588
FXUS21 KWNC 131857
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MARCH 13 2024
SYNOPSIS: A BROAD AREA OF MID-LEVEL LOW PRESSURE IS FORECAST OVER THE
CONTIGUOUS U.S. (CONUS) DURING LATE MARCH WHICH FAVORS A WET PATTERN. THIS
MID-LEVEL LOW PRESSURE AND ASSOCIATED SURFACE LOW PRESSURE DEVELOPMENT ELEVATE
CHANCES OF HEAVY PRECIPITATION ACROSS THE LOWER TO MIDDLE MISSISSIPPI VALLEY
AND EASTERN CONUS. AN INCREASED RISK OF HEAVY SNOW EXISTS FOR THE NORTHERN TO
CENTRAL ROCKIES AND AN EARLY SPRING SNOWSTORM COULD AFFECT AREAS FROM THE
NORTH-CENTRAL GREAT PLAINS TO THE UPPER MISSISSIPPI VALLEY.
HAZARDS
MODERATE RISK OF HEAVY PRECIPITATION FOR PARTS OF THE GULF COAST, THU-FRI, MAR
21-22.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE GULF COAST, LOWER
MISSISSIPPI VALLEY, AND SOUTHEAST, THU-WED, MAR 21-27.
SLIGHT RISK OF HEAVY PRECIPITATION FOR THE EASTERN CONUS, LOWER OHIO VALLEY,
AND MIDDLE MISSISSIPPI VALLEY, FRI-WED, MAR 22-27.
SLIGHT RISK OF HEAVY SNOW FOR THE NORTHERN TO CENTRAL ROCKIES, NORTHERN TO
CENTRAL PLAINS, AND UPPER MISSISSIPPI VALLEY, THU-WED, MAR 21-27.
SLIGHT RISK OF HIGH WINDS FOR MUCH OF THE HIGH PLAINS AND SOUTHWEST, THU-WED,
MAR 21-27.
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PARTS OF THE SOUTHEAST AND
MID-ATLANTIC, THU, MAR 21.
DETAILED SUMMARY
FOR SATURDAY MARCH 16 - WEDNESDAY MARCH 20:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR THURSDAY MARCH 21 - WEDNESDAY MARCH 27: THE GEFS, ECMWF, AND CANADIAN
ENSEMBLE MEANS DEPICT A BROAD AND AMPLIFIED 500-HPA TROUGH OVER MUCH OF THE
LOWER 48 STATES DURING WEEK-2; THE LONGWAVE TROUGH AXIS SHIFTING BACK-AND-FORTH
BETWEEN THE ROCKIES AND MISSISSIPPI VALLEY. THIS LONGWAVE PATTERN ALONG WITH
ENHANCED MOISTURE IN THE SOUTHERN STREAM IS LIKELY TO BRING PERIODS OF
RAINFALL, POTENTIALLY HEAVY, TO THE LOWER AND MIDDLE MISSISSIPPI VALLEY AND
EASTERN CONUS. ON MARCH 21, MODEL SOLUTIONS REMAIN CONSISTENT THAT AN
OVERRUNNING TYPE EVENT AFFECTS THE GULF COAST AS MOIST, WARM AIR ADVECTION
OVERSPREADS THIS REGION. BASED ON THE ECMWF PROBABILISTIC EXTREMES TOOL (PET)
AND 24-HOURS AMOUNTS FROM THE UNCALIBRATED GEFS AND ECMWF ENSEMBLE MEANS, A
MODERATE RISK OF HEAVY PRECIPITATION (MORE THAN 1 INCH) IS DESIGNATED FROM
BATON ROUGE, LA TO TALLAHASSEE, FL ON MARCH 21-22. A BROADER SLIGHT RISK OF
HEAVY PRECIPITATION INCLUDES MORE OF EASTERN TEXAS, THE LOWER MISSISSIPPI
VALLEY, AND SOUTHEAST. BY MARCH 22, A LOW PRESSURE SYSTEM IS EXPECTED TO TRACK
EASTWARD WHICH SUPPORTS AN EXPANSION OF THE SLIGHT RISK TO INCLUDE THE EAST
COAST. THE SLIGHT RISK ALSO COVERS THE MIDDLE MISSISSIPPI VALLEY, LOWER OHIO
VALLEY, AND TENNESSEE VALLEY BASED ON THE LONGWAVE PATTERN AND SUPPORT FROM THE
UNCALIBRATED ECMWF MODEL OUTPUT. THE SLIGHT RISK OF HEAVY PRECIPITATION IS
VALID THROUGH THE ENTIRETY OF WEEK-2 SINCE THIS WET PATTERN IS EXPECTED TO
PERSIST THROUGH AT LEAST THE THE END OF MARCH.
