437
FXUS01 KWBC 200752
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
351 AM EDT THU JUL 20 2023
VALID 12Z THU JUL 20 2023 - 12Z SAT JUL 22 2023
...AN ACTIVE THURSDAY FEATURING SEVERE STORMS CAPABLE OF CAUSING
FLASH FLOODING IN THE CENTRAL PLAINS, MID-SOUTH, GREAT LAKES, AND
NORTHEAST...
...LENGTHY & DANGEROUS HEAT WAVE TO CONTINUE ACROSS THE SOUTHERN
TIER & IN THE WEST...
...COOLER AND MORE COMFORTABLE AIR-MASS TO ENGULF THE GREAT PLAINS
AND MIDWEST...
A STRONG COLD FRONT PRESSING SOUTH AND EAST THROUGH THE NATION'S
HEARTLAND WILL COLLIDE WITH AN EXCEPTIONALLY HOT AND MUGGY
AIR-MASS TO PRODUCE WIDESPREAD THUNDERSTORMS TODAY AND INTO
THURSDAY NIGHT. THE REGION MOST AT-RISK FOR SEVERE STORMS AND
EXCESSIVE RAINFALL IS THE CENTRAL HIGH PLAINS. THE WEATHER
PREDICTION CENTER (WPC) HAS A MODERATE RISK (THREAT LEVEL 3/4) FOR
EXCESSIVE RAINFALL, WHILE THE STORM PREDICTION CENTER HAS AN
ENHANCED RISK (THREAT LEVEL 3/5) FOR SEVERE WEATHER. ROBUST
THUNDERSTORM ACTIVITY COULD PRODUCE ANY COMBINATION OF DAMAGING
WINDS, LARGE HAIL, TORNADOES, AND FLASH FLOODING THERE. THE SEVERE
WEATHER AND FLASH FLOOD THREAT IS ALSO PRESENT FOR MANY LOCATIONS
FARTHER EAST. WPC HAS A SLIGHT RISK IN PLACE THAT STRETCHES FROM
SOUTHERN KANSAS AND NORTHERN OKLAHOMA ALL THE WAY TO THE TENNESSEE
VALLEY AND SOUTHERN APPALACHIANS. THERE IS ALSO A SLIGHT RISK IN
PLACE OVER PORTIONS OF THE NORTHERN MID-ATLANTIC AND IN NORTHEAST
OHIO. SPC ALSO HAVE AN EXPANSIVE SLIGHT RISK AREAS EAST OF THE
MISSISSIPPI RIVER THAT ENCOMPASSES THE EASTERN GREAT LAKES, THE
OHIO VALLEY, AND PARTS OF THE SOUTHEAST.
BY FRIDAY THE COLD FRONT CONTINUES TO ADVANCE FARTHER SOUTH AND
EAST, PLACING THE BEST THREAT FOR STRONG-TO-SEVERE STORMS OVER THE
MID-SOUTH AND NORTHEAST. WPC HAS ISSUED A PAIR OF SLIGHT RISKS IN
THESE AREAS GIVEN THE POTENTIAL FOR EXCESSIVE RAINFALL RATES IN
LOCATIONS THAT FEATURE OVERLY SATURATED SOILS. IN ADDITION, THE
FRONT WILL SET UP OVER EASTERN NEW MEXICO, WHERE A COMBINATION OF
SLOWER MOVING STORMS AND HEAVY RAINFALL HAS LED TO A SLIGHT RISK
OF EXCESSIVE RAINFALL BEING ISSUED THERE. SPC HAS SEVERAL MARGINAL
RISK AREAS FOR SEVERE WEATHER THAT INCLUDE SOUTHERN ARIZONA,
NORTHEAST NEW MEXICO, PORTIONS OF THE CENTRAL HIGH PLAINS, FROM
ARKANSAS TO THE SOUTHEAST COAST, AND IN THE MID-ATLANTIC. BY
SATURDAY MORNING, MUCH OF THE MID-SOUTH AND NORTHEAST WILL TREND
DRIER AS THE COLD FRONT EXITS OFF THE EAST COAST. HOWEVER, THE
FRONT BECOMES STATIONARY OVER THE GULF COAST STATES, SETTING UP A
STORMY SATURDAY IN THE SOUTH.
FOR THE REMAINDER OF THE WORK-WEEK, MUCH OF THE SOUTHERN TIER AND
WESTERN THIRD OF THE U.S. WILL REMAIN MIRED IN THIS PROLONGED AND
DANGEROUS HEAT WAVE. RECORD BREAKING DAYTIME HIGHS AND WARM
MORNING LOWS WILL BE COMMON FROM THE DESERT SOUTHWEST AND SOUTH
TEXAS ALL THE WAY EAST TO FLORIDA. THE FORECAST CALLS FOR DAYTIME
HIGHS TO SOAR INTO THE TRIPLE DIGITS IN THE DESERT SOUTHWEST AND
SOUTHERN PLAINS, WHILE THE GULF COAST AND MID-SOUTH CAN EXPECT
DAYTIME HIGHS IN THE UPPER 90S THAT COINCIDE WITH OPPRESSIVELY
HIGH DEW POINTS THROUGH FRIDAY, RESULTING IN SWELTERING HEAT
INDICES AS HIGH AS 120 DEGREES IN SOME SPOTS. MEANWHILE, DAILY LOW
TEMPERATURES REMAIN QUITE WARM WITH BREAKING RECORD WARM DAILY
MINIMUMS EXPECTED, WHICH WILL LIMIT RELIEF FROM THE HEAT
OVERNIGHT. FLORIDA WILL ALSO CONTEND WITH STIFLING HEAT THANKS IN
LARGE PART TO WELL ABOVE NORMAL SEA SURFACE TEMPERATURES AND
LIGHTER THAN NORMAL WINDS ACROSS THE SUNSHINE STATE. PLEASE VISIT
HEAT.GOV, AS WELL AS THE KEY MESSAGES ISSUED BY THE WEATHER
PREDICTION CENTER AND CLIMATE PREDICTION CENTER FOR MORE
INFORMATION ON IMPACTS FROM THE HEAT WAVE.
WHILE THE COLD FRONT TRAVERSING THE COUNTRY IS RESPONSIBLE IN
LARGE PART FOR THE SEVERE WEATHER AND HEAVY RAINFALL THE NEXT
COUPLE DAYS, IT ALSO BRINGS COOLER TEMPERATURES AND MORE
COMFORTABLE HUMIDITY LEVELS TO THE NORTHERN PLAINS AND MIDWEST. BY
FRIDAY, PARTS OF THE CENTRAL PLAINS COULD SEE DAYTIME HIGHS THAT
ARE AS LOW AS 15-20 DEGREES BELOW NORMAL. THIS WELCOMED REPRIEVE
FROM THE HEAT ACROSS PARTS OF THE SOUTH WILL ARRIVE BY SATURDAY,
INCLUDING IN THE MID-ATLANTIC AND NORTHEAST WHERE DAYTIME HIGHS
LOOK TO BE SEVERAL DEGREES BELOW NORMAL AND HUMIDITY LEVELS THAT
ARE MORE REFRESHING FOR MID-LATE JULY. IN CONTRAST, THE HEAT WAVE
WILL BE ANCHORED ALONG AND WEST OF THE ROCKIES LATE FRIDAY AND
INTO SATURDAY WHERE MORE RECORD BREAKING HEAT IS FORECAST.
MULLINAX
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