783
FXUS02 KWBC 100801
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
401 AM EDT WED SEP 10 2025
VALID 12Z SAT SEP 13 2025 - 12Z WED SEP 17 2025
..OVERVIEW
A PESKY MEAN UPPER FLOW PATTERN NOW OVER OUR FINE NATION WILL TEND
TO LINGER THIS WEEKEND INTO NEXT WEEK AS HIGHLIGHTED BY RENEWING
TROUGH POSITIONS OVER THE EASTERN AND THE WESTERN LOWER 48 THAT
SANDWICH A WARMING CENTRAL U.S. RIDGE. SLOWLY PROGRESSIVE SYSTEMS
WILL REPEATEDLY WORK THROUGH THE WESTERN U.S. MEAN TROUGH TO SHIFT
FOCUS OF ENHANCED RAIN CHANCES FROM THE NORTHWEST/WEST OUT ACROSS
THE ROCKIES/PLAINS. THE GREAT LAKES REGION TO NORTHEAST SHOULD ALSO
BE UNSETTLED/WET AS NORTHERN STREAM TROUGH/LOW ENERGY MAY ROBUSTLY
DIG TO THE LEE OF THE RIDGE INTO THE AREA. HEAVY RAIN MAY PERSIST
INTO THE WEEKEND FOR SOUTH FLORIDA AND ALONG/OFFSHORE THE COASTAL
CAROLINAS AND POSSIBLY INTO NEW ENGLAND AS DEEPENED MOISTURE
INTERACTS WITH A WAVY AND WINDY WESTERN ATLANTIC FRONT FEEDING INTO
A MODERATE COASTAL LOW NOW TRENDING CLOSER OFFSHORE.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS AND ENSEMBLES CONTINUE TO FAVOR OVERALL PERSISTENCE OF WHAT
IS PROVING TO BE A SLOW TO DISLODGE MID-LARGER SCALE UPPER FLOW
PATTERN. A SUMMERTIME UPPER RIDGE SUPPORTS PRE-FRONTAL HEAT OVER
THE CENTRAL U.S.. THIS RIDGE IS SANDWICHED BETWEEN UPPER TROUGH
POSITIONS OVER THE WEST AND INTO THE NORTHEAST AND OVER THE
SOUTHEAST THAT HOLD/REFORM AS SLOWLY TRANSIENT EMBEDDED ENERGIES
PERIODICALLY RENEW. FORECAST SPREAD AND CYCLE TO CYCLE VARIANCES IS
LESS THAN STELLAR WITH EMBEDDED FEATURES, LENDING PREFERENCE FOR
ENSEMBLE MEAN FORECASTS. THE WPC PRODUCT SUITE WAS PRIMARILY
DERIVED FROM THE 01 UTC NATIONAL BLEND OF MODELS (NBM) ALONG WITH
12 UTC ECMWF/CANADIAN ENSEMBLE MEANS. THESE MEANS OFFERED A MORE
AMPLIFIED SOLUTION COMPARED TO GEFS MEAN. THIS SOLUTION SEEMED TO
BETTER FIT OVERALL PATTERN NATURE INCLUDING SUPPORT FOR NORTHERN
STREAM UPPER TROUGHING/LOW DEVELOPMENT OVER THE NORTHEAST THAT
COULD INTERACT WITH EXPECTED COASTAL LOW DEVELOPMENTS TO BRING
RAINS AND UNSETTLED WEATHER CONDITIONS MORE ONSHORE THAN THE NBM.
THE LATEST 00 UTC MODEL SUITE HAS STRONGLY TRENDED IN THIS
DIRECTION, BOLSTERING FORECAST CONFIDENCE AS WE GET CLOSER IN TIME.
..WEATHER/HAZARDS HIGHLIGHTS
A PERSISTENT AND WAVY FRONTAL SYSTEM OVER THE GULF AND FLORIDA
WILL LINGER JUST OFF/UP THE EASTERN SEABOARD INTO NEXT WEEK. THIS
WILL PROVIDE A MAIN FOCUS FOR TROPICAL MOISTURE TO POOL TO FUEL A
ELONGATED PLUME OF ENHANCED WRAPPING RAINS. A DAY 4/SATURDAY
EXCESSIVE RAINFALL OUTLOOK (ERO) MARGINAL RISK AREA REMAINS OVER
SOUTH FLORIDA FOR RAINFALL LEADING INTO LATER DAY FRONTAL PASSAGE.
SCATTERED SHOWERS COULD CONTINUE INTO NEXT WEEK BEHIND THE MAIN
FRONT, BUT WITH MOISTURE LEVELS CLOSER TO NORMAL. FARTHER NORTH,
MODELS NOW SHOW MOST MOISTURE ALONG/JUST OFFSHORE THE COASTAL
CAROLINAS/MID-ATLANTIC CAROLINA AND UP INTO NEW ENGLAND, TRENDING
FAVORABLY WITH WAVY FRONTAL BOUNDARY/COASTAL LOW SHIFTS. EXPECT
WINDY COASTAL/MARITIME FLOW AND HAZARDS TO MONITOR REGARDLESS.
FOR THE WEST, RAIN AND THUNDERSTORMS SHOULD FOCUS OVER THE
NORTHERN PLAINS THIS WEEKEND, YIELDING MARGINAL RISKS FOR POSSIBLE
FLOODING CONCERNS EACH DAY. GRADUAL FLOW AND FRONTAL TRANSLATION
DOWNSTREAM COULD ALSO SUPPORT RAIN INTO THE MIDWEST WHILE
UNCERTAIN FLOW MAY YIELD RAINS IN THE NORTHEAST EARLY NEXT WEEK.
THE NEXT ROUND OF TROUGHING WILL PUSH INTO THE WEST THIS WEEKEND
AND SPREAD ANOTHER ROUND OF PRECIPITATION FIRST TO THE PACIFIC
NORTHWEST AND INTO THE NORTHERN GREAT BASIN AND ROCKIES EARLY NEXT
WEEK.
COOLER THAN NORMAL TEMPERATURES ESPECIALLY FOR HIGHS ARE LIKELY
ACROSS THE WESTERN U.S. UNDERNEATH PERIODS OF UPPER TROUGHING. NEAR
TO SLIGHTLY BELOW AVERAGE TEMPERATURES ARE ALSO FORECAST FOR THE
EAST. BUT UNDERNEATH THE UPPER RIDGE IN BETWEEN THESE FEATURES,
EXPECT ABOVE AVERAGE TEMPERATURES FOR THE PLAINS TO MISSISSIPPI
VALLEY. TEMPERATURE ANOMALIES OF +10 TO +20 DEGREES WILL LEAD TO
HIGHS IN THE 90S AS FAR NORTH AS NEBRASKA AND IOWA INTO LATE THIS
WEEK, THOUGH POTENTIALLY BECOMING MORE SUPPRESSED TO THE SOUTH INTO
NEXT WEEK GIVEN UPPER FLOW TRENDS AND SOUTHWARD FRONTAL TRENDS.
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