745
FXUS21 KWNC 101824
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT OCTOBER 10 2024
SYNOPSIS: A GENERALLY QUIET PATTERN IS PREDICTED ACROSS THE CONTIGUOUS U.S.
(CONUS) DURING WEEK-2, WITH MID-LEVEL HIGH PRESSURE SHIFTING INTO THE EAST
FAVORING A WARMING TREND. LATE IN WEEK-1 INTO THE OUTSET OF WEEK-2, MID-LEVEL
LOW PRESSURE IS FORECAST TO DIG INTO THE WESTERN CONUS. THIS FEATURE, COMBINED
WITH RETURN FLOW AROUND SURFACE HIGH PRESSURE IN THE EAST, FAVORS AN UPTICK IN
PRECIPITATION CHANCES ACROSS THE GREAT PLAINS WHICH MAY HELP ALLEVIATE ONGOING
DROUGHT CONDITIONS. ENHANCED ONSHORE FLOW MAY BRING ROUNDS OF HEAVY
PRECIPITATION INTO THE PACIFIC NORTHWEST. FLOODING IN THE WAKE OF HURRICANE
MILTON REMAINS A CONCERN OVER PARTS OF FLORIDA.
HAZARDS
SLIGHT RISK FOR HEAVY PRECIPITATION ACROSS PORTIONS OF THE PACIFIC NORTHWEST,
FRI-SUN, OCT 18-20.
POSSIBLE FLOODING FOR THE NORTHERN AND CENTRAL FLORIDA PENINSULA.
RISK OF RAPID ONSET DROUGHT (ROD) ACROSS PORTIONS OF EASTERN TEXAS, NORTHERN
LOUISIANA, AND SOUTHERN ARKANSAS.
DETAILED SUMMARY
FOR SUNDAY OCTOBER 13 - THURSDAY OCTOBER 17:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY OCTOBER 18 - THURSDAY OCTOBER 24: SHORTWAVE TROUGHING IS FORECAST TO
QUICKLY MOVE THROUGH THE EASTERN CONUS LATE IN WEEK-1, WITH A TRANSITION TO
ANOMALOUS RIDGING IN THE BEGINNING OF WEEK-2. WHILE SOME RESIDUAL BELOW-NORMAL
TEMPERATURES MAY LINGER ACROSS PARTS OF THE EAST ON DAY-8, THE GREATEST
POTENTIAL FOR HAZARDOUS COLD AND POTENTIAL FROSTS AND FREEZES IS NOW WITHIN THE
WEEK-1 TIME FRAME. THE ECENS PROBABILISTIC EXTREMES TOOL (PET) DEPICTS MUCH OF
THE EAST CONTINUING TO HAVE A 20-40 PERCENT CHANCE MINIMUM TEMPERATURES FALL
BELOW THE 15TH CLIMATOLOGICAL PERCENTILE ON DAY-8. HOWEVER, PROBABILITIES IN
THE GEFS PET ARE BELOW 20 PERCENT, AND THE UNCALIBRATED 0Z ECENS AND GEFS
GENERALLY DEPICT MINIMUM TEMPERATURES IN THE 40S DEG F ACROSS LOW ELEVATION
AREAS, WITH THE COLDEST TEMPERATURES CONFINED TO THE APPALACHIANS AND NORTHERN
NEW ENGLAND WHICH IS MORE CONSISTENT WITH CLIMATOLOGY. THEREFORE, THE MUCH
BELOW NORMAL TEMPERATURE HAZARDS ACROSS THE EASTERN U.S. HAVE BEEN DISCONTINUED.
HURRICANE MILTON MADE LANDFALL ON OCT 9 NEAR SIESTA KEY, FLORIDA. WHILE THE
SYSTEM AND ASSOCIATED HEAVY RAIN HAVE EXITED INTO THE ATLANTIC, EXTENSIVE
FLOODING IS ONGOING AND IS FORECAST TO CONTINUE THROUGH WEEK-1 AND POSSIBLY
INTO WEEK-2. THEREFORE, THE FLOODING POSSIBLE AREA REMAINS POSTED ACROSS THE
NORTHERN AND CENTRAL FLORIDA PENINSULA. MODELS AND THE PETS INDICATE ENHANCED
CHANCES FOR INCREASED RAINFALL OVER PORTIONS OF SOUTH FLORIDA DURING THE
PERIOD, BUT AMOUNTS ARE MARGINAL AND NO RELATED PRECIPITATION HAZARD IS POSTED
AT THIS TIME.
