379
FXUS21 KWNC 141935
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT MARCH 14 2024
SYNOPSIS: A BROAD MID-LEVEL TROUGH IS FORECAST TO SLOWLY MOVE EASTWARD FROM THE
ROCKIES TO THE ATLANTIC SEABOARD, CAUSING ONE OR MORE SURFACE LOW PRESSURE
SYSTEMS TO MOVE THROUGH PARTS OF THE EASTERN CONTIGUOUS U.S. (CONUS). THIS
ENHANCES THE ODDS OF HEAVY PRECIPITATION ACROSS THE LOWER TO MIDDLE MISSISSIPPI
VALLEY AND EASTERN CONUS, BUT THE TIMING AND LOCATIONS OF SURFACE STORM
DEVELOPMENT ARE UNCERTAIN. THERE IS AN INCREASED RISK OF HEAVY SNOW FARTHER
NORTH FROM THE NORTHERN TO CENTRAL ROCKIES INTO PARTS OF THE CENTRAL AND
NORTHERN PLAINS AND THE UPPER MISSISSIPPI VALLEY. THE POTENTIAL FOR A TIGHT
PRESSURE GRADIENT AROUND ANY SURFACE STORM SYSTEMS THAT DEVELOP RAISES THE RISK
OF HIGH WINDS ACROSS MUCH OF THE ROCKIES AND HIGH PLAINS, AND OVER MUCH OF THE
EASTERN HALF OF THE CONUS.
HAZARDS
SLIGHT RISK OF HEAVY PRECIPITATION FOR MUCH OF THE LOWER MISSISSIPPI VALLEY,
THE SOUTHEAST, AND THE ATLANTIC SEABOARD, FRI-THU, MAR 22-28.
SLIGHT RISK OF HEAVY SNOW FOR THE NORTHERN TO CENTRAL ROCKIES, NORTHERN TO
CENTRAL PLAINS, UPPER MISSISSIPPI VALLEY, AND NORTHERN GREAT LAKES, FRI-TUE,
MAR 22-26.
SLIGHT RISK OF HIGH WINDS FOR MUCH OF THE EASTERN ROCKIES AND THE HIGH PLAINS,
FRI-TUE, MAR 22-26.
SLIGHT RISK OF HIGH WINDS FOR THE LOWER MISSISSIPPI VALLEY AND MUCH OF THE
EASTERN CONUS, FRI-THU, MAR 22-28.
DETAILED SUMMARY
FOR SUNDAY MARCH 17 - THURSDAY MARCH 21:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY MARCH 22 - THURSDAY MARCH 28: THE GEFS, ECMWF, AND CANADIAN ENSEMBLE
MEANS DEPICT A BROAD AND AMPLIFIED 500-HPA TROUGH OVER MUCH OF THE LOWER 48
STATES EARLY WEEK-2 WHICH GRADUALLY SHIFTS EASTWARD AND WEAKENS. THE MID-LEVEL
TROUGH AXIS, HOWEVER, MAY SHIFT BACK-AND-FORTH BETWEEN THE ROCKIES AND THE
APPALACHIANS BEFORE REACHING THE ATLANTIC SEABOARD AT THE END OF WEEK-2, AND
SOME TOOLS SHOW A SEPARATE SOUTHERN STREAM MID-LEVEL TROUGH CENTER WHICH MOVES
NORTHEASTWARD AHEAD OF THE PRIMARY SYSTEM, WHICH WOULD GENERATE A SURFACE STORM
SYSTEM IN THE EAST DURING THE FIRST HALF OF WEEK-2 BEFORE ANOTHER STORM IS
TRIGGERED WHEN THE PRIMARY MID-LEVEL TROUGH MOVES INTO THE EAST LATER WEEK-2.
THE TIMING AND EVOLUTION OF SURFACE STORM SYSTEMS IS UNCERTAIN AT THIS TIME,
WITH THE MODELS IN POOR AGREEMENT REGARDING SPECIFICS DESPITE GOOD AGREEMENT ON
THE BROAD PATTERN. AS A RESULT, CYCLONIC MID-LEVEL FLOW, PLUS ENHANCED MOISTURE
FROM THE SOUTHERN STREAM, IS LIKELY TO BRING PERIODS OF POTENTIALLY HEAVY
PRECIPITATION TO THE LOWER AND MIDDLE MISSISSIPPI VALLEY AND EASTERN CONUS, AND
A SLIGHT RISK OF HEAVY PRECIPITATION IS POSTED FOR THIS BROAD AREA. GIVEN MODEL
INCONSISTENCY ON THE SPECIFICS OF TIMING, STRENGTH, AND LOCATION OF INDIVIDUAL
STORM SYSTEMS, THE RISK EXTENDS THROUGH ALL OF WEEK-2, ALTHOUGH ANY PERIODS OF
HEAVY PRECIPITATION WILL BE OF SHORTER DURATION.
