607
FXUS02 KWBC 290703
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
303 AM EDT WED APR 29 2026
VALID 12Z SAT MAY 02 2026 - 12Z WED MAY 06 2026
..OVERVIEW
SEVERAL DISTURBANCES ROTATING AROUND A PERSISTENT UPPER LEVEL
CLOSED LOW CENTERED OVER ONTARIO AND QUEBEC WILL HELP TO REINFORCE
BROADLY DEEP TROUGHING ACROSS THE EASTERN U.S. THIS WEEKEND INTO
NEXT WEEK. THIS PATTERN TYPICAL OF SPRINGTIME WILL LIKELY KEEP
CONDITIONS COOL AND UNSETTLED ACROSS PARTS OF THE NORTHEAST, MID-
ATLANTIC, GREAT LAKES, AND UPPER MIDWEST. MEANWHILE, A WEEKEND
FRONTAL SYSTEM WITH PLENTY OF MOISTURE WILL THREATEN PORTIONS OF
THE SOUTHEAST AND FLORIDA WITH HEAVY RAIN AND ISOLATED FLOODING
CONCERNS. THEN ANOTHER PACIFIC LOW TRIES TO PUSH INLAND LATE IN THE
WEEKEND INTO EARLY NEXT WEEK, POSSIBLY BRINGING SOME LOW ELEVATION
RAIN AND MOUNTAIN SNOW SHOWERS TO PARTS OF THE WEST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
A FAIRLY STABLE MID/UPPER LEVEL PATTERN IS EXPECTED TO PERSIST
THROUGH THE MEDIUM RANGE PERIOD, FEATURING A LARGE UPPER LOW AND
BROAD TROUGHING ACROSS THE EASTERN U.S., AND A DEVELOPING REX BLOCK
ACROSS THE WESTERN U.S. THE LATEST GUIDANCE CONTINUES TO HAVE A
GOOD HANDLE ON THE OVERALL PATTERN, WITH GENERALLY ONLY MINOR
SPATIAL AND TEMPORAL DIFFERENCES AMONGST THE VARYING MODELING
SUITES. THOUGH MINOR, THE MAIN SOURCES OF UNCERTAINTY DEAL WITH
SEVERAL SMALLER SCALE WAVES ROTATING AROUND THE LARGE PARENT UPPER
LOW SPINNING OVER SOUTHEAST CANADA... IN ADDITION TO HOW QUICKLY
THE CUT-OFF PACIFIC LOW PORTION OF THE REX BLOCK PUSHES INLAND.
GIVEN THE STABLE NATURE OF THE PATTERN AND THE GOOD REPRESENTATION
BY BOTH DETERMINISTIC AND ENSEMBLE GUIDANCE, THE WPC FORECAST WAS
PRODUCED UTILIZING A COMPOSITE BLEND OF THE 00Z/06Z ECMWF, EC-AIFS,
GFS, CMC, AND UKMET. FOR DAYS 6 AND 7, THE BLEND SHIFTED SOME OF
THE WEIGHTING OF DETERMINISTIC MODELS TOWARDS THE EC AND GEFS
ENSEMBLE MEANS. OVERALL, THIS MADE FOR A FORECAST THAT SMOOTHED OUT
SOME OF THE SMALLER SCALE DIFFERENCES, OFFERED GOOD STABILITY AND
CONTINUITY WITH THE PREVIOUS FORECAST, AND WAS IN LINE WITH THE
NATIONAL BLEND OF MODELS.