TROUGHING IS FORECAST TO AMPLIFY ACROSS THE WEST AT THE START OF THE PERIOD
FAVORING ENHANCED PRECIPITATION CHANCES ACROSS THE GREAT PLAINS, AIDED BY
RETURN SOUTHERLY FLOW AROUND SURFACE HIGH PRESSURE OVER THE EAST. BOTH THE GEFS
AND ECENS PETS DEPICT SOME AREAS OF THE SOUTHERN PLAINS HAVING AT LEAST A 20
PERCENT CHANCE 3-DAY PRECIPITATION TOTALS EXCEED THE 85TH CLIMATOLOGICAL
PERCENTILE AND 1-INCH. HOWEVER, NO RELATED PRECIPITATION HAZARD IS DESIGNATED
AS THE DAILY TOTALS IN THE UNCALIBRATED ENSEMBLES ARE LESS THAN A HALF-INCH AND
ANY PRECIPITATION WOULD BE BENEFICIAL CONSIDERING THE ONGOING DROUGHT
CONDITIONS. GIVEN THE UPTICK IN THE PRECIPITATION SIGNALS OVER THE CENTRAL
CONUS, THE RAPID ONSET DROUGHT (ROD) RISK IS REDUCED SUBSTANTIALLY, WITH ONLY
PORTIONS OF EASTERN TEXAS, NORTHERN LOUISIANA, AND SOUTHERN ARKANSAS INCLUDED
IN THE ELEVATED ROD RISK AREA. THESE AREAS REMAIN FAVORED TO HAVE NEAR- TO
BELOW-NORMAL PRECIPITATION DURING WEEK-2, ALONG WITH THE POTENTIAL FOR
TEMPERATURES IN THE 80S DEG F SUPPORTING HIGHER EVAPOTRANSPIRATION RATES.
THE MID-LEVEL PATTERN IS FORECAST TO REMAIN CONDUCIVE FOR ENHANCED ONSHORE FLOW
ACROSS THE NORTHWESTERN CONUS DURING WEEK-2, WITH THE POTENTIAL FOR ANOTHER
TROUGH TO DROP SOUTHWARD FROM ALASKA. BOTH THE ECENS AND GEFS PETS DEPICT AT
LEAST A 20 PERCENT CHANCE 3-DAY PRECIPITATION TOTALS EXCEED THE 85TH
CLIMATOLOGICAL PERCENTILE AND 1.5 INCHES OVER THE PACIFIC NORTHWEST EARLY IN
THE PERIOD. WHILE THIS IS MARGINAL IN TERMS OF A HAZARD, THERE HAS BEEN A
GRADUAL UPTICK IN PRECIPITATION SIGNALS DURING THE PAST FEW DAYS. THEREFORE, A
SLIGHT RISK OF HEAVY PRECIPITATION IS HIGHLIGHTED ACROSS WESTERN PORTIONS OF
WASHINGTON AND OREGON, OCT 18-20. THE UNCALIBRATED GEFS AND ASSOCIATED PET
DEPICT MUCH STRONGER COLD SIGNALS ACROSS THE WEST EARLY IN WEEK-2 COMPARED TO
THE ECENS GUIDANCE. DUE TO THESE DIFFERENCES, ALONG WITH THE COLDEST
TEMPERATURES ALIGNED WITH CLIMATOLOGY, NO RELATED TEMPERATURE HAZARD IS POSTED.
HOWEVER, SOME SNOW CANNOT BE RULED OUT ACROSS HIGHER ELEVATIONS OF THE CASCADES
AND ROCKIES. ONSHORE FLOW IS ALSO FORECAST TO CONTINUE ACROSS SOUTHEASTERN
ALASKA, ALTHOUGH PRECIPITATION AMOUNTS AND WIND SPEEDS ARE UNLIKELY TO REACH
HAZARDS THRESHOLDS, WHICH ARE HIGHER COMPARED TO OVER THE NORTHWESTERN CONUS.
FORECASTER: THOMAS COLLOW
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