223
FXUS02 KWBC 011924
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
324 PM EDT SAT AUG 1 2026
VALID 12Z TUE AUG 04 2026 - 12Z SAT AUG 08 2026
...HEAT WAVE LIKELY TO CONTINUE ACROSS THE SOUTHWEST AND
INTERMOUNTAIN WEST THROUGH NEXT WEEK...
..OVERVIEW
THE UPPER RIDGE CURRENTLY DOMINATING THE WEATHER PATTERN ACROSS
THE WESTERN HALF OF THE COUNTRY WILL WEAKEN SLIGHTLY AND GET
SUPPRESSED SOUTH EARLY NEXT WEEK AS A STRONG COLD FRONT IS FORECAST
TO BRING MUCH COOLER AIR THROUGH THE NORTHWEST AND INTO THE
NORTHERN PLAINS THE FIRST HALF OF THE WEEK. HOWEVER, EXCESSIVE HEAT
WILL BE PERSISTENT ACROSS THE SOUTHWESTERN QUADRANT OF THE
COUNTRY, AND SHOULD GRADUALLY SPREAD NORTHEAST INTO THE CENTRAL
ROCKIES/PLAINS AS THE UPPER RIDGE RE-INTENSIFIES, AS WELL AS
FARTHER EAST ACROSS THE SOUTH AS IT COULD JOIN WITH SUBTROPICAL
ATLANTIC RIDGING COMING IN FOR LATER WEEK. MEANWHILE, A HANDFUL OF
FRONTAL SYSTEMS IN THE CENTRAL AND EASTERN U.S. WILL TRIGGER
SCATTERED SHOWERS AND THUNDERSTORMS THROUGH THE WEEK. MONSOON
CONVECTION IS POSSIBLE IN THE SOUTHWEST AS WELL.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE FIRST SYSTEM OF NOTE AT THE START OF THE PERIOD TUESDAY WILL BE
A LIKELY CLOSED UPPER LOW ATOP THE EASTERN U.S. THIS LOW HAS
TRENDED FARTHER SOUTH IN MOST 00Z AND NOW 12Z GUIDANCE COMPARED TO
A DAY AGO, YIELDING MORE QPF AND POP COVERAGE IN THE SOUTHEAST.
WILL NOTE THAT THE AIGFS AND EC-AIFS WERE THE FIRST TO CATCH ONTO
THIS SOUTHERN TREND. THE LOW SHOULD GRADUALLY OPEN UP AND ERODE AS
IT LIFTS NORTH/NORTHEAST INTO MIDWEEK, AND THE FRONTAL PATTERN AT
THE SURFACE SEEMS RATHER UNCERTAIN AND COMPLEX. HOWEVER, THE BASE
OF THE NORTH-CENTRAL U.S. TROUGH, THE COLD FRONT AHEAD OF IT, AND
THUS THE RAIN AXIS ARE FAIRLY AGREEABLE THROUGH MIDWEEK. INTO LATE
WEEK, THERE ARE INCREASING DIFFERENCES IN THE POSITIONS OF ENERGIES
ALOFT WITHIN THE PERSISTENT BROAD NORTH-CENTRAL U.S. TROUGH. THE
FLOW PATTERN IN THE NORTHWEST ALSO SHOWS SOME UNCERTAINTIES, WITH
QUESTIONS ON TIMING OF PACIFIC ENERGY COMING IN, AND NO REAL
CONSENSUS EMERGING YET. THE WPC FORECAST USED A MULTI-MODEL BLEND
FOR THE EARLY PART OF THE FORECAST PERIOD, WITH ENSEMBLE MEAN
WEIGHTING GRADUALLY INCREASING TO HALF BY DAY 7 AMID INCREASING
SPREAD.
..WEATHER/HAZARDS HIGHLIGHTS
THOUGH MUCH MORE SUPPRESSED COMPARED TO THE SHORT RANGE,
WIDESPREAD MAJOR TO EXTREME HEATRISK WILL CONTINUE FOR MUCH OF THE
SOUTHWEST THROUGH MUCH OF NEXT WEEK. THEN, HEAT SHOULD BUILD AGAIN
GRADUALLY NORTHWARD ACROSS THE INTERMOUNTAIN WEST AND ROCKIES TO
THE HIGH PLAINS, AS WELL AS EASTWARD IN THE MID-SOUTH AND SOUTHEAST
AS THE UPPER RIDGE EXPANDS. SEE KEY MESSAGES ISSUED BY WPC FOR
THIS EVENT FOR ADDITIONAL INFORMATION REGARDING THIS LONG LASTING
AND DANGEROUS HEAT WAVE. TEMPERATURES ACROSS THE EAST SHOULD BE
GENERALLY NEAR AVERAGE.
A REASONABLY STRONG FRONT WILL PUSH THROUGH THE MIDWEST AND
CENTRAL PLAINS TUESDAY-WEDNESDAY AND TRIGGER A CORRIDOR OF
POTENTIALLY HEAVY RAIN AND THUNDERSTORMS ALONG AND AHEAD OF IT.
MEANWHILE, WEAK FRONTAL BOUNDARIES WILL ALLOW FOR SHOWERS AND
THUNDERSTORMS TO BE SCATTERED ACROSS THE EAST, WITH SOME LOCALLY
HEAVY TO EXCESSIVE RAINFALL POSSIBLE THERE AS WELL. THESE
INTERACTING FEATURES SHOULD ALLOW FOR ADDITIONAL ROUNDS OF RAIN AND
STORMS ACROSS THE NORTH- CENTRAL TO EASTERN U.S. THROUGH LATE
WEEK. ELSEWHERE, MONSOONAL CONVECTION IS LIKELY FOR ARIZONA AND NEW
MEXICO IN PARTICULAR, WITH SCATTERED CONVECTION OCCASIONALLY
REACHING PORTIONS OF UTAH AND COLORADO.
TATE/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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