..WEATHER/HAZARDS HIGHLIGHTS
AN OCCLUDING LOW PRESSURE SYSTEM PIVOTING ACROSS SOUTHEAST CANADA
WILL CONTINUE TO FOSTER COOL, BREEZY, AND SHOWERY CONDITIONS OVER
PARTS OF THE NORTHEAST THROUGH THE WEEKEND. SOME LIGHT SNOW MAY
FALL ACROSS THE HIGHER ELEVATIONS OF NORTHERN NEW ENGLAND AND THE
INTERIOR NORTHEAST AS COLDER AIR WRAPS IN ON THE BACKSIDE OF THE
LOW, BUT ANY ACCUMULATIONS ARE EXPECTED TO BE MINIMAL. ADDITIONAL
DISTURBANCES ROTATING AROUND THE PRIMARY LOW OVER SOUTHEAST CANADA
MAY PUSH A FEW COLD FRONTS AND CHANCES FOR SHOWERS INTO THE UPPER
MIDWEST, GREAT LAKES, AND NORTHEAST LATER THIS WEEKEND INTO NEXT
WEEK, KEEPING TEMPERATURES NEAR TO BELOW SEASONAL NORMS. CHILLY
NIGHTTIME LOWS MAY ALSO LEAD TO FROST AND FREEZE CONCERNS OVER
PARTS OF THE OHIO VALLEY, MID-ATLANTIC, AND CENTRAL APPALACHIANS
THIS WEEKEND AS WELL.
THE DEVELOPING FRONTAL SYSTEM THAT IS EXPECTED TO BRING HEAVY RAIN
AND POTENTIAL FLOODING CONCERNS FROM TEXAS TO THE LOWER
MISSISSIPPI VALLEY AND DEEP SOUTH THURSDAY AND FRIDAY WILL SHIFT
EASTWARD INTO THE SOUTHEAST ON SATURDAY. AS THE FRONTAL WAVE FUELED
BY STILL IMPRESSIVE MOISTURE AND FORCING TRACKS TOWARDS THE MID-
ATLANTIC COAST, A TRAILING COLD FRONT WILL TRIGGER CLUSTERS OF
THUNDERSTORMS CAPABLE OF PRODUCING HEAVY RAINFALL RATES AND THE
POTENTIAL FOR ISOLATED INSTANCES OF RUNOFF AND POOR DRAINAGE/URBAN
FLOODING. WHILE MUCH OF THE REGION REMAINS IN SIGNIFICANT TO SEVERE
DROUGHT, DRY SOILS MAY QUICKLY BECOME OVERWHELMED AND HAVE A MORE
DIFFICULT TIME ABSORBING HEAVY DOWNPOURS, ESPECIALLY IF THEY OCCUR
OVER A VERY SHORT PERIOD OF TIME. AS A RESULT, THE DAY 4/SATURDAY
MARGINAL RISK ERO WAS MAINTAINED FROM THE FLORIDA PANHANDLE
NORTHEASTWARD TO EASTERN NORTH CAROLINA. THEN LOOKING AHEAD TO
SUNDAY, THE COLD FRONT THAT FOLLOWS IN THE WAKE OF THE
STRENGTHENING COASTAL LOW MOVING OUT TO SEA MAY STALL ACROSS
FLORIDA. SHOULD THIS OCCUR, THE STALLED FRONTAL ZONE WOULD THEN
BECOME A FOCUS FOR ADDITIONAL HEAVY RAIN GIVEN PLENTIFUL MOISTURE
POOLING ALONG THE BOUNDARY. THUS, A DAY 5/SUNDAY MARGINAL RISK ERO
WAS INTRODUCED FOR MUCH OF CENTRAL FLORIDA.
A SLOW-MOVING PACIFIC LOW SPINNING OFF THE COAST OF CALIFORNIA
LATE THIS WEEKEND MAY TRY PUSH ACROSS CALIFORNIA AND THE GREAT
BASIN DURING THE FIRST HALF OF NEXT WEEK. THERE REMAINS SOME
UNCERTAINTY WITH HOW QUICKLY THE LOW WILL ADVANCE INLAND, BUT
SHOULD IT DO SO, ENOUGH MOISTURE WILL LIKELY BE DRAWN IN TO SUPPORT
SCATTERED LOW ELEVATION RAIN AND MOUNTAIN SNOW SHOWERS ACROSS THE
WEST, ALONG WITH COOLER TEMPERATURES FOLLOWING SEVERAL DAYS OF
UNSEASONABLE WARMTH.
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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