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FXUS21 KWNC 071819
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT OCTOBER 07 2024
SYNOPSIS: AT THE OUTSET OF THE PERIOD, MID-LEVEL LOW PRESSURE IS FORECAST TO
QUICKLY MOVE THROUGH THE EASTERN CONTIGUOUS U.S. (CONUS) RESULTING IN A PERIOD
OF BELOW-NORMAL TEMPERATURES OVER THE REGION. HOWEVER, PREVAILING MID-LEVEL
HIGH PRESSURE FAVORS PERSISTENT ABOVE-NORMAL TEMPERATURES ACROSS THE REMAINDER
OF THE CONUS, WITH MODERATING TEMPERATURES LIKELY FOR THE EAST BY THE MIDDLE OF
THE PERIOD. FLOODING IN THE WAKE OF HURRICANE MILTON REMAINS A CONCERN FOR
PARTS OF THE COASTAL SOUTHEAST AND FLORIDA. ADDITIONAL TROPICAL MOISTURE MAY
IMPACT SOUTH FLORIDA DURING WEEK-2, ALTHOUGH THERE IS MUCH UNCERTAINTY.
HAZARDS
SLIGHT RISK FOR MUCH BELOW NORMAL TEMPERATURES FOR ACROSS PORTIONS OF THE
MIDWEST, TENNESSEE AND OHIO VALLEYS, APPALACHIANS, MID-ATLANTIC, AND NORTHEAST,
TUE-WED, OCT 15-16.
SLIGHT RISK FOR HEAVY PRECIPITATION ACROSS PORTIONS OF SOUTH FLORIDA, TUE-SAT,
OCT 15-19.
SLIGHT RISK FOR HIGH WINDS ACROSS COASTAL PORTIONS OF CALIFORNIA, TUE-THU, OCT
15-17.
POSSIBLE FLOODING FOR PARTS OF THE FLORIDA PENINSULA AND COASTAL SOUTHEAST.
RISK OF RAPID ONSET DROUGHT (ROD) ACROSS PORTIONS OF THE GREAT PLAINS AND
MISSISSIPPI VALLEY.
DETAILED SUMMARY
FOR THURSDAY OCTOBER 10 - MONDAY OCTOBER 14:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY OCTOBER 15 - MONDAY OCTOBER 21: COMPARED TO YESTERDAY, THE 0Z GEFS,
ECENS, AND CMCE MODELS HAVE TRENDED TOWARD A MORE AMPLIFIED SHORTWAVE TROUGH
PROGRESSING ACROSS THE EASTERN CONUS AT THE END OF WEEK-1 AND INTO THE START OF
WEEK-2. THIS FEATURE FAVORS A SHORT BURST OF ANOMALOUSLY COLD TEMPERATURES
ACROSS THE REGION, AND GIVEN THE TIME OF YEAR, IT IS LIKELY THAT SOME LOCATIONS
WILL EXPERIENCE THEIR FIRST FROST OR FREEZE. SURFACE HIGH PRESSURE IS FORECAST
TO BE CENTERED OVER THE TENNESSEE VALLEY AND APPALACHIANS, SETTING UP IDEAL
RADIATIONAL COOLING CONDITIONS. THE GEFS AND ECENS PROBABILISTIC EXTREMES TOOLS
(PETS) BOTH DEPICT A BROAD AREA OF THE EAST HAVING A 20-40 PERCENT CHANCE THAT
MINIMUM TEMPERATURES FALL BELOW THE 15TH CLIMATOLOGICAL PERCENTILE ON DAYS 8
AND 9, WITH ELEVATED CHANCES FOR TEMPERATURES TO FALL BELOW 40 DEG F EXTENDING
THROUGH PARTS OF THE OHIO AND TENNESSEE VALLEYS AND INTERIOR MID-ATLANTIC. THE
BEST CHANCES FOR SUBFREEZING TEMPERATURES ARE INDICATED ACROSS PORTIONS OF THE
INTERIOR NORTHEAST AND NEW ENGLAND. AS A RESULT OF THESE PREDICTED COLDER
TEMPERATURES AND THE POSSIBILITY OF A FROST OR FREEZE OVER SUSCEPTIBLE
VEGETATION, A SLIGHT RISK FOR MUCH BELOW NORMAL TEMPERATURES IS HIGHLIGHTED
ACROSS PORTIONS OF THE MIDWEST, TENNESSEE AND OHIO VALLEYS, APPALACHIANS,
MID-ATLANTIC, AND NORTHEAST, OCT 15-16. OF NOTE IS THAT THIS LOOKS LIKE A QUICK
SHOT OF COLD AIR, WITH WARMING TEMPERATURES BY THE MIDDLE OF THE PERIOD AS
UPSTREAM RIDGING EXPANDS ACROSS THE CONUS. FOR THIS REASON, NEAR- TO
ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR THE WEEK-2 PERIOD AS A WHOLE OVER
MUCH OF THE HIGHLIGHTED REGION.