ALTHOUGH MINOR RIVER FLOODING IS LIKELY TO PERSIST ACROSS PARTS OF THE
SOUTHEAST, ESPECIALLY CLOSER TO THE GULF COAST, A FLOODING HAZARD IS NOT
DESIGNATED SINCE WIDESPREAD, MODERATE RIVER FLOODING IS NOT ANTICIPATED. THE
HEAVIEST RAINFALL LATER NEXT WEEK IS EXPECTED TO BE WHERE 30-DAY PRECIPITATION
HAS AVERAGED CLOSER TO NORMAL OR EVEN BELOW-NORMAL.
THE BROAD 500-HPA TROUGH ALOFT IS EXPECTED TO BRING PERIODS OF ACCUMULATING
SNOW, POTENTIALLY HEAVY, ACROSS THE NORTHERN TO CENTRAL ROCKIES. THE LONGWAVE
PATTERN WITH AN INCREASING CHANCE OF AN EARLY SPRING SNOWSTORM ALONG WITH THE
GEFS SNOW WATER EQUIVALENT PET SUPPORT A SLIGHT RISK OF HEAVY SNOW FROM THE
CENTRAL HIGH PLAINS NORTHEAST TO THE UPPER MISSISSIPPI VALLEY. DUE TO TIMING
UNCERTAINTY, THE SLIGHT RISK OF HEAVY SNOW IS VALID THROUGH THE ENTIRETY OF
WEEK-2. THE LONGWAVE TROUGH IS EXPECTED TO PROMOTE LEE SIDE CYCLOGENESIS
SOMETIME DURING WEEK-2 WHICH RESULTS IN A SLIGHT RISK OF HIGH WINDS FOR MUCH OF
THE HIGH PLAINS AND PARTS OF THE SOUTHWEST FROM MARCH 21 TO 27.
FOLLOWING AN INCREASED RISK OF A DAMAGING FREEZE ACROSS THE SOUTHEAST AND
MID-ATLANTIC ON MARCH 19 AND 20, TEMPERATURES ARE FORECAST TO QUICKLY MODERATE.
A SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES IS POSTED FOR PARTS OF THE
MID-ATLANTIC AND SOUTHEAST WHERE THE GEFS AND ECMWF PETS DEPICT MINIMUM
TEMPERATURES HAVING MORE THAN A 20 PERCENT CHANCE OF FALLING BELOW 32 DEGREES F
ON MARCH 21. ALTHOUGH BELOW-NORMAL TEMPERATURES ARE FAVORED ACROSS THE NORTHERN
GREAT PLAINS, MINIMUM TEMPERATURES ARE FORECAST TO REMAIN ABOVE COLD HAZARDOUS
THRESHOLDS AND THE GROWING SEASON HAS NOT STARTED YET.
THE MID-LEVEL TROUGH WEST OF THE ALEUTIANS COUPLED WITH MID-LEVEL RIDGING OVER
MAINLAND ALASKA IS LIKELY TO RESULT IN ABOVE-NORMAL TEMPERATURES FOR ALL OF
ALASKA. ALTHOUGH ABOVE-NORMAL PRECIPITATION IS FAVORED ACROSS WESTERN ALASKA,
PRECIPITATION AMOUNTS ARE EXPECTED TO BE BELOW HAZARDS THRESHOLDS.
FORECASTER: BRAD PUGH
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