627
FXUS21 KWNC 272043
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST FEBRUARY 27 2024
SYNOPSIS: MODEL ENSEMBLES DEPICT AN ENHANCED FLOW OF GULF OF MEXICO MOISTURE
MOVING OVER MUCH OF THE EASTERN CONTIGUOUS U.S. (CONUS) AT THE OUTSET OF
WEEK-2, BRINGING THE POTENTIAL FOR HEAVY PRECIPITATION. A STALLED FRONTAL
SYSTEM PROLONGS THE RISK FOR HEAVY PRECIPITATION OVER THE SOUTHEAST U.S.INTO
THE MIDDLE OF THE FORECAST PERIOD. A PASSING MID-LEVEL DISTURBANCE BRINGS THE
POTENTIAL FOR HEAVY SNOW TO HIGHER ELEVATIONS IN PORTIONS OF THE WESTERN CONUS.
MODELS DEPICT SIMILAR DISTURBANCES MOVING OVER THE GREAT PLAINS AND GREAT LAKES
REGIONS DURING WEEK-2, BRINGING WITH THEM THE POTENTIAL FOR HIGH WINDS.
HAZARDS
MODERATE RISK FOR HEAVY PRECIPITATION FOR PORTIONS OF THE TENNESSEE AND LOWER
MISSISSIPPI VALLEYS, AND SOUTHEAST U.S., WED-THU, MAR 6-7.
SLIGHT RISK FOR HEAVY PRECIPITATION FOR PORTIONS OF THE TENNESSEE, OHIO, AND
LOWER MISSISSIPPI VALLEYS, SOUTHERN APPALACHIANS, MID-ATLANTIC, AND
SOUTHEASTERN U.S., WED-SUN, MAR 6-10.
SLIGHT RISK FOR HEAVY PRECIPITATION FOR PORTIONS OF THE CENTRAL APPALACHIANS,
MID-ATLANTIC, AND NORTHEAST U.S., WED-FRI, MAR 6-8.
SLIGHT RISK FOR HIGH WINDS FOR PORTIONS OF THE GREAT PLAINS, MIDDLE AND UPPER
MISSISSIPPI VALLEY, AND GREAT LAKES REGION, WED-SUN, MAR 6-10.
SLIGHT RISK FOR HEAVY SNOW FOR THE KLAMATH AND SIERRA NEVADA MOUNTAINS AND
HIGHER ELEVATIONS OF WESTERN NEVADA, AS WELL AS HIGHER ELEVATIONS FOR MUCH OF
THE INTERIOR WEST, WED-FRI, MAR 6-8.
DETAILED SUMMARY
FOR FRIDAY MARCH 01 - TUESDAY MARCH 05:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY MARCH 06 - TUESDAY MARCH 12: THERE ARE SEVERAL AREAS OF ACTIVE
WEATHER DEPICTED IN TODAY’S MODEL SOLUTIONS AT THE OUTSET OF WEEK-2, HOWEVER
THERE IS SIGNIFICANT MODEL SPREAD PARTICULARLY OVER THE WESTERN CONUS, LEADING
TO INCREASED UNCERTAINTY IN TODAY’S WEEK-2 HAZARDS OUTLOOK. THE MOST ACTIVE
WEATHER DEPICTED IN TODAY’S SOLUTIONS REMAINS OVER THE SOUTHEAST CONUS, WITH
AMPLE MOISTURE FLOWING INTO A SERIES OF FAST-MOVING SURFACE LOW PRESSURE
SYSTEMS MOVING OFF THE ROCKIES AND TRIGGERING WIDESPREAD ENHANCED PRECIPITATION
WITH THE POTENTIAL FOR THUNDERSTORM ACTIVITY OVER THE SOUTHEAST , PARTICULARLY
AT THE OUTSET OF WEEK-2. THE GEFS AND ECMWF PRECIPITATION PROBABILISTIC
EXTREMES TOOLS (PETS) BOTH INDICATE AT LEAST A 20% CHANCE OF 3-DAY
PRECIPITATION TOTALS TO EXCEED THE 85TH PERCENTILE AND 1 INCH FOR MUCH OF THE
SOUTHEAST, AND TENNESSEE AND LOWER MISSISSIPPI VALLEYS FOR MARCH 6-10. THE
ECMWF IS PARTICULARLY BULLISH, WITH PROBABILITIES EXCEEDING 40% OVER PORTIONS
OF THE SOUTHEASTERN CONUS, AND EVEN EXCEEDING 60% OVER PORTIONS OF THE
MID-ATLANTIC AND NORTHEAST U.S. GIVEN THESE HIGH PROBABILITIES, A MODERATE RISK
FOR HEAVY PRECIPITATION IS POSTED FOR MARCH 6-7 WHERE MODEL AGREEMENT IS
GREATEST AND WHERE THE HIGHEST PRECIPITATION TOTALS ARE HIGHLIGHTED.
