954
FXUS02 KWBC 021856
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
256 PM 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 THAN NORMAL AND UNSETTLED THROUGH
EARLY NEXT WEEK. MEANWHILE, SURGING MONSOONAL MOISTURE WITH A
POSSIBLE TROPICAL CONNECTION MAY LEAD TO INCREASING RAINFALL
POTENTIAL AND LOCALIZED FLASH FLOODING THIS WEEKEND ACROSS PARTS OF
THE SOUTHWEST. HEAVY RAINFALL POTENTIAL MAY ALSO INCREASE ACROSS
THE NORTH-CENTRAL U.S. EARLY NEXT WEEK AS A STRENGTHENING LOW
PRESSURE SYSTEM MOVES ACROSS THE REGION.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE IS IN GOOD AGREEMENT ON THE SYNOPTIC SCALE PATTERN
THROUGH THE PERIOD, WITH TROUGHING OVER THE WEST AND EAST COASTS
AND RIDGING IN BETWEEN. THE NORTHERN SIDE OF THE RIDGE WILL BE
ERODED AS AN UPPER LEVEL LOW/TROUGH MOVES ACROSS THE NORTHWEST AND
NORTH-CENTRAL U.S. NEXT WEEK, AND THE UPPER LEVEL PATTERN WILL
BECOME MORE ZONAL ACROSS THE EAST. MEANWHILE, THE WEST COAST TROUGH
WILL LIKELY BE REINFORCED AS ADDITIONAL ENERGY DIGS SOUTH ALONG
THE COAST MID-NEXT WEEK.
SOME UNCERTAINTY REMAINS WITH DETAILS OF INDIVIDUAL SYSTEMS
THROUGH THE PERIOD, AND THERE IS A SIGNIFICANT SPREAD IN THE
PRECIPITATION FORECAST ACROSS THE SOUTHWEST. SOME MODELS SHOW
MOISTURE ASSOCIATED WITH TROPICAL CYCLONE MARIE PUSHING UP INTO THE
SOUTHWEST, BUT OTHER MODELS SHOW LITTLE ADDITIONAL MOISTURE. THE
UKMET IS THE ONLY DETERMINISTIC MODEL STILL HANGING ON TO A TRACK
BRINGING MARIE NORTH TOWARDS SOUTHERN CALIFORNIA. THE CURRENT
FORECAST THINKING IS TO FAVOR A DRIER SOLUTION WITH MOST MODEL
GUIDANCE NOW PUSHING MARIE WEST INTO THE PACIFIC AND SHOWING WEAK
RIDGING EXTENDING ACROSS THE SOUTHERN U.S. AND INTO THE SOUTHWEST.
THE WPC FORECAST WAS INITIATED WITH A NEAR EVEN BLEND OF THE
AVAILABLE DETERMINISTIC AND AI GUIDANCE (EXCLUDING THE UKMET), AND
ENSEMBLE MEANS WERE ADDED IN INCREASING AMOUNTS THROUGH EARLY NEXT
WEEK TO HELP SMOOTH OUT MODEL 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 SUNDAY INTO NEXT WEEK.
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 TO PARTS
OF THE EASTERN U.S. THIS WEEKEND WILL ALSO CREATE A CHANCE FOR
SEVERE WEATHER AS A FRONTAL WAVE INTERACTS WITH MOISTURE AND
INSTABILITY OVER THE CAROLINAS ON SATURDAY. THE PRIMARY SEVERE
THUNDERSTORM HAZARD WILL BE DAMAGING WINDS, BUT LOCALLY HEAVY
RAINFALL WILL BE POSSIBLE AS WELL. THUNDERSTORMS AND HEAVY RAINFALL
MAY ALSO BE POSSIBLE ACROSS THE NORTH-CENTRAL U.S. EARLY NEXT WEEK
AS A STRENGTHENING LOW PRESSURE SYSTEM MOVES NORTHEAST ACROSS THE
REGION. THIS LOW WILL LIKELY TRIGGER WIDESPREAD SHOWERS AND STORMS,
AND PRECIPITATION TOTALS IN THIS REGION HAVE BEEN TRENDING UPWARDS
OVER THE PAST 24 HOURS.
IN BETWEEN THE UPPER LOW ACROSS THE PACIFIC NORTHWEST AND RIDGE
OVER THE CENTRAL U.S., SOUTHWESTERLY FLOW WILL USHER SURGES OF
MONSOONAL MOISTURE INTO PARTS OF THE SOUTHWEST AND INTERMOUNTAIN
WEST THIS WEEKEND INTO EARLY NEXT WEEK. THERE MAY BE SOME POSSIBLE
TROPICAL CONNECTION TO TROPICAL CYCLONE MARIE LEADING TO A LOW BUT
NON-ZERO FLASH FLOODING THREAT WITH SHOWERS AND THUNDERSTORMS.
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.
DOLAN/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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