512
FXUS02 KWBC 011938
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
338 PM EDT TUE SEP 1 2026
VALID 12Z FRI SEP 04 2026 - 12Z TUE SEP 08 2026
...DANGEROUS LATE-SUMMER HEAT WAVE WILL CONTINUE ACROSS PARTS OF
THE CENTRAL U.S. INTO EARLY NEXT WEEK, BUT EASE IN THE SOUTHEAST
LATE THIS WEEK...
..OVERVIEW
DANGEROUSLY HOT WEATHER WILL CONTINUE ACROSS MUCH OF THE CENTRAL
U.S. THROUGH THE WEEKEND INTO EARLY NEXT WEEK, WHILE A COLD FRONT
WILL BRING RELIEF TO PARTS OF THE SOUTHERN MID-ATLANTIC/SOUTHEAST
AFTER A COUPLE MORE VERY HOT DAYS ON FRIDAY AND SATURDAY. IN
CONTRAST, PERSISTENT TROUGHING SHOULD KEEP MUCH OF THE PACIFIC
NORTHWEST COOL, SHOWERY, AND UNSETTLED INTO EARLY NEXT WEEK.
LOCALLY HEAVY RAINFALL AND SEVERE WEATHER ARE POSSIBLE ALONG A
FRONTAL ZONE FROM THE MIDWEST TO THE OHIO VALLEY, CENTRAL
APPALACHIANS, AND MID-ATLANTIC ON FRIDAY, WITH POSSIBLE CHANCES
FARTHER SOUTH INTO THE CAROLINAS ON SATURDAY. MONSOONAL MOISTURE
RETURNS LATE WEEK INTO THE WEEKEND WITH A TROPICAL CONNECTION
POTENTIALLY LEADING TO ENHANCED RAINFALL FOR PARTS OF THE SOUTHWEST
INTO NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
DEEP TROUGHING ALONG THE WEST COAST, HIGHLY AMPLIFIED RIDGING OVER
THE CENTRAL U.S., AND MORE TROUGHING ALONG THE EAST COAST WILL
CONTINUE TO BE THE DOMINANT FEATURES OF THE LARGE SCALE PATTERN
INTO EARLY NEXT WEEK. MODELS ARE GENERALLY IN GOOD AGREEMENT WITH
THE PATTERN THROUGH MOST OF THE WEEKEND, BUT UNCERTAINTY INCREASES
LEADING INTO NEXT WEEK. THE FIRST NOTABLE MODEL DIFFERENCE IN THE
12Z MODEL CYCLE PRIMARILY STEMS FROM TIMING/PLACEMENT OF ONE
SHORTWAVE EJECTING EASTWARD FROM THE NORTHWEST LOW ATOP THE RIDGE
SUNDAY-MONDAY. THE GFS KEEPS THIS STRONG ENOUGH (POTENTIALLY
COMBINING WITH CANADIAN ENERGY DIGGING) TO SUPPRESS THE RIDGE IN
THE NORTHERN TIER EARLY NEXT WEEK, UNLIKE CONSENSUS. THEN THE TRACK
OF THE NORTHWEST TROUGH SLOWLY EASTWARD AS IT OPENS UP IS ALSO
SOMEWHAT QUESTIONABLE, BUT DID SEE THAT THE 12Z AIFS NOW JUMPED
WEST AND MATCHES BETTER WITH CONSENSUS, AFTER EARLIER AIFS RUNS
WERE EAST.
ADDITIONALLY, THE EVOLUTION OF THE WESTERN U.S. TROUGHING WILL
HAVE IMPLICATIONS ON THE FUTURE TRACK OF EASTERN PACIFIC TROPICAL
SYSTEM MARIE. OLDER GFS RUNS IN PARTICULAR HAVE BEEN OUTLIERS IN
SHOWING MARIE'S TRACK MOVING NEAR/INTO SOUTHERN CALIFORNIA AND THE
SOUTHWEST. NEWER RUNS HAVE TRENDED AWAY FROM THIS SOLUTION MORE
TOWARD THE NON-NCEP AND AI CONSENSUS. THOUGH A HANDFUL OF ENSEMBLE
MEMBERS (GEFS AND EC BOTH) STILL ALLOW FOR THIS TYPE OF TRACK, SO
NHC AND WPC WILL CONTINUE TO MONITOR.