ADDITIONALLY, A SLIGHT RISK FOR HEAVY PRECIPITATION IS POSTED FOR MUCH OF THE
SOUTHEASTERN CONUS FOR MARCH 6-10 AS HEAVY PRECIPITATION IS FAVORED TO PERSIST
BEYOND THE BEGINNING OF WEEK-2 ALONG A STALLED FRONTAL SYSTEM. A SLIGHT RISK
FOR HEAVY PRECIPITATION IS POSTED FOR PORTIONS OF THE MID-ATLANTIC AND
NORTHEAST U.S. FOR MARCH 6-8 WHERE, IN SPITE OF LARGE MODEL SPREAD, A STRONG
SIGNAL EXISTS IN THE ECMWF PET AND THE RISK OF HEAVY PRECIPITATION CANNOT BE
DISCOUNTED. FINALLY, BOTH DETERMINISTIC AND ENSEMBLE SOLUTIONS FROM THE GEFS
AND ECMWF DEPICT TIGHT PRESSURE GRADIENTS FORMING OVER THE GREAT PLAINS AND
GREAT LAKES REGIONS AS THESE LOW PRESSURE SYSTEMS MOVE OFF THE ROCKIES,
RESULTING IN THE POTENTIAL FOR HIGH WINDS. THIS IS ALSO SUPPORTED BY THE ECMWF
PET FOR HIGH WIND, INDICATING A 20% PROBABILITY OF WIND SPEEDS EXCEEDING THE
85TH PERCENTILE AND AT LEAST 20 MPH OVER THESE AREAS FROM MARCH 6TH THROUGH AT
LEAST THE 10TH, THEREFORE A SLIGHT RISK FOR HIGH WINDS IS POSTED OVER THIS PART
OF THE COUNTRY THROUGH THE MIDDLE OF WEEK-2..
THE OTHER MAJOR FEATURE IN TODAY’S MODEL SOLUTIONS IS A LOW PRESSURE SYSTEM
MOVING OFF THE NORTH PACIFIC AND INTO THE INTERMOUNTAIN WEST EARLY IN WEEK-2.
THIS STORM SYSTEM IS WELL-DEPICTED IN GEFS AND ECMWF ENSEMBLE SOLUTIONS, AND
THE GEFS PET FOR SNOW WATER EQUIVALENT (SWE) INDICATES AT LEAST A 20%
PROBABILITY OF 3-DAY SWE ACCUMULATION EXCEEDING THE 85TH PERCENTILE AND 1 INCH
FOR THE SIERRA NEVADA AND KLAMATH RANGES, HIGHER ELEVATIONS OF WESTERN NEVADA,
AS WELL AS MOST OF THE ROCKIES AND HIGHER ELEVATIONS OF THE CENTRAL GREAT
BASIN. THEREFORE, A SLIGHT RISK FOR HEAVY SNOW IS POSTED FOR THE AREAS LISTED
FOR MARCH 6-8. WHILE THERE ARE INDICATIONS THAT THIS SYSTEM, AS WELL AS A
SECOND SYSTEM LATER IN WEEK-2, HAVE THE POTENTIAL TO BRING HEAVY PRECIPITATION
AND HIGH WIND CLOSER TO THE COAST, THERE IS TOO MUCH UNCERTAINTY TO JUSTIFY
POSTING ANY CORRESPONDING HAZARDS AT THIS TIME.
FORECASTER: DANNY BARANDIARAN
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