257
FXUS02 KWNH 290723
PREEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
322 AM EDT THU MAY 29 2025
VALID 12Z SUN JUN 01 2025 - 12Z THU JUN 05 2025
..PATTERN OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
A COMPLEX MULTI-STREAM FLOW PATTERN INTO NEXT WEEK IS PROVING
DIFFICULT TO DECIPHER DESPITE SIMILARITIES IN RECENT GUIDANCE WITH
THE LARGER SCALE FLOW EVOLUTION. THE MODELS AND MACHINE LEARNING
MODELS INCREASINGLY VARY OVER TIME WITH INTERACTIONS OF SMALL-MID
SCALE SYSTEMS TENDING TO DIG INTO OVERALL LARGER SCALE UPPER TROUGH
POSITIONS OVER THE WEST AND SHIFTING JUST OFF THE EAST COAST TO
INCLUDE POTENTIAL FOR A SEPARATED CLOSED LOW. WHILE LATITUDINAL
PLACEMENT OF A LOW IS QUITE VARIED IN GUIDANCE, DEVELOPMENT SEEMS
REASONABLE GIVEN AMPLIFIED/WARMING UPPER RIDGING SANDWICHED
UPSTREAM OVER THE CENTRAL TO EAST-CENTRAL U.S.. GIVEN UNCERTAINTY
OVER MUCH OF THE DOMAIN, BUT CONSIDERING SYSTEM POTENTIAL, OPTED
TO LEAN ON A GEFS/ECMWF/CANADIAN ENSEMBLE MEAN BLEND ACROSS THE
DOMAIN THAT OFFERS DECENT SYSTEM DEFINITION WHILE MAINTAINING MAX
WPC PRODUCT CONTINUITY, ALL PENDING BETTER FORECAST CLUSTERING.
..WEATHER/HAZARDS HIGHLIGHTS
A SERIES OF SHORTWAVES WILL CONTINUE TO DIG INTO AN AMPLIFIED
UPPER TROUGH WORKING SLOWLY OFF THE EAST COAST AND POTENTIALLY
DEVELOPING A SEPARATED CLOSED LOW. A WAVY TRAILING FRONT WILL
SETTLE NEARBY FROM THE WESTERN ATLANTIC SOUTHWESTARD TO THE GULF.
WHILE UNCERTAIN LOWS COULD ACT TO BRING SOME ACTIVITY INTO COASTAL
AREAS UP THE SEABOARD SUNDAY AND INTO NEXT WEEK, PARTICULAR RUNOFF
ISSUES MAY DEVELOP WITH TIME FOR SOUTH FLORIDA URBAN AREAS GIVEN
DEEPEST LOWER LATITUDE MOISTURE AVAILABILIY AND SUPPORT TO MONITOR.
GUIDANCE CONTINUES TO OVERALL FAVOR UPPER TROUGH AMPLIFICATION WITH
MULTIPLE SYSTEMS INTO THE WEST ALONG WITH LEAD EJECTION OF A
ACTIVTY FOCUSING SOUTHERN STREAM CLOSED SYSTEM FROM OFFSHORE BAJA
THROUGH THE SOUTHWEST INTO THE ROCKIES. THIS TRANSITION WILL ACT
TO PROVIDE RELIEF FROM WEEKEND HEAT OVER PORTIONS OF THE WEST WITH
THE BUILDING OF A MUCH MORE UNSETTLED AND INCREASINGLY WET FLOW
PATTERN FARTHER INLAND AND DOWNSTREAM OVER THE INTERMOUNTAIN WEST
AND ESPECIALLY THE NORTHERN ROCKIES THROUGH MIDWEEK. DESPITE THE
CALENDAR FLIPPING INTO JUNE, THIS PATTERN WILL SUPPORT SOME THREAT
FOR ENHANCED MOUNTAIN SNOW IN THE HIGHEST ELEVATIONS OF THE
NORTHERN ROCKIES. FABORABLE UPPER SUPPORT AND FRONTAL TRANSLATION
ALONG WITH DOWNSTREAM CYCLO/FRONTOGENESIS OVER THE PLAINS INTO NEXT
WEEK SHOULD ALSO ACT TO ENHANCE NORTHERN ROCKIES TO NORTHERN
PLAINS PRECIPITATION AND EMERGING CONVECTIVE PATTERN TO DEVELOP
OVER THE NORTH-CENTRAL U.S. DURING NEXT WEEK.
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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