475
FXUS01 KWBC 220748
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
348 AM EDT TUE AUG 22 2023
VALID 12Z TUE AUG 22 2023 - 12Z THU AUG 24 2023
...EXTREMELY DANGEROUS HEAT WILL PERSIST ACROSS A WIDESPREAD
REGION SPANNING FROM THE MIDWEST TO GULF COAST THIS WEEK...
...HEAVY RAIN AND GUSTY WINDS ASSOCIATED WITH TROPICAL STORM
HAROLD TO IMPACT SOUTH TEXAS TODAY...
...SCATTERED FLASH FLOODING CONCERNS EXIST ACROSS PARTS OF THE
GREAT BASIN AND SOUTHWEST...
A SEARING AUGUST HEAT WAVE IS SET TO CONTINUE THIS WEEK UNDERNEATH
A POTENT UPPER LEVEL RIDGE ANCHORED OVER THE MID-MISSISSIPPI
VALLEY. THE OPPRESSIVE HEAT WILL IMPACT A WIDESPREAD REGION FROM
THE MIDWEST TO THE GULF COAST, INCLUDING MUCH OF THE GREAT PLAINS
AS WELL. HIGH TEMPERATURES THROUGHOUT THESE AREAS ARE FORECAST TO
REACH INTO THE UPPER 90S AND LOW 100S EACH DAY THROUGH AT LEAST
THURSDAY. WHEN FACTORING IN BRUTAL HUMIDITY LEVELS, MAXIMUM HEAT
INDICES COULD APPROACH 120 DEGREES. WHILE IT IS NOT UNCOMMON FOR
AUGUST TO FEATURE DANGEROUS HEAT, THESE TEMPERATURES ARE EXTREMELY
ANOMALOUS AND LIKELY TO BREAK NUMEROUS DAILY AND POTENTIALLY
MONTHLY RECORDS. IN FACT, HIGHS ARE FORECAST TO REACH UP TO 20
DEGREES ABOVE AVERAGE THROUGHOUT IOWA AND NEIGHBORING STATES OVER
THE NEXT FEW DAYS. VERY WARM OVERNIGHT TEMPERATURES ONLY DROPPING
INTO THE UPPER 70S AND LOW 80S WILL COMPOUND THE IMPACTS
ASSOCIATED WITH THIS POTENTIALLY DEADLY HEAT WAVE. HEAT ALERTS
(EXCESSIVE HEAT WARNINGS, WATCHES, AND ADVISORIES) HAVE BEEN
ISSUED FROM MINNEAPOLIS TO NEW ORLEANS, WHICH INCLUDES 22 STATES
AND ROUGHLY 100 MILLION PEOPLE. TAKE THE HEAT SERIOUSLY AND AVOID
EXTENDED TIME OUTDOORS. TEMPERATURES AND HEAT INDICES WILL REACH
LEVELS THAT WOULD POSE A HEALTH RISK, AND BE POTENTIALLY DEADLY TO
ANYONE WITHOUT EFFECTIVE COOLING AND/OR ADEQUATE HYDRATION.
REMEMBER, HEAT IS THE NUMBER-ONE-WEATHER-RELATED CAUSE OF DEATH IN
THE UNITED STATES.
NEWLY FORMED TROPICAL STORM HAROLD LOCATED OVER THE WESTERN GULF
OF MEXICO IS ANTICIPATED TO CONTINUE ITS WESTWARD MOTION AND
IMPACT SOUTH TEXAS TODAY WITH HEAVY RAIN AND GUSTY WINDS. RAINFALL
AMOUNTS OF 3 TO 5 INCHES, WITH ISOLATED HIGHER AMOUNTS UP TO 7
INCHES, THROUGH EARLY WEDNESDAY COULD PRODUCE SCATTERED AREAS OF
FLASH FLOODING. A SLIGHT RISK (LEVEL 2/4) OF EXCESSIVE RAINFALL
HAS BEEN ISSUED FOR THE REGION. ADDITIONALLY, TROPICAL STORM FORCE
WINDS WILL ACCOMPANY THE SYSTEM AS IT PROGRESSES INLAND, AS WELL
AS ROUGH SURF ALONG THE COAST. BY WEDNESDAY AND THURSDAY, HAROLD
AND ITS REMNANT MOISTURE IS FORECAST TO PUSH INTO NORTHERN MEXICO
AND THE SOUTHWEST/SOUTHERN ROCKIES. THIS MAY LEAD TO ADDITIONAL
FLASH FLOODING CONCERNS, ESPECIALLY NEAR THE MORE FLOOD-PRONE SLOT
CANYONS IN UTAH ON THURSDAY.
OTHERWISE, SCATTERED FLASH FLOODING REMAINS POSSIBLE ACROSS THE
NORTHERN GREAT BASIN AND INTERMOUNTAIN WEST TODAY AS ANOMALOUS
MOISTURE CONTENT AND UNIFORM SOUTHERLY FLOW ALLOWS FOR POTENTIALLY
TRAINING SHOWERS/THUNDERSTORMS. FARTHER EAST, PRECIPIATION CHANCES
CONTINUE TO CIRCUMVENT THE STRONG UPPER HIGH OVER THE MIDWEST AND
PROGRESS FROM THE GREAT LAKES TODAY TO THE NORTHEAST/CENTRAL
APPALACHIANS BY WEDNESDAY AND THURSDAY. SOME ISOLATED
THUNDERSTORMS COULD CONTAIN DAMAGING WIND GUSTS. THE WEST AND
NORTHEAST WILL ENJOY BELOW AVERAGE TEMPERATURES TO GO ALONG WITH
RAIN CHANCES, AS HIGHS FOR THE MOST LOCATIONS REMAIN IN THE 70S
AND LOW 80S
SNELL
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