MODEL PREFERENCE CONTINUES TO LEAN AWAY FROM THE GFS SOLUTIONS
(NOW FOR THE NORTHERN TIER, PREVIOUSLY FOR THE MARIE TRACK), AND
TOWARD THE EC/CMC, AI MODELS, AND INCREASING PROPORTIONS OF THE
ENSEMBLE MEANS AS THE PERIOD PROGRESSED.
..WEATHER/HAZARDS HIGHLIGHTS
INTENSE LATE-SUMMER HEAT WILL CONTINUE ACROSS THE CENTRAL U.S.
THROUGH THE WEEKEND INTO NEXT WEEK AS A LARGE MID/UPPER RIDGE
DOMINATES THE REGION. THE WELL ABOVE NORMAL TEMPERATURES 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 OHIO VALLEY, MID-ATLANTIC, AND SOUTHEAST LATE
THIS WEEK, BUT SHOULD GRADUALLY LESSEN IN MAGNITUDE/COVERAGE OVER
THE WEEKEND AS A COLD FRONT DROPS IN FROM THE NORTH. PLEASE
CONTINUE TO SEE WPC'S KEY MESSAGES FOR MORE DETAILS ON THIS LONG
LASTING HEAT WAVE.
IN STARK CONTRAST FROM THE HEAT ACROSS THE CENTRAL AND EASTERN
U.S., COOLER THAN NORMAL TEMPERATURES WILL REMAIN IN PLACE ACROSS
THE NORTHWEST THROUGH EARLY NEXT WEEK AS PERSISTENT CLOUDS AND
SHOWERS ASSOCIATED WITH DEEP TROUGHING OVER THE WEST COAST LINGER
OVER 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 SEVERE WEATHER FROM THE MIDWEST TO THE OHIO VALLEY,
CENTRAL APPALACHIANS, AND MID-ATLANTIC ON FRIDAY. SOME, THOUGH
PERHAPS LESSER, CHANCES FOR SEVERE WEATHER AND FLOODING CONCERNS
ARE POSSIBLE FARTHER SOUTH INTO THE CAROLINAS ON SATURDAY. THE
STRONGEST STORMS WILL BE CAPABLE OF PRODUCING DAMAGING WINDS, AND
PERHAPS SOME HAIL AND A FEW ISOLATED TORNADOES. STORMS COULD ALSO
CONTAIN HEAVY RAIN RATES THAT COULD LEAD TO SCATTERED INSTANCES OF
FLASH FLOODING.
SURGING MONSOONAL MOISTURE WILL FOSTER MORE NUMEROUS SHOWERS AND
THUNDERSTORMS ACROSS PARTS OF THE SOUTHWEST/FOUR CORNERS STATES ON
FRIDAY, WITH POTENTIAL FOR ISOLATED TO SCATTERED FLASH FLOODING.
FARTHER NORTH, RAIN IS FORECAST FOR THE PACIFIC NORTHWEST TO
NORTHERN ROCKIES UNDERNEATH THE UPPER LOW, WITH A NONZERO FLOODING
CHANCE AS WELL. RAIN CHANCES SHOULD PERSIST IN THESE AREAS INTO
SATURDAY. MORE SURGES OF MOISTURE ARE LIKELY SUNDAY AND MONDAY,
WITH COVERAGE LIKELY COMBINING ACROSS THE INTERMOUNTAIN WEST, WITH
SOME POSSIBLE TROPICAL CONNECTION TO MARIE. WHILE THE CURRENT
THINKING 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. STAY TUNED TO NHC AND WPC FOR UPDATES.
TATE/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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