612
FXUS01 KWBC 120800
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 AM EDT WED JUL 12 2023
VALID 12Z WED JUL 12 2023 - 12Z FRI JUL 14 2023
...ADDITIONAL ROUNDS OF SEVERE WEATHER AND FLASH FLOODING PERSIST
ACROSS THE MIDWEST, MISSISSIPPI VALLEY, AND PLAINS OVER THE NEXT
COUPLE DAYS...
..HEAVY RAIN POTENTIAL RETURNS TO THE NORTHEAST THURSDAY
...BUILDING HEAT WAVE CONTINUES TO EXPAND ACROSS MUCH OF THE
SOUTHERN TIER OF THE U.S....
A COMPLEX SUMMER-TIME SETUP CONTINUES TO UNFOLD ACROSS THE CENTRAL
U.S. WITH MULTIPLE CORRIDORS OF SEVERE WEATHER AND HEAVY RAINFALL
EXPECTED WEDNESDAY. A SHORTWAVE WILL ROTATE AROUND THE BASE OF A
BROAD HUDSON BAY LOW PROVIDING BROAD ASSENT OVER A SLOW-MOVING
SURFACE FRONTAL SYSTEM DRAPED THROUGH THE MIDWEST/MISSISSIPPI
VALLEY/PLAINS. DEEP GULF MOISTURE POOLING ALONG AND TO THE SOUTH
OF THE BOUNDARY AND WARM SUMMER-TIME TEMPERATURES WILL PROVIDE THE
INSTABILITY FOR WIDESPREAD ROBUST THUNDERSTORM DEVELOPMENT
PRODUCING EFFICIENT HEAVY RAINFALL THROUGHOUT MUCH OF THE
MIDWEST/MISSISSIPPI VALLEY. ONGOING CONVECTION EARLY WEDNESDAY
MORNING AS WELL AS ADDITIONAL CONVECTION THAT FORMS WILL ALSO
LIKELY LEAD TO MULTIPLE OUTFLOW BOUNDARIES PROVIDING ADDITIONAL
FOCUSED AREAS OF STORM DEVELOPMENT LEADING TO MULTIPLE CORRIDORS
OF HEAVY RAINFALL TOTALS AND THE RISK FOR FLASH FLOODING.
CURRENTLY, A MODERATE RISK OF EXCESSIVE RAINFALL (LEVEL 3/4) IS IN
EFFECT WEDNESDAY FOR PORTIONS OF FAR SOUTHWEST ARKANSAS AND
NORTHWEST LOUISIANA WHERE HEAVY RAINFALL OVERNIGHT HAS LED TO VERY
SENSITIVE GROUND CONDITIONS WITH ADDITIONAL HEAVY RAINFALL
EXPECTED, POSING A LOCALLY INCREASED RISK OF SCATTERED TO
WIDESPREAD INSTANCES OF FLASH FLOODING. A BROAD SLIGHT RISK (LEVEL
2/4) EXTENDS INTO THE LOWER MISSISSIPPI VALLEY AND CENTRAL GULF
COAST, WITH ADDITIONAL SLIGHT RISKS COVERING PORTIONS SOUTHEAST
KANSAS/SOUTHWEST MISSOURI AS WELL AS PORTIONS OF THE UPPER
MISSISSIPPI VALLEY AND LOWER GREAT LAKES. THERE IS ALSO A BROAD
SLIGHT RISK OF SEVERE WEATHER (LEVEL 2/5) OUTLINED BY THE STORM
PREDICTION CENTER COVERING THE MIDDLE/LOWER MISSOURI AND MIDDLE
MISSISSIPPI VALLEYS WHERE SOME OF THE MORE ROBUST AND ORGANIZED
STORMS/CONVECTIVE SYSTEMS MAY PRODUCE SOME LARGE HAIL AND DAMAGING
WINDS. AS THE INITIAL SHORTWAVE DEPARTS TO THE EAST, LESS ACTIVITY
IS EXPECTED THURSDAY, ALTHOUGH SOME ADDITIONAL LOCALLY HEAVY
RAINFALL AND A SEVERE THUNDERSTORM OR TWO WILL REMAIN POSSIBLE
ACROSS THE AREA AS THE FRONTAL BOUNDARY AND BUOYANT SUMMERTIME
AIRMASS CONTINUE TO REMAIN IN THE REGION. TEMPERATURES WILL BE HOT
AHEAD OF THE FRONT BUT WILL BE MUCH BELOW AVERAGE BEHIND IT ON
WEDNESDAY. HIGHS WILL BE IN THE UPPER 60S TO MID 70S FOR MUCH OF
THE NORTHERN PLAINS AND GREAT LAKES REGION. TEMPERATURES WILL
REBOUND ON THURSDAY FOR MOST LOCATIONS INTO THE UPPER 70S TO MID
80S.