HURRICANE MILTON HAS RAPIDLY INTENSIFIED INTO A CATEGORY-5 HURRICANE. THE
NATIONAL HURRICANE CENTER (NHC) FORECASTS SOME WEAKENING OF THE SYSTEM PRIOR TO
STRIKING THE WEST COAST OF FLORIDA LATE WEDNESDAY. MILTON, ALONG WITH A
PRECURSOR DISTURBANCE, IS FORECAST TO BRING VERY HEAVY RAINFALL (LOCALLY MORE
THAN 10 INCHES) ACROSS PORTIONS OF THE FLORIDA PENINSULA, WITH HEAVY RAINFALL
POSSIBLY EXTENDING NORTHWARD INTO SOUTHEAST GEORGIA AND COASTAL SOUTH CAROLINA.
WHILE THIS RAIN IS FORECAST DURING THE WEEK-1 PERIOD, THE FLOODING CONCERNS ARE
LIKELY TO LINGER INTO WEEK-2 SUPPORTING A POSSIBLE FLOODING HAZARD OVER THESE
AFOREMENTIONED AREAS.
THERE ARE SOME INDICATIONS IN THE MODELS FOR ANOTHER ROUND OF TROPICAL MOISTURE
MOVING NORTHWARD OUT OF THE CARIBBEAN DURING WEEK-2. THE AREA OF SURFACE HIGH
PRESSURE OVER THE EAST FAVORS ANY MOISTURE BEING KEPT FURTHER SOUTH, AND IT IS
TOO UNCERTAIN AS TO WHETHER OR NOT THERE WILL BE AN ORGANIZED TROPICAL CYCLONE
VERSUS WEAKER WAVES OF ENHANCED RAINFALL. HOWEVER, THE GEFS AND ECENS PETS BOTH
DEPICT SOME ISOLATED AREAS OF AT LEAST A 20 PERCENT CHANCE 3-DAY RAINFALL
EXCEEDS THE 85TH CLIMATOLOGICAL PERCENTILE AND 1-INCH DURING THE EARLY AND
MIDDLE PARTS OF THE PERIOD OVER THE SOUTHERN FLORIDA PENINSULA. GIVEN THE
ANTECEDENT HEAVY RAINFALL FROM MILTON AND ASSOCIATED FLOODING FORECAST OVER THE
REGION, ANY ADDITIONAL RAINFALL, EVEN IF MARGINAL, WILL EXACERBATE ONGOING
FLOODING. THEREFORE, A SLIGHT RISK OF HEAVY PRECIPITATION IS HIGHLIGHTED ACROSS
SOUTH FLORIDA, OCT 15-19.
WARM, DRY WEATHER IS FORECAST ACROSS THE WESTERN AND CENTRAL CONUS DURING
WEEK-2. THE RAPID ONSET DROUGHT (ROD) RISK AREA OVER THE GREAT PLAINS AND
WESTERN MISSISSIPPI VALLEY IS MAINTAINED BASED ON THE ANTICIPATED ANOMALOUSLY
WARM TEMPERATURES, 30-DAY PRECIPITATION DEFICITS, LOW SOIL MOISTURE, AND LITTLE
PREDICTED RAINFALL DURING THE NEXT TWO WEEKS. AN ENHANCED THERMAL GRADIENT MAY
RESULT IN INCREASED WIND SPEEDS ALONG COASTAL CALIFORNIA. WHILE THERE IS NO
SIGNAL IN THE PETS, THE UNCALIBRATED 0Z GEFS AND ECENS DEPICT ELEVATED CHANCES
FOR WIND SPEEDS GREATER THAN 20-KNOTS OFF THE CALIFORNIA COAST EARLY IN THE
PERIOD. THEREFORE, A SLIGHT RISK FOR HIGH WINDS IS POSTED FOR OCT 15-17.
NO HAZARDS ARE FORECAST ACROSS ALASKA AS IMPACTFUL WEATHER RELATED TO A SURFACE
LOW OVER THE GULF OF ALASKA HAS SHIFTED INTO THE WEEK-1 PERIOD AND THE SYSTEM
IS FORECAST TO WEAKEN BY THE START OF WEEK-2. THERE ARE SOME WEAK SIGNALS FOR
INCREASED ONSHORE FLOW DEVELOPING ACROSS THE PACIFIC NORTHWEST AS THE MEAN
TROUGHING SHIFTS EASTWARD, BUT NOTHING WARRANTING ANY RELATED HAZARDS AT THIS
TIME.
FORECASTER: THOMAS COLLOW
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