239
FXUS01 KWBC 160801
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 AM EDT WED AUG 16 2023
VALID 12Z WED AUG 16 2023 - 12Z FRI AUG 18 2023
...DANGEROUS HEAT WAVE CONTINUES OVER THE PACIFIC
NORTHWEST/NORTHERN ROCKIES AS HEAT BUILDS BACK IN OVER TEXAS
THURSDAY...
..SEVERE THUNDERSTORMS POSSIBLE FOR THE UPPER MIDWEST WEDNESDAY
...SHOWERS, THUNDERSTORMS, AND ISOLATED FLASH FLOODING WILL
CONTINUE ACROSS THE FOUR CORNERS REGION...
AN EXPANSIVE UPPER-LEVEL RIDGE WILL REMAIN IN PLACE OVER THE
PACIFIC NORTHWEST/NORTHERN ROCKIES THE NEXT COUPLE OF DAYS
ALLOWING FOR A DANGEROUS HEAT WAVE TO CONTINUE. FORECAST HIGH
TEMPERATURES WILL BE IN THE LOW TO MID-100S FOR INTERIOR LOCATIONS
WITH LOW 90S AROUND PUGET SOUND. THE HEAT WILL EXPAND FURTHER INTO
THE NORTHERN ROCKIES AND ADJACENT NORTHERN HIGH PLAINS ON
THURSDAY. NUMEROUS NEAR RECORD-TYING/BREAKING HIGHS ARE POSSIBLE,
WITH OVERNIGHT LOWS REMAINING WARM AND AT SIMILARLY HIGH
RECORD-TYING/BREAKING LEVELS. THE DURATION AND INTENSITY OF THE
HEAT IS LEADING TO A MORE SIGNIFICANT HEALTH RISK TO THE REGION
THAN TYPICAL SUMMER HEAT, PARTICULARLY FOR THOSE WITHOUT ADEQUATE
AIR CONDITIONING. A PACIFIC SYSTEM MOVING IN FROM THE NORTHWEST
MAY BEGIN TO PROVIDE SOME RELIEF FOR WESTERN PORTIONS OF
WASHINGTON AND OREGON ON THURSDAY, BEFORE A MORE EXPANSIVE COOL
DOWN IS EXPECTED FRIDAY JUST BEYOND THE CURRENT FORECAST PERIOD.
MEANWHILE, MUCH OF THE SOUTH WILL CONTINUE TO SEE A BRIEF REPRIEVE
FROM THE RECENT OPPRESSIVE HEAT THANKS TO A LINGERING FRONTAL
BOUNDARY STRETCHING FROM THE CAROLINAS SOUTHWEST ALONG THE GULF
COAST AND INTO TEXAS. HIGHS WILL BE NEAR OR EVEN A BIT BELOW MORE
REASONABLE SUMMER-TIME AVERAGES, WITH LOW TO MID 90S FOR FLORIDA
AND THE CENTRAL GULF COAST AND MID-80S FURTHER NORTH INTO THE
SOUTHEAST. AREAS SOUTH OF THE BOUNDARY ALONG THE WESTERN GULF
COAST AND SOUTH TEXAS WILL REMAIN VERY HOT, WITH LOW TO MID-100S
EXPECTED. PORTIONS OF WEST TEXAS WILL ALSO SEE TEMPERATURES RETURN
INTO THE LOW 100S AS AN UPPER-LEVEL RIDGE BEGINS TO EXPAND
EASTWARD. UNFORTUNATELY, WITH THIS EASTWARD RIDGE EXPANSION, MOST
OF TEXAS WILL SOAR BACK INTO THE MID- TO UPPER 100S ON THURSDAY,
WITH NUMEROUS RECORD-TYING/BREAKING HIGHS POSSIBLE. THIS HEAT WAVE
IS EXPECTED TO EXPAND ACROSS MUCH OF THE CENTRAL AND SOUTHERN U.S.
IN THE COMING DAYS. PLEASE SEE WPC'S HEAT KEY MESSAGES FOR MORE
INFORMATION ON THESE HEAT WAVES.
BEYOND THE HEAT HEADLINES, SCATTERED SHOWERS AND THUNDERSTORMS ARE
EXPECTED WEDNESDAY TO THE SOUTHEAST OF THE STATIONARY BOUNDARY
ALONG PORTIONS OF THE COASTAL CAROLINAS SOUTHWARD THROUGH FLORIDA.
