087
FXUS02 KWBC 071845
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
245 PM 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 NEXT WEEK...
...STRONG THUNDERSTORMS AND HEAVY RAIN THREATS FROM THE CENTRAL
PLAINS TO THE GREAT LAKES/MIDWEST SUNDAY INTO NEXT WEEK...
..OVERVIEW
AMPLIFIED FLOW ACROSS THE NORTHERN TIER OF THE LOWER 48 BECOMES
INCREASINGLY ZONAL WITH TIME, WITH COOLER AIR MASS MOST CONSTRAINED
TO THE NORTHERN PLAINS AND NORTHWEST. PRONOUNCED RIDGING ACROSS THE
NORTHEAST FLATTENS/WEAKENS WITH TIME.
..GUIDANCE/PREDICTABILITY ASSESSMENT
LATEST GUIDANCE SHOWS REASONABLE AGREEMENT ON THE UPPER LEVEL
PATTERN THROUGH THE PERIOD, RESULTING IN ABOVE AVERAGE FORECAST
CONFIDENCE. FOR PRESSURES/FRONTS/QPF, THE WPC MEDIUM-RANGE PRODUCT
SUITE WAS PRIMARILY DERIVED FROM A BLEND OF THE 06Z GFS/ AND 00Z
ECMWF/CANADIAN/UKMET EARLY ON BEFORE INCREASING THE USE OF THE 00Z
NAEFS/00Z ECMWF MEAN TOWARDS MID NEXT WEEK. OTHERWISE, THE GRIDS
ARE MOSTLY DERIVED FROM THE 13Z NBM.
..WEATHER/HAZARDS HIGHLIGHTS
MODIFYING/WEAKENING HIGH PRESSURE REMAINS OVER PORTIONS OF THE
EASTERN U.S. THIS WEEKEND INTO NEXT WEEK, WITH TEMPERATURES
JUST ABOVE EARLY TO MID-AUGUST AVERAGES. HIGH MOISTURE CONTENT AND
INSTABILITY NEAR A FRONT IN CONNECTION WITH A RETROGRADING UPPER
LEVEL LOW WILL LIKELY FOCUS SOME LOCALIZED HEAVY RAIN ACROSS
PORTIONS OF THE SOUTHEAST AND GULF COAST; MARGINAL RISKS OF
EXCESSIVE RAINFALL WERE ADDED IN THESE AREAS FOR SUNDAY AND MONDAY.
STRONG CONVECTION WITH HEAVY RAINFALL WILL WORK INTO THE CENTRAL
PLAINS AND GREAT LAKES/MIDWEST AS SHORTWAVES ROUND A MID-LEVEL
RIDGE AND INTERACT WITH DOWNSTREAM FRONTAL ZONES. A SLIGHT RISK OF
EXCESSIVE RAINFALL WAS ADDED FOR SUNDAY, WITH A MARGINAL RISK
CONTINUING FOR MONDAY, WHERE MOISTURE, LIFT, AND INSTABILITY
MAXIMIZE WITHIN AN AREA WHERE EFFECTIVE BULK SHEAR COULD LEAD TO
CONVECTIVE ORGANIZATION.
MEANWHILE, THE SOUTHWEST/SOUTHERN ROCKIES MAY SEE SOME TEMPERATURE
MODERATING MONSOON SHOWERS AND THUNDERSTORMS THIS WEEKEND INTO
EARLY NEXT WEEK GIVEN SOME CONNECTION TO THE TROPICALLY ACTIVE EAST
PACIFIC AND A SHIFT OF THE SUBTROPICAL RIDGE NORTH OF THE
U.S./MEXICAN BORDER BY SUNDAY. 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 A TIME ACROSS THE SOUTHEAST U.S. FROM
SUNDAY THROUGH TUESDAY, 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 SLIGHTLY ABOVE AVERAGE TEMPERATURES IN THE 90S, BUT
WITH AMPLE HUMIDITY ALLOWING FOR SOME AREAS OF MAJOR HEATRISK
THERE AS WELL.
ROTH
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
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