536
FXUS02 KWBC 131959
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
359 PM EDT SAT SEP 13 2025
VALID 12Z TUE SEP 16 2025 - 12Z SAT SEP 20 2025
..OVERVIEW
THE MOST PROMINENT UPPER-AIR FEATURE NEXT WEEK IS TROUGHING OVER
THE NORTH-CENTRAL STATES THAT SHIFTS TO THE GREAT LAKES BY NEXT
WEEKEND. RIDGES AND ABOVE NORMAL TEMPERATURES ARE ON EITHER SIDE
OF THIS TROUGH WITH FURTHER TROUGHING OVER THE SOUTHEAST THAT
BRINGS RAIN CHANCES AS IT LIFTS OVER OR OFF THE MID- ATLANTIC
THROUGH MIDWEEK AND AN APPROACHING TROUGH OVER THE NORTHEAST
PACIFIC THAT LIKELY CLOSES INTO A LOW OVER WASHINGTON STATE IN THE
MID TO LATE WEEK TIMEFRAME. TROUGHING IN THE EAST WITH THE
POTENTIAL FOR A LINGERING CLOSED LOW WOULD BRING INCREASING RAIN
CHANCES ALONG AT LEAST COASTAL AREAS OF THE CAROLINAS/SOUTHERN MID-
ATLANTIC.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 12Z MODEL GUIDANCE SUITE AGREES ON MOST ASPECTS OF THE SYNOPTIC
SCALE PATTERN ACROSS THE CONTINENTAL U.S. TO START THE FORECAST
PERIOD TUESDAY. THE LOW THAT IS LIKELY TO DEVELOP ALONG THE STALLED
FRONTAL BOUNDARY OFF THE EAST COAST HAS TRENDED MORE TO THE NORTH
COMPARED TO LAST NIGHT'S FORECAST, AND THE LOW OVER MANITOBA HAS
TRENDED A LITTLE MORE TO THE SOUTH. THERE IS ALSO A SLIGHTLY FASTER
PROGRESSION OF THE COLD FRONT CROSSING THE CENTRAL PLAINS AND
MIDWEST TUESDAY INTO WEDNESDAY.
THE OVERALL WEATHER PATTERN GETS MORE COMPLICATED GOING INTO THE
END OF THE WEEK, PARTICULARLY ACROSS THE NORTHERN TIER STATES WITH
A TROUGH OVER THE PACIFIC NORTHWEST, CLOSED LOW OVER THE MIDWEST,
AND A NARROW RIDGE AXIS EXTENDING NORTH ACROSS THE ROCKIES AND
INTO CENTRAL CANADA, AND A WEAKER TROUGH OVER NEW ENGLAND. THE
MODELS STILL HAVE SUBSTANTIAL MESOSCALE DIFFERENCES BY THIS TIME,
AND THEREFORE AN INCREASE IN THE ENSEMBLE MEANS WAS USED BY FRIDAY
AND SATURDAY.
..WEATHER/HAZARDS HIGHLIGHTS
UPPER TROUGHING OVER THE NORTHERN PLAINS TUESDAY AND WEDNESDAY WILL
ENCOURAGE ENHANCED GULF MOISTURE TRANSPORT UP THE PLAINS WITH
CONVERGENCE AHEAD OF A SLOW MOVING FRONTAL SYSTEM. PATCHY AREAS OF
HEAVY RAIN IS LIKELY OVER THE CENTRAL PLAINS BOTH DAYS. THE
MARGINAL RISK AREAS ACROSS THIS REGION HAVE BEEN MAINTAINED WITH
JUST MINOR ADJUSTMENTS. ANOTHER AREA TO WATCH WILL BE THE SOUTHERN
ROCKIES, WHERE MONSOONAL MOISTURE GETS INTO SOUTHWEST NEW MEXICO
ON TUESDAY AND THEN INTO WESTERN TEXAS, WHICH WARRANTS INCLUSION
OF AN ENLARGED DAY 4 MARGINAL RISK ERO FROM SOUTHEAST ARIZONA TO
NORTHERN NEW MEXICO, AND A DAY 5 MARGINAL HAS BEEN INTRODUCED A
LITTLE TO THE EAST OF THE DAY 4 OUTLOOK WITH ADDITIONAL CONVECTION
LIKELY ON WEDNESDAY.
OTHERWISE, THE LOW MOVING UP NEAR THE OUTER BANKS OF NC AND THE
DELMARVA SHOULD BRING SOME ONSHORE FLOW AND RAIN. THERE HAS BEEN A
TREND OVER THE PAST FEW MODEL CYCLES FOR MORE SUBSTANTIAL RAINFALL
MOVING INLAND ACROSS NC AND VA, SO THIS WILL CONTINUE TO BE CLOSELY
MONITORED IN THE DAYS AHEAD, BUT NOT WARRANTING ANY ERO RISK AREAS
AT THIS TIME. MEANWHILE, THE TRAILING PORTION OF THE STATIONARY
FRONT WILL LINGER OVER OR NEAR SOUTH FLORIDA TUESDAY THROUGH THE
REST OF THE WEEK, AND A MARGINAL RISK FOR WEDNESDAY HAS BEEN
INTRODUCED HERE.
ELSEWHERE, THE RIDGE AXIS OVER THE SOUTHWEST SHIFTS EAST STARTING
WEDNESDAY WHICH WILL SEND ANOMALOUS MOISTURE NORTH OVER SOUTHERN CA
LATER IN THE WEEK AND POTENTIALLY EXCESSIVE RAINFALL. AN UPPER
RIDGE WILL PROMOTE HOT TEMPERATURES CENTERED ON THE MIDWEST AND
MISSISSIPPI VALLEY THROUGH AT LEAST MID-NEXT WEEK, WITH ANOMALIES
OF 10-20 DEGREES ABOVE AVERAGE. TEMPERATURES WELL IN THE 90S WILL
BE COMMON, AND A HANDFUL OF RECORD HIGHS ARE POSSIBLE BUT CURRENTLY
DO NOT LOOK TO BE WIDESPREAD. RECENT MODEL TRENDS CONTINUE TO
FAVOR SOME WARMER THAN AVERAGE TEMPERATURES TO MOVE INTO THE
NORTHEAST AS THE WEEK PROGRESSES. INITIALLY COOLER THAN AVERAGE
TEMPERATURES IN THE NORTHWEST LOOK TO MODERATE AS THE WEEK
PROGRESSES.
JACKSON/HAMRICK
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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