292
FXUS02 KWBC 311943
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
343 PM EDT FRI JUL 31 2026
VALID 12Z MON AUG 03 2026 - 12Z FRI AUG 07 2026
...HEAT WAVE LIKELY TO CONTINUE ACROSS THE SOUTHWEST AND
INTERMOUNTAIN WEST INTO NEXT WEEK...
..OVERVIEW
THE UPPER RIDGE 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. MEANWHILE, A SLOWLY DISSIPATING FRONT
MERGING WITH A WAVE LIFTING FROM THE MIDWEST TO THE NORTHEAST WILL
TRIGGER SCATTERED SHOWERS AND THUNDERSTORMS, WHICH WILL GRADUALLY
EDGE TOWARD THE EAST COAST THROUGH MUCH OF THE WEEK. 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 TOWARD THE SOUTHEAST AS IT COULD JOIN WITH SUBTROPICAL
ATLANTIC RIDGING COMING IN FOR LATER WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
EARLY NEXT WEEK EVEN FOR DAY 3-4, THERE IS ALREADY A FAIR AMOUNT
OF MODEL SPREAD WITH THE PATTERN IN THE EASTERN U.S., AS VORTICITY
PLACEMENT WITHIN A TROUGH LEADS TO DIFFERENCES AT THE SURFACE AND
ALOFT. THE 12Z MODEL GUIDANCE HAS CONVERGED SOMEWHAT THOUGH,
SHOWING AN UPPER/SURFACE LOW OVER THE OHIO VALLEY BY TUESDAY,
THOUGH AI MODELS TENDED TO BE SLIGHTLY WEAKER BUT FARTHER SOUTH.
UPSTREAM, TROUGHING ACROSS THE NORTHWEST EARLY WEEK WILL PUSH EAST
ACROSS THE NORTHERN TIER AND LIKELY BROADEN, WITH JUST SOME TYPICAL
MODEL DIFFERENCES IN SHORTWAVE AND FRONTAL TIMING. UPPER RIDGING
IS FORECAST TO SPREAD ACROSS THE SOUTHERN TIER AS THE SOUTHWEST
HIGH BROADENS AND SUBTROPICAL ATLANTIC RIDGING EXPANDS WEST. THIS
IS BROADLY WELL HANDLED BY THE DYNAMICAL AND AI MODELS.
THE WPC FORECAST USED A MULTI-MODEL BLEND EARLY IN THE FORECAST
PERIOD, WITH INCREASING PROPORTIONS OF THE ENSEMBLE MEANS MID TO
LATE PERIOD, THOUGH STILL MAINTAINING OVER HALF DETERMINISTIC
MODELS. THIS HELPS SMOOTH OUT THE BIGGER DIFFERENCES WHILE
MAINTAINING GOOD AGREEMENT WITH THE PREVIOUS WPC FORECAST AS WELL.
..WEATHER/HAZARDS HIGHLIGHTS
HEAT ACROSS MUCH OF THE INTERMOUNTAIN WEST FOR THE SHORT RANGE
SHOULD BE SUPPRESSED SOUTHWARD BY MONDAY AS A COLD FRONT SINKS
ACROSS THE NORTHERN TIER AND BRINGS BELOW AVERAGE TEMPERATURES TO
THE NORTHERN ROCKIES/PLAINS. HOWEVER, 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.
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO OVERSPREAD THE EAST
COAST STATES INTO MONDAY AS MOISTURE IS ADVECTED NORTHWARD AHEAD
OF THE EASTERN U.S. UPPER TROUGH. RAINFALL COULD BE MOST IMPACTFUL
ACROSS PORTIONS OF THE NORTHERN MID-ATLANTIC AND NORTHEAST, WHERE
A SLIGHT RISK OF EXCESSIVE RAINFALL IS IN PLACE. RAIN AND STORMS
LIKELY LINGER ACROSS THE EAST AHEAD OF THE NEXT TROUGH INTO THE
GREAT LAKES MID TO LATE NEXT WEEK.
ELSEWHERE ACROSS THE CONTIGUOUS U.S., MOST OF THE MONSOONAL
RAINFALL SHOULD BE CONFINED TO EASTERN ARIZONA AND INTO CENTRAL NEW
MEXICO, WITH SCATTERED CONVECTION REACHING INTO PORTIONS OF UTAH
AND COLORADO. A CORRIDOR OF SHOWERS AND STORMS IS LIKELY AHEAD OF
THE FRONT THAT CROSSES THE DAKOTAS AND INTO MINNESOTA EARLY IN THE
WEEK, AND THIS MAY ALSO BE ACCOMPANIED WITH SOME SEVERE WEATHER.
HEAVY RAIN SEEMS POSSIBLE IN THE CENTRAL PLAINS/MID-MISSISSIPPI
VALLEY INTO TUESDAY-WEDNESDAY WITH THAT FRONT.
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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