358
FXUS21 KWNC 111804
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MARCH 11 2024
SYNOPSIS: SURFACE HIGH PRESSURE, WITH ANOMALOUSLY COLD TEMPERATURES, IS
FORECAST TO SHIFT SOUTHEASTWARD ACROSS THE CENTRAL AND EASTERN CONTIGUOUS U.S.
(CONUS) BY EARLY NEXT WEEK. ON MARCH 19 AND 20, THERE IS AN INCREASED RISK OF A
DAMAGING FREEZE TO PARTS OF THE SOUTHERN GREAT PLAINS, SOUTHEAST, AND
MID-ATLANTIC DUE TO THE EARLY GREEN UP OF VEGETATION. BY MARCH 22, MID-LEVEL
LOW PRESSURE IS EXPECTED TO BECOME MORE CENTERED OVER THE ROCKIES OR GREAT
PLAINS. A RETURN OF A WET PATTERN IS ANTICIPATED FOR THE SOUTHEAST AND LOWER
MISSISSIPPI VALLEY LATER IN WEEK-2.
HAZARDS
MODERATE RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PARTS OF THE SOUTHERN GREAT
PLAINS, LOWER MISSISSIPPI VALLEY, AND SOUTHEAST, TUE-WED, MAR 19-20.
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PARTS OF THE SOUTHERN GREAT
PLAINS, LOWER MISSISSIPPI VALLEY, SOUTHEAST, OHIO VALLEY, AND MID-ATLANTIC,
TUE-THU, MAR 19-21.
MODERATE RISK OF HIGH WINDS FOR THE NORTHEAST, CENTRAL APPALACHIANS, AND
MID-ATLANTIC, TUE, MAR 19.
SLIGHT RISK OF HIGH WINDS FOR THE GREAT LAKES, NORTHEAST, CENTRAL APPALACHIANS,
AND MID-ATLANTIC, TUE-WED, MAR 19-20.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE LOWER MISSISSIPPI VALLEY,
TENNESSEE VALLEY, AND SOUTHEAST, FRI-MON, MAR 22-25.
DETAILED SUMMARY
FOR THURSDAY MARCH 14 - MONDAY MARCH 18:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY MARCH 19 - MONDAY MARCH 25: THE MAJOR HAZARD DURING MID TO LATE
MARCH APPEARS TO BE THE POTENTIAL FOR A WIDESPREAD FREEZE ON MARCH 19 AND 20,
EXTENDING FROM THE SOUTHERN GREAT PLAINS TO THE PIEDMONT AREAS OF THE
SOUTHEAST. MANY OF THESE AREAS HAVE EXPERIENCED AN EARLY GREEN UP OF VEGETATION
AND THE WARMTH LATER THIS WEEK WILL ACCELERATE THE GREEN UP AND EXPAND IT
NORTHWARD TO THE OHIO VALLEY AND MID-ATLANTIC. A MODERATE RISK OF MUCH
BELOW-NORMAL TEMPERATURES IS POSTED FOR PORTIONS OF THE SOUTHEAST, LOWER
MISSISSIPPI VALLEY, AND SOUTHERN GREAT PLAINS WHERE THE GEFS AND ECMWF
REFORECAST TOOLS DEPICT MINIMUM TEMPERATURES HAVING AT LEAST A 30 PERCENT
CHANCE OF FALLING BELOW FREEZING AND WOULD LIKELY BE MOST VULNERABLE TO A
FREEZE. A BROADER SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES (MARCH 19-21)
EXTENDS CLOSER TO THE GULF COAST WHERE THE REFORECAST TOOLS HAVE A 20 TO 30
PERCENT CHANCE OF MINIMUM TEMPERATURES FALLING BELOW 40 DEGREES F. THE SLIGHT
RISK ALSO COVERS AREAS OF THE OHIO VALLEY AND MID-ATLANTIC WHERE A FREEZE IS
PROBABLE NEXT WEEK BUT IT IS UNCLEAR HOW IMPACTFUL IT WOULD BE AS THE LAST
SPRING FREEZE TYPICALLY OCCURS DURING APRIL.
EARLY NEXT WEEK, THE GEFS, ECMWF, AND CANADIAN ENSEMBLE MEANS ARE IN GOOD
AGREEMENT AND CONSISTENT THAT A SURFACE LOW PRESSURE SYSTEM DEEPENS OVER THE
CANADIAN MARITIMES. THE STRONG PRESSURE GRADIENT BETWEEN THIS SURFACE LOW AND A
1024-HPA TO 1032-HPA HIGH OVER THE SOUTH-CENTRAL CONUS IS LIKELY TO BRING GUSTY
WINDS TO THE GREAT LAKES AND NORTHEAST ON MARCH 19. THEREFORE, A SLIGHT TO
MODERATE RISK OF HIGH WINDS IS WARRANTED FOR THOSE AREAS.
THE GEFS, ECMWF, AND CANADIAN ENSEMBLE MEANS DEPICTS A RETROGRESSION OF THE
LONGWAVE PATTERN OVER NORTH AMERICA AND THE NORTH PACIFIC DURING LATE MARCH
WITH AN AMPLIFIED 500-HPA RIDGE (TROUGH) BECOMING CENTERED OVER MAINLAND ALASKA
(WEST-CENTRAL CONUS). DOWNSTREAM OF THE AMPLIFIED TROUGH AXIS, A SLIGHT RISK OF
HEAVY PRECIPITATION IS POSTED FOR PARTS OF THE SOUTHEAST (MARCH 22-25) WHERE
THE GEFS AND ECMWF REFORECAST TOOLS HAVE AT LEAST A 20 PERCENT CHANCE THAT
3-DAY PRECIPITATION AMOUNTS EXCEED 1 INCH AND THE 85TH PERCENTILE. ALTHOUGH
MINOR RIVER FLOODING IS EXPECTED TO PERSIST FOR PARTS OF THE SOUTHEAST THROUGH
LATE MARCH, A FLOODING HAZARD IS NOT POSTED SINCE WIDESPREAD MODERATE RIVER
FLOODING IS UNLIKELY. THE AMPLIFIED TROUGH ALOFT IS EXPECTED TO PROMOTE
ACCUMULATING SNOWFALL THROUGHOUT THE ROCKIES, BUT UNCERTAINTY ON SNOWFALL
AMOUNTS PRECLUDES A HEAVY SNOW HAZARD AT THIS TIME.
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 MUCH OF ALASKA,
PRECIPITATION AMOUNTS ARE EXPECTED TO BE BELOW HAZARDS THRESHOLDS.
FORECASTER: BRAD PUGH
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