083
FXUS02 KWBC 140800
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 AM EDT SUN SEP 14 2025
VALID 12Z WED SEP 17 2025 - 12Z SUN SEP 21 2025
..OVERVIEW
A BLOCKY/SLOW MOVING UPPER AIR PATTERN DEVELOPS OVER NORTH AMERICA
BY MIDWEEK WITH RIDGING OVER THE MOUNTAIN WEST AND MIDWEST WITH
TROUGHING OVER THE WEST COAST, NORTH-CENTRAL STATES, AND NORTHEAST
LINGERING INTO THIS WEEKEND. WETTER THAN NORMAL CONDITIONS CAN BE
EXPECTED MIDWEEK OVER THE MID-ATLANTIC, SOUTH FLORIDA, MUCH OF THE
GREAT PLAINS INTO THE MIDWEST, AND THE DESERT SOUTHWEST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
00Z GLOBAL GUIDANCE SUITE AGREES ON A BLOCKED PATTERN FROM A RIDGE
SHIFTING OVER CENTRAL CANADA WEDNESDAY TO FRIDAY WHICH MAINTAINS
SLOW MOVING TROUGHS OVER THE WEST COAST, NORTH-CENTRAL STATES
(CLOSED LOW THERE) AND OVER THE NORTHEAST. THE WEDNESDAY LOW
ALONG/OVER THE MID-ATLANTIC COAST IS IN MUCH BETTER AGREEMENT (EX-
AIFS WAS FIRST TO DEPICT IT HUGGING THE COAST AND BRINGING AMPLE
RAINFALL) AND THE CLOSED LOW TRACKING FROM THE DAKOTAS THURSDAY TO
IOWA BY SATURDAY. ALSO, THERE'S BEEN A TREND FOR THE LOW ALONG THE
CALIFORNIA COAST THURSDAY/FRIDAY TO RETROGRADE OFFSHORE FRIDAY
NIGHT THEN POTENTIALLY SHIFTING BACK TO SHORE (CMC/GFS) OR
CONTINUING OUT TO SEA (EC). THE 00Z UKMET IS A NOTABLE OUTLIER FOR
EASTERN CANADIAN TROUGHING AND THE LOW MOVING TOWARD THE MIDWEST.
A NON-UKMET GENERAL MODEL BLEND OF DETERMINISTIC GUIDANCE IS
REASONABLE THROUGH FRIDAY WITH WEIGHT TOWARD ENSEMBLE SOLUTIONS
THIS WEEKEND GIVEN UNCERTAINTY WITH LOW/TROUGH PLACEMENT.
..WEATHER/HAZARDS HIGHLIGHTS
SOUTHWARD SHIFTING OF THE UPPER TROUGH/LOW DOWN THE DAKOTAS
WEDNESDAY WILL CONTINUE TO BRING ENHANCED GULF MOISTURE UP THE
PLAINS WITH CONVERGENCE AHEAD OF A SLOW MOVING FRONTAL SYSTEM.
AREAS OF HEAVY RAIN ARE LIKELY TO CONTINUE DRIFTING EAST FROM THE
CENTRAL PLAINS TO THE MIDWEST WEDNESDAY/THURSDAY AND WARRANT
MARGINAL EROS FOR BOTH DAYS 4 AND 5. INCREASING MONSOONAL MOISTURE
OVER NEW MEXICO THROUGH THE TEXAS PANHANDLE ON WEDNESDAY WARRANTS
MAINTENANCE OF THE MARGINAL ERO THERE.
NOTABLE PACIFIC MOISTURE SURGE UP CALIFORNIA AND THE LOWER COLORADO
RIVER REGION INTO THE GREAT BASIN IS ON TAP FOR THURSDAY AS THE
UPPER RIDGE AXIS OVER CA EARLY THIS WEEK SHIFTS EAST TO THE
INTERMOUNTAIN WEST. GUIDANCE IS QUITE VARIED IN QPF THERE, BUT
DIURNALLY DRIVEN CONVECTION INITIATING ON TERRAIN WARRANTS A DAY 5
MARGINAL ERO FOR SOUTHERN CA.
A STALLED FRONT OVER THE SOUTHERN FLORIDA PENINSULA PROVIDES FOCUS
FOR MUCH ABOVE NORMAL MOISTURE TO CONVERGE WHICH WARRANTS
MAINTENANCE OF THE DAY 4 MARGINAL ERO. THE FRONT LIKELY SHIFTS
OFF THE PENINSULA THURSDAY, SO NO DAY 5 ERO WAS RAISED FOR FLORIDA
AT THIS TIME.
ELSEWHERE, THE SOUTHWEST RIDGE AXIS SHIFTING EAST TO THE
INTERMOUNTAIN WEST ON WEDNESDAY FOCUSES MORE INTERIOR SOUTHWEST
HEAT LATER THIS WEEK. AN UPPER RIDGE WILL PROMOTE HEAT OVER THE
SOUTHEAST THROUGH LATE IN THE WEEK TEMPERATURES CENTERED ON THE
MIDWEST AND MISSISSIPPI VALLEY THROUGH AT LEAST MID-NEXT WEEK, WITH
ANOMALIES OF 10-15 DEGREES ABOVE AVERAGE. WARMER THAN AVERAGE
TEMPERATURES MOVE FROM THE MIDWEST TO THE NORTHEAST IN THE LATER
HALF OF THE WEEK AS WELL.
JACKSON
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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