316
FXUS02 KWBC 070646
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
246 AM EDT THU AUG 7 2025
VALID 12Z SUN AUG 10 2025 - 12Z THU AUG 14 2025
...MAJOR HEAT THREAT FOCUS SHIFTS FROM THE SOUTHWEST AND SOUTH-
CENTRAL PLAINS TO THE MIDWEST/GREAT LAKES/NORTHEAST THIS PERIOD...
...STRONG THUNDERSTORMS AND HEAVY RAIN THREATS FROM THE CENTRAL
PLAINS TO THE GREAT LAKES/MIDWEST SUNDAY TO EARLY-MID NEXT WEEK...
..OVERVIEW
IT MAINLY REMAINS THE CASE THAT DYNAMIC MEAN UPPER TROUGHING WILL
GRADUALLY WORK EAST ACROSS THE NORTHERN U.S., DRIVING STRONG TO
SEVERE THUNDERSTORM CHANCES FROM THE NORTH-CENTRAL PLAINS TO THE
MIDWEST/GREAT LAKES. A WAVY FRONTAL BOUNDARY WILL LINGER ALONG THE
GULF AND SOUTHEAST COASTS, RESULTING IN UNSETTLED WET WEATHER FOR
PORTIONS OF THE SOUTHEAST/FLORIDA AND SOUTHERN MID-ATLANTIC AS NHC
MONITORS ANY COASTAL LOWS FOR POTENTIAL TROPICAL DEVELOPMENT.
MEANWHILE, AN EXPANDING UPPER RIDGE WILL SPREAD A HEATWAVE FROM THE
SOUTHWEST AND SOUTH-CENTRAL PLAINS TO THE MIDWEST/GREAT
LAKES/NORTHEAST THIS WEEKEND INTO NEXT WEEK. THERE MAY ALSO BE AN
UPTICK IN MONSOONAL MOISTURE FLOW INTO THE SOUTHWEST/SOUTHERN
ROCKIES BY THE WEEKEND WITH SOME CONNECTION TO THE EAST PACIFIC.
..GUIDANCE/PREDICTABILITY ASSESSMENT
LATEST GUIDANCE CONTINUES TO SHOW REALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN THROUGH THE PERIOD, RESULTING IN ABOVE AVERAGE
FORECAST CONFIDENCE. ALL AVAILABLE GUIDANCE IS CAPTURING THE
SYNOPTIC PATTERN WELL, WITH STRONG UPPER RIDGING THAT HAS ANCHORED
OVER THE SOUTHWEST EXPANDING HEAT RISKS THROUGH THE SOUTH-CENTRAL
PLAINS TO THE MIDWEST/GREAT LAKES/NORTHEAST IN ADVANCE OF A DEEP
TROUGH AND LEAD SURFACE FRONTAL SYSTEM SLATED TO MOVE SLOWLY
EASTWARD OVER THE NORTHERN U.S. WITH SEVERAL EMBEDDED SHORTWAVES.
HOWEVER, THERE IS SOME UNCERTAINTY IN THE DETAILS OF THE SENSIBLE
WEATHER AT THE SURFACE, WITH SOME DIFFERENCES IN PRECIPITATION
AMOUNTS AND LOCATIONS. OVERALL, THE GENERAL CONSENSUS IS FOR THE
HEAVIEST RAIN TO FOCUS OVER THE NORTH-CENTRAL PLAINS/UPPER MIDWEST
AND FROM THE SOUTHEAST COAST/FLORIDA TO THE SOUTHERN MID-ATLANTIC.
IN THE SOUTHEAST AND EASTERN GULF/FLORIDA, PRECIPITATION INTENSITY
AND LOCATION IS ALSO PENDING FRONTAL WAVE OR TROPICAL DEVELOPMENT.
