988
FXUS02 KWBC 230621
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
221 AM EDT THU APR 23 2026
VALID 12Z SUN APR 26 2026 - 12Z THU APR 30 2026
..OVERVIEW
AN AMPLIFIED AND PROGRESSIVE SPRING PATTERN CONTINUES ACROSS MUCH
OF CONUS AS A SURFACE LOW AND FRONTAL PASSAGE MOVES NORTHEASTWARD
FROM THE CENTRAL PLAINS INTO THE UPPER MIDWEST AND ACROSS EASTERN
U.S., WHICH WILL BRING SHOWERS AND THUNDERSTORMS TO THE AREA
THROUGH NEXT WEDNESDAY. IN ADDITION, TROUGHING OVER THE WEST WILL
SHIFT INLAND, BRING CHANCES FOR LOW ELEVATION RAIN AND MOUNTAIN
SNOW ACROSS THE INTERMOUNTAIN WEST/ROCKIES INTO THE PLAINS.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST DETERMINISTIC MODEL RUNS CONTINUE TO SHOW REASONABLY
GOOD AGREEMENT ON THE LARGER SCALE EVOLUTION THROUGH THE FIRST
PORTION OF THE PERIOD. LATER IN THE PERIOD, THE GFS GUIDANCE SHOWS
A FASTER PROGRESSION WITH THE TROUGH OVER THE THE SOUTH-CENTRAL
CANADA. THE GEFS AND ECENS ENSEMBLE MEANS PROVIDES A STABLE
INTERMEDIATE SOLUTION TO ADDRESS TIMING AND AMPLITUDE DIFFERENCES
OF THE SHORTWAVE ENERGY EMBEDDED WITHIN THE TROUGH OVER THE
NORTHERN TIER, AS WELL AS THE PACIFIC ENERGY OFF THE WEST COAST.
THEREFORE, THE FORECAST LEANS TOWARDS A BLEND OF THE
GFS/ECMWF/UKMET/CANADIAN/EC- AIFS TOWARDS THE START OF THE PERIOD,
WITH INCORPORATING THE GEFS/ECMWF/CANADIAN ENSEMBLE MEANS AFTER
DAY 4.
..WEATHER/HAZARDS HIGHLIGHTS
THE CLOSED UPPER LOW AND TROUGH OVER NORTHERN HIGH PLAINS/SOUTH-
CENTRAL CANADA WILL CONTINUE TO SLOWLY LIFT AND HOVER OVER SOUTHERN
CANADA THROUGH THE PERIOD. THE SYSTEM WILL CARRY MULTIPLE EMBEDDED
SHORTWAVES ROTATING ROUND THE BASE OF THE TROUGH, ALONG WITH
NORTHERN TIER SECONDARY FRONTAL PASSAGES AND CANADIAN HIGH
PRESSURE ONSET. THIS WILL BRING LOWER ELEVATION RAIN AND TERRAIN
ENHANCED SNOW ACROSS PARTS OF THE INTERMOUNTAIN WEST, ROCKIES AND
THE PLAINS. THE TROUGH EXTENDING OFF THE WEST COAST WILL EJECT
SHORTWAVE ENERGY FLOW EASTWARD INTO THE SOUTHWEST THROUGH SUNDAY.
THIS WILL REINVIGORATE A ROUND OF WIDESPREAD RAIN/MOUNTAIN SNOWS
ALONG/NORTH OF THE MAIN SYSTEM TRACK FROM THE GREAT BASIN TO THE
ROCKIES, LINGERING INTO EARLY NEXT WEEK ALONG WITH A THREAT OF
STRONG GUSTY WINDS, ESPECIALLY OVER THE SOUTH- CENTRAL
ROCKIES/HIGH PLAINS.
A STRENGTHENING SURFACE LOW AND FRONTAL BOUNDARY WILL MOVE ACROSS
THE CENTRAL PLAINS/MISSISSIPPI VALLEY INTO THE MIDWEST BY MONDAY,
SERVING AS A FOCUS FOR REPEATED ROUND OF SHOWERS AND THUNDERSTORMS
INTO NEXT WEEK ACROSS THE AREA. STRENGTHENING SOUTHERLY FLOW WILL
TRANSPORT WARM MOISTURE FROM THE GULF INTO THE PLAINS/MIDWEST,
WHICH WILL SUPPORT THE POTENTIAL FOR ORGANIZED CONVECTION AND
CORRIDORS OF LOCALLY MODERATE TO HEAVY RAINFALL. THE COMBINATION OF
LARGE SCALE FORCING AND INCREASING INSTABILITY ALONG THE FRONT WILL
SUPPORT WIDESPREAD CLUSTERS OF STRONG TO SEVERE THUNDERSTORMS WITH
THE POTENTIAL FOR LOCALLY HEAVY RAINFALL AND ISOLATED FLASH
FLOODING OVER PARTS OF PLAINS/MISSISSIPPI VALLEY. THIS FLOOD
THREAT IS HIGHLIGHTED BY A MARGINAL RISK AREA IN THE DAY 4/SUNDAY
EXCESSIVE RAINFALL OUTLOOK (ERO). THE SYSTEM GRADUALLY TRACKS INTO
EASTERN U.S. BY TUESDAY, SHIFTING THE CHANCES FOR HEAVY RAINFALL
AND THUNDERSTORMS OVER PARTS OF SOUTHEAST AND THE OHIO/TENNESSEE
VALLEY. THIS FLOOD THREAT IS HIGHLIGHTED BY A MARGINAL RISK AREA
IN THE DAY 5/MONDAY EXCESSIVE RAINFALL OUTLOOK (ERO). MEANWHILE,
AS THE PRIMARY LOW DEEPENS AND TRACKS FROM THE CENTRAL PLAINS
TOWARDS THE UPPER MIDWEST AND GREAT LAKES EARLY NEXT WEEK, A BROAD
REGION OF PRECIPITATION AND STRONG GUSTY WINDS WILL DEVELOP NORTH
AND WEST OF THE LOW/FRONTAL SYSTEM. THE SYSTEM WILL BRING A MIX OF
ENHANCED STRATIFORM RAIN AND EMBEDDED CONVECTION.
AHEAD OF THE FRONT, ABOVE NORMAL TEMPERATURES ACROSS THE SOUTHERN PLAINS,
SOUTHEAST, MID- ATLANTIC AND GREAT LAKES WILL PERSIST AHEAD OF THE
COLD FRONT UNTIL TUESDAY. 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. ON TUESDAY, PACIFIC NORTHWEST WILL BEGIN
TO TREND SLIGHTLY ABOVE AVERAGE AS A UPPER RIDGE MOVES INTO THE
REGION.
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page