291
FXUS01 KWBC 140820
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
419 AM EDT MON AUG 14 2023
VALID 12Z MON AUG 14 2023 - 12Z WED AUG 16 2023
...FLASH FLOODING AND SEVERE THUNDERSTORMS POSSIBLE FOR THE GREAT
LAKES/OHIO VALLEY/MID-ATLANTIC MONDAY, LINGERING ALONG THE COAST
INTO TUESDAY...
...PORTIONS OF THE SOUTH TO SEE A BRIEF REPRIEVE FROM THE HEAT
MID-WEEK AS A HEAT WAVE INTENSIFIES ACROSS THE PACIFIC NORTHWEST
INTO THE NORTHERN ROCKIES...
...MONSOONAL SHOWERS CONTINUE ACROSS THE FOUR CORNERS REGION WITH
SOME LOCALLY HEAVY DOWNPOURS POSSIBLE...
A CONSOLIDATING/ORGANIZING FRONTAL SYSTEM WILL PUSH EASTWARD FROM
THE MISSISSIPPI VALLEY TOWARDS THE EAST COAST TODAY AIDED IN PART
BY AN UNSEASONABLY STRONG UPPER-LEVEL WAVE DROPPING SOUTH FROM
CANADA. STRONG LIFT AS WELL AS VERY MOIST, SOUTHERLY FLOW AHEAD OF
AND AROUND THE SYSTEM WILL TRIGGER SCATTERED TO WIDESPREAD SHOWERS
AND THUNDERSTORMS MONDAY STRETCHING FROM THE GREAT LAKES SOUTH
INTO THE UPPER OHIO/TENNESSEE VALLEYS EASTWARD THROUGH THE
APPALACHIANS AND INTO THE MID-ATLANTIC. TWO AREAS OF CONCERN HAVE
ARISEN FOR FLASH FLOODING WITH SLIGHT RISKS OF EXCESSIVE RAINFALL
(LEVEL 2/4) IN PLACE. THE FIRST COVERS AREAS AROUND SOUTHERN LAKE
MICHIGAN WHERE SLOW MOVING, WIDESPREAD STORMS MAY LEAD TO LONG
DURATION, HEAVY RAINFALL TOTALS. THE SECOND STRETCHES FROM THE
UPPER TENNESSEE/OHIO VALLEYS EAST THROUGH THE APPALACHIANS INTO
THE MID-ATLANTIC WHERE SOME ORGANIZED LINES AS WELL AS INDIVIDUAL
STORMS WILL BOTH HAVE THE POTENTIAL TO PRODUCE VERY HEAVY
DOWNPOURS WITH ANOMALOUSLY HIGH MOISTURE IN THE REGION. IN
ADDITION TO FLASH FLOODING, THE STORM PREDICTION CENTER HAS
OUTLINED THIS REGION FOR A SLIGHT RISK (LEVEL 2/5) OF SEVERE
WEATHER AS STRENGTHENING UPPER-LEVEL FLOW WITH THE APPROACHING
WAVE WILL PROVIDE ENOUGH SHEAR FOR MORE ROBUST, ORGANIZED STORMS
WHICH MAY PRODUCE SOME INSTANCES OF DAMAGING WINDS AS WELL AS A
FEW TORNADOES. THE COLD FRONT WILL SLOW AS IT APPROACHES THE EAST
COAST MONDAY NIGHT, ALLOWING FOR RENEWED STORM DEVELOPMENT TUESDAY
AHEAD OF THE FRONT FROM THE DELMARVA SOUTH THROUGH THE EASTERN
CAROLINAS, WHERE SLIGHT RISKS FOR EXCESSIVE RAINFALL AND SEVERE
WEATHER ARE IN PLACE. HIGHS AHEAD OF THE FRONT IN THE MID-ATLANTIC
WILL REMAIN SEASONABLY WARM AND IN THE MID-80S TO MID-90S, WHILE
LOCATIONS TO THE NORTH OF THE SYSTEM INTO NEW ENGLAND AND BEHIND
THE FRONT INTO THE GREAT LAKES/MIDWEST WILL BE UNSEASONABLY COOLER
AND MAINLY IN THE 70S.
