565
FXUS02 KWBC 071949
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
349 PM EDT FRI AUG 7 2026
VALID 12Z MON AUG 10 2026 - 12Z FRI AUG 14 2026
...MULTI-DAY HEAVY RAINFALL POTENTIAL FOR OHIO VALLEY AND CENTRAL
APPALACHIANS MONDAY THROUGH WEDNESDAY...
..OVERVIEW
LOW PRESSURE OVER HUDSON BAY AND UPPER LEVEL HIGH PRESSURE OVER THE
FOUR CORNERS STATES LINGER TO MIDWEEK. THE RIDGE SLIDES TO THE
SOUTHEAST REST OF THE WEEK WHILE THE DOMINANT LOW OVER CANADA IS
FARTHER NORTH, SETTING UP MORE ZONAL FLOW OVER THE CENTRAL/NORTHERN
PORTIONS OF THE CONUS. A TROUGH LOOKS TO APPROACH CALIFORNIA LATE
IN THE WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
FINE AGREEMENT AMONG THE ECMWF/GFS WITH THE STRENGTH AND POSITION
OF THE SOUTHWEST RIDGE AND TROUGHING ACROSS CENTRAL CANADA THROUGH
MIDWEEK. THE CMC IS STRONGER WITH THE LOW LINGERING LONGER OVER
HUDSON BAY, SO IT HAD DIMINISHED INFLUENCE ON THE FORECAST. THE
06Z EC-AIFS WAS MORE PROGRESSIVE EAST WITH THE SOUTHWEST HIGH
AROUND MIDWEEK, BUT THE 12Z SLOWED THIS A BIT.
A GENERAL MODEL BLEND WEIGHTED TOWARD THE EC/GFS WAS USED DAYS 3-5
WITH SOME GEFS/ECENS FOR DAYS 6/7. NBM QPF WAS AMENDED WITH THE
GFS/ECMWF AND THEN THAT FOOTPRINT WAS ENHANCED WITH THE EC-AIFS.
..WEATHER/HAZARDS HIGHLIGHTS
A LONG FRONTAL ZONE EXTENDS EAST FROM THE CENTRAL PLAINS NEXT WEEK.
THE EASTERN END GENERALLY WORKS SOUTH THROUGH THE WEEK.
THUNDERSTORMS AND HEAVY RAINFALL WILL FOCUS AROUND THIS BOUNDARY,
WITH A LIKELIHOOD FOR A MULTI- DAY HEAVY RAINFALL EVENT FOR PARTS
OF THE OHIO VALLEY AND CENTRAL APPALACHIANS MONDAY THROUGH
WEDNESDAY.
THE UPPER RIDGE OVER THE SOUTHWEST SHIFTS EASTWARD THROUGH
MIDWEEK. THE SURFACE RIDGE AHEAD OVER THE GULF COAST WILL MAINTAIN
MOIST, SOUTHERLY FLOW OVER THE SOUTHERN PLAINS, GULF COAST AND
SOUTHEAST, WHERE HEAT INDICES COULD REACH 105 TO 115 DEGREES IN
SOME PLACES FOR MULTIPLE DAYS. OVERNIGHT TEMPERATURES IN THE MID TO
UPPER 70S WILL OFFER LITTLE TO NO RELIEF FOR THOSE WITHOUT
ADEQUATE COOLING AND/OR HYDRATION. TEMPERATURES COOL ACROSS THE
NORTHERN PLAINS/UPPER MIDWEST AND GREAT LAKES BY MONDAY WITH BELOW
NORMAL TEMPERATURES INCHING SOUTH TO CENTRAL SECTIONS OF THE
COUNTRY THROUGH THE WEEK BEHIND THE COLD FRONT.
THE SHIFTING RIDGE AND AN APPROACHING TROUGH TO CALIFORNIA LATE IN
THE WEEK WILL REINVIGORATE MOIST SOUTHERLY FLOW INTO THE
SOUTHWEST AND PROMOTE INCREASED MONSOONAL ACTIVITY. EXPECT
INSTANCES OF FLASH FLOODING, ESPECIALLY OVER VULNERABLE SURFACES
SUCH AS SLOT CANYONS AND DRY WASHES.
JACKSON
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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