543
FXUS02 KWBC 031933
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
333 PM EDT MON AUG 3 2026
VALID 12Z THU AUG 06 2026 - 12Z MON AUG 10 2026
...HEAT WAVE CONTINUES THIS WEEK FOR THE SOUTHWEST AND
INTERMOUNTAIN WEST, EXPANDING NORTHEASTWARD WITH TIME...
..OVERVIEW
A STRONG UPPER-LEVEL RIDGE WILL PERSIST OVER THE SOUTHWESTERN U.S.
AND EXPAND NORTH AND EAST OVER THE WEEKEND TO ALLOW EXCESSIVE HEAT
TO EXPAND ACROSS THE INTERMOUNTAIN WEST INTO THE HIGH PLAINS.
MONSOON CONVECTION WILL INCREASE IN THE SOUTHWEST, WHICH SHOULD
HELP LIMIT TEMPERATURES MIDWEEK. MEANWHILE, UPPER TROUGHING WILL
DOMINATE THE PATTERN FOR THE NORTH- CENTRAL AND NORTHEASTERN U.S.
WITH SEVERAL FRONTAL BOUNDARIES MOVING EAST ACROSS THESE REGIONS
AND TRIGGERING SCATTERED SHOWERS AND STORMS. EARLY NEXT WEEK,
TROUGHING WILL ALSO DEVELOP OVER THE PACIFIC NORTHWEST, ACCOMPANIED
BY COOLING TEMPERATURES BEHIND A WEAK COLD FRONT.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS SHOW STRONG AGREEMENT ON THE SYNOPTIC SCALE PATTERN THROUGH
EARLY NEXT WEEK, WITH AN EXPECTED AMOUNT OF DIFFERENCES IN THE
DETAILS. THE MAIN QUESTION WITH THIS FORECAST WILL BE TIMING AND
LOCATION OF SHORTWAVES EMBEDDED IN THE BROAD TROUGH OVER THE
NORTH-CENTRAL U.S. AND NORTHEAST. THESE WAVES WILL IMPACT FRONTAL
EVOLUTION AT THE SURFACE AND IMPACT PRECIPITATION CHANCES. THERE
ARE ALSO SOME TIMING AND EVOLUTION DIFFERENCES WITH ENERGY MOVING
INTO THE NORTHWEST LATE THIS WEEKEND INTO EARLY NEXT WEEK, THOUGH
UNCERTAINTY IS GRADUALLY DECREASING. OVERALL MODELS ARE HANDLING
PRECIPITATION CHANCES WELL, BUT THE SEPARATION BETWEEN THE
SOUTHWESTERN RIDGE AND SUBTROPICAL ATLANTIC RIDGE COULD RESULT IN
INCREASING PRECIPITATION CHANCES FOR THE GULF COAST THROUGH THE
PERIOD.
GIVEN GOOD AGREEMENT, THE WPC FORECAST USED A NEAR EVEN BLEND OF
DETERMINISTIC GUIDANCE THROUGH THE END OF THE WEEK, WITH
INCREASING CONTRIBUTIONS FROM ENSEMBLE MEANS WITH DETERMINISTIC
GUIDANCE FOR THE WEEKEND AND EARLY NEXT WEEK. THIS MAINTAINED GOOD
CONTINUITY WITH THE PREVIOUS FORECAST.
..WEATHER/HAZARDS HIGHLIGHTS
FOR MIDWEEK, A SLIGHTLY WEAKER UPPER RIDGE WILL ALLOW FOR
LESSENING HEATRISK ACROSS THE SOUTHWEST COMPARED TO THE SHORT RANGE
PERIOD, THOUGH MODERATE HEATRISK WILL STILL BE WIDESPREAD WITH
ISOLATED MAJOR AND EXTREME VALUES. HEAT SHOULD BUILD GRADUALLY
NORTHWARD ACROSS THE INTERMOUNTAIN WEST AND ROCKIES TO THE HIGH
PLAINS LATE THIS WEEK INTO THE WEEKEND, AND EASTWARD TOWARDS THE
MISSISSIPPI VALLEY NEXT WEEK AS THE UPPER RIDGE EXPANDS.
TEMPERATURES ACROSS THE NORTHERN TIER AND INTO THE EAST SHOULD BE
GENERALLY NEAR AVERAGE MOST OF THE PERIOD, WITH A SLIGHT COOLING
TREND EXPECTED FOR THE PACIFIC NORTHWEST IN THE WAKE OF A WEAK/DRY
COLD FRONT THIS WEEKEND.
A REASONABLY STRONG FRONT WILL BE MOVING THROUGH THE MIDWEST AND
CENTRAL PLAINS BY THURSDAY WITH A CORRIDOR OF POTENTIALLY HEAVY
RAIN AND THUNDERSTORMS ALONG AND AHEAD OF THE FRONTAL BOUNDARY.
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 AND EASTERN U.S. THROUGH LATE WEEK
AS THE MEAN FRONTAL BOUNDARY MAY STALL FOR A BIT. A WET PATTERN
MAY SET UP BY THE WEEKEND AND EARLY NEXT WEEK, ESPECIALLY FOR THE
SOUTHEAST, AS TROPICAL MOISTURE ROUNDS THE WEST SIDE OF THE
SUBTROPICAL ATLANTIC RIDGE. 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.
DOLAN/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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