THE UPPER-LEVEL SHORTWAVE AS WELL AS SURFACE FRONTAL SYSTEM WILL
TRANSLATE EASTWARD THURSDAY TOWARDS THE EAST COAST, BRINGING
RETURNING CHANCES FOR THUNDERSTORMS AND HEAVY RAINFALL FROM THE
OHIO VALLEY INTO THE NORTHEAST. MEAN SOUTHERLY FLOW IN THE LOW
LEVELS AHEAD OF THE SYSTEM WILL DRAW MOISTURE BACK NORTHWARD
ACROSS THE REGION, HELPING TO FUEL HEAVY DOWNPOUR-PRODUCING
SHOWERS AND THUNDERSTORMS. SLIGHT RISKS OF EXCESSIVE RAINFALL HAVE
BEEN OUTLINED FOR PORTIONS OF UPSTATE NEW YORK AND INTERIOR NEW
ENGLAND AS WELL AS THE UPPER OHIO VALLEY. INTERIOR NEW ENGLAND
REMAINS PARTICULARLY SENSITIVE TO ANY ADDITIONAL RAINFALL
FOLLOWING SIGNIFICANT RAINFALL EARLIER THIS WEEK, WITH ADDITIONAL
INSTANCES OF FLASH FLOODING MORE LIKELY. SHOWERS AND THUNDERSTORMS
ARE ALSO EXPECTED THROUGH THE TENNESSEE VALLEY AND INTO THE
SOUTHEAST WITH SOME LOCALLY HEAVY RAINFALL POSSIBLE. FORECAST HIGH
TEMPERATURES WILL BE A BIT ABOVE AVERAGE AND SUMMER-TIME HOT
THROUGHOUT THE REGION WITH MID TO UPPER 80S FOR NEW ENGLAND, THE
INTERIOR NORTHEAST, AND THE OHIO VALLEY AND LOW TO MID-90S FOR THE
MID-ATLANTIC, CAROLINAS, AND SOUTHEAST.
MEANWHILE, A STAGNANT UPPER-LEVEL HIGH IN PLACE OVER THE
SOUTHWEST/NORTHERN MEXICO WILL NOT ONLY REMAIN IN PLACE BUT BEGIN
TO BUILD IN COVERAGE, PARTICULARLY TO THE NORTHWEST OVER THE GREAT
BASIN AND CALIFORNIA. WIDESPREAD HEAT-RELATED ADVISORIES AND
WARNINGS REMAIN IN PLACE ACROSS THE CENTRAL/SOUTHERN PLAINS AND
LOWER MISSISSIPPI VALLEY AS WELL AS PORTIONS OF THE DESERT
SOUTHWEST AND CALIFORNIA. FOR LOCATIONS FURTHER EAST IN THE PLAINS
AND INTO THE LOWER MISSISSIPPI VALLEY, TEMPERATURES IN THE UPPER
90S AND LOW 100S COMBINED WITH HIGH HUMIDITY WILL MAKE IT FEEL
LIKE 105-110 DEGREES, LOCALLY AS HIGH AS 115 ON WEDNESDAY.
TEMPERATURES LOOK TO FALL A BIT ON THURSDAY BRINGING A BIT OF
RELIEF TO PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS, WHILE
CONDITIONS REMAIN HOT IN TEXAS. SIMILARLY HOT CONDITIONS WILL BE
IN PLACE TO THE WEST AS HUMIDITY VALUES WILL BE LOWER BUT AIR
TEMPERATURES SOAR INTO THE MID TO UPPER 100S FOR WEST TEXAS AND
PORTIONS OF THE SOUTHWEST AND INTO THE 110S IN THE DESERT
SOUTHWEST. A FEW RECORD-TYING/BREAKING HIGHS ARE POSSIBLE FOR WEST
TEXAS ON WEDNESDAY. THE HEAT WILL BEGIN TO BUILD INTO THE GREAT
BASIN AND INTERIOR CALIFORNIA ON THURSDAY, WITH HIGHS IN THE
RISING INTO THE MID-90S TO LOW 100S. UNFORTUNATELY, THE LONG TERM
OUTLOOK FOR THE REGION SHOWS A CONTINUED HEATWAVE THROUGH THIS
WEEKEND AND INTO NEXT WEEK. WHILE NOT NOTABLY HIGHER THAN AVERAGE,
A CONTINUED UPTICK IN TEMPERATURES INTO THE MID-90S ARE RELATIVELY
HIGH, AND NEAR RECORD-TYING/BREAKING LEVELS. WHEN COMBINED WITH
THE HUMIDITY, IT WILL FEEL LIKE 105-110 DEGREES. ELSEWHERE,
CONDITIONS WILL BE GENERALLY TRANQUIL WITH NEAR-AVERAGE HIGH
TEMPERATURES FOR THE NORTHWEST AHEAD OF HOTTER TEMPREATURES
EXPECTED THIS WEEKEND.
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