254
FXUS02 KWBC 012000
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 PM EDT FRI MAY 1 2026
VALID 12Z MON MAY 04 2026 - 12Z FRI MAY 08 2026
..OVERVIEW
A SYNOPTIC SCALE UPPER-LEVEL LOW MEANDERING OVER CENTRAL TO
SOUTHEASTERN CANADA WILL BRING A SURGE OF COLD AIR THROUGH THE
EASTERN TWO-THIRDS OF THE COUNTRY DURING THE MEDIUM-RANGE PERIOD.
MEANWHILE, AN UPPER-LEVEL LOW/TROUGH IS FORECAST TO MOVE ACROSS THE
SOUTHWEST WITH UNCERTAIN TIMING AND DETAILS ON HOW THE LOW/TROUGH
WILL BE EJECTED AND THEN INTERACT WITH THE NORTHERN STREAM BROAD
TROUGHING OVER THE EASTERN HALF OF THE COUNTRY LATER NEXT WEEK,
WITH THE POTENTIAL OF CYCLOGENESIS LATE NEXT WEEK OVER NEW ENGLAND.
IN ADDITION, WINTRY PRECIPITATION IS FORECAST FOR THE FRONT RANGE
AREA EARLY TO MIDDLE OF NEXT WEEK DURING THE EJECTION OF THE
SOUTHWEST U.S. UPPER LOW/TROUGH.
..GUIDANCE/PREDICTABILITY ASSESSMENT AND PREFERENCES
THE CORRIDOR WHERE MODELS ARE STILL STRUGGLING IS FROM THE EAST-
CENTRAL U.S. TO THE NORTHEAST FROM MIDDLE TO LATE NEXT WEEK. THIS
HAS TO DO WITH THE DEGREE OF TILT THE INCOMING TROUGH IS FORECAST
TO DIP INTO THE NORTHERN U.S. AND HOW THE UPPER TROUGH/LOW IN THE
SOUTHWEST IS EJECTED AND CAPTURED BY THE NORTHERN TROUGH IN THE
EAST-CENTRAL U.S. THE NBM HAS LATELY BEEN TRENDING TOWARD A FASTER
EJECTION OF THE MERGER THROUGH THE EASTERN U.S. LATE NEXT WEEK,
WHICH WOULD FAVOR THE FASTER GEFS AND EC-AIFS SOLUTIONS, ALONG WITH
A COLDER SOLUTION FOR THE NORTHERN U.S. HOWEVER, THE SLOWEST
GUIDANCE FROM CMC/CMC MEAN SHOW FRONTAL WAVE DEVELOPMENT AROUND
THURSDAY OVER THE RIGHT ENTRANCE REGION OF THE UPPER JET, A
SCENARIO SUPPORTED BY THE MAJORITY OF THE LATEST GUIDANCE INCLUDING
THE AI-GFS, THE 12Z ECMWF AND ESPECIALLY THE 12Z GFS. BY NEXT
FRIDAY, THERE IS GOOD MODEL CONSENSUS FOR AN INTENSIFYING COASTAL
CYCLONE TO PASS CLOSE TO NEW ENGLAND, WITH THE 12Z GFS AND ECMWF
BEING THE MORE PROMINENT EXAMPLES FOR THIS SCENARIO.
IN THE VICINITY OF THE FRONT RANGE TO THE HIGH PLAINS, THERE HAS
BEEN GOOD MODEL SIGNAL FOR A PERIOD OF WINTRY PRECIPITATION EARLY
TO MIDWEEK ON THE NORTHERN EDGE OF THE SOUTHWEST U.S. UPPER SYSTEM
FORECAST TO EJECT OUT OF THE ROCKIES. THE NEW NBM DID INCREASE QPF
ACROSS THE FRONT RANGE TO THE HIGH PLAINS POSSIBLY DUE TO STRONGER
UPSLOPE FLOW FROM THE COLD AIR INTRUSION FROM THE NORTH. A
CONSENSUSOF THE EC MEAN AND GEFS MEAN WAS USED TO LOWER THE QPF
IN THIS VICINITY.
THE WPC MEDIUM-RANGE FORECAST CHARTS ARE BASED ON THE CONSENSUS OF
40% FROM THE 00Z EC/EC MEAN, 40% FROM THE 06Z GFS/GEFS, 20% FROM
THE CMC AND CMC MEAN, WITH INCREASING PROPORTIONS FROM THE ENSEMBLE
MEANS TOWARD DAY 7.
