703
FXUS02 KWBC 020703
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
303 AM EDT SUN AUG 2 2026
VALID 12Z WED AUG 05 2026 - 12Z SUN AUG 09 2026
...HEAT WAVE LIKELY TO CONTINUE ACROSS THE SOUTHWEST AND
INTERMOUNTAIN WEST THROUGH NEXT WEEK, EXPANDING EASTWARD WITH
TIME...
..OVERVIEW
THE UPPER RIDGE CURRENTLY DOMINATING THE WEATHER PATTERN ACROSS
THE WESTERN HALF OF THE COUNTRY WILL WEAKEN SLIGHTLY AND GET
SUPPRESSED SOUTH BY THE START OF THE MEDIUM RANGE PERIOD 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 WITH
MONSOON CONVECTION IN THE SOUTHWEST AS WELL.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS SHOW GOOD AGREEMENT ON THE LARGE SCALE PATTERN EVOLUTION
THROUGH THE PERIOD WHICH FEATURES A NORTHERN STREAM TROUGH THROUGH
THE NORTH-CENTRAL U.S. AND A SPRAWLING SOUTHERN TIER RIDGE. THE
MAIN FOCUS OF UNCERTAINTY CONTINUES TO BE WITH THE POSITIONS OF
VARIOUS ENERGIES ALOFT WITHIN THE BROADER TROUGH, ESPECIALLY THE
LATTER PART OF THE WEEK AND INTO THE WEEKEND. WEAK ENERGY MOVING
INTO THE NORTHWEST ALSO SHOWS SOME VARIABILITY. THE ECMWF/ECENS
SEEMS A BIT FASTER THAN CONSENSUS IN THE NORTHWEST LATE WEEK. THERE
IS AGREEMENT FOR THE SOUTHERN RIDGE TO EXPAND AND POSSIBLY CONNECT
UP WITH THE SUBTROPICAL ATLANTIC RIDGE, BUT UNCERTAINTY ON ANY
EMBEDDED WEAKNESSES OVER THE SOUTHEAST/MID-SOUTH WHICH MAY ACT TO
KEEP THE TWO MORE SEPARATE FEATURES. ACROSS THE BOARD, THERE ARE
NOT ANY REAL CLEAR OUTLIERS, SO A GENERAL BLEND OF THE
DETERMINISTIC GUIDANCE WORKED WELL FOR THE FIRST HALF OF THE
PERIOD, INCREASING THE WEIGHTING OF THE ENSEMBLE MEANS A BIT LATER
IN THE PERIOD TO HELP SMOOTH OUT INCREASING UNCERTAINTY.
..WEATHER/HAZARDS HIGHLIGHTS
THOUGH MUCH MORE SUPPRESSED COMPARED TO THE SHORT RANGE, SOME
MAJOR TO EXTREME HEATRISK WILL CONTINUE FOR 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 NORTHERN TIER AND INTO
THE EAST SHOULD BE GENERALLY NEAR AVERAGE MOST OF THE PERIOD.
A REASONABLY STRONG FRONT WILL PUSH INTO THE MIDWEST AND CENTRAL
PLAINS BY 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 AS THE MEAN FRONTAL
BOUNDARY MAY STALL FOR A BIT. ELSEWHERE, MONSOONAL CONVECTION IS
LIKELY FOR ARIZONA AND NEW MEXICO IN PARTICULAR, WITH SCATTERED
CONVECTION OCCASIONALLY REACHING PORTIONS OF UTAH AND COLORADO. THE
REMAINDER OF THE WEST INTO THE NORTHERN PLAINS SHOULD BE MOSTLY
DRY DURING THE PERIOD.
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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