764
FXUS21 KWNC 292005
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST FEBRUARY 29 2024
SYNOPSIS: A SURFACE LOW PRESSURE SYSTEM IS FORECAST TO MOVE QUICKLY OFF THE
GREAT PLAINS AND INTO THE ATLANTIC OCEAN EARLY IN WEEK-2, BRINGING POTENTIALLY
HEAVY PRECIPITATION TO MUCH OF THE SOUTHEASTERN CONTIGUOUS U.S. (CONUS). THIS
SYSTEM AND A SECOND LOW PRESSURE FORECAST TO FORM LATER IN THE PERIOD RESULT IN
THE POTENTIAL FOR PERIODS OF HIGH WIND OVER THE GREAT PLAINS AND GREAT LAKES
REGIONS. INCREASING VAPOR TRANSPORT OFF THE PACIFIC IS FAVORED TO BRING
ENHANCED PRECIPITATION AND WIND TO THE WEST COAST FOR MUCH OF WEEK-2, AS WELL
AS THE POTENTIAL FOR HEAVY SNOW OVER THE INTERIOR WEST IN THE MIDDLE OF THE
FORECAST PERIOD.
HAZARDS
SLIGHT RISK FOR HEAVY PRECIPITATION FOR PORTIONS OF THE TENNESSEE, OHIO, AND
LOWER AND MIDDLE MISSISSIPPI VALLEYS, SOUTHERN AND CENTRAL APPALACHIANS,
MID-ATLANTIC, AND SOUTHEASTERN U.S., FRI-SUN, MAR 8-10.
SLIGHT RISK FOR HEAVY PRECIPITATION FOR COASTAL PORTIONS OF THE WEST COAST,
FRI-TUE, MAR 8-12.
SLIGHT RISK FOR HIGH WINDS FOR PORTIONS OF THE GREAT PLAINS, MIDDLE AND UPPER
MISSISSIPPI AND OHIO VALLEYS, AND GREAT LAKES REGION, FRI-WED, MAR 8-13.
SLIGHT RISK FOR HIGH WINDS FOR COASTAL PORTIONS OF THE WEST COAST, FRI-TUE, MAR
8-12.
SLIGHT RISK FOR HEAVY SNOW FOR THE KLAMATH AND SIERRA NEVADA MOUNTAINS,
FRI-TUE, MAR 8-12.
SLIGHT RISK FOR HEAVY SNOW FOR PORTIONS OF THE CENTRAL AND SOUTHERN ROCKIES AND
HIGHER ELEVATIONS OF THE CENTRAL GREAT BASIN, SUN-TUE, MAR 10-12.
DETAILED SUMMARY
FOR SUNDAY MARCH 03 - THURSDAY MARCH 07:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY MARCH 08 - THURSDAY MARCH 14: AT THE OUTSET OF WEEK-2 MODEL
SOLUTIONS CONTINUE TO DEPICT A ROBUST SURFACE LOW PRESSURE OVER THE GREAT
PLAINS WITH AN ASSOCIATED AREA OF ENHANCED PRECIPITATION AHEAD OF IT AS IT
QUICKLY MOVES EAST. THE GEFS AND ECMWF PRECIPITATION PROBABILISTIC EXTREMES
TOOLS (PETS) BOTH INDICATE AT LEAST A 20% CHANCE OF 3-DAY PRECIPITATION TOTALS
EXCEEDING THE 85TH PERCENTILE AND 1 INCH FOR MUCH OF THE TENNESSEE, OHIO, AND
LOWER AND MIDDLE MISSISSIPPI VALLEYS, SOUTHERN APPALACHIANS, MID-ATLANTIC, AND
SOUTHEASTERN U.S. FOR MARCH 8-10, THEREFORE A SLIGHT RISK FOR HEAVY
PRECIPITATION IS POSTED. LATER IN WEEK-2 A SECOND LEE CYCLOGENESIS EVENT IS
FAVORED, HOWEVER THERE IS SIGNIFICANT DISAGREEMENT ON THIS SYSTEM WITH THE
GEFS SPINNING UP A POTENT SURFACE LOW WHILE THE ECMWF FAVORS A WEAKER SYSTEM.
