543
FXUS02 KWBC 220621
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
221 AM EDT WED APR 22 2026
VALID 12Z SAT APR 25 2026 - 12Z WED APR 29 2026
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE REMAINS IN FAIRLY GOOD AGREEMENT THROUGH DAY 5,
PARTICULARLY WITH RESPECT TO THE EVOLUTION OF THE WESTERN TROUGH
AND DOWNSTREAM SURFACE CYCLONE. THE LATEST RUNS OF THE
DETERMINISTIC GUIDANCE SHOW REASONABLE CLUSTERING ON THE TIMING AND
TRACK OF THE SYSTEM, THOUGH THE GFS REMAINS A BIT FASTER AND
SLIGHTLY MORE PROGRESSIVE WITH THE COLD FRONT. THE ENSEMBLES
CONTINUE TO SUPPORT A GOOD CONSENSUS APPROACH, ESPECIALLY AFTER DAY
5, WHERE SPREAD INCREASES REGARDING THE AMPLITUDE AND TIMING OF
THE PACIFIC ENERGY MOVING TOWARDS THE WESTERN U.S. OVERALL, THE
FORECAST MAINTAINED A MULTI-MODEL BLEND WITH THE
GFS/ECMWF/UKMET/CANADIAN MODELS, WHILE INCORPORATING THE
GEFS/ECMWF/CANADIAN ENSEMBLE MEANS LATER IN THE PERIOD TO SMOOTH
OUT SOME OF THE SMALLER SCALE DIFFERENCES.
..WEATHER/HAZARDS HIGHLIGHTS
THE UPPER LOW AND TROUGH OVER THE NORTHERN HIGH PLAINS WILL
GRADUALLY LIFT AND SETTLE INTO SOUTH-CENTRAL CANADA BY THE WEEKEND,
CARRYING MULTIPLE EMBEDDED SHORTWAVES ROTATING AROUND THE BASE OF
THE TROUGH. THIS WILL CONTINUE TO BRING PERIODS OF LOW ELEVATION
RAIN AND MOUNTAIN SNOW, WITH LOCALLY HEAVIER PRECIPITATION POSSIBLE
ALONG FAVORED TERRAIN OVER THE INTERMOUNTAIN WEST, ROCKIES, AND
INTO THE PLAINS. MOST ACCUMULATING SNOW WILL PRIMARILY BE CONFINED
TO HIGHER ELEVATIONS, WITH MAIN IMPACTS LIMITED TO HIGH MOUNTAIN
PASSES AND MOUNTAIN TOWNS, ALBEIT SPILLING INTO THE NORTHERN HIGH
PLAINS. IN ADDITION, STRONG GUSTY WINDS ARE EXPECTED ACROSS PARTS
OF THE SOUTHWEST, ROCKIES, AND THE PLAINS.
THIS PACIFIC SYSTEM WILL SUPPORT AN EASTWARD PROJECTION OF A
SURFACE LOW AND COLD FRONT ACROSS THE MISSISSIPPI VALLEY INTO THE
EAST THROUGH THE WEEKEND. INCREASING SOUTHERLY FLOW AHEAD OF THE
SYSTEM WILL SUPPORT ROBUST MOISTURE TRANSPORT FROM THE GULF. THIS
MOISTURE COMBINED WITH FAVORABLE UPPER-LEVEL FORCING AND
INSTABILITY, WILL PROMOTE A BROAD AREA OF SHOWERS AND THUNDERSTORMS
ACROSS CENTRAL/SOUTHERN U.S. INTO EASTERN U.S. ORGANIZED HEAVY
RAINFALL AND WIDE SPREAD CLUSTERS OF STRONG TO SEVERE THUNDERSTORMS
WILL EXTEND FROM PARTS OF THE SOUTH- CENTRAL PLAINS INTO THE UPPER
MIDWEST FROM SUNDAY INTO MONDAY AND THE OHIO VALLEY INTO PARTS OF THE
SOUTHEAST ON TUESDAY, WHERE TRAINING CONVECTION MAY DEVELOP ALONG
THE FRONT. THE POTENTIAL FOR LOCALLY HEAVY RAINFALL AND ISOLATED
FLASH FLOODING OVER PARTS OF SOUTH-CENTRAL PLAINS AND MID-LOWER
MISSISSIPPI VALLEY IS HIGHLIGHTED BY A MARGINAL RISK AREA IN DAY
4/SATURDAY AND DAY 5/SUNDAY EXCESSIVE RAINFALL OUTLOOK (ERO).
PERSISTENT UPPER TROUGHING OVER THE WEST WILL MAINTAIN A COOL AND
UNSETTLED WEATHER PATTERN, PARTICULARLY ACROSS THE PACIFIC
NORTHWEST, NORTHERN CALIFORNIA, AND THE NORTHERN/CENTRAL ROCKIES
THROUGH THE WEEKEND AND INTO THE NEXT WEEK. THE PATTERN WILL BRING
ROUNDS OF PRECIPITATION, WITH THE HEAVIEST TOTALS FAVORED ALONG
COASTAL RANGES AND WINDWARD MOUNTAIN SLOPES. LOWER ELEVATION WILL
PRIMARILY FALL AS RAIN, WHILE HIGHER ELEVATION WILL SEE PERIODS OF
LATE- SEASON MOUNTAIN SNOW AS POST- FRONTAL COLD AIR FILTERS DOWN
INTO THE WEST. ANOTHER SOUTHERN STREAM OF PACIFIC ENERGY WILL
APPROACH THE WEST COAST, WHICH MAY REINVIGORATE ANOTHER ROUND OF
WIDESPREAD RAIN/MOUNTAIN SNOWS ALONG/NORTH OF THE MAIN SYSTEM TRACK
FROM THE GREAT BASIN TO THE ROCKIES, LINGERING THERE INTO EARLY
NEXT WEEK.
AS THE PRIMARY LOW DEEPENS AND TRACKS FROM THE CENTRAL PLAINS
TOWARDS THE UPPER MIDWEST AND GREAT LAKES BY MONDAY, A BROAD REGION
OF PRECIPITATION AND STRONG GUSTY WINDS WILL DEVELOP NORTH AND
WEST OF THE LOW AND FRONTAL SYSTEM. THE SYSTEM WILL BRING CHANCES
FOR A MIX OF STRATIFORM RAIN AND EMBEDDED CONVECTION WITH PERIODS
OF ENHANCED RAINFALL ALONG CENTRAL AND EASTERN U.S.
ABOVE NORMAL TEMPERATURES ACROSS THE SOUTHERN PLAINS, SOUTHEAST,
MID- ATLANTIC AND GREAT LAKES WILL PERSIST AHEAD OF THE COLD FRONT
UNTIL TUESDAY WHEN THE UPPER GREAT LAKES TRANSITION TO COOLER
TEMPERATURES. MEANWHILE, BELOW AVERAGE TEMPERATURE CONTINUE FOR
MUCH OF THE WEST AND NORTHERN/CENTRAL PLAINS UNDER THE TROUGHING
THROUGH MONDAY. MODERATE TEMPERATURES ACROSS THE CENTRAL U.S.
RETURN ON TUESDAY.
OUDIT
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, EXCESSIVE RAINFALL OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY MESSAGES ARE AT:
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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