985
FXUS21 KWNC 071853
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST MARCH 07 2024
SYNOPSIS: MID-LEVEL LOW PRESSURE INITIALLY FORECAST OVER THE GREAT PLAINS IS
PREDICTED TO SHIFT TO THE NORTHEASTERN U.S. LATER IN WEEK-2, WHILE INCREASING
IN AMPLITUDE. THIS FEATURE IS LIKELY TO RESULT IN ENHANCED CHANCES FOR HEAVY
PRECIPITATION AND THUNDERSTORMS ACROSS THE LOWER MISSISSIPPI VALLEY AND
SOUTHEAST EARLY IN WEEK-2. AS THE ASSOCIATED COLD FRONT PROGRESSES OFF THE
ATLANTIC COAST, ELEVATED WIND SPEEDS ALONG WITH RELATIVELY COOLER TEMPERATURES
ARE FAVORED TO BUILD INTO THE EAST BY THE MIDDLE OF THE PERIOD. STRONG ONSHORE
FLOW FAVORS HEAVY PRECIPITATION ACROSS SOUTHEAST ALASKA AT THE OUTSET OF THE
PERIOD, WITH BUILDING MID-LEVEL HIGH PRESSURE FORECAST TO LEAD TO RELATIVELY
DRIER CONDITIONS BEGINNING ON DAY-9.
HAZARDS
MODERATE RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE SOUTHERN PLAINS, LOWER
MISSISSIPPI VALLEY, AND SOUTHEAST, FRI-SAT, MAR 15-16.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE SOUTH-CENTRAL AND
SOUTHEASTERN CONUS, AND THE MID-ATLANTIC, FRI-SUN, MAR 15-17.
SLIGHT RISK OF HIGH WINDS ACROSS PORTIONS OF THE FOUR CORNERS REGION, GREAT
PLAINS, AND MIDDLE MISSISSIPPI VALLEY, FRI-SAT, MAR 15-16.
SLIGHT RISK OF HIGH WINDS ACROSS PORTIONS OF THE NORTHERN PLAINS AND MUCH OF
THE EASTERN CONUS, SAT-THU, MAR 16-21.
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE MIDDLE AND
LOWER MISSISSIPPI AND TENNESSEE VALLEYS, AND SOUTHEAST, SUN-THU, MAR 17-21.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS SOUTHEAST ALASKA, FRI, MAR 15.
SLIGHT RISK OF HIGH WINDS ACROSS SOUTHEAST ALASKA, FRI, MAR 15.
POSSIBLE FLOODING FOR PARTS OF THE LOWER MISSISSIPPI AND TENNESSEE VALLEYS,
SOUTHEAST, AND SOUTHERN APPALACHIANS.
DETAILED SUMMARY
FOR SUNDAY MARCH 10 - THURSDAY MARCH 14:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY MARCH 15 - THURSDAY MARCH 21: THERE IS GOOD AGREEMENT AMONG THE 0Z
GEFS, ECMWF, AND CANADIAN ENSEMBLES IN REGARDS TO MID-LEVEL TROUGHING ACROSS
THE CENTRAL CONTIGUOUS U.S. (CONUS) AT THE OUTSET OF THE PERIOD. THIS TROUGH IS
FORECAST TO GRADUALLY SHIFT EASTWARD AND LEAD TO POTENTIALLY IMPACTFUL WEATHER
ACROSS MUCH OF THE EASTERN HALF OF THE CONUS THROUGHOUT WEEK-2. MODELS INDICATE
AN AREA OF SURFACE LOW PRESSURE TRACKING NORTHWARD ACROSS THE MISSISSIPPI
VALLEY AND GREAT LAKES EARLY IN THE PERIOD, WITH A TRAILING COLD FRONT
PROGRESSING THROUGH THE EAST. HEAVY PRECIPITATION AND POSSIBLY THUNDERSTORMS
ARE FORECAST ACROSS PORTIONS OF THE SOUTH-CENTRAL AND SOUTHEASTERN CONUS. WHILE
THE GEFS AND ECMWF PETS GENERALLY DEPICT PROBABILITIES OF 20-40 PERCENT FOR
