238
FXUS01 KWBC 290801
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 AM EDT MON JUL 29 2024
VALID 12Z MON JUL 29 2024 - 12Z WED JUL 31 2024
...FLASH FLOODING POSSIBLE IN THE OHIO/TENNESSEE VALLEYS AND
CENTRAL/SOUTHERN APPALACHIANS THROUGH EARLY THIS WEEK...
...SCATTERED SEVERE THUNDERSTORMS FORECAST ACROSS PORTIONS OF THE
NORTHERN PLAINS MONDAY AND UPPER MIDWEST TUESDAY...
...DANGEROUS MID-SUMMER HEAT WAVE TO BEGIN EXPANDING ACROSS THE
CENTRAL U.S. ON MONDAY...
BOUTS OF THUNDERSTORMS ARE EXPECTED TO CONTINUE OVER PORTIONS OF
THE OHIO/TENNESSEE VALLEYS AND SPREAD FURTHER INTO THE
CENTRAL/SOUTHERN APPALACHIANS TO START OFF THE WORK WEEK. AN
ACTIVE UPPER-LEVEL PATTERN FEATURING AT LEAST A COUPLE SHORTWAVES
AND AN APPROACHING SURFACE FRONTAL SYSTEM FROM THE WEST WILL HELP
TO FOCUS STORM DEVELOPMENT OVER THE OHIO/TENNESSEE VALLEYS AND
EVENTUALLY INTO THE SOUTHERN APPALACHIANS MONDAY. PLENTIFUL
MOISTURE IN PLACE WILL ALSO CONTINUE TO LEAD TO THE THREAT OF
HEAVIER RAIN RATES, WITH INCREASING STORM COVERAGE INTO THE
EVENING AND POTENTIAL BACK BUILDING/REPEATED ROUNDS OF STORMS
RAISING THE CHANCE FOR LOCALLY HEAVY RAINFALL TOTALS. AS SUCH, A
SLIGHT RISK OF EXCESSIVE RAINFALL (LEVEL 2/4) IS IN PLACE FOR THE
THREAT OF SOME SCATTERED FLASH FLOODING. IN ADDITION, SUFFICIENT
INSTABILITY/SHEAR WILL BE IN PLACE OVER THE OHIO VALLEY FOR A
COUPLE MORE INTENSE STORMS, AS WELL AS THE THREAT FOR A MORE
ORGANIZED STORM COMPLEX LATER MONDAY EVENING. THE STORM PREDICTION
CENTER HAS INCLUDED A SLIGHT RISK (LEVEL 2/5) FOR SEVERE WEATHER
AS WELL MAINLY FOR THE THREAT OF DAMAGING WINDS. A SIMILAR PATTERN
WILL BE IN PLACE ON TUESDAY, WITH THE FOCUS SHIFTING FURTHER INTO
THE SOUTHERN AND CENTRAL APPALACHIANS AS THE UPPER-LEVEL ENERGY
AND SURFACE FRONTAL SYSTEM MOVE EASTWARD. ANOTHER SLIGHT RISK OF
EXESSIVE RAINFALL IS IN EFFECT HERE FOR ADDITIONAL INSTANCES OF
FLASH FLOODING. OUTSIDE OF THE FLASH FLOODING THREAT, SCATTERED
THUNDERSTORMS WITH MODERATE TO LOCALLY HEAVY RAINFALL ARE EXPECTED
MORE BROADLY OVER THE MIDWEST/SOUTHEAST MONDAY, AND ALSO OVER
PORTIONS OF NEW ENGLAND AS A COASTAL LOW APPROACHES. RAIN CHANCES
WILL EXPAND OVER THE MID-ATLANTIC/NORTHEAST AS THE SYSTEM
APPROACHES FROM THE WEST ON TUESDAY. FORECAST HIGH TEMPERATURES
ACROSS THE EAST WILL VARY DEPENDING ON CLOUD/STORM COVERAGE, WITH
MOSTLY MID-80S TO LOW 90S EXPECTED.
SOME ADDITIONAL STORMS WILL BE POSSIBLE FURTHER WEST ALONG THE
FRONTAL BOUNDARY INTO THE UPPER MIDWEST AND NORTHERN PLAINS.
