737
FXUS02 KWBC 141900
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SAT JUN 14 2025
VALID 12Z TUE JUN 17 2025 - 12Z SAT JUN 21 2025
...MULTI-DAY EXCESSIVE RAINFALL/FLASH FLOODING AND SEVERE WEATHER
THREAT FOR THE NORTH-CENTRAL U.S./MIDWEST THROUGH NEXT MIDWEEK...
..SOUTHWEST U.S. TO SOUTH/SOUTHEAST U.S. HEAT THREAT NEXT WEEK
..GENERAL OVERVIEW
SIGNIFICANT SEVERE WEATHER AND EXCESSIVE RAINFALL/FLASH FLOODING
THREATS WILL SPREAD ACROSS THE NORTH-CENTRAL U.S./MIDWEST EARLY TO
MID NEXT WEEK AND INTO LATER NEXT WEEK OVER THE EAST AS UPPER-
LEVEL TROUGH ENERGIES INTERSECT AND OVERRIDE WAVY FRONTAL AND WARM
SECTOR BOUNDARIES WITH ENHANCED POOLED MOISTURE AND INSTABILITY.
HIGH HEAT WILL LINGER OVER THE SOUTHWEST INTO NEXT WEEK, WITH A
PROTRACTED PERIOD OF HOT/MUGGY CONDITIONS ON TAP FOR THE SOUTH-
CENTRAL TO THE SOUTHEAST U.S. THROUGH MID-LATER NEXT WEEK. THERE IS
ALSO SOME SIGNAL FOR AN INCREASE IN TROPICAL MOISTURE AND RAINFALL
INTO SOUTH TEXAS AND WESTERN GULF COAST BY NEXT WEEKEND.
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE CONTINUES TO INDICATE THAT A HIGHLY UNSETTLED AND ACTIVE
ZONAL FLOW PATTERN WILL CONTINUE INTO EARLY TO MID NEXT WEEK WITH
MULTIPLE SHORT-WAVE TROUGH ENERGIES TRAVERSING THE CENTRAL/EASTERN
U.S. KEEPING UNSETTLED WEATHER IN THE FORECAST, BUT WITH LESS
SPECIFICITY IN LOCAL DETAILS. UPSTREAM, A DEEP UPPER-LOW OVER THE
NORTHEASTERN PACIFIC LOOKS TO BE THE SOURCE FOR ADDITIONAL UPPER-
WAVES INCLUDING ONE THAT WILL TRAVERSE THE CONUS MIDWEEK HELPING
TO DENT UPPER RIDGING OVER THE SOUTHWESTERN TO SOUTH-CENTRAL U.S..
BY LATE WEEK, GUIDANCE ALSO CONTINUES TO AGREE THERE WILL BE A
SHIFT TO A MUCH MORE AMPLIFIED PATTERN FOLLOWING THE PROGRESSION OF
THE NOTED UPPER-WAVE TO THE EAST COAST, WITH A STRONGER UPPER-
RIDGE BEGINNING TO BUILD/EXPAND NORTHWARD OVER THE SOUTHWESTERN TO
CENTRAL U.S. IN ITS WAKE WHILE THE UPPER-LOW OVER THE NORTHEASTERN
PACIFIC BEGINS TO SHIFT SOUTHWARD AND OVERSPREAD PORTIONS OF THE
NORTHWESTERN U.S. AND THE WEST COAST, EVENTUALLY LEADING TO AN
AMPLIFIED UPPER TROUGH DUG INTO THE WEST NEXT WEEKEND. A NORTHWARD
SHIFT OF THE STORM TRACK SHOULD BEGIN TO TREND DOWN PRECIPITATION
CHANCES OVER MUCH OF THE CENTRAL/EASTERN U.S. FOR THIS TIMEFRAME.
THERE IS UNCERTAINTY REGARDING A POTENTIAL INFLUX OF TROPICAL
MOISTURE/RAINFALL INTO SOUTH TEXAS AND THE WEST GULF COAST NEXT
WEEKEND. THE 06/12 UTC GFS RUNS HAVE TRENDED MUCH DRIER THAN PRIOR
GFS RUNS, MORE IN LINE WITH RECENT ECMWF RUNS, BUT THE 00/12 UTC
CANADIAN ARE NOW COPIOUSLY WETTER THAN YESTERDAYS RUNS. WPC QPF
HAS AGAIN BEEN MANUALLY ADJUSTED WAY DOWNWARD VERSUS THE NATIONAL
BLEND OF MODELS FOR NEXT WEEKEND GIVEN COLLABORATION WITH THE NHC
THAT DOES NOT DENOTE ANY ORGANIZED FEATURES AT THIS TIME.