THIS MODEL SPREAD INCREASES FORECAST UNCERTAINTY REGARDING PRECIPITATION, BUT
THE SYNOPTIC SETUP FOR BOTH SYSTEMS FAVORS STRONG WINDS OVER THE GREAT PLAINS
AND INTO THE GREAT LAKES. THE PETS FOR HIGH WINDS ARE NOT AS SUPPORTIVE AS IN
PREVIOUS DAYS BUT MSLP SOLUTIONS FROM THE GEFS CONTINUE TO DEPICT TIGHT
PRESSURE GRADIENTS FORMING AND TRACKING FROM THE CENTRAL PLAINS OVER TOWARDS
THE OHIO VALLEY, INDICATING AN ENHANCED POTENTIAL FOR HIGH WINDS. THEREFORE, A
SLIGHT RISK FOR HIGH WIND IS POSTED FOR PORTIONS OF THE GREAT PLAINS, MIDDLE
AND UPPER MISSISSIPPI AND OHIO VALLEYS, AND GREAT LAKES REGION FOR MARCH 8-13.
OVER THE COURSE OF THE WEEK-2 PERIOD MODELS FAVOR A RELOADING OF MID-LEVEL
TROUGHING AND INCREASED STORMINESS AFFECTING THE WEST COAST. MODEL SPREAD IS
QUITE HIGH, BUT THE GEFS AND ECMWF PETS FOR HEAVY PRECIP INDICATE AT LEAST A
20% PROBABILITY OF 3-DAY PRECIPITATION TOTALS EXCEEDING 1 INCH ALONG THE WEST
COAST. THE ECMWF HAS BEEN FAVORING A WETTER SOLUTION BOTH IN TIME AND SPACE
THAN THE GEFS IN DAYS PAST, BUT TODAY THE MODELS HAVE SWAPPED WITH THE GEFS NOW
INDICATING A HIGHER POTENTIAL FOR HEAVY PRECIPITATION. DESPITE THIS
UNCERTAINTY, THE SYNOPTIC PATTERN DEPICTED BY THE MODELS REMAINS FAVORABLE FOR
ENHANCED PRECIPITATION ALONG THE WEST COAST AND THIS IS WELL-SUPPORTED BY THE
PETS, DIFFERENCES NOTWITHSTANDING. THEREFORE, A SLIGHT RISK FOR HEAVY
PRECIPITATION IS POSTED FOR MARCH 8-12 SPANNING THE ENTIRE WEST COAST, ALONG
WITH A MATCHING SLIGHT RISK FOR HIGH WINDS ALONG THE IMMEDIATE COAST. A SLIGHT
RISK FOR HEAVY SNOW IS ALSO POSTED FOR THE SIERRA NEVADA, KLAMATH, AND CASCADE
MOUNTAINS FOR MARCH 8-12. MOISTURE ASSOCIATED WITH THE SYSTEM IS FAVORED TO
MOVE GRADUALLY INLAND, BRINGING POTENTIALLY HEAVY SNOW TO THE INTERIOR WEST.
THIS IS WELL-INDICATED BY THE GEFS SNOW WATER EQUIVALENT (SWE) PET, WITH BROAD
COVERAGE ACROSS THE WEST OF AT LEAST A 20% PROBABILITY OF 3-DAY ACCUMULATED SWE
TO EXCEED THE 85TH PERCENTILE, WITH AMOUNTS OVER AN INCH DISTRIBUTED OVER MOST
OF THE HIGHER ELEVATIONS IN THE GREAT BASIN AND ACROSS THE ROCKIES, WARRANTING
A SLIGHT RISK OF HEAVY SNOW HIGHLIGHTING THESE AREAS FOR MARCH 10-12.
FORECASTER: DANNY BARANDIARAN
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