868
FXUS01 KWBC 022001
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 PM EDT SAT SEP 02 2023
VALID 00Z SUN SEP 03 2023 - 00Z TUE SEP 05 2023
...RISK FOR SCATTERED FLASH FLOODING IN THE INTERMOUNTAIN WEST AS
UNSETTLED AND COOL WEATHER PATTERN CONTINUES...
...MANY RECORD-TYING/BREAKING TEMPERATURES POSSIBLE AS HOT WEATHER
REMAINS IN PLACE OVER THE NORTHERN PLAINS/UPPER MIDWEST...
...UNSEASONABLY HOT TEMPERATURES FOR THE MID-ATLANTIC TO END THE
HOLIDAY WEEKEND...
AN UNSETTLED AND COOL PATTERN WILL REMAIN OVER MUCH OF THE WEST
THIS WEEKEND AS AN UPPER-LEVEL LOW HAS STALLED OUT OVERHEAD. WAVES
OF UPPER-LEVEL ENERGY ROTATING AROUND THE LOW AND A LINGERING
FRONTAL BOUNDARY WILL HELP TO TRIGGER WIDESPREAD SHOWERS AND
THUNDERSTORMS, WITH A FOCUS ON THE INTERMOUNTAIN WEST. PLENTIFUL,
ANOMALOUSLY HIGH SURFACE MOISTURE WILL BE IN PLACE TO CONTRIBUTE
TO NUMEROUS HEAVY RAIN PRODUCING STORMS BOTH DUE TO THE
COVERAGE/DURATION AND INTENSITY OF THE DOWNPOURS. THERE IS A
SLIGHT RISK OF EXCESSIVE RAINFALL IN PLACE FOR PORTIONS OF THE
NORTHERN GREAT BASIN/NORTHERN ROCKIES SUNDAY WHERE THE BEST
COMBINATION OF UPPER-LEVEL ENERGY AND MOISTURE/INSTABILITY WILL
LEAD TO THE HIGHEST CHANCE FOR SOME SCATTERED INSTANCES OF FLASH
FLOODING. THE UPPER-LEVEL WAVE WILL BEGIN TO MOVE EASTWARD ON
MONDAY, WITH THE THREAT FOR HEAVY RAINFALL SHIFTING INTO THE
NORTHERN ROCKIES/ADJACENT HIGH PLAINS. AN ADDITIONAL SLIGHT RISK
OF EXCESSIVE RAINFALL IS IN PLACE WITH A CONTINUED RISK FOR SOME
SCATTERED FLASH FLOODING. HIGH TEMPERATURES WILL REMAIN
UNSEASONABLY COOL FOR EARLY SEPTEMBER ACROSS MOST OF THE WEST.
FORECAST HIGHS BOTH SUNDAY AND MONDAY WILL RANGE IN THE 60S AND
70S FOR MUCH OF THE PACIFIC NORTHWEST, WESTERN GREAT BASIN, AND
CALIFORNIA, WITH ONLY THE DESERT SOUTHWEST SEEING HOTTER
TEMPERATURES INTO THE 90S AND LOW 100S. THESE COOLER TEMPERATURES
WILL ALSO SPREAD INTO THE NORTHERN ROCKIES/ADJACENT HIGH PLAINS
AND EASTERN GREAT BASIN MONDAY.
MEANWHILE, TO THE EAST, A BROAD UPPER-LEVEL RIDGE WILL KEEP
TEMPERATURES UNSEASONABLY HOT FOR MUCH OF THE CENTRAL/EASTERN U.S.
IT WHAT HAS ALREADY BEEN A LONG, HOT SUMMER, HIGHS WILL REMAIN IN
THE UPPER 90S TO LOW 100S FOR TEXAS AND THE SOUTHERN PLAINS, AS
WELL AS PORTIONS OF THE CENTRAL PLAINS.
HOWEVER, MUCH OF THE FOCUS WILL BE ON THE NORTHERN PLAINS AND
UPPER MIDWEST WHERE HIGHS INTO THE LOW 100S ARE UPWARDS OF 20-30
DEGREES ABOVE AVERAGE AND WILL BE AT RECORD-TYING/BREAKING LEVELS.
SOME MONTHLY RECORDS ARE EVEN POSSIBLE. THE UNUSUAL NATURE OF HEAT
OF THIS MAGNITUDE THIS TIME OF YEAR WILL HEIGHTEN THE RELATED
HEALTH RISKS, ESPECIALLY OVER A HOLIDAY WEEKEND. THE UPPER-LEVEL
WAVE OVER THE WEST WILL CONTINUE EASTWARD INTO TUESDAY HELPING TO
DRIVE A PAIR OF FRONTAL SYSTEMS INTO THE REGION, BRINGING A CHANCE
FOR SHOWERS AND STORMS AND EVENTUAL RELIEF FROM THE HEAT JUST
BEYOND THE CURRENT FORECAST PERIOD INTO WEDNESDAY. THE
UNSEASONABLY HOT WEATHER WILL ALSO OVERSPREAD THE NORTHEAST BY
SUNDAY. HIGHS WILL RANGE IN THE MID- TO UPPER 80S SUNDAY BEFORE
REACHING AS HIGH AS THE LOW 90S ON MONDAY. SOME
RECORD-TYING/BREAKING TEMPERATURES WILL BE POSSIBLE IN THE
MID-ATLANTIC AS HIGHS SOAR INTO THE MID-90S. ELSEWHERE, A WEAK
UPPER-LEVEL WAVE AND LINGERING FRONTAL BOUNDARY WILL BRING A
CHANCE OF SOME THUNDERSTORMS TO THE LOWER MISSISSIPPI VALLEY.
HIGHS ACROSS THE LOWER MISSISSIPPI VALLEY AND INTO THE SOUTHEAST
AND FLORIDA WILL ALSO BE MORE SEASONABLE COMPARED TO THE REST OF
THE CENTRAL/EASTERN U.S., WITH MID-80S AND UPPER 90S EXPECTED FOR
SUNDAY AND MONDAY.
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