3-DAY PRECIPITATION TOTALS EXCEEDING THE 85TH CLIMATOLOGICAL PERCENTILE OR
1-INCH, THE UNCALIBRATED GUIDANCE IS MORE ROBUST OVER THESE AREAS. THE 0Z ECMWF
ENSEMBLE INDICATES PROBABILITIES ABOVE 20 PERCENT ACROSS PARTS OF THE SOUTHERN
PLAINS AND LOWER MISSISSIPPI VALLEY FOR 3-DAY PRECIPITATION TOTALS EXCEEDING
2-INCHES, WITH 24-HOUR TOTALS EXCEEDING THREE QUARTERS OF AN INCH IN THE 0Z
ECMWF AND GEFS ENSEMBLE MEANS OVER SOME AREAS. GIVEN THESE SIGNALS, A MODERATE
RISK OF HEAVY PRECIPITATION IS HIGHLIGHTED ACROSS PORTIONS OF THE SOUTHERN
PLAINS, LOWER MISSISSIPPI VALLEY, AND SOUTHEAST, MAR 15-16, WITH A MORE
EXPANSIVE SLIGHT RISK THAT EXTENDS NORTHWARD INTO THE MIDDLE MISSISSIPPI
VALLEY, SOUTHERN APPALACHIANS, AND SOUTHERN MID-ATLANTIC THROUGH MAR 17.
ALTHOUGH THE FRONTAL PASSAGE IS LIKELY TO BRING ENHANCED PRECIPITATION CHANCES
TO THE ENTIRE EASTERN SEABOARD BY THE MIDDLE OF THE PERIOD, THERE IS LESS
CONFIDENCE ON REACHING HAZARDS CRITERIA OVER NORTHERN AREAS. THE ECMWF PET
BRINGS PROBABILITIES FOR 3-DAY PRECIPITATION TOTALS EXCEEDING THE 85TH
CLIMATOLOGICAL PERCENTILE AND 1-INCH INTO PARTS OF THE NORTHERN MID-ATLANTIC
AND NORTHEAST, ALTHOUGH THERE IS LESS SUPPORT FROM THE GEFS PET AND
UNCALIBRATED GUIDANCE. TRENDS WILL CONTINUE TO BE MONITORED FOR A POSSIBLE
NORTHWARD EXTENSION OF THE SLIGHT RISK IN TOMORROW’S OUTLOOK. ANTECEDENT HEAVY
PRECIPITATION PREDICTED DURING WEEK-1 BASED ON FORECASTS FROM THE WEATHER
PREDICTION CENTER, COMBINED WITH EXPECTED HEAVY WEEK-2 PRECIPITATION, SUPPORTS
A POSSIBLE FLOOD RISK FOR PORTIONS OF THE SOUTHEASTERN CONUS. FLOODING CONCERNS
COULD ALSO INCREASE ACROSS PARTS OF THE MID-ATLANTIC AND NORTHEAST IF THE
HEAVIER PRECIPITATION EXPANDS NORTHWARD, BUT CONFIDENCE IS TOO LOW TO INCLUDE
AT THIS TIME GIVEN THE UNCERTAINTY IN THE PRECIPITATION FORECAST.
ELEVATED WIND SPEEDS ARE FORECAST TO ACCOMPANY THIS SYSTEM AS WELL. INITIALLY,
THE STRONGEST WINDS ARE FAVORED ACROSS THE FOUR CORNERS AND GREAT PLAINS,
CO-LOCATED WITH THE FORECAST TROUGH AXIS POSITIONING AT THE OUTSET OF THE
PERIOD. GUSTY WINDS MAY EXACERBATE WILDFIRE RISK WHERE THERE ARE ALREADY
ONGOING WILDFIRES, ESPECIALLY OVER THE TEXAS PANHANDLE. THEREFORE, A SLIGHT
RISK FOR HIGH WINDS REMAINS IN PLACE FOR THESE AREAS, MAR 15-16. AS THE TROUGH
AND ASSOCIATED FRONTAL SYSTEM PROGRESS EASTWARD, THE STRONGEST WIND SIGNALS ARE
FORECAST TO SHIFT EAST AND NORTH BY THE MIDDLE OF WEEK-2. THIS IS EVIDENCED BY
AN INCREASING PRESSURE GRADIENT ACROSS THE MIDWEST THROUGH THE EAST COAST, AND
IN THE ECMWF PET, WHICH DEPICTS PROBABILITIES OF AT LEAST 20 PERCENT FOR WIND
SPEEDS REACHING THE 85TH CLIMATOLOGICAL PERCENTILE AND 20-MPH OVER SOME AREAS.