ACCORDINGLY, THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY
DERIVED FROM A COMPOSITE BLEND OF REASONABLY WELL CLUSTERED
GUIDANCE FROM THE 06 UTC GFS/AIFS AND 00 UTC ECMWF/UKMET/CANADIAN
MODELS ALONG WITH COMPATIBLE NATIONAL BLEND OF MODELS AND WPC
CONTINUITY FOR TUESDAY INTO THURSDAY. RELIED UPON A BLEND OF THE
GFS/ECMWF AND GEFS/ECMWF/CANADIAN ENSEMBLE MEANS FOR LATER NEXT
WEEK. THE WPC BLENDED SOLUTIONS HAVE GOOD ENSEMBLE AND MACHINE
LEARNING MODEL SUPPORT AND SEEM IN LINE LATEST 12 UTC GUIDANCE.
..WEATHER/HAZARDS HIGHLIGHTS
OVERALL, IT GENERALLY STILL REMAINS THE CASE THAT HIGHLY UNSETTLED
WEATHER WILL REMAIN IN THE FORECAST ACROSS MUCH OF THE
CENTRAL/EASTERN U.S. THROUGH AT LEAST THE MIDDLE OF NEXT WEEK AS
NUMEROUS EMBEDDED IMPULSES IN THE UPPER- LEVELS OVERRIDE FRONTAL
BOUNDARIES WITH SEASONABLE MOISTURE IN PLACE. UNCERTAINTY REMAINS
WITH THE SPECIFIC DAY-TO-DAY DETAILS GIVEN THE SHORT-WAVE ENERGIES,
FRONTAL PLACEMENT, AND LIKELY MESOSCALE BOUNDARIES FROM PRIOR
DAYS' STORMS DRIVING NEW DEVELOPMENT EACH DAY. HOWEVER, A MORE
FOCUSED CORRIDOR IS APPARENT ACROSS THE CENTRAL/NORTHERN PLAINS
INTO THE UPPER MIDWEST WITH DAILY STRONG TO SEVERE THUNDERSTORM
CHANCES ALONG A COUPLE FRONTAL BOUNDARIES. ON DAY 4, TUESDAY, QPF
IN THE GUIDANCE SHOWS THE POTENTIAL FOR LOCALLY HEAVY, MULTI-INCH
RAINFALL TOTALS WITH WIDESPREAD/POTENTIALLY ORGANIZED CONVECTION,
AND A SLIGHT RISK ERO IS IN PLACE ACROSS PORTIONS OF THE MIDDLE
MISSOURI VALLEY INTO THE UPPER-MID MISSISSIPPI VALLEY. THIS REGION
WILL HAVE ALSO EXPERIENCED SEVERAL DAYS OF RAINFALL PRIOR TO THE
DAY 4 PERIOD, SO ANTECEDENT CONDITIONS SHOULD REMAIN WET. SOME
ADDITIONAL AREAL ADJUSTMENTS MAY BE NECESSARY, PARTICULARLY ON THE
SOUTHERN END. THEN, ON DAY 5, WEDNESDAY, THE FOCUS SHOULD SHIFT A
BIT EASTWARD FROM THE UPPER MISSISSIPPI VALLEY INTO THE GREAT LAKES
REGION AND A MARGINAL RISK ERO REMAINS. QPF IN THE MODEL GUIDANCE
AND A CONTINUED FAVORABLE PATTERN FOR ORGANIZED CONVECTIVE
DEVELOPMENT SUGGEST THAT A LOCALIZED HIGHER THREAT IS POSSIBLE, BUT
GREATER UNCERTAINTY IN THE LOCATION/AREAL COVERAGE OF THIS THREAT
AS WELL AS LESS SENSITIVE ANTECEDENT CONDITIONS COMPARED TO THE
PRIOR DAY PRECLUDE HIGHER PROBABILITIES AT THIS TIME. IN ADDITION
TO HEAVY RAINFALL/FLASH FLOODING, THE STORM PREDICTION CENTER HAS
ALSO HIGHLIGHTED PORTIONS OF THE CENTRAL PLAINS ON TUESDAY AND THE