THE WPC MEDIUM-RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A
BLEND OF BEST CLUSTERED GUIDANCE OF THE 18 UTC GFS/GEFS MEAN AND
12 UTC ECMWF/CANADIAN AND THEIR ENSEMBLE MEANS THROUGH MEDIUM RANGE
TIME SCALES ALONG WITH COMPATIBLE GUIDANCE FROM WPC CONTINUITY AND
THE NATIONAL BLEND OF MODELS IN A PATTERN WITH SEEMINGLY ABOVE
NORMAL PREDICTABILITY. THE BLENDING PROCESS TENDS TO MITIGATE
VARIANCES CONSISTENT WITH INDIVIDUAL FEATURE PREDICTABILITY.
APPLIED HIGHER WEIGHTING IN THIS BLEND TO THE 12 UTC ECMWF/ECMWF
ENSEMBLE MEAN THAT IN GENERAL HOLD ONTO THE UPPER RIDGE/HIGH ACROSS
THE DESERT SOUTHWEST AND OVER FLORIDA MORE SO THAN THE OTHER
GUIDANCE. AMPLIFIED UPPER RIDGES TEND TO LINGER. THE LATEST 00 UTC
GUIDANCE SUITE OVERALL REMAINS IN LINE WITH THIS FORECAST PLAN TO
NOW INCLUDE THE UKMET THAT HAS TRENDED TOWARD THE MAJORITY CLUSTER.
..WEATHER/HAZARDS HIGHLIGHTS
A QUITE SLOW TO DISLODGE COOLED HIGH PRESSURE AIRMASS WILL LINGER
OVER PORTIONS OF THE EASTERN U.S. THIS WEEKEND, FURTHER MODERATING
NEXT WEEK. HIGH MOISTURE CONTENT AND INSTABILITY NEAR A FRONT ON
THE LEADING EDGE OF THIS AIRMASS WILL LIKELY FOCUS SOME LOCALIZED
HEAVY RAIN IN PARTICULAR OVER THE COASTAL SOUTHEAST AND FLORIDA.
LOCALLY STRONG CONVECTION WITH HEAVY RAIN WILL WORK TO THE CENTRAL
PLAINS AND GREAT LAKES/MIDWEST AS SHORTWAVES ROUND TO THE LEE OF
AN UPPER RIDGE TO INTERACT WITH DOWNSTREAM FRONTAL ZONES. WPC'S
DAY 4/5 EROS SHOW MARGINAL RISK AREAS SUNDAY/MONDAY AS MOISTURE
AND INSTABILITY POOL. A SLIGHT RISK AREA MAY ULTIMATELY BE NEEDED
GIVEN LOCAL POTENTIAL FOR TRAILING FRONT REPEAT/TRAINING OF CELLS.
MEANWHILE, THE SOUTHWEST/SOUTHERN ROCKIES MAY SEE SOME TEMPERATURE
MODERATING MONSOON SHOWERS THIS WEEKEND INTO EARLY NEXT WEEK GIVEN
SOME CONNECTION TO THE TROPICALLY ACTIVE EAST PACIFIC. DAY 4/5 ERO
MARGINAL RISK AREAS FOCUS ACTIVITY IN SOUTHERN ARIZONA/NEW MEXICO.
COOLER THAN AVERAGE TEMPERATURES WILL CONTINUE ON THE COOL SIDE OF
THE MAIN FRONTAL SYSTEM FOR THE EAST/SOUTHEAST U.S., WHILE HEAT
LINGERS ACROSS THE SOUTHWEST AND SOUTHERN/CENTRAL PLAINS.
HEAT WILL ALSO SPREAD ACROSS PORTIONS OF THE MIDWEST AND GREAT
LAKES LATE THIS WEEKEND THEN EVENTUALLY THE NORTHEAST, WHICH MAY
CREATE A MAJOR HEATRISK. FLORIDA IS FORECAST TO SEE SEASONABLE
TEMPERATURES IN THE 90S, BUT WITH AMPLE HUMIDITY ALLOWING FOR SOME
AREAS OF MAJOR HEATRISK THERE AS WELL.
SCHICHTEL
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 (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page