DEEP MOISTURE RESIDING OVER THE REGION MAY CONTRIBUTE TO SOME
LOCALLY HEAVY DOWNPOURS AND AN ISOLATED INSTANCE OR TWO OF FLASH
FLOODING. STORM CHANCES SHOULD CONTINUE IN FLORIDA THROUGH
THURSDAY. TO THE NORTH, A STRENGTHENING LOW PRESSURE SYSTEM OVER
SOUTH-CENTRAL CANADA/THE NORTHERN PLAINS WILL SWEEP EASTWARD
ACROSS THE UPPER MIDWEST WEDNESDAY. MOIST RETURN FLOW AHEAD OF THE
SYSTEM AS WELL AS STRENGTHENING FLOW ALOFT AS AN UPPER-LEVEL
SHORTWAVE DROPS SOUTH OVER THE REGION WILL PROVIDE THE NECESSARY
INGREDIENTS FOR ROBUST, ORGANIZED STORM DEVELOPMENT ALONG THE COLD
FRONT. THE STORM PREDICTION CENTER HAS OUTLINED A SLIGHT RISK
(LEVEL 2/5) OF SEVERE WEATHER FOR THE THREAT OF SOME DAMAGING
WINDS AND LARGE HAIL. STORM CHANCES WILL CONTINUE THROUGH THE
OVERNIGHT HOURS LATE WEDNESDAY/EARLY THURSDAY OVER THE GREAT LAKES
AS THE SYSTEM MOVES EASTWARD AND THEN INTO THE NORTHEAST FOR
THURSDAY. AN ISOLATED CHANCE WILL REMAIN FOR A SEVERE THUNDERSTORM
AND/OR LOCALLY HEAVY RAINFALL. HIGH TEMPERATURES WILL BE NEAR
AVERAGE FOR MUCH OF THE NORTHEAST AND MID-ATLANTIC, WITH 80S AND
LOW 90S FORECAST. HIGHS WILL BE BELOW AVERAGE IN NEW ENGLAND (70S)
AND PORTIONS OF THE OHIO/MIDDLE MISSISSIPPI VALLEY (LOW TO
MID-80S). AHEAD OF THE STORM SYSTEM, HIGHS WILL RANGE FROM THE
MID-80S IN THE UPPER MIDWEST TO THE UPPER 90S FOR PORTIONS OF THE
CENTRAL PLAINS AND UPPER MISSOURI VALLEY. COOLER TEMPERATURES WILL
FOLLOW THE COLD FRONT PASSAGE FOR MUCH OF THIS REGION ON THURSDAY,
WITH HIGHS DROPPING INTO THE MID-70S TO LOW 80S.
ANOMALOUSLY HIGH MOISTURE IN PLACE OVER THE FOUR CORNERS REGION
AND GREAT BASIN WILL CONTINUE TO LEAD TO DAILY, SCATTERED
THUNDERSTORM CHANCES. SOME LOCALLY HEAVY DOWNPOURS ARE POSSIBLE
WITH AN ISOLATED RISK OF FLASH FLOODING, PARTICULARLY FOR MORE
SENSITIVE LOCATIONS SUCH AS URBAN AREAS, BURN SCARS, DRY WASHES,
AND SLOT CANYONS. HIGH TEMPERATURES BROADLY ACROSS THE SOUTHERN
TIER OF THE WEST WILL RANGE FROM THE 70S ALONG COASTAL CALIFORNIA,
THE MID-80S IN THE PRECIPITATION COOLED FOUR CORNERS REGION, AND
LOW TO MID-90S FOR THE CENTRAL/SOUTHERN ROCKIES AND GREAT BASIN.
MORE ANOMALOUS TEMPERATURES ARE EXPECTED FOR THE INTERIOR
CALIFORNIA VALLEYS, WITH HEAT ADVISORIES IN PLACE FOR HIGHS IN THE
MID-100S. HIGH TEMPERATURES WILL ALSO CLIMB BACK INTO THE 110S FOR
THE DESERT SOUTHWEST, WITH HEAT-RELATED ADVISORIES AND WARNINGS IN
PLACE AS RECORD-TYING/BREAKING LEVEL HEAT IS POSSIBLE BY THURSDAY.
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