784
FXUS02 KWBC 041833
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
233 PM EDT TUE AUG 4 2026
VALID 12Z FRI AUG 07 2026 - 12Z TUE AUG 11 2026
...HEAT WAVE CONTINUES THROUGH THE WEEKEND FOR THE SOUTHWEST, WITH
SOME EXPANSION INTO THE INTERMOUNTAIN WEST...
..OVERVIEW
A STRONG UPPER-LEVEL RIDGE WILL PERSIST OVER THE SOUTHWESTERN U.S.
AND EXPAND NORTH AND EAST OVER THE WEEKEND TO ALLOW EXCESSIVE HEAT
TO EXPAND ACROSS THE INTERMOUNTAIN WEST INTO THE HIGH PLAINS.
MEANWHILE, EXPECT A PROGRESSIVE NORTHERN STREAM WITH A TROUGH AND
SURFACE FRONT MOVING ACROSS THE NORTHERN U.S. INTO THE EAST WITH A
CONTINUED WET PATTERN. A TREND FOR HEAVIER RAINFALL IS LOOKING MORE
LIKELY ACROSS PORTIONS OF THE GREAT LAKES AND VICINITY NEXT WEEK.
TROUGHING WILL ALSO MOVE INTO THE NORTHWEST, AND SHOULD FINALLY
WEAKEN THE SOUTHWEST RIDGE, ENDING THE OPPRESSIVE HEAT WAVE.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST DETERMINISTIC AND MEAN GUIDANCE REMAINS WELL CLUSTERED
ON AN OVERALL FAIRLY PREDICTABLE SYNOPTIC PATTERN THIS WEEKEND AND
INTO EARLY NEXT WEEK. A PAIR OF UPPER-HIGHS WILL BE IN PLACE OVER
THE SUBTROPICAL ATLANTIC AND SOUTHWEST WITH A NORTHERN STREAM
SITUATED ALONG THE NORTHER TIER/CANADIAN BORDER BENEATH AND UPPER-
LOW HOVERING AROUND HUDSON BAY. MOST OF THE FORECAST UNCERTAINTY IS
TIED TO PRECIPITATION COVERAGE/AMOUNTS BOTH ON THE WESTERN SIDE OF
THE UPPER-HIGH THROUGH THE SOUTHEAST/OHIO VALLEY AND ALONG THE
EAST COAST AS WELL AS THROUGH THE MIDWEST AS EMBEDDED ENERGIES
ROUND THE UPPER-LOW IN THE NORTHERN STREAM. THE LATEST NBM QPF
LOOKED TO BE ON THE LIGHTER SIDE OVERALL FOR THE SOUTHEAST/OHIO
VALLEY AND ALONG THE EAST COAST, THOUGH WITH SPORADIC/UNCERTAIN
PERIODS OF CONVECTION SAW LITTLE REASON TO DEVIATE FROM THE 13Z NBM
FOR NOW. MUCH OF THE DETERMINISTIC GUIDANCE ALSO SHOWS THE
POTENTIAL FOR AN AXIS OF HEAVIER PRECIPITATION ALONG A COLD FRONT
PUSHING INTO THE INTERIOR NORTHEAST/OHIO VALLEY WEST THROUGH THE
GREAT LAKES/MIDWEST EARLY NEXT WEEK. THE LATEST NBM SHOWED SIMILAR
POTENTIAL AND APPEARED TO BE A GOOD COMPROMISE POSITION WISE FOR
NOW WITH THE HEAVIEST RAINFALL FOCUSED ON THE UPPER MIDWEST/GREAT
LAKES MONDAY AND THEN THE LOWER GREAT LAKES/UPPER OHIO VALLEY INTO
TUESDAY. THE UPDATED WPC FORECAST PACKAGE USED A COMPOSITE BLEND OF
THE ECMWF/ECMWF AIFS/GFS/CMC/UKMET GIVEN THE GOOD OVERALL
AGREEMENT. A CONTRIBUTION FROM THE ECENS MEAN WAS INCLUDED FOR THE
LATTER PART OF THE PERIOD GIVEN THE TIME-LIMITED UKMET AND ALSO AS
THE GFS CONTRIBUTION WAS BROUGHT DOWN DUE TO A BIT MORE INTENSE
CYCLOGENESIS IN THE LEE OF THE ROCKIES EARLY NEXT WEEK COMPARED TO
THE OTHER GUIDANCE. THE 13Z NBM WAS SUFFICIENT FOR MOST REGIONS
QPF-WISE AS NOTED WITH JUST A MODEST INCREASE OF QPF THROUGHOUT THE
SOUTHWEST GIVEN ACTIVE MONSOON ACTIVITY.
..WEATHER/HAZARDS HIGHLIGHTS
FOR MIDWEEK, A SLIGHTLY WEAKER UPPER RIDGE WILL ALLOW FOR
LESSENING HEATRISK ACROSS THE SOUTHWEST COMPARED TO THE SHORT RANGE
PERIOD, THOUGH MODERATE HEATRISK WILL STILL BE WIDESPREAD WITH
ISOLATED MAJOR AND EXTREME VALUES. HEAT SHOULD BUILD GRADUALLY
NORTHWARD ACROSS THE INTERMOUNTAIN WEST AND ROCKIES TO THE HIGH
PLAINS LATE THIS WEEK INTO THE WEEKEND, AND EASTWARD TOWARDS THE
MISSISSIPPI VALLEY NEXT WEEK AS THE UPPER RIDGE EXPANDS. AREAS OF
SMOKE WILL ALSO REMAIN LIKELY GIVEN ACTIVE FIRES. HEAT ACROSS THE
SOUTHWEST SHOULD FINALLY WANE BY EARLY NEXT WEEK WITH INCREASING
MONSOONAL MOISTURE AND A WEAKENING UPPER RIDGE. TEMPERATURES ACROSS
THE NORTHERN TIER AND INTO THE EAST SHOULD BE GENERALLY NEAR
AVERAGE MOST OF THE PERIOD, WITH A SLIGHT COOLING TREND EXPECTED
FOR THE PACIFIC NORTHWEST IN THE WAKE OF A WEAK/DRY COLD FRONT THIS
WEEKEND.
INTERACTION BETWEEN A WEAKENING FRONT IN THE EAST AND A STRONG ONE
INTO THE NORTHERN PLAINS AND GREAT LAKES LATER THIS WEEK WILL
ALLOW FOR ONGOING SHOWERS AND STORMS ACROSS THE MIDWEST TO THE
EAST. A WET PATTERN LOOKS TO SET UP BY THE WEEKEND AND INTO EARLY
NEXT WEEK, ESPECIALLY FOR THE SOUTH AND SOUTHEAST, AS TROPICAL
MOISTURE ROUNDS THE WEST SIDE OF THE SUBTROPICAL ATLANTIC RIDGE.
MORE WIDESPREAD, MODERATE TO HEAVY RAINFALL IS ALSO LOOKING
INCREASINGLY LIKELY ACROSS PORTIONS OF THE UPPER MIDWEST/GREAT
LAKES/UPPER OHIO VALLEY EARLY NEXT WEEK. MONSOONAL MOISTURE IS
LIKELY TO CONTINUE INTO NEXT WEEK FOR ARIZONA AND NEW MEXICO,
REACHING PORTIONS OF UTAH AND COLORADO AS WELL. THE REMAINDER OF
THE WEST INTO THE NORTHERN PLAINS SHOULD BE MOSTLY DRY DURING THE
PERIOD.
PUTNAM/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
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