823
FXUS02 KWBC 261825
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
225 PM EDT SUN JUL 26 2026
VALID 12Z WED JUL 29 2026 - 12Z SUN AUG 02 2026
...LONG DURATION HEAT WAVE EXPECTED FOR MUCH OF THE WESTERN AND
SOUTHERN U.S. THROUGH NEXT WEEKEND AND BEYOND...
..PATTERN OVERVIEW
THE MAIN THEME GOING INTO THE MIDDLE OF THE WEEK WILL BE A LARGE
UPPER RIDGE SITUATED ACROSS THE ROCKIES AND WESTERN HIGH PLAINS,
AND EXTENDING NORTHWARD INTO SOUTH-CENTRAL CANADA. AN UPPER TROUGH
WITH A CLOSED LOW IS EXPECTED OVER THE NORTHEAST PACIFIC, AND A
MORE AMPLIFIED TROUGH OVER THE NORTHEAST STATES WILL LIKELY SUPPORT
PERIODS OF HEAVY RAINFALL ON WEDNESDAY. THIS GENERAL PATTERN HOLDS
TRUE GOING INTO THE END OF THE WEEK AS THE RIDGE EXPANDS FARTHER
TO THE WEST TO INCLUDE THE INTERMOUNTAIN WEST, AND GENERAL
TROUGHING LIKELY CONTINUES FOR THE EAST COAST WITH SOME ABATEMENT
IN RAINFALL COVERAGE AS THE DEEP MOISTURE PLUME EXITS THE COAST.
DAILY AFTERNOON AND EVENING THUNDERSTORMS ARE EXPECTED FROM THE
CENTRAL ROCKIES TO THE DESERT SOUTHWEST EARLY IN THE PERIOD, WITH
SOME WEAKENING OF MONSOONAL MOISTURE EXPECTED INTO NEXT WEEKEND AS
THE UPPER HIGH EXPANDS OVER THE REGION.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON THE OVERALL
LARGE SCALE PATTERN THROUGH THE PERIOD. UNCERTAINTY IN TIMING OF
EVOLUTION OF SHORTWAVES ACTING TO REINFORCE THE EASTERN TROUGH
CONTINUES. THIS INCLUDES THE UPPER LOW AS IT LIFTS OUT OF NEW
ENGLAND LATE THIS WEEK AND ANOTHER SHORTWAVE ACROSS THE GREAT LAKES
WHICH MAY EXPAND SOUTH AND WESTWARD NEXT WEEKEND ACROSS THE
MIDWEST AND TENNESSEE VALLEY. THIS COULD SHRINK THE WESTERN UPPER
RIDGE WESTWARD, ALSO AIDED BY SHORTWAVE ENERGY ADVANCING INTO THE
NORTHWEST AT THE SAME TIME. THE GFS SEEMS WEAKEST ON THIS,
MAINTAINING A SLIGHTLY STRONGER RIDGE THAN CONSENSUS WOULD SUGGEST.
THE WPC FORECAST TODAY WAS BASED ON A BLEND OF THE DETERMINISTIC
AND EC-AIFS MODELS FOR THE FIRST HALF OF THE PERIOD, TRANSITIONING
TO 60/40 SPLIT OF THE ENSEMBLE MEANS AND THE DETERMINISTIC GFS,
ECMWF, AND CMC. THIS HELPS MITIGATE SOME OF THE LATER PERIOD
UNCERTAINTIES AND ALSO MAINTAINS GOOD CONTINUITY WITH THE PREVIOUS
WPC FORECAST.
..WEATHER/HAZARDS HIGHLIGHTS
EXTREME HEAT WILL CONTINUE TO MAKE WEATHER HEADLINES ACROSS A
LARGE EXPANSE OF THE COUNTRY GOING INTO NEXT WEEK. WIDESPREAD UPPER
90S AND LOW 100S ARE EXPECTED FROM MONTANA TO THE WESTERN DAKOTAS,
WHICH IS 10-15 DEGREES ABOVE AVERAGE IN MANY CASES. IT WILL ALSO
BE VERY HOT AND HUMID FROM TEXAS TO THE GULF COAST STATES WITH
HIGHS RANGING FROM 95 ACROSS THE DEEP SOUTH TO 105 DEGREES FOR
CENTRAL TEXAS ON MOST DAYS, WITH SOME AREAS OF EXTREME HEAT RISK
GIVEN THE LONGEVITY OF THE HEAT AND EXPECTED HEAT INDICES EXCEEDING
110 DEGREES AT TIMES. IT WILL ALSO BE QUITE HOT FROM THE DESERT
SOUTHWEST AND EXTENDING NORTH ACROSS THE INTERMOUNTAIN WEST WITH
THE UPPER RIDGE EXERTING ITS INFLUENCE, WITH 110S FOR THE LOWER
ELEVATIONS OF SOUTHERN ARIZONA AND SOUTHERN INTERIOR CALIFORNIA,
AND NEAR 100 DEGREES NORTHWARD TO THE GREATER SALT LAKE CITY AREA.
OVERNIGHT LOWS WILL ALSO BE ABOVE NORMAL FOR MANY OF THESE SAME
AREAS. THE OPPOSITE WILL LIKELY BE THE CASE FOR THE EAST COAST WITH
READINGS NEAR AVERAGE OR SLIGHTLY BELOW.
AN ORGANIZED LOW PRESSURE SYSTEM CROSSING THE NORTHEAST U.S. ON
WEDNESDAY, IN COMBINATION WITH AN AMPLIFYING UPPER LEVEL SHORTWAVE
TROUGH, WILL FUEL THE DEVELOPMENT OF NUMEROUS SHOWERS AND STORMS
FROM UPSTATE NEW YORK TO NEW ENGLAND. A SLIGHT RISK OF EXCESSIVE
RAINFALL IS HIGHLIGHTED FOR PORTIONS OF SOUTHERN NEW ENGLAND GIVEN
THE POTENTIAL FOR 1-2 INCHES OF RAINFALL, WITH LOCALLY HIGHER
AMOUNTS WITH THE STRONGER STORMS, WHICH COULD BE ENOUGH TO PRODUCE
FLOODING FOR SOME AREAS. THERE MAY BE SOME LINGERING RAINFALL
ACROSS EASTERN NEW ENGLAND THURSDAY AS THE LOW PRESSURE SYSTEM
SLOWLY DEPARTS THE REGION.
ELSEWHERE ACROSS THE COUNTRY, MONSOONAL MOISTURE WILL REMAIN IN
PLACE TO START THE PERIOD FROM EASTERN ARIZONA TO CENTRAL NEW
MEXICO, AND EXTENDING NORTHWARD ACROSS THE COLORADO ROCKIES.
SCATTERED TO NUMEROUS SHOWERS AND STORMS ARE EXPECTED LATER THIS
WEEK, WITH SOME ABATEMENT IN COVERAGE GOING INTO THE WEEKEND.
FARTHER EAST ACROSS THE PLAINS AND MIDWEST, NORTHWEST FLOW ALOFT
AROUND THE NORTHEASTERN AND EASTERN PERIPHERY OF THE UPPER RIDGE
SHOULD SUPPORT THE DEVELOPMENT OF SOME MESOSCALE CONVECTIVE
COMPLEXES.
SANTORELLI/HAMRICK
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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