834
FXUS21 KWNC 091848
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT OCTOBER 09 2023
SYNOPSIS: MID-LEVEL TROUGHING AND SURFACE HIGH PRESSURE CONTINUE TO BRING
CHANCES FOR MUCH BELOW NORMAL TEMPERATURES INTO PORTIONS OF THE EASTERN
CONTIGUOUS U.S. (CONUS) EARLY IN WEEK-2. MEANWHILE, PRECIPITATION CHANCES
REMAIN FAVORED ACROSS PORTIONS OF SOUTHEAST ALASKA AND THE PACIFIC NORTHWEST
BUT ARE NOT FORECAST TO REACH HAZARDOUS THRESHOLDS.
HAZARDS
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES ACROSS PARTS OF THE MIDDLE
MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS, TUE-THU, OCT 17-19.
DETAILED SUMMARY
FOR THURSDAY OCTOBER 12 - MONDAY OCTOBER 16:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY OCTOBER 17 - MONDAY OCTOBER 23: AN AMPLIFIED 500-HPA HEIGHT PATTERN
IS FORECAST ACROSS NORTH AMERICA AND THE SURROUNDING AREAS DURING WEEK-2. A
DEEP TROUGH IS FORECAST ACROSS THE NORTHEAST PACIFIC BRINGING TROUGHING AND
NEGATIVE 500-HPA HEIGHT ANOMALIES TO PARTS OF WESTERN ALASKA AND OFFSHORE OF
THE PACIFIC NORTHWEST. RIDGING AND POSITIVE 500-HPA HEIGHT ANOMALIES ARE
FAVORED FROM THE ROCKY MOUNTAINS INTO THE PLAINS, AND TROUGHING IS AGAIN
FAVORED ACROSS THE EASTERN CONUS.
A TROUGH LOCATED IN THE NORTHEAST PACIFIC IS FAVORED TO PROMOTE ABOVE-NORMAL
PRECIPITATION IN THE PACIFIC NORTHWEST AND SOUTHEAST ALASKA. THE GEFS AND ECMWF
PROBABILISTIC EXTREMES TOOLS (PETS) INDICATE A 20% CHANCE OF PRECIPITATION
EXCEEDING THE 85TH PERCENTILE DURING MUCH OF THE PERIOD. HOWEVER, 3 DAY
PRECIPITATION AMOUNTS ARE FORECAST TO BE AROUND 1 INCH OF PRECIPITATION IN THE
PACIFIC NORTHWEST AND 2 INCHES IN SOUTHEAST ALASKA. THESE AMOUNTS WOULD NOT BE
HAZARDOUS IN THESE REGIONS. THEREFORE, NO ASSOCIATED PRECIPITATION HAZARD IS
POSTED AT THIS TIME.
WITH RIDGING BUILDING INTO THE ROCKIES, NORTHERLY MID-LEVEL FLOW IS FAVORED
ACROSS THE MISSISSIPPI, OHIO, AND TENNESSEE VALLEYS. SURFACE HIGH PRESSURE IS
ALSO FORECAST ACROSS THE CENTER OF THE CONUS EARLY IN THE PERIOD. THIS WOULD
BRING CONDITIONS FOR COOL NIGHTS ACROSS THE REGION. THE GEFS AND ECMWF PETS
INDICATE A 20 PERCENT CHANCE FOR TEMPERATURES TO FALL BELOW THE 15TH
CLIMATOLOGICAL PERCENTILE AND 40 DEG F ACROSS THIS REGION. FURTHER NORTH,
TEMPERATURES ARE LESS LIKELY TO FALL BELOW THE 15TH PERCENTILE AND MORE LIKELY
TO HAVE ALREADY SEEN AN END TO THE GROWING SEASON. THEREFORE, A SLIGHT RISK OF
MUCH BELOW NORMAL TEMPERATURES IS POSTED FOR THE MIDDLE MISSISSIPPI, OHIO, AND
TENNESSEE VALLEYS FOR OCT 17-19.
FORECASTER: RYAN BOLT
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