234
FXUS02 KWBC 060700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT SUN SEP 6 2026
VALID 12Z WED SEP 09 2026 - 12Z SUN SEP 13 2026
...PROLONGED LATE-SUMMER HEAT WAVE LINGERS FOR THE CENTRAL/
SOUTHERN PLAINS TO THE MID/LOWER MISSISSIPPI VALLEY THROUGH MUCH OF
NEXT WEEK...
..OVERVIEW
AN UPPER LOW IN SOUTH-CENTRAL CANADA ON TUESDAY WILL ROUND THE TOP
OF A PERSISTENT SOUTHERN TIER RIDGE, TRACKING OVER THE CANADIAN
PRAIRIES TO JAMES BAY BY WEDNESDAY. THIS SYSTEM AND ITS ATTENDANT
COLD FRONT BRINGS SHOWERS FROM PARTS OF THE GREAT LAKES TO
NORTHEAST AND MIDWEST WEDNESDAY AND THURSDAY. MARIE AND A CLOSED
LOW OFF THE PACIFIC NORTHWEST COAST WILL INTERACT FARTHER OFFSHORE,
MEANING LESS DIRECT MOISTURE INFLUX FROM HURRICANE MARIE. A
STRONGER NORTHERN STREAM DISTURBANCE OVER THE PACIFIC NORTHWEST
WILL WORK WITH ANOTHER TROUGH OVER SOUTHERN CANADA TO GENERATE A
FASTER FLOW PATTERN OVER THE NORTHERN TIER LATE WEEK. THIS SHOULD
HELP TO SUPPRESS A PERSISTENT SOUTHERN TIER RIDGE A BIT, WITH SOME
HEAT RELIEF ESPECIALLY INTO NEXT WEEKEND ACROSS THE SOUTH.
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE SHOWS REASONABLE AND INCREASING AGREEMENT ON THE OVERALL
UPPER LEVEL PATTERN AND EVOLUTION THROUGH AT LEAST THE FIRST HALF
OF THE PERIOD. AN UPPER LOW WELL OFF THE WEST COAST LOOKS TO REMAIN
THERE FOR MOST OF THE PERIOD, WHICH SHOULD ABSORB REMNANTS OF
MARIE. THERE IS MUCH LESS OF A TREND FOR INCREASING MOISTURE ACROSS
THE WEST ASSOCIATED WITH MARIE NOW THAN THERE WAS A FEW DAYS AGO.
MEANWHILE, MANY MODELS, INCLUDING THE GFS AND ECMWF) SHOW ANOTHER
TROUGH INTO THE NORTHWEST AROUND THURSDAY, COMBINING WITH CANADIAN
ENERGY TO CREATE A FASTER FLOW AND DEEPER TROUGH INTO THE CENTRAL
U.S. BY NEXT WEEKEND. THE EXCEPTION TO THIS IS THE CMC WHICH
COMBINES THIS NORTHWEST ENERGY WITH THE UPPER LOW OFFSHORE,
ALLOWING FOR THE CANADIAN TROUGH TO RACE FORWARD REACHING THE
NORTHEAST BY DAY 7. ENSEMBLES SHOW MORE SUPPORT FOR THE GFS/ECMWF
SOLUTION RATHER THAN THE CMC AND THAT IS WHERE THE WPC FORECAST
LEANED AS WELL. THE WPC FORECAST WAS BASED HEAVIER ON THE AGREEABLE
DETERMINISTIC MODELS EARLY IN THE PERIOD, AND INCORPORATED MORE
ENSEMBLE MEAN GUIDANCE BY LATE PERIOD. ALSO MAINTAINED GOOD
AGREEMENT WITH WPC CONTINUITY AS WELL.
..WEATHER/HAZARDS HIGHLIGHTS
THE LONG DURATION HEAT WAVE IS EXPECTED TO LINGER OVER THE
MID/LOWER MISSISSIPPI VALLEY TO SOUTHERN TEXAS THROUGH MUCH OF NEXT
WEEK WITH WIDESPREAD MAJOR TO EXTREME HEATRISK. KEY MESSAGES
REMAIN IN EFFECT WITH SEVERAL FORECAST RECORD HIGHS FORECAST. AS
THE TROUGH FROM THE NORTHWEST MOVES EASTWARD NEXT WEEKEND, THE HEAT
LOOKS TO WANE SOMEWHAT FOR THE SOUTH AS THE RIDGE GETS SUPPRESSED
AND BUILDS MORE INTO THE SOUTHEAST.
THE UPPER LOW THROUGH SOUTHERN CANADA WILL BRING WEDNESDAY-
THURSDAY LIGHT TO LOCALLY MODERATE RAINFALL ALONG THE MAIN COLD
FRONT AS IT SINKS THROUGH THE MIDWEST AND NORTHEAST. THIS TROUGH
MAY ALSO BRING HIGH WINDS IN PARTS OF THE NORTHERN PLAINS/UPPER
GREAT LAKES INTO WEDNESDAY. MONSOONAL MOISTURE WILL CONTINUE FOR
THE SOUTHWEST AND SOUTHERN ROCKIES THROUGH THE WEEK. THERE HAS BEEN
A CLEAR TREND FOR A DRIER WEST AS MOISTURE FROM MARIE REMAINS
OFFSHORE. SOME INCREASE IN PRECIPITATION CHANCES EXIST LATE WEEK
INTO THE WEEKEND, ESPECIALLY ACROSS THE NORTHERN AND CENTRAL
ROCKIES, WITH INCREASING TROUGHING OVER THE REGION. WIDESPREAD
RAINFALL SHOULD ALSO EXPAND ACROSS THE NORTH-CENTRAL U.S. AS WELL
AHEAD OF THIS TROUGH.
SANTORELLI
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page