THE CONSENSUS OF THE ENSEMBLE MEANS PLACES MORE PRECIPITATION ON CENTRAL
TENNESSEE, THE NORTHERN REACHES OF ALABAMA AND GEORGIA, AND THE WESTERN HALVES
OF THE CAROLINAS THAN IN SURROUNDING AREAS. HOWEVER, THE CONSENSUS OF THE TOOLS
ARE NOT CONSISTENT IN THE TIMING OF THE HEAVIEST PRECIPITATION HERE, AND THE
CANADIAN ENSEMBLE MEAN SHOWS HEAVIER AMOUNTS ALONG THE IMMEDIATE ATLANTIC
SEABOARD. FOR THESE REASONS, NO MODERATE RISK OF HEAVY PRECIPITATION IS POSTED.
THE HEAVY RAINFALL MAY CAUSE MINOR RIVER FLOODING ACROSS PARTS OF THE
SOUTHEAST, BUT A FLOODING HAZARD IS NOT DESIGNATED SINCE WIDESPREAD, MODERATE
RIVER FLOODING IS NOT ANTICIPATED.
ANY SURFACE LOW PRESSURE DEVELOPMENT IN THE CENTRAL OR EASTERN CONUS HAS THE
POTENTIAL TO INTENSIFY SIGNIFICANTLY, AS INDICATED BY SOME MODELS. SURFACE
PRESSURES DROP AS LOW AS 980 MB IN A FEW OF THE DETERMINISTIC TOOLS AND
ENSEMBLE MEMBERS. THUS, A SLIGHT RISK OF HIGH WINDS IS POSTED FOR MANY OF THE
SAME AREAS AT RISK FOR HEAVY PRECIPITATION, PLUS WESTERN SECTIONS OF THE
NORTHEAST, WHICH COULD BE AFFECTED BY A COASTAL SYSTEM AND/OR A STORM TRACKING
THROUGH THE GREAT LAKES.
FARTHER NORTH, THE BROAD 500-HPA TROUGH ALOFT IS EXPECTED TO BRING PERIODS OF
ACCUMULATING SNOW - POTENTIALLY HEAVY - TO THE NORTHERN AND CENTRAL ROCKIES,
THE ADJACENT HIGH PLAINS, MUCH OF THE NORTHERN GREAT PLAINS, THE UPPER
MISSISSIPPI VALLEY, AND THE NORTHERN GREAT LAKES REGION, AT LEAST PARTIALLY
DRIVEN BY LEE-SIDE CYCLOGENESIS IN THE WESTERN PLAINS.. THE GEFS SNOW WATER
EQUIVALENT PROBABILITY EXTREMES TOOL (PET) SUPPORTS A SLIGHT RISK OF HEAVY SNOW
ACROSS THIS REGION, AS DOES THE EUROPEAN ENSEMBLE MEAN. DUE TO TIMING
UNCERTAINTY, THE SLIGHT RISK OF HEAVY SNOW IS VALID THROUGH THE MIDDLE OF
WEEK-2, BEFORE THE MID-LEVEL TROUGH AXIS SHIFTS CLOSER TO THE ATLANTIC
SEABOARD. ANY LEE-SIDE CYCLOGENESIS HAS THE POTENTIAL TO GENERATE HIGH WINDS
FROM PARTS OF THE EASTERN ROCKIES INTO THE HIGH PLAINS.
MID-LEVEL RIDGING OVER MAINLAND ALASKA IS LIKELY TO RESULT IN ABOVE-NORMAL
TEMPERATURES THROUGHOUT THE STATE, ESPECIALLY EARLY IN THE PERIOD, WHEN ALL OF
THE ENSEMBLE MEANS SHOW TEMPERATURES 15 TO 25 DEGREES F ABOVE NORMAL. THESE
ANOMALIES, HOWEVER, ARE NOT EXPECTED TO BRING TEMPERATURES TO HAZARDS
THRESHOLDS, AND THE UNUSUAL WARMTH IS EXPECTED TO MODERATE LATER IN THE PERIOD
AS THE MID-LEVEL RIDGE DEAMPLIFIES. PRECIPITATION TOTALS AND WIND SPEEDS ARE
EXPECTED TO REMAIN CLOSE TO AVERAGE AND BELOW HAZARDS THRESHOLDS THROUGHOUT
WEEK-2 OVER THE STATE AS WELL.
FORECASTER: RICH TINKER
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