THEREFORE, ANOTHER SLIGHT RISK OF HIGH WINDS IS HIGHLIGHTED ACROSS MUCH OF THE
NORTHERN PLAINS AND THE EASTERN CONUS, MAR 16-21. MULTIPLE EPISODES OF HIGH
WINDS ARE POSSIBLE THROUGHOUT THE PERIOD WITH NOT ALL AREAS IMPACTED AT ANY
GIVEN TIME.
THE INCREASED NORTHERLY FLOW MAY ALSO BEGIN TO USHER IN RELATIVELY COOLER
TEMPERATURES ACROSS THE EASTERN HALF OF THE CONUS TOWARD THE END OF WEEK-2,
WITH THE POTENTIAL NEGATIVE ARCTIC OSCILLATION AND MJO PROGRESSION FAVORING
THIS COOLER PATTERN INTO LATE MARCH. BOTH THE GEFS AND ECMWF PETS DEPICT AT
LEAST A 40 PERCENT CHANCE OF MINIMUM TEMPERATURES FALLING BELOW 40 DEG F
STARTING ON DAY-10 (MAR 17) OVER THE MIDDLE MISSISSIPPI AND TENNESSEE VALLEYS,
AND AT LEAST A 20 PERCENT CHANCE FOR TEMPERATURES REACHING THIS THRESHOLD
EXPANDING INTO PARTS OF THE DEEP SOUTH. GIVEN ANTECEDENT WARM CONDITIONS AND
INCREASING VEGETATION GREEN-UP, A SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES
IS HIGHLIGHTED ACROSS PARTS OF THE MIDDLE AND LOWER MISSISSIPPI AND TENNESSEE
VALLEYS, AND SOUTHEAST, MAR 17-21 DUE TO POSSIBLE ADVERSE IMPACTS ON VEGETATION
RESULTING FROM THE FLIP TO A COOLER PATTERN.
FOR ALASKA, THERE IS GOOD MODEL AGREEMENT INDICATING A TRANSITION IN THE
MID-LEVEL HEIGHT PATTERN FROM TROUGHING ACROSS THE STATE AT THE ONSET OF WEEK-2
TO RIDGING BY THE MIDDLE OF WEEK-2. MULTIPLE MODEL ENSEMBLE MEANS SHOW THE
POTENTIAL FOR STRONG ONSHORE FLOW INTO SOUTHEAST ALASKA LATE IN WEEK-1 INTO THE
START OF WEEK-2 DUE TO THE PREDICTED STRONG PRESSURE GRADIENT ASSOCIATED WITH
THE AFOREMENTIONED PATTERN TRANSITION. THE GEFS AND ECMWF PETS INDICATE AT
LEAST A 20 PERCENT CHANCE OF 3-DAY PRECIPITATION TOTALS EXCEEDING THE 85TH
CLIMATOLOGICAL PERCENTILE AND 1-INCH OVER SOME AREAS. MUCH OF THIS IS
CONCENTRATED ON DAY-8 (MAR 15) BASED ON 24-HOUR DAILY ENSEMBLE MEANS.
THEREFORE, A SLIGHT RISK OF HEAVY PRECIPITATION IS HIGHLIGHTED ACROSS SOUTHEAST
ALASKA, MAR 15, ALONG WITH A SLIGHT RISK OF HIGH WINDS DUE TO THE PREDICTED
STRONG PRESSURE GRADIENT, AS WELL AS ADDITIONAL SUPPORT FROM THE ECMWF PET. A
RELATIVELY DRIER PATTERN IS FAVORED ACROSS THIS REGION BY THE MIDDLE OF WEEK-2
AS RIDGING BECOMES MORE DOMINANT.
FORECASTER: THOMAS COLLOW
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