681
FXUS02 KWBC 240704
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
304 AM EDT FRI APR 24 2026
VALID 12Z MON APR 27 2026 - 12Z FRI MAY 01 2026
...A LOW PRESSURE SYSTEM WILL PRODUCE HEAVY RAIN AND SEVERE
WEATHER ACROSS THE EAST-CENTRAL U.S. ON MONDAY...
..OVERVIEW
AN ACTIVE PATTERN CONTINUES ACROSS THE CONUS NEXT WEEK, BEGINNING
WITH A STRENGTHENING LOW PRESSURE SYSTEM THAT IS SET TO BRING HEAVY
RAIN AND SEVERE WEATHER ACROSS PORTIONS OF THE MISSISSIPPI VALLEY
ON MONDAY. AS THE MAIN LOW PUSHES ACROSS THE GREAT LAKES INTO
SOUTHERN CANADA, THE TRAILING COLD FRONT WILL PRESS ACROSS THE EAST
TUESDAY INTO WEDNESDAY AND BRING VARYING RAIN CHANCES THERE. THE
SOUTHERN PORTION OF THE FRONT WILL SAG INTO THE SOUTHEASTERN U.S.
BEFORE STALLING OUT, SUPPORTING NUMEROUS SHOWERS AND STORMS AND
POTENTIALLY ANOTHER HEAVY RAIN RISK. MEANWHILE, A PACIFIC SYSTEM
WILL LIKELY SLIDE ACROSS SOUTHERN CALIFORNIA AND THE SOUTHWEST MID
TO LATE WEEK, BRINGING CHANCES FOR LOW ELEVATION RAIN AND MOUNTAIN
SNOW ACROSS THE INTERMOUNTAIN WEST, ROCKIES, AND PLAINS.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST GUIDANCE HAS A FAIRLY DECENT HANDLE ON THE LARGE SCALE
PATTERN THROUGH MOST OF THE MEDIUM RANGE PERIOD, FEATURING BROAD
TROUGHING FROM THE CENTRAL TO EASTERN U.S., RIDGING OVER THE
PACIFIC NORTHWEST, AND AN UPPER LOW MOVING ACROSS THE SOUTHWEST
U.S. WITH THAT BEING SAID, THE SMALLER SCALE DETAILS REMAIN MORE
UNCERTAIN. THIS IS PARTICULARLY THE CASE WITH THE FORECAST TRACK
AND EVOLUTION OF THE SOUTHWEST UPPER LOW, AS THE TIMING AND
AMPLITUDE OF DOWNSTREAM SHORTWAVES ON THE BACKSIDE OF BROAD UPPER
TROUGHING RESULTS IN SIGNIFICANT RUN-TO-RUN DIFFERENCES OF THE
UPPER LOW'S FORWARD SPEED, POSITIONING, AND SENSIBLE WEATHER.
FOR THIS FORECAST ITERATION, THE COMPOSITE BLEND LEANED ON A
LARGER PERCENTAGE OF THE ECMWF AND GEFS ENSEMBLE MEANS, INCREASING
FROM 40% ON DAY 3 TO 60% BY DAY 7. THE REMAINING BLEND COMPRISED OF
DETERMINISTIC RUNS OF THE 12Z EC-AIFS, THE 12Z ECMWF, AND THE 18Z
GFS, WHICH MORE CLOSELY RESEMBLED A CONSENSUS AND PAIRED BETTER
WITH THE AFOREMENTIONED ENSEMBLE MEANS. TAKEN TOGETHER, THIS BLEND
MADE FOR A REASONABLE REPRESENTATION OF THE LARGE SCALE PATTERN
WHILE REDUCING THE NOISE OF THE SMALLER SCALE RUN-TO-RUN
DIFFERENCES.