EMBEDDED UPPER-LEVEL ENERGY WILL HELP TO TRIGGER ONE ROUND OF
STORMS OVER THE NORTHERN PLAINS ON MONDAY. STRONGER UPPER-LEVEL
FLOW WILL LEAD TO MORE DEEP-LAYER SHEAR HERE THAN FURTHER EAST,
WITH ANOTHER SLIGHT RISK OF SEVERE WEATHER FOR THE THREAT OF SOME
VERY LARGE HAIL AS WELL AS SIGNIFICANT DAMAGING WINDS IF STORMS
CONSOLIDATE/GROW UPSCALE INTO AN ORGANIZED SYSTEM LATER IN THE
EVENING. ANOTHER ROUND OF SEVERE WEATHER IS POSSIBLE DOWNSTREAM
OVER THE UPPER MIDWEST TUESDAY AS YET ANOTHER UPPER-LEVEL IMPULSE
HELPS TO TRIGGER STORMS ALONG THE FRONTAL BOUNDARY. VERY HIGH
MOISTURE WILL LEAD TO STRONG TO EXTREME INSTABILITY, WITH A SLIGHT
RISK IN PLACE FOR THE CHANCE OF MORE DAMAGING WINDS.
OUTSIDE OF THE SEVERE WEATHER THREAT, HEAT WILL BECOME THE BIG
STORY MORE BROADLY OVER THE CENTRAL U.S. OVER THE NEXT FEW DAYS AS
AN UPPER-LEVEL HIGH STRENGTHENS/EXPANDS OVER THE REGION. FORECAST
HIGH TEMPERATURES MONDAY AND TUESDAY ARE EXPECTED TO SOAR INTO THE
LOW TO MID-100S OVER THE CENTRAL PLAINS, WITH UPPER-90S TO LOW
100S TO THE WEST OVER MUCH OF THE HIGH PLAINS, AND MID- TO UPPER
90S FOR THE MIDDLE AND LOWER MISSISSIPPI VALLEY. HIGH HUMIDITY
VALUES OVER THE MISSISSIPPI VALLEY AND EASTERN PORTIONS OF THE
PLAINS WILL LEAD TO HEAT INDICES IN THE 105-110 DEGREE RANGE,
POTENTIALLY AS HIGH AS 115 FOR SOME LOCATIONS, WITH WIDESPREAD
HEAT-RELATED WARNINGS/ADVISORIES IN PLACE. WARM MORNING LOWS ONLY
DROPPING INTO THE MID- TO UPPER 70S WILL PROVIDE LITTLE RELIEF
FROM THE HEAT OVERNIGHT. THIS COMBINATION OF HOTTER TEMPERATURES
TO THE WEST, HIGHER HEAT INDICES TO THE EAST, AND THE MULTI-DAY
DURATION OF THIS HEAT WAVE WILL INCREASE THE DANGER NOT ONLY TO
MORE SENSITIVE GROUPS, BUT ALSO THE GENERAL PUBLIC, PARTICULARLY
THOSE WITHOUT ADEQUATE AIR CONDITIONING.
A STAGNANT TROUGHING PATTERN OVER THE WEST WILL KEEP TEMPERATURES
MOSTLY BELOW AVERAGE ACROSS THE REGION, ESPECIALLY OVER PORTIONS
OF THE PACIFIC NORTHWEST AND NORTHERN GREAT BASIN/ROCKIES.
FORECAST HIGHS MONDAY-TUESDAY RANGE BETWEEN THE 60S AND 70S ALONG
THE PACIFIC COAST, THE 70S AND 80S IN THE PACIFIC NORTHWEST AND
NORTHERN GREAT BASIN/ROCKIES, THE 80S AND 90S FOR INTERIOR
CALIFORNIA AND THE CENTRAL GREAT BASIN/FOUR CORNERS REGION, AND
100S IN THE DESERT SOUTHWEST. A COLD FRONT PASSING THROUGH THE
PACIFIC NORTHWEST WILL BRING SOME RAIN CHANCES ON MONDAY,
SPREADING INTO THE NORTHERN ROCKIES TUESDAY. SMOKE FROM AREA
WILDFIRES WILL ALSO CONTINUE TO PLAGUE PARTS OF THE WEST,
PARTICULARLY OVER PORTIONS OF THE NORTHERN GREAT BASIN, RESULTING
IN POOR AIR QUALITY AND AREAS OF REDUCED VISIBILITY.
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