978
FXUS01 KWBC 231932
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
331 PM EDT WED AUG 23 2023
VALID 00Z THU AUG 24 2023 - 00Z SAT AUG 26 2023
...RECORD HEAT TO CONTINUE THROUGH THIS WEEK FOR THE MID SECTION
OF THE NATION, BUT RELIEF IS IN SIGHT FOR SOME BY THE WEEKEND...
...HEAVY RAINS AND LOCALIZED FLASH FLOODING POSSIBLE FROM THE
SOUTHWEST INTO THE SOUTHERN GREAT BASIN AND CENTRAL ROCKIES, AND
FROM THE EASTERN GREAT LAKES INTO THE MID-ATLANTIC AND NORTHEAST...
THE ANOMALOUSLY STRONG MID TO UPPER LEVEL RIDGE THAT HAS BEEN
DRIVING THE MOST RECENT EPISODE OF THE PERSISTENT SUMMER 2023 U.S.
HEAT WAVE WILL CONTINUE TO PRODUCE RECORD HEAT AND HEAT INDEX
VALUES OVER THE NEXT FEW DAYS ACROSS LARGE PORTIONS OF THE NATION
FROM THE MID-WEST, SOUTH THROUGH THE MISSISSIPPI VALLEY, ACROSS
EASTERN PORTIONS OF THE PLAINS AND INTO THE CENTRAL GULF COAST.
ACROSS THESE REGIONS TRIPLE DIGIT HIGH TEMPERATURES ARE LIKELY
OVER THE NEXT TWO DAYS. WHEN COMBINED WITH HIGH DEW POINT VALUES
FROM THE MID 70S TO LOWER 80S, MAXIMUM HEAT INDEX VALUES OF 110 TO
120 ARE LIKELY. ACROSS THESE AREAS, EXCESSIVE HEAT WARNINGS AND
HEAT ADVISORIES ARE IN EFFECT FOR NEARLY 120 MILLION PEOPLE. THE
GOOD NEWS IS THAT THERE ARE CHANGES ON THE HORIZON, WITH COOLER
TEMPERATURES LIKELY TO BEGIN TO PUSH FROM NORTH TO SOUTH BY THE
END OF THIS WEEK INTO THIS WEEKEND AS THE MID TO UPPER LEVEL RIDGE
BEGINS TO WEAKEN AND A COLD FRONT PUSHES SOUTH. AREAS OF THE
UPPER MISSISSIPPI VALLEY INTO THE MID-WEST WILL BE FIRST TO SEE
COOLER TEMPERATURES BY FRIDAY, WITH THE BIG CITIES OF MINNEAPOLIS
AND CHICAGO SEEING AN END TO THE HEAT WAVE. BY THE WEEKEND THE
COOLER TEMPERATURES WILL MAKE IT INTO KANSAS CITY AND ST. LOUIS,
BUT HEAT AND HIGH HEAT INDICES WILL CONTINUE FARTHER TO THE SOUTH
ACROSS THE SOUTHERN PLAINS, LOWER MISSISSIPPI VALLEY, GULF COAST
AND SOUTHEAST THROUGH THE WEEKEND.
AROUND THE PERIPHERIES OF THIS HEAT DOME, ACTIVE SHOWERS AND
THUNDERSTORMS ARE POSSIBLE FROM THE SOUTHWEST INTO PORTIONS OF THE
GREAT BASIN AND CENTRAL ROCKIES. ACROSS THESE REGIONS, ABOVE
AVERAGE MOISTURE VALUES FROM THE REMNANTS OF HAROLD,THAT MADE
LANDFALL ON THE TEXAS GULF COAST ON TUESDAY, WILL ROTATE CLOCKWISE
AROUND THE STRONG MID TO UPPER LEVEL HIGH OVER THE CENTRAL U.S.
AND INTO PORTIONS OF THE SOUTHWEST, SOUTHERN GREAT BASIN AND
CENTRAL ROCKIES REGION. THESE ABOVE AVERAGE MOISTURE VALUES WILL
SUPPORT THE POTENTIAL FOR HEAVY RAINS AND LOCALIZED FLASH FLOODING
OVER THE NEXT TWO DAYS.
ACTIVE SHOWERS AND THUNDERSTORMS ARE ALSO LIKELY ON THE NORTHERN
AND NORTHEASTERN PERIPHERIES OF THE STRONG MID U.S. UPPER RIDGE
FROM THE EASTERN GREAT LAKES, SOUTHEASTWARD INTO THE MID-ATLANTIC
AND INTO THE NORTHEAST. PERIODS OF ACTIVE SHOWERS AND
THUNDERSTORMS ARE POSSIBLE ACROSS THESE AREAS BEGINNING WEDNESDAY
NIGHT AND CONTINUING INTO FRIDAY. THIS WILL SUPPORT THE POTENTIAL
FOR LOCALLY HEAVY RAINS AND ISOLATED FLASH FLOODING ACROSS THESE
AREAS.
IN ADDITION TO THE HEAVY RAIN THREAT OVER THE LOWER LAKES INTO THE
MID-ATLANTIC, THERE WILL ALSO BE THE POTENTIAL FOR SEVERE
THUNDERSTORMS OVER THE NEXT TWO DAYS ACROSS THESE AREAS, WITH HIGH
WINDS AND LARGE HAIL THE GREATEST THREAT.
ORAVEC
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