603
FXUS02 KWBC 110813
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
413 AM EDT FRI SEP 11 2026
VALID 12Z MON SEP 14 2026 - 12Z FRI SEP 18 2026
...HAZARDOUS HEAT OVER THE SOUTHERN PLAINS AS HEAVY RAIN AND SEVERE
WEATHER THREATS EMERGE ACROSS THE UPPER MIDWEST/GREAT LAKES EARLY
NEXT WEEK...
..OVERVIEW
AN UPPER-LEVEL RIDGE CENTERED OVER THE SOUTHEAST WILL RETROGRADE
INTO THE SOUTHERN PLAINS AND EVENTUALLY THE WEST NEXT WEEK. THIS
RIDGE WILL BE RESPONSIBLE FOR HAZARDOUS HEAT FOR THE SOUTH-CENTRAL
U.S.. ROUNDS OF SHORTWAVE ENERGY PROPAGATING THROUGH THE
NORTH-CENTRAL U.S. WILL FUEL SEVERE WEATHER AND EXCESSIVE RAINFALL
CONCERNS ACROSS PORTIONS OF THE UPPER MIDWEST/GREAT LAKES EARLY
NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS ARE IN GOOD AGREEMENT ON THE EVOLUTION OF THE SOUTHERN
RIDGE, WHILE MORE UNCERTAINTY EXISTS REGARDING THE EVOLUTION OF A
NORTHWESTERN TROUGH. AI MODELS DIVERGE FROM CONSENSUS WITH RESPECT
TO THE TROUGHS PROPAGATING THROUGH THE NORTHWEST AS THE AI MODELS
ATTEMPT TO SPLIT FLOW, WHILE THE REST OF THE MODELS KEEP A MORE PHASED
SOLUTION.
A GENERAL MODEL BLEND CONSISTING OF THE AVAILABLE DETERMINISTIC
AND AI GUIDANCE IS USED ON DAYS 3-5. THE AI MODELS ARE REMOVED FROM
THE BLEND ON DAYS 6 AND 7 AND REPLACED WITH A MORE ENSEMBLE MEAN
FAVORED BLEND DUE TO UNCERTAINTIES ON THE TIMING AND AMPLITUDE OF
THE WEST COAST TROUGH.
..WEATHER/HAZARDS HIGHLIGHTS
A SYSTEM MOVING THROUGH THE CENTRAL U.S. WILL STALL ONE OF ITS
ATTENDANT FRONTS OVER THE GREAT PLAINS, UPPER MIDWEST AND GREAT
LAKES NEXT WEEK. THIS WILL LEAD TO A MULTI-DAY HEAVY RAIN THREAT
WITH THE POTENTIAL FOR EXCESSIVE RAINFALL LEADING TO FLASH FLOODING
TO DEVELOP. THIS THREAT IS EXPECTED TO BEGIN OVER THE UPPER
MIDWEST/GREAT LAKES ON MONDAY ALONG WITH SOME SEVERE WEATHER
POTENTIAL EXTENDING FROM THE CENTRAL PLAINS TO THE MIDDLE
MISSISSIPPI VALLEY. THE EXCESSIVE RAINFALL THREAT REDEVELOPS OVER
THE CENTRAL PLAINS INTO THE MIDDLE/UPPER MISSISSIPPI VALLEY ON
TUESDAY AND CONTINUES THROUGH WEDNESDAY.
A RIDGE OVER THE SOUTH WILL GENERATE ABOVE AVERAGE TEMPERATURES
ACROSS THE CENTRAL/SOUTHERN PLAINS AND INTO THE LOWER MISSISSIPPI
VALLEY NEXT WEEK. HEAT INDICES BETWEEN 100-110 DEGREES MAY SUPPORT
EXCESSIVE HEAT RISK OVER PORTIONS OF THE AFOREMENTIONED AREAS
BETWEEN MONDAY AND WEDNESDAY.
THE RETURN OF THE CENTRAL U.S. RIDGE SHOULD REINVIGORATE MONSOONAL
STORMS ACROSS THE SOUTHWEST BEGINNING EARLY NEXT WEEK. MOIST
SOUTHERLY FLOW INTO THE SOUTHWEST COULD PRODUCE ISOLATED INSTANCES
OF FLASH FLOODING ACROSS PORTIONS OF EASTERN ARIZONA THROUGH MUCH
OF NEW MEXICO. BURN SCARS, DRY WASHES AND SLOT CANYONS ARE
ESPECIALLY SENSITIVE TO ANY HEAVY RAINFALL THAT OCCURS.
KEBEDE
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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