BIG BEND
REGIONS. ANTICIPATED ABOVE NORMAL TEMPERATURES COMBINED WITH BELOW-NORMAL
PRECIPITATION AND ENHANCED WIND SPEEDS INCREASES THE POTENTIAL FOR WILDFIRES
THROUGHOUT THE WEEK-2 PERIOD.
FORECASTER: DANNY BARANDIARAN
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