..WEATHER/HAZARDS HIGHLIGHTS
AS THE UPPER-LEVEL LOW CONTINUES TO MEANDER OVER CENTRAL TO
SOUTHEASTERN CANADA THROUGH THE MEDIUM-RANGE PERIOD, A COLD AIR
MASS FROM CANADA IS FORECAST TO SURGE INTO MUCH OF THE EASTERN
HALF OF THE COUNTRY, BRINGING WIDESPREAD COLDER THAN NORMAL
TEMPERATURES FOR EARLY MAY INTO THE REGION WHERE FROST/FREEZE IS
POSSIBLE FROM THE UPPER MIDWEST TO THE CENTRAL APPALACHIANS. AHEAD
OF THE COLD FRONT, EXPECT SHOWERS AND THUNDERSTORMS ACROSS UPPER
MIDWEST, OHIO VALLEY, GREAT LAKES AND NORTHEAST ON MONDAY, WITH
GUSTY WINDS ACROSS FROM THE SOUTHERN PLAINS TO THE OHIO VALLEY AND
INTO THE NORTHEAST. AS THE FRONT SLOWLY MOVES SOUTHWARD AND
INTERACTS WITH WARM GULF MOISTURE, SHOWERS AND THUNDERSTORMS WILL
DEVELOP OVER PARTS OF THE MID/LOWER MISSISSIPPI VALLEY, MID-
ATLANTIC, AND SOUTHEAST BY MIDWEEK. WITH THE COMBINATION OF UPPER-
LEVEL FORCING AND ORGANIZED THUNDERSTORMS PRODUCING HEAVY RAINFALL,
LOCALIZED FLOODING MAY BE POSSIBLE ACROSS MID/LOWER MISSISSIPPI
VALLEY INTO OHIO/TENNESSEE VALLEY. THIS FLOOD THREAT IS REPRESENTED
BY THE MARGINAL RISK ON DAY 5/TUESDAY ERO.
ADDITIONALLY, THE COLD FRONT WILL BRING BELOW NORMAL TEMPERATURES
BEHIND THE FRONT, ESPECIALLY OVER PARTS OF NORTHERN/CENTRAL
PLAINS, CALIFORNIA, AND SOUTHWEST, WHERE TEMPERATURES WILL DROP
10-15 DEGREES BELOW AVERAGE THROUGH MIDWEEK. WITH THE COLDER
TEMPERATURES, CHANCES FOR SOME MIXED PRECIPITATION OVER THE
NORTHERN PARTS OF THE UPPER GREAT LAKES/MIDWEST WILL BE POSSIBLE
TUESDAY THROUGH THURSDAY. BY FRIDAY, AN INTENSIFYING COASTAL
CYCLONE COULD PASS CLOSE TO NEW ENGLAND BRINGING SOME POTENTIAL OF
HEAVY WET SNOW FARTHER NORTH BUT UNCERTAINTY IS HIGH AT PRESENT
TIME.
OVER THE WESTERN U.S., A UPPER LOW/TROUGH APPROACHING THE COAST
WILL BRING PRECIPITATION OVER THE AREA FOR THE FIRST PORTION OF
NEXT WEEK. WITH SUFFICIENT MOISTURE AND INSTABILITY, EXPECT LOW
ELEVATION SHOWERS AND POSSIBLE THUNDERSTORMS, AS WELL AS SOME HIGH
ELEVATION SNOW ACROSS CALIFORNIA AND GREAT BASIN. A SECONDARY COLD
FRONT WILL DROP INTO THE ROCKIES/PLAINS BY TUESDAY, EXPANDING THE
CHANCE FOR SHOWERS AND THUNDERSTORMS ACROSS THE AREA. EXPECT
FLOODING POTENTIAL TO INCREASE AS TRAINING MAY DEVELOP ALONG THE
SLOW-MOVING FRONT. OVER THE PACIFIC NORTHWEST, POSSIBLE RECORD
BREAKING WARM TEMPERATURES MAY DEVELOP ON TUESDAY AS AN RIDGE
PUSHES INLAND. AS THE RIDGE CONTINUES TO MOVE EASTWARD, ABOVE
NORMAL TEMPERATURES WILL RETURN ACROSS MUCH OF WESTERN U.S. BY
THURSDAY.
KONG/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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