461
FXUS01 KWBC 210815
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 AM EDT TUE MAY 21 2024
VALID 12Z TUE MAY 21 2024 - 12Z THU MAY 23 2024
...AN INCREASING THREAT OF SEVERE WEATHER AND EXCESSIVE RAINFALL
AS WELL AS HIGH WINDS EXPECTED TO OVERSPREAD THE NORTHERN PLAINS
AND UPPER MIDWEST TODAY THROUGH TONIGHT AND INTO WEDNESDAY
MORNING...
...SEVERE WEATHER AND HEAVY RAIN THREAT WILL EMERGE ACROSS THE
SOUTHERN PLAINS TO THE MID-MISSISSIPPI VALLEY ON WEDNESDAY...
...COOL CONDITIONS WITH PERIODS OF SHOWER AND HIGH ELEVATION SNOW
CHANCES FROM THE ROCKIES TO THE PACIFIC NORTHWEST...
...WELL ABOVE AVERAGE TEMPERATURES ACROSS THE CENTRAL PLAINS WILL
BE REPLACED BY COOLER CONDITIONS BUT SUMMER-LIKE WEATHER EXPECTED
TO CONTINUE ACROSS THE SOUTHERN PLAINS TO THE NORTHEAST...
A PERSISTENT WEATHER PATTERN WILL CONTINUE TO SEND ENERGETIC AND
FAST-MOVING WEATHER SYSTEMS ONSHORE FROM THE PACIFIC OCEAN INTO
THE NORTHWEST THROUGH THE SHORT-RANGE FORECAST PERIOD. THESE
SYSTEMS WILL TEND TO INTENSIFY AS THEY REACH INTO THE MID-SECTION
OF THE COUNTRY. ONE SUCH SYSTEM IS DEVELOPING AND TRACKING TOWARD
THE NORTHEAST ACROSS THE CENTRAL PLAINS THIS MORNING. THE THREAT
OF SEVERE WEATHER AND HEAVY RAIN WILL BE EXPANDING TOWARD THE
UPPER MIDWEST BY TONIGHT ALONG WITH INCREASINGLY WINDY CONDITIONS
WHEN THE LOW PRESSURE SYSTEM IS FORECAST TO BECOME QUITE DEEP AND
INTENSE. THUNDERSTORMS THAT ERUPT AHEAD OF A POTENT COLD FRONT
MAY CONTAIN DAMAGING WIND GUSTS, LARGE HAIL, AND A FEW TORNADOES,
FROM THE CENTRAL PLAINS TO THE GREAT LAKES, AND ESPECIALLY OVER
IOWA, WHERE THE STORM PREDICTION CENTER HAS ISSUED A MODERATE RISK
OF SEVERE THUNDERSTORMS FOR LATER TODAY. HEAVY RAIN MAY ALSO LEAD
TO SCATTERED INSTANCES OF FLASH FLOODING THROUGH TONIGHT ACROSS
THE UPPER MIDWEST. THE CENTER OF THE SYSTEM WILL BEGIN TO MOVE
INTO SOUTHERN CANADA BY WEDNESDAY MORNING WITH THE HEAVY RAIN
THREAT QUICKLY DECREASING ACROSS THE GREAT LAKES BUT THE WINDS
WILL TAKE EXTRA TIME TO SUBSIDE THERE.
AS THE LOW PRESSURE SYSTEM BEGINS TO MOVE AWAY INTO SOUTHERN
CANADA ON WEDNESDAY, THE TRAILING COLD FRONT WILL BECOME NEARLY
STATIONARY ACROSS THE SOUTHERN PLAINS WHERE THE NEXT PHASE OF
SEVERE WEATHER AND EXCESSIVE RAINFALL IS FORECAST TO EMERGE. IT
APPEARS THAT THESE THREATS WILL EXPAND TOWARD THE MID-MISSISSIPPI
VALLEY WEDNESDAY NIGHT WHERE THUNDERSTORMS WILL TEND TO BECOME
SLOW-MOVING.
MEANWHILE, COOL AND UNSETTLED WEATHER UNDERNEATH A BROAD UPPER
TROUGH IS ANTICIPATED TO REMAIN LOCKED-IN OVER THE NORTHWEST AND
ROCKIES THROUGH AT LEAST MIDWEEK. SNOW IS POSSIBLE INTO THE HIGHER
ELEVATIONS OF WYOMING AND COLORADO TODAY. ANOTHER UPPER TROUGH
WILL THEN BRING THE NEXT ROUND OF MOUNTAIN SNOWS AND LOW-ELEVATION
RAIN INTO THE NORTHWEST ON WEDNESDAY BEFORE OVERSPREADING THE
NORTHERN ROCKIES BY EARLY ON THURSDAY WHERE SNOW LEVELS COULD DROP
TO AROUND 7000 FEET. HIGH TEMPERATURES IN THESE REGIONS ARE ALSO
EXPECTED TO REMAIN ON THE COOLER SIDE AND 10 TO 25 DEGREES BELOW
AVERAGE.
FOR AREAS SOUTH AND EAST OF THE MAIN STORM SYSTEM IMPACTING THE
CENTRAL U.S. THIS WEEK, HIGHS ARE EXPECTED TO SOAR ABOVE AVERAGE
AND INTO POTENTIALLY RECORD-BREAKING TERRITORY FOR CERTAIN SPOTS.
WIDESPREAD HIGHS INTO THE 80S AND LOW 90S ARE FORECAST FROM THE
MIDWEST AND DEEP SOUTH TO THE NORTHEAST THROUGH WEDNESDAY, WITH
MID-TO-UPPER 90S AND TRIPLE DIGITS IN PARTS OF SOUTH TEXAS AND THE
SOUTHERN HIGH PLAINS. THIS HEAT COULD BE PARTICULARLY DANGEROUS
FOR PEOPLE DEALING WITH A LOSS OF POWER IN PARTS OF TEXAS. WARM
OVERNIGHT TEMPERATURES WILL OFFER LITTLE RELIEF AND HIGH HUMIDITY
COULD ALSO LEAD TO HEAT INDEX READINGS OVER 110 DEGREES.
KONG/SNELL
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