484
FXUS02 KWBC 250745
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
345 AM EDT SAT JUL 25 2026
VALID 12Z TUE JUL 28 2026 - 12Z SAT AUG 1 2026
***LENGTHY HEAT WAVE EXPECTED FOR MUCH OF THE WESTERN AND SOUTHERN
U.S. ALONG WITH ACTIVE MONSOONAL PATTERN OVER THE ROCKIES***
..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. A BROAD UPPER
TROUGH IS EXPECTED OVER THE NORTHEAST PACIFIC, AND A MORE
AMPLIFIED RIDGE OVER THE NORTHEAST STATES WILL LIKELY SUPPORT
PERIODS OF HEAVY RAINFALL TUESDAY INTO 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. DAILY AFTERNOON AND EVENING
THUNDERSTORMS ARE EXPECTED FROM THE CENTRAL ROCKIES TO THE DESERT
SOUTHWEST WITH PLENTY OF MONSOONAL MOISTURE IN PLACE.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 00Z MODEL GUIDANCE SUITE IS IN GOOD OVERALL AGREEMENT ON THE
SYNOPTIC SCALE PATTERN ACROSS THE CONTINENTAL U.S. THROUGH THE
MIDDLE OF THE WEEK, WITH A GENERAL DETERMINISTIC MODEL COMPROMISE
SERVING AS A STARTING POINT IN THE FORECAST PROCESS. LOOKING AHEAD
TO THE END OF THE WEEK, THE MODELS AGREE BEST ON THE UPPER RIDGE
EXPANDING ACROSS THE WEST (WITH POTENTIAL FOR A 600DM HIGH CENTERED
OVER UTAH BY LATE FRIDAY). THE GREATEST DIFFERENCES ARE NOTED
ACROSS SOUTHERN CANADA WITH SHORTWAVE ENERGY TRACKING AROUND THE
NORTHERN PERIPHERY OF THE HIGH, AND THE DEGREE OF DOWNSTREAM
TROUGHING ACROSS THE EAST COAST REGION. THE AIFS AND CMC ARE MORE
AMPLIFIED WITH THE TROUGH OVER THE CENTRAL APPALACHIANS BY SATURDAY
COMPARED TO THE GFS AND ECMWF. THE ENSEMBLE MEANS WERE GRADUALLY
INCREASED TO ABOUT 50% BY SATURDAY.
..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 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 TO 105 DEGREES 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 AND MID-
ATLANTIC REGION ON TUESDAY, IN COMBINATION WITH AN AMPLIFYING UPPER
LEVEL SHORTWAVE TROUGH, WILL FUEL THE DEVELOPMENT OF NUMEROUS
SHOWERS AND STORMS FROM VIRGINIA TO NEW ENGLAND. A MARGINAL RISK OF
EXCESSIVE RAINFALL WILL BE VALID FOR PORTIONS OF THIS REGION GIVEN
THE POTENTIAL FOR 1-2 INCHES OF RAINFALL WITH THE STRONGER STORMS,
WHICH COULD BE ENOUGH TO PRODUCE FLOODING FOR SOME AREAS. THERE IS
ALSO A THREAT OF SEVERE WEATHER ACROSS PORTIONS OF THE MID-ATLANTIC
IN THE WARM SECTOR OF THE LOW PRESSURE SYSTEM, WITH DAMAGING WINDS
BEING THE PRIMARY HAZARD WITH THE STRONGEST STORMS.
ELSEWHERE ACROSS THE COUNTRY, MONSOONAL MOISTURE WILL REMAIN
ENTRENCHED ACROSS THE FOUR CORNERS REGION AND INCLUDING THE
CENTRAL AND SOUTHERN ROCKIES. SCATTERED TO NUMEROUS SHOWERS AND
STORMS ARE EXPECTED MOST DAYS, WITH THE GREATEST COVERAGE EXPECTED
ACROSS NORTHERN NEW MEXICO INTO CENTRAL COLORADO. FARTHER EAST
ACROSS THE PLAINS AND MIDWEST, NORTHWEST FLOW ALOFT AROUND THE
NORTHERN PERIPHERY OF THE UPPER RIDGE SHOULD SUPPORT THE
DEVELOPMENT OF SOME MESOSCALE CONVECTIVE COMPLEXES, BUT THE TIMING
AND PLACEMENT OF THESE REMAIN UNCERTAIN AT THIS TIME.
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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