291
FXUS02 KWBC 011859
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 PM EDT TUE JUL 1 2025
VALID 12Z FRI JUL 04 2025 - 12Z TUE JUL 08 2025
...HEAVY RAIN/FLASH FLOODING THREATS FOR BOTH FLORIDA PENINSULA AND
THE NORTH-CENTRAL PLAINS/UPPER MIDWEST THROUGH FRIDAY/SATURDAY...
...HAZARDOUS HEAT AND HUMIDITY EXPECTED TO SPREAD FROM WEST TO
EAST ACROSS THE NORTHERN TIER STATES THROUGH THE HOLIDAY WEEKEND...
..PATTERN OVERVIEW
AMPLIFIED UPPER TROUGHING OVER THE NORTHEAST WILL LIFT OUT OVER THE
UPCOMING HOLIDAY WEEKEND AS MULTIPLE PACIFIC SHORTWAVES DIG INTO A
WEST COAST MEAN UPPER TROUGH WHICH WILL HELP TO KEEP IT IN PLACE
HEADING INTO NEXT WEEK. IN BETWEEN, A BUILDING UPPER RIDGE WILL
SPREAD A THREAT OF HAZARDOUS HEAT FROM WEST TO EAST ACROSS THE
NORTHERN TIER STATES THIS HOLIDAY WEEKEND INTO EARLY NEXT WEEK.
MEANWHILE, A CONTINUED SERIES OF STRONG TO SEVERE CONVECTIVE
FORCING AND LOCAL HEAVY RAIN FUELING IMPULSES AND FRONTS WILL
PROGRESS ATOP/AROUND THE RIDGE FROM THE NORTH-CENTRAL U.S. TO THE
MIDWEST INTO THE NORTHEAST. MEANWHILE, TROPICAL MOISTURE APPEARS TO
LINGER NEAR A SLOW-TO-DISSIPATE STATIONARY FRONT ACROSS THE
FLORIDA PENINSULA THROUGH THE HOLIDAY WEEKEND.
...GUIDANCE/PREDICTABILITY ASSESSMENT
THE WPC MEDIUM RANGE PRODUCT SUITE WAS DERIVED FROM A COMPOSITE
BLEND OF DETERMINISTIC AND ENSEMBLE GUIDANCE FROM THE 00Z ECMWF/EC
MEAN, 06Z GFS/GEFS, 00Z CMC/CMC MEAN, ALONG WITH THE NATIONAL
BLEND OF MODELS. AS FORECAST SPREAD AND UNCERTAINTY INCREASE OVER
TIME WITHIN AVERAGE SEASONAL NORMS, THE BLEND LEANS HEAVILY TOWARD
THE ENSEMBLE MEANS BY THE END OF THE FORECAST PERIOD FOR EARLY
NEXT WEEK. WPC CONTINUITY IS WELL-MAINTAINED.
..WEATHER/HAZARDS HIGHLIGHTS
THUNDERSTORMS WITHIN DEEP TROPICAL MOISTURE AND INSTABILITY WILL
SUPPORT HEAVY CONVECTIVE DOWNPOURS ALONG/SOUTH OF A LINGERING AND
SLOW-TO-DISSIPATE FRONT ACROSS FLORIDA THROUGH THE UPCOMING HOLIDAY
WEEKEND. WPC EXCESSIVE RAINFALL OUTLOOK (ERO) MARGINAL RISK AREAS
ARE IN PLACE FOR DAY 4/FRIDAY AND DAY 5/SATURDAY IN A REGION ACROSS
WEST-CENTRAL FLORIDA PENINSULA PRECEDED BY HEAVY RAINS AND
ANOMALOUS GULF TROPICAL MOISTURE. LATEST GUIDANCE HAS CONTINUED TO
BACK OFF ON EXPLICIT QPF AMOUNTS DESPITE A FAVORABLE PATTERN
FEEDING OFF THE EASTERN GULF WHERE THE NHC HAS BEEN MONITORING FOR
THE POTENTIAL OF TROPICAL CYCLONE FORMATION.
MONSOONAL MOISTURE WITH SOME CONNECTION TO CURRENT EASTERN PACIFIC
HURRICANE FLOSSIE AND SOME GULF MOISTURE FROM RECENT BARRY MAY
BOOST RAIN POTENTIAL THAT MAY LINGER INTO FRIDAY OVER THE BIG
BEND AND VICINITY. MODEL GUIDANCE HAS GENERALLY BACKED OFF ON
THE QPF AMOUNTS.
PERIODIC AFTERNOON AND NOCTURNAL STRONG TO SEVERE STORMS/MCS
ACTIVITY OFFER HEAVY RAIN/RUNOFF POTENTIAL TO FOCUS FROM THE
NORTH-CENTRAL PLAINS TO THE UPPER MIDWEST LATE WEEK INTO SATURDAY
AS UPPER TROUGH/IMPULSE ENERGIES WORK OVER THE NORTHERN PERIPHERY
OF THE MAIN CENTRAL U.S. UPPER RIDGE WHERE MOISTURE/INSTABILITY
TENDS TO BE LIFTED NEAR A WAVY DRAPING FRONT. WPC ERO MARGINAL
RISK AREAS HAVE BEEN MAINTAINED FOR DAY 4/FRIDAY AND DAY
5/SATURDAY. FROM THE WEEKEND TO EARLY NEXT WEEK, SHOWERS AND
EMBEDDED THUNDERSTORMS COULD REFIRE ACROSS THE NORTH-CENTRAL STATES
WHERE EJECTION OF UPPER-LEVEL SHORTWAVES FROM THE NORTHERN ROCKIES
WILL INTERACT WITH THE WAVY FRONTAL ZONE WHICH COULD LEAD TO
LOCALLY ENHANCED RAINFALL IN PORTIONS OF THE NORTHERN HIGH PLAINS
TO THE NORTHERN PLAINS. MEANWHILE, A WAVE OF HEAT AND HUMIDITY
IS EXPECTED TO SPREAD FROM WEST TO EAST ACROSS THE NORTHERN TIER
STATES INCLUDING THE OHIO VALLEY AND MID-ATLANTIC THROUGH THE
HOLIDAY WEEKEND AROUND THE UPPER RIDGE.
KONG/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
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