266
FXUS02 KWBC 230658
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 AM EDT WED APR 23 2025
VALID 12Z SAT APR 26 2025 - 12Z WED APR 30 2025
..WEST/ROCKIES TO CENTRAL U.S. SPRING STORM
..OVERVIEW
ORGANIZED SHOWERS AND THUNDERSTORMS WITH LOCALLY HEAVY DOWNPOURS
WILL FOCUS WITH WRAPPED FLOW ACROSS THE NORTHEAST INTO THE WEEKEND
AS A DEEPLY WAVY FRONTAL SYSTEM MOVES OVER AND OFFSHORE.
MEANWHILE, UNSETTLING AND COOLING UPPER TROUGHING WILL MOVE FROM
ACORSS THE WEST AND PRODUCE WIDESPREAD MODERATE PRECIPITATION.
EXPECT ENHANCED SNOW FOR HIGHER ELEVATIONS FROM THE CASCADES DOWN
TO THE SIERRA AND INLAND TO THE NORTH-CENTRAL INTERMOUNTAIN
WEST/ROCKIES THIS WEEKEND, WITH ROCKIES ACTIVITY ENHANCED BY LEE
CYCLOGENESIS AND FRONTOGENESIS INTO EARLY NEXT WEEK. DEEP MOIST
INFLOW AHEAD OF THE UPPER TROUGH AND DEVELOPING STORM SYSTEM WILL
SIGNIFICANTLY INCREASE A SPREAD OF RAINS AND STRONG THUNDERSTORMS
ACROSS THE CENTRAL TO EAST CENTRAL U.S. INTO EARLY-MID NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL AND ENSEMBLE FORECAST SPREAD REMAINS REASONABLE FOR MOST
SYSTEMS WITHIN A BROADLY SIMILAR LARGER SCALE PATTERN EVOLUTION,
ALBEIT WITH CONTINUED UNCERTAINTIES WITH WAVE TIMING AND LOCAL
CONVECTION FOCI. THERE IS STILL A GROWING SIGNAL FAVORING FLOW
AMPLITUDE AND ENERGETIC MAIN SYSTEM CYCLOGENESIS AND FRONTOGENESIS.
ACCORDINGLY, THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY
DERIVED FROM A BROAD COMPOSITE BLEND OF BEST CLUSTERED GUIDANCE
FROM THE 18 UTC GFS/GEFS MEAN AND THE 12 UTC ECMWF/UKMET/CANADIAN
AND ECMWF ENSEMBLE MEANS ALONG WITH A COMPATIBLE 01 UTC NATIONAL
BLEND OF MODELS. THIS PLAN MAINTAINS GOOD WPC PRODUCT CONTINUITY,
GENERALLY IN LINE WITH RECENT MACHINE LEARNING GUIDANCE AND LATEST
AVAILABLE 00 UTC MODEL AND ENSEMBLE GUIDANCE.
..WEATHER/HAZARDS HIGHLIGHTS
SLOWLY PROGRESSIVE UPPER SHORTWAVES WITH WAVY SURFACE SYSTEMS
REMAIN SLATED TO BRING SOME CONCENTRATED ENHANCED RAINS OVER THE
NORTHEAST INTO SATURDAY, WITH TRAILING FRONTAL CONVECTIVE ACTIVITY
TO THE SOUTH SWEEPING THROUGH AND EXITING THE EASTERN SEABOARD. A
WPC DAY 4/SATURDAY EXCESSIVE RAINFALL OUTLOOK (ERO) MARGINAL RISK
AREA IS IN PLACE OVER THE NORTHEAST MID-ATLANTIC AND NEW ENGLAND.
MEANWHILE, AMPLIFIED UPPER TROUGH AND SURFACE SYSTEM DRIVE OVER
THE WEST THIS WEEKEND OFFERS WIDESPREAD RAINS AND ENHANCED SNOWS
FOR HIGHER ELEVATIONS FROM THE CASCADES DOWN TO THE SIERRA AND
INLAND OVER THE NORTH-CENTRAL INTERMOUNTAIN WEST. NORTH-CENTRAL
ROCKIES SNOW THREATS RAMP INTO NEXT WEEK WITH CONTINUED STORM
GENESIS. THE WPC WINTER WEATHER OUTLOOK AS LINKED BELOW ALONG WITH
OTHER WPC PRODUCTS DEPICTS THE MOST LIKELY MOUNTAIN LOCATIONS.
DOWNSTREAM, RETURN MOISTURE STREAMING IN AHEAD OF DEEP SYSTEM
GENESIS WILL FUEL ROUNDS OF HEAVY RAIN AND THUNDERSTORMS ACROSS
PORTIONS OF THE CENTRAL U.S. FROM THE WEEKEND INTO NEXT WEEK. A
MARGINAL RISK ERO AREA FOR DAY 4/SATURDAY INCLUDES PORTIONS OF
TEXAS AND OKLAHOMA AND A LARGE PORTION OF KANSAS GIVEN FAVORABLE
UPPER TROUGH DIFFLUENCE COMBINED WITH FRONT/DRYLINE INSTABILITIES.
WHILE NO WPC DAY 5/SUNDAY RISK AREA WAS INTRODUCED AT THIS TIME
DUE TO COVERAGE/LOCAL UNCERTAINTIES, SCATTERRED CONVECTIVE
DOWNPOURS BOTH OVER THE NORTHERN PLAINS AND DOWN OVER THE SOUTH-
CENTRAL PLAINS WILL BE MONITORRED FOR A MORE DEFINED GUIDANCE
SIGNAL TO ISSUE AN ERO UPGRADE. ACTIVITY WILL BE IN THE PROCESS OF
INCREASINGLY TRANSFORMING INTO AN EMERGING COMMA-SHAPED RAINFALL
AREA BROADLY PROGRESSING OVER THE CENTRAL U.S. AND THEN INTO SOME
MOISTURE LADEN SOILS OF THE EAST-CENTRAL U.S. EARLY-MID NEXT WEEK
GIVEN FURTHER SURFACE LOW AND WAVY FRONTAL STRUCTURE DEVELOPMENT
AND EVOLUTION. EPISODES OF SEVERE WEATHER WILL ALSO CONTINUED TO BE
MONITORRED BY SPC AS PREDICTABILITY GROWS CLOSER TO THE EVENT.
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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