UPPER MISSISSIPPI VALLEY WEDNESDAY FOR A SEVERE WEATHER RISK AS
SEASONABLY STRONG INSTABILITY AND SUFFICIENT SHEAR WILL BRING THE
THREAT FOR LARGE HAIL AND DAMAGING WINDS, PARTICULARLY WITH ANY
ORGANIZED CONVECTIVE SYSTEMS. EXPECT THE FOCUS FOR STORMS TO SHIFT
SOUTH AND EASTWARD THURSDAY- SATURDAY WITH EASTWARD MOVEMENT OF
UPPER- TROUGHING/ASSOCIATED SURFACE FRONTAL BOUNDARIES AND UPPER-
LEVEL RIDGING BEGINNING TO BUILD IN OVER THE CENTRAL U.S, THOUGH
SOME ADDITIONAL SHORTWAVE ENERGY COULD BRING RENEWED PRECIPITATION
CHANCES TO THE MIDWEST. A SIGNAL ALSO REMAINS FOR AN ENHANCED
TROPICAL MOISTURE FEED FROM THE GULF TO NORTHEAST MEXICO AND SOUTH
TEXAS/WEST GULF COAST NEXT WEEKEND TO MONITOR FOR SIGNS OF SYSTEM
DEVELOPMENT OUT FROM THE BAY OF CAMPECHE/VICINITY WITH THE
POTENTIAL FOR HEAVY RAINFALL. THE APPROACH OF AN UPPER-LOW/PACIFIC
SYSTEM LOOKS TO BRING SOME INCREASING PRECIPITATION CHANCES TO THE
PACIFIC NORTHWEST AND OVER THE WEST LATE NEXT WEEK/WEEKEND.
EXPECT ABOVE AVERAGE TEMPERATURES ACROSS THE INTERMOUNTAIN WEST
AND ADJACENT PORTIONS OF THE PLAINS AND SOUTHWEST TO GENERALLY
PERSIST THROUGH NEXT WEEK AS AN AMPLIFYING PATTERN WILL SUPPORT
BROADENING UPPER-RIDGING FOLLOWING THE PASSAGE OF AN UPPER-WAVE
EARLIER IN THE WEEK. SOME MORE LOCALLY INTENSE HEAT WILL CONTINUE
ACROSS PORTIONS OF THE SOUTHWEST INTO THE SOUTHERN HIGH PLAINS/WEST
TEXAS THROUGH AT LEAST TUESDAY AS HIGHS RISE INTO THE LOW TO
MID-100S. SUMMER- LIKE TEMPERATURES/MUGGY CONDITIONS WILL EXPAND
FROM THE PLAINS EAST THROUGH THE MISSISSIPPI/OHIO VALLEYS AND INTO
THE SOUTHEAST/MID- ATLANTIC AHEAD OF AN UPPER-WAVE/COLD FRONT. THE
MOST INTENSE HEAT WILL LIKELY FOCUS ALONG THE GULF COAST, THE LOWER
MISSISSIPPI VALLEY, AND ALONG THE EASTERN SEABOARD NORTH THROUGH
THE CAROLINAS AND INTO THE SOUTHERN MID- ATLANTIC, WITH HEAT
INDICES GREATER THAN 105 EXPECTED. THE COLD FRONT PASSAGE MAY BRING
SOME RELATIVELY MORE COMFORTABLE CONDITIONS FROM THE OHIO VALLEY
EAST INTO CAROLINAS/MID-ATLANTIC LATE NEXT WEEK/WEEKEND. HIGHS WILL
BEGIN TO TREND RELATIVELY COOLER AND BELOW AVERAGE ACROSS PORTIONS
OF THE NORTHWEST AND POSSIBLY FURTHER SOUTH ALONG THE WEST COAST
BY LATE NEXT WEEK/WEEKEND AS AN UPPER-LOW FROM THE NORTHEAST
PACIFIC BEGINS TO OVERSPREAD THE REGION.
PUTNAM
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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