889
FXUS02 KWBC 020816
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
416 AM EDT WED SEP 2 2026
VALID 12Z SAT SEP 05 2026 - 12Z WED SEP 09 2026
...DANGEROUS LATE-SUMMER HEAT WAVE WILL SHIFT INTO THE SOUTH-
CENTRAL U.S. THIS WEEKEND INTO EARLY NEXT WEEK...
..OVERVIEW
THE FOCUS FOR INTENSE LATE-SUMMER HEAT WILL SHIFT INTO THE SOUTH-
CENTRAL U.S. THIS WEEKEND INTO NEXT WEEK WHILE A COLD FRONT BRINGS
RELIEF TO THE SOUTHERN MID-ATLANTIC AND SOUTHEAST AFTER ONE MORE
HOT DAY AND POTENTIAL SEVERE WEATHER ON SATURDAY. IN CONTRAST, A
SLOW-MOVING UPPER LOW SPINNING OVER THE PACIFIC NORTHWEST SHOULD
KEEP MUCH OF THE REGION COOLER THEN NORMAL AND UNSETTLED THROUGH
EARLY NEXT WEEK. MEANWHILE, SURGING MONSOONAL MOISTURE AND A
POSSIBLE TROPICAL CONNECTION MAY LEAD TO HEAVIER RAINFALL AND
LOCALIZED FLASH FLOODING THIS WEEKEND ACROSS PARTS OF THE
SOUTHWEST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS ARE GENERALLY IN GOOD AGREEMENT WITH THE LARGE SCALE
PATTERN THROUGH MOST OF THE WEEKEND, FEATURING PERSISTENT TROUGHING
AND A SLOW-MOVING UPPER LOW OVER THE WEST COAST/PACIFIC NORTHWEST,
STOUT RIDGING ACROSS THE CENTRAL U.S., AND LINGERING TROUGHING
ACROSS THE NORTHEAST AND ALONG THE EAST COAST. THIS GENERAL PATTERN
MOSTLY PERSISTS INTO NEXT WEEK, THOUGH GUIDANCE BEGINS TO DIFFER
ON THE EVOLUTION OF THE TROUGHING/UPPER LOW IN THE NORTHWEST AND
WHETHER OR NOT IT REINFORCES ITSELF OR ADVANCES EASTWARD AND HELPS
SUPPRESS THE CENTRAL U.S. RIDGE.
THE WPC FORECAST CONTINUES TO FAVOR A NON-NCEP BLEND GIVEN SOME
LINGERING INFLUENCES OF TROPICAL STORM MARIE TRACKING A LITTLE TOO
FAR NORTH COMPARED TO CONSENSUS, AS WELL AS BEING TOO STRONG WITH A
DIGGING SHORTWAVE OVER SOUTH-CENTRAL CANADA WHICH SUPPRESSES THE
CENTRAL U.S. RIDGE TOO QUICKLY. THE INITIAL PREFERRED BLEND WAS A
MIX OF NON-NECP DETERMINISTIC GUIDANCE AND AI GUIDANCE LED BY THE
EC-AIFS AND THE AI-GFS. LATER ON THE PERIOD, MORE WEIGHTING WAS
PLACED ON THE EC AND GEFS ENSEMBLE MEANS WHICH PRESERVED LARGE
SCALE FEATURES WHILE SMOOTHING SMALLER SCALE DIFFERENCES.
..WEATHER/HAZARDS HIGHLIGHTS
A DANGEROUS LATE-SUMMER HEAT WAVE WILL CONTINUE TO BRING EXTREMELY
HOT TEMPERATURES TO THE CENTRAL U.S. THROUGH THE WEEKEND INTO NEXT
WEEK AS A LARGE MID/UPPER RIDGE REMAINS CENTERED OVER THE REGION.
HIGH TEMPERATURES WELL INTO THE 90S AND LOW 100S COMBINED WITH HIGH
HUMIDITY AND VERY WARM OVERNIGHT LOWS IN THE MID 70S WILL RESULT
IN WIDESPREAD AREAS OF MAJOR TO EXTREME HEATRISK AND A CONCERN FOR
HEAT-RELATED ILLNESSES. HOT CONDITIONS ARE ALSO FORECAST ACROSS THE
SOUTHERN MID-ATLANTIC AND SOUTHEAST FOR ONE MORE DAY ON SATURDAY,
BUT A COLD FRONT WILL BRING SOME RELIEF BEHIND A PASSING COLD FRONT
SUNDAY INTO NEXT WEEK. PLEASE CONTINUE TO SEE WPC'S KEY MESSAGES
FOR MORE DETAILS ON THIS LONG LASTING HEAT WAVE.
MEANWHILE, COOLER THAN NORMAL TEMPERATURES WILL REMAIN IN PLACE
ACROSS THE NORTHWEST THROUGH EARLY NEXT WEEK AS PERSISTENT CLOUDS
AND SHOWERS ASSOCIATED WITH DEEP TROUGHING AND A SLOW-MOVING UPPER
LOW REMAIN ENTRENCHED ACROSS THE REGION. HIGH TEMPERATURES WILL
MOSTLY TOP OUT IN THE 50S, 60S, AND 70S, WHICH IS ROUGHLY 10-15
DEGREES BELOW SEASONAL NORMS.
THE FRONTAL SYSTEM THAT WILL BRING RELIEF FROM THE HEAT ACROSS
PARTS OF THE EASTERN U.S. THIS WEEKEND WILL FIRST INTERACT WITH
SUFFICIENT MOISTURE AND INSTABILITY TO PRODUCE LOCALLY HEAVY
RAINFALL AND POSSIBLE SEVERE WEATHER ACROSS THE SOUTHERN MID-
ATLANTIC INTO THE CAROLINA PIEDMONT ON SATURDAY. THE STRONGEST
STORMS WILL BE CAPABLE OF PRODUCING DAMAGING WINDS, WITH HAIL AND
PERHAPS AN ISOLATED TORNADO NOT RULED OUT. STORMS COULD ALSO
CONTAIN HEAVY RAIN RATES THAT COULD LEAD TO LOCALIZED FLASH
FLOODING, MAINLY IN URBAN AREAS.
IN BETWEEN THE UPPER LOW ACROSS THE PACIFIC NORTHWEST AND RIDGE
OVER THE CENTRAL U.S., SOUTHWESTERLY FLOW WILL USHER IN SURGES OF
MONSOONAL MOISTURE ACROSS PARTS OF THE SOUTHWEST AND INTERMOUNTAIN
WEST THIS WEEKEND INTO EARLY NEXT WEEK. THIS HIGHLY ANOMALOUS
MOISTURE WILL SUPPORT THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS,
WITH SOME POSSIBLE TROPICAL CONNECTION TO TROPICAL STORM MARIE
LEADING TO A LOW BUT NON-ZERO FLASH FLOODING THREAT. WHILE THE
CURRENT THINKING STILL FAVORS A TRACK FOR MARIE THAT STAYS FAR AWAY
FROM SOUTHERN CALIFORNIA, THERE IS STILL A THREAT OF TROPICAL
MOISTURE ENHANCING MONSOONAL RAINFALL AND THUS LEADING TO
ADDITIONAL CONCERNS FOR FLASH FLOODING. SEE THE LATEST DAY 4 AND 5
EROS FOR MORE DETAILS AND STAY TUNED TO NHC AND WPC FOR FUTURE
UPDATES.
MILLER
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC
MEDIUM RANGE HAZARDS OUTLOOK CHART AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,
QUANTITATIVE PRECIPITATION FORECAST, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY MESSAGES
ARE AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=ERO
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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