827
FXUS02 KWBC 230656
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
256 AM EDT FRI MAY 23 2025
VALID 12Z MON MAY 26 2025 - 12Z FRI MAY 30 2025
...LINGERING HEAVY RAIN AND FLASH FLOODING THREATS TO FOCUS ACROSS
THE SOUTH INTO EARLY NEXT WEEK...
..GUIDANCE/PREDICTABILITY ASSESSMENT
RECENT MODELS HAVE OFFERED A REASONABLY SIMILAR MID-LARGER SCALE
PATTERN EVOLUTION VALID FOR EARLY NEXT WEEK DESPITE COMPLEX AND
SLOWLY TRANSITIONAL FLOW. BEST CLUSTERED GUIDANCE OF THE 18 UTC GFS
AND 12 UTC ECMWF/CANADIAN HAVE GOOD ENSEMBLE AND MACHINE LEARNING
MODEL SUPPORT, AND A COMPOSITE BLEND SEEMS TO MITIGATE MUCH OF THE
SMALLER SCALE SYSTEM AND WEATHER FOCUS DETAILS AS CONSISTENT WITH
INDIVIDUAL PREDICTABILITY. FORECAST SPREAD CHARACTERISTICALLY
INCREASES THROUGH MID-LATER NEXT WEEK, BUT A BLEND OF BEST
CLUSTERED GUIDANCE OF THE 12 UTC ECMWF/NAEFS ENSEMBLE MEANS AND 12
UTC ECMWF MAINTAINS DECENT WPC PRODUCT CONTINUITY IN LINE WITH
LATEST 00 UTC GUIDANCE TRENDS THROUGH THESE LONGER TIME FRAMES.
..WEATHER/HAZARDS HIGHLIGHTS
A WET AND WAVY WEST-EAST ORIENTED FRONT WILL BE WELL IN PLACE OVER
THE SOUTH MEMORIAL DAY. MOISTURE AND INSTABILITY IN PLACE WILL
FUEL ACTIVITY WITH HEAVY RAIN RATES IN AREAS LIKELY TO RECEIVE
PRECURSOR SHORT RANGE RAINS TO MOISTEN SOILS. THE DAY 4/MONDAY WPC
EXCESSIVE RAINFALL OUTLOOK (ERO) STILL SHOWS A MARGINAL RISK AREA
FROM EASTERN TEXAS TO THE SOUTHERN APPALACHIANS. WITHIN THIS AREA,
A SLIGHT RISK AREA HAS BEEN INTRODUCED FROM FAR NORTHEAST TEXAS
THROUGH CENTRAL TENNESSEE AND NORTHERN ALABAMA GIVEN AN INCREASING
FAVORABLE GUIDANCE FOCUS, INCLUDING INSTABILITY/RIGHT ENTRANCE
REGION UPPER JET SUPPORT. BY TUESDAY INTO WEDNESDAY, THE EVENTUAL
DOMINANT LOW ON THE FRONTAL SYSTEM SHOULD LIFT NORTHEAST TOWARD THE
APPALACHIANS AND ONWARD TO BRING LOCALIZED HEAVY RAIN TO PORTIONS
OF THE EASTERN SEABOARD, ESPECIALLY THE MID-ATLANTIC, WHILE THE
TRAILING FRONT LINGERS TO FOCUS SHOWERS AND STORMS ACROSS THE
SOUTH. A WPC DAY 5 ERO MARGINAL RISK AREA WAS INTRODUCED FOR THIS
ELONGATED THREAT AREA GIVEN STILL DEEP MOISTURE AND UPPER SUPPORT.
FARTHER NORTH, THE INITIAL TROUGH SHOULD PRODUCE SOME MODEST
PRECIPITATION IN THE CENTRAL ROCKIES (EVEN SOME SNOW IN THE HIGHEST
PEAKS), WITH MODERATE CONVECTION OVER THE NORTHERN/CENTRAL PLAINS
EARLY NEXT WEEK. THE FRONTAL BOUNDARY CURLING BACK INTO THE
SOUTHERN/CENTRAL ROCKIES AND HIGH PLAINS COULD HELP PRODUCE
SCATTERED CONVECTION THERE NEXT WEEK AS WELL. MEANWHILE, ROUNDS OF
FRONTS COMING THROUGH THE PACIFIC NORTHWEST COULD ALLOW FOR LIGHT
TO MODERATE PRECIPITATION. SUMMERTIME SCATTERED STORMS ARE ALSO
LIKELY ACROSS THE FLORIDA PENINSULA.
HOT WEATHER WILL PARTICULARLY LINGER INTO MONDAY FOR PARTS OF
TEXAS. TEMPERATURES FROM WELL INTO THE 90S TO TRIPLE DIGITS WILL
FOCUS AREAS OF MAJOR HEATRISK IN SOUTHERN TEXAS. MEANWHILE, COOLER
THAN NORMAL TEMPERATURES BY 5 TO 15 DEGREES WILL TAKE HOLD OVER
THE NORTH-CENTRAL TO EASTERN U.S. INTO EARLY NEXT WEEK UNDERNEATH
UPPER TROUGHING. THE TROUGH AND FRONT PRESSING SOUTH WILL ALLOW FOR
TEMPERATURES TO COOL IN THE SOUTHERN TIER MONDAY AND TUESDAY. THE
COOLER TEMPERATURES SHOULD GRADUALLY MODERATE CLOSER TO NORMAL AS
NEXT WEEK PROGRESSES. BUT IN THE WEST, A BUILDING UPPER RIDGE WILL
LEAD TO WARMER THAN AVERAGE TEMPERATURES BY 10 TO 20 DEGREES FOR
SEVERAL DAYS SPREAD FROM THE GREAT BASIN TO THE WEST/NORTHWEST.
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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