..WEATHER/HAZARDS HIGHLIGHTS
A POTENT NEGATIVELY-TILTED SHORTWAVE EJECTING OUT OF THE CENTRAL
ROCKIES AND ACROSS THE CENTRAL PLAINS AND UPPER MIDWEST WILL
SUPPORT THE RAPID STRENGTHENING OF A SURFACE LOW PRESSURE SYSTEM
ON MONDAY. FLOW AROUND THE LOW WILL DRAW ANOMALOUS MOISTURE AND
INSTABILITY NORTHWARD FROM THE GULF, SETTING THE STAGE FOR NUMEROUS
SHOWERS AND THUNDERSTORMS ACROSS THE MISSISSIPPI VALLEY MONDAY
AFTERNOON AND EVENING WITH THE POTENTIAL FOR HEAVY RAIN AND SEVERE
WEATHER. THE STORM PREDICTION CENTER HAS HIGHLIGHTED THE MID-
MISSISSIPPI VALLEY AS HAVING THE GREATEST THREAT FROM THUNDERSTORMS
THAT COULD PRODUCE DAMAGING WINDS, LARGE HAIL, AND EVEN A FEW
TORNADOES. HEAVY RAIN THAT CAN LEAD TO FLASH FLOODING WILL ALSO BE
A CONCERN, ESPECIALLY AS CLUSTERS OF THUNDERSTORMS WITH HIGH
RAINFALL RATES MERGE AND REPEATEDLY TRAIN OVER THE SAME AREAS. A
MARGINAL RISK REMAINS IN PLACE FROM THE UPPER MIDWEST TO THE LOWER
MISSISSIPPI VALLEY FOR THE DAY 4/MONDAY ERO, WITH AN OVERALL
BROADENING AND EXPANSION WITH THIS FORECAST UPDATE GIVEN THE
EXPANSIVE MOISTURE AND INSTABILITY IN PLAY.
AS THE STRONG SURFACE LOW LIFTS ACROSS THE GREAT LAKES AND TRACKS
INTO SOUTHERN CANADA, THE COLD FRONT TRAILING IN THE WAKE OF THE
LOW WILL SLIDE TO THE SOUTH AND EAST TUESDAY INTO WEDNESDAY,
SPREADING SHOWERS AND THUNDERSTORMS INTO THE EASTERN U.S. THE FRONT
WILL BEGIN TO LOSE STEAM AND STALL OUT OVER THE SOUTH-CENTRAL TO
SOUTHEASTERN U.S. INTO TUESDAY, BECOMING THE FOCUS FOR ANOTHER
ROUND OF HEAVY RAIN AND POSSIBLE SEVERE WEATHER. SIGNIFICANT
MOISTURE AND INSTABILITY POOLING ALONG THE STALLING BOUNDARY COULD
LEAD TO CLUSTERS OF STORMS WITH HIGH RAINFALL RATES, SUPPORTING THE
POTENTIAL FOR ISOLATED INSTANCES OF FLASH FLOODING. AS A RESULT, A
MARGINAL RISK ERO WAS INTRODUCED FROM THE ARKLATEX REGION EASTWARD
TO THE MID-SOUTH AND TENNESSEE VALLEY FOR DAY 5/TUESDAY.
BY MID TO LATE WEEK, A PACIFIC SYSTEM WILL LIKELY PUSH INLAND
ACROSS SOUTHERN CALIFORNIA, THE SOUTHWEST, AND THE FOUR CORNERS
STATES, SPREADING LIGHT TO MODERATE LOW ELEVATION RAIN AND HIGHER
ELEVATION MOUNTAIN SNOW INTO THE REGION. PRECIPITATION MAY EXPAND
AND INTENSIFY AS IT REACHES THE CENTRAL AND SOUTHERN PLAINS BY
THURSDAY OR FRIDAY.
WARMER THAN AVERAGE TEMPERATURES ARE LIKELY TO CONTINUE ACROSS THE
SOUTHERN PLAINS THROUGH MIDWEEK, AND AHEAD OF THE COLD FRONT INTO
THE MISSISSIPPI AND OHIO VALLEYS THROUGH EARLY NEXT WEEK.
TEMPERATURES IN THE 90S WILL BE COMMON ACROSS TEXAS. MEANWHILE,
BELOW AVERAGE TEMPERATURES WILL CONTINUE FOR MUCH OF THE WEST AND
NORTHERN/CENTRAL PLAINS UNDER THE BROAD TROUGHING THROUGH MONDAY
BEFORE SHIFTING INTO THE NORTH-CENTRAL U.S. THROUGH MIDWEEK. COOLER
THAN NORMAL TEMPERATURES IN THE WAKE OF THE COLD FRONT WILL THEN
CONTINUE TO EXPAND TO THE SOUTH AND EAST THURSDAY INTO FRIDAY,
WHILE THE PACIFIC NORTHWEST WARMS BACK CLOSER TO OR SLIGHTLY ABOVE
NORMAL.
MILLER
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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