589
FXUS02 KWBC 291859
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 PM 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 EVOLUTION THROUGH THE PERIOD,
BUT STILL WITH PLENTY OF UNCERTAINTY IN THE DETAILS. THE MAIN
SOURCES OF UNCERTAINTY DEAL WITH SEVERAL SMALLER SCALE WAVES/ENERGY
ROTATING AROUND THE LARGE PARENT UPPER LOW SPINNING OVER SOUTHEAST
CANADA, AS WELL AS HOW QUICKLY THE CUT-OFF PACIFIC LOW PORTION OF
THE REX BLOCK PUSHES INLAND OVER THE SOUTHWEST. AN EQUAL MODEL
COMPROMISE BETWEEN THE GFS, ECMWF, CMC, UKMET, AND EC-AIFS SUFFICED
FOR THE FIRST HALF OF THE FORECAST PERIOD, SHIFTING TOWARDS MORE
WEIGHTING ON THE ENSEMBLE MEANS FOR THE LATTER HALF. THIS APPROACH
REMAINS IN LINE WITH PREVIOUS WPC FORECAST AS WELL AS THE 13Z NBM,
WHICH SERVED AS A GOOD STARTING POINT FOR THE WPC DAY 4-7 SENSIBLE
WEATHER GRIDS.
..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 FROM THE
SOUTHEAST INTO FLORIDA. WITH MUCH OF THE REGION IN SEVERE DROUGHT,
AND AFTER COORDINATION WITH THE WFOS, RESTRICTED THE DAY 4/SUNDAY
ERO TO JUST FAR SOUTHEAST GEORGIA AND NORTHERN FLORIDA WHERE THE
BETTER MOISTURE ANOMALIES AND INSTABILITY WILL BE PRESENT. THIS
TRIMS OUT MUCH OF THE REMAINDER OF THE SOUTHEAST WHERE RAINFALL
SHOULD BE MORE BENEFICIAL. ON 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 CONTINUES FOR MUCH OF CENTRAL FLORIDA.
A SLOW-MOVING PACIFIC LOW SPINNING OFF THE COAST OF CALIFORNIA
LATE THIS WEEKEND SHOULD 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 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.
SANTORELLI/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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