TO THE SOUTH, DANGEROUS HEAT WILL CONTINUE MONDAY THANKS TO A WELL
ANCHORED UPPER-LEVEL RIDGE WITH WIDESPREAD HEAT-RELATED ADVISORIES
AND WARNINGS SPANNING FROM FLORIDA NORTH TO THE CAROLINAS AND WEST
TO TEXAS/OKLAHOMA. HIGH TEMPERATURES ONCE AGAIN ARE FORECAST TO
RANGE FROM THE MID-90S IN FLORIDA AND THE CAROLINAS, THE UPPER 90S
TO LOW 100S FOR THE SOUTHEAST INTO THE LOWER MISSISSIPPI VALLEY,
AND AS HIGH AS THE MID-100S INTO PORTIONS OF TEXAS. THESE
TEMPERATURES WHEN COMBINED WITH HIGH HUMIDITY WILL ALLOW FOR HEAT
INDICES AS HIGH AS 110 TO 120F FOR MANY LOCATIONS. NUMEROUS
RECORD-TYING/BREAKING HIGHS ARE FORECAST, WITH SIMILARLY
RECORD-LEVEL WARM LOW TEMPERATURES IN THE UPPER 70S TO LOW 80S
PROVIDING LITTLE RELIEF FROM THE HEAT OVERNIGHT. FORTUNATELY, THE
NOTED STRONG UPPER-LEVEL WAVE/COLD FRONT PUSHING SOUTHEASTWARD
WILL BRING A BRIEF REPRIEVE TO NORTHERN PORTIONS OF THE REGION BY
TUESDAY. HIGHS FROM NORTHERN GEORGIA WEST THROUGH NORTH TEXAS WILL
DROP TO MUCH MORE SEASONABLE VALUES IN THE MID-80S TO LOW 90S, AND
EVEN UPPER 70S FOR PORTIONS OF THE MID-SOUTH. THE HEAT WILL REMAIN
OPPRESSIVE TUESDAY TO THE SOUTH OF THE FRONT FROM SOUTH TEXAS EAST
ALONG THE GULF COAST TO FLORIDA AND NORTHEASTWARD INTO THE
CAROLINAS, BUT EVEN SOME OF THESE LOCATIONS MAY SEE A BIT OF
RELIEF INTO MID-WEEK AS WELL.
ANOTHER MAJOR HEATWAVE WILL CONTINUE TO BUILD TODAY OVER THE
PACIFIC NORTHWEST/NORTHERN ROCKIES IN RELATION TO A STRENGTHENING
RIDGE OF HIGH PRESSURE OVERHEAD. HIGH TEMPERATURES WILL RANGE FROM
THE LOW 90S AROUND PUGET SOUND, THE UPPER 90S TO LOW 100S FOR THE
INTERIOR NORTHWEST AND NORTHERN ROCKIES, AND THE MID-100S TO
POTENTIALLY OVER 110 DEGREES FOR THE INTERIOR VALLEYS WEST OF THE
CASCADES IN OREGON. NUMEROUS NEAR RECORD-TYING/BREAKING HIGHS ARE
POSSIBLE HERE AS WELL. THESE TEMPERATURES COMBINED WITH THE
DURATION OF HEAT, EXPECTED TO CONTINUE THROUGH THIS WEEK, WILL
INCREASINGLY POSE A HEIGHTENED HEALTH RISK, ESPECIALLY FOR THOSE
WITHOUT ADEQUATE AIR CONDITIONING.
DAILY ROUNDS OF THUNDERSTORM ACTIVITY CAN BE EXPECTED ACROSS THE
FOUR CORNERS REGION NORTHWESTWARD INTO THE GREAT BASIN AND
PORTIONS OF THE SIERRA THANKS IN PART TO MONSOONAL MOISTURE AND A
LINGERING FRONTAL BOUNDARY NEAR THE REGION. ANY OF THESE STORMS
MAY HAVE THE POTENTIAL TO PRODUCE HEAVY DOWNPOURS WITH AN ISOLATED
THREAT FOR FLASH FLOODING. DAILY HIGHS WILL BE NEAR SEASONAL
AVERAGES WITH 70S IN PROXIMITY OF THE CALIFORNIA COAST, LOW TO
MID-90S FOR THE GREAT BASIN, AND 100S FOR THE DESERT SOUTHWEST.
HIGHS IN THE INTERIOR CALIFORNIA VALLEYS WILL TREND A BIT HOTTER
WITH MID-100S EXPECTED AND HEAT ADVISORIES IN PLACE. WITH COOLER,
POST-FRONTAL AIR FILTERING SOUTH INTO THE CENTRAL U.S., PORTIONS
OF THE CENTRAL/SOUTHERN HIGH PLAINS/ROCKIES WILL HAVE SOME COOLER
HIGHS THAN POINTS WEST ON MONDAY; MAINLY IN THE UPPER 70S TO LOW
80S. TEMPERATURES WILL BEGIN TO RAPIDLY REBOUND TUESDAY AS
CONDITIONS MODERATE FOLLOWING THE FRONTAL PASSAGE, WITH HIGHS
JUMPING BACK INTO THE UPPER 80S TO LOW 90S.
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