690
FXUS61 KBOX 291209
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
809 AM EDT WED APR 29 2026
WHAT HAS CHANGED
NO SIGNIFICANT CHANGES.
KEY MESSAGES
- INCREASING CLOUDS TODAY WITH BENEFICIAL RAINFALL MOVING IN TONIGHT
AND THURSDAY.
- UNSETTLED AND COOLER THIS WEEKEND INTO EARLY NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...INCREASING CLOUDS TODAY WITH BENEFICIAL RAINFALL
MOVING IN TONIGHT AND THURSDAY.
SHOULD BE A MOSTLY DRY START TO THE DAY OUTSIDE COASTAL AREAS OF
MASSACHUSETTS WHERE DRIZZLE AND PATCHY FOG WILL LIKELY BE ONGOING.
OTHERWISE, EXPECT A LULL IN THE ACTIVITY BY THE LATE MORNING AND
EARLY AFTERNOON. AREAS OF RAIN AND SCATTERED SHOWERS INCREASE IN
COVERAGE LATER THIS AFTERNOON AND EVENING. INITIALLY, THERE WILL BE
TWO AREAS OF PRECIPITATION, SHOWERS ASSOCIATED WITH THE INVERTED
TROUGH NEAR THE COAST, AND A MORE WIDESPREAD SHIELD OF RAIN
ASSOCIATED WITH INCOMING LOW PRESSURE. THE BULK OF THE RAIN FALLS
OVERNIGHT INTO THURSDAY MORNING WITH PASSAGE OF UPPER TROUGH FROM
OHIO VALLEY AND SECONDARY SURFACE LOW THAT TRACKS FROM MID ATLANTIC
TO CAPE COD. STILL LOOKS LIKE A FAIRLY QUICK HITTING EVENT, WITH THE
BULK OF THE RAIN WRAPPING UP FROM WEST TO EAST THROUGH THE MORNING.
ANY LINGERING AREAS OF SHOWERS AND DRIZZLE ACROSS THE CAPE AND
ISLANDS COME TO AN END AROUND SUNSET. COULD ALSO SEE A FEW RUMBLES
OF THUNDER EMBEDDED WITHIN ANY HEAVIER ELEMENTS THURSDAY MORNING.
OVERALL, THIS WILL BE A QUICK HITTING AND WEAK SYSTEM WITH MEAGER
DYNAMICS ALOFT. RAINFALL TOTALS SHOULD BE MORE BENEFICIAL WITH MOST
AREAS AREAS PICKING UP 0.25 TO 1.00" OF MUCH NEEDED RAINFALL,
PERHAPS A LITTLE MORE IN NORTHERN MA.
ASTRO TIDES ARE FAIRLY LOW SO COASTAL FLOODING IS NOT MUCH OF A
CONCERN ALONG E MA COAST. PERSISTENT ONSHORE FLOW MAY BRING A SURGE
OF UP TO 1 FOOT LATER IN WEEK, BUT BY THEN WINDS TURN OFFSHORE AS
SURFACE LOW LIFTS FARTHER TO THE NORTH.
KEY MESSAGE 2...UNSETTLED AND COOLER THIS WEEKEND INTO EARLY NEXT
WEEK.
AMPLIFIED PATTERN LATER THIS WEEK AND OVER THE WEEKEND AS A BUILDING
RIDGE OF HIGH PRESSURE OVER CENTRAL CANADA TRAPS A UPPER LEVEL LOW
OVER SOUTHERN ONTARIO. SOUTHERN NEW ENGLAND SHOULD BE FAR ENOUGH
REMOVED FROM COLDEST AIR ALOFT TO KEEP US MOSTLY DRY, ESPECIALLY
GIVEN W/NW FLOW, BUT PATTERN CERTAINLY FAVORS DIURNAL CLOUDS AND
PERHAPS A FEW AFTERNOON SPRINKLES FRIDAY, SATURDAY, AND SUNDAY.
IT DOES LOOK LIKE UPPER LOW MAY LIFT FARTHER NORTH EARLY NEXT WEEK,
ALLOWING FOR MORE OF A ZONAL FLOW ACROSS NORTHERN TIER OF STATES
WHICH WOULD LEAD TO DRIER AND MILDER WEATHER MONDAY AND TUESDAY.
HOWEVER, MODELS ARE NOTORIOUS FOR BREAKING DOWN THESE BLOCKY
PATTERNS TOO QUICKLY, SUCH THAT IT MAY TAKE A LITTLE LONGER TO SEE
IMPROVING CONDITIONS. FOR NOW, FORECAST REFLECTS MODEL BLEND TO IRON
OUT THE UNCERTAINTY.
AVIATION /12Z WEDNESDAY THROUGH SUNDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
12Z TAF UPDATE:
TODAY...MODERATE CONFIDENCE (CEILINGS).
VFR FOR WESTERN/CENTRAL TERMINALS. IFR FOR EAST COAST TERMINALS
THIS AM. CEILINGS MAY BRIEFLY LIFT TO MVFR OR SCATTER BRIEFLY
NEAR THE COAST EARLY AFTERNOON. THIS IS LOWER CONFIDENCE, BUT
IS MORE LIKELY TO HAPPEN AT BOS THAN THE CAPE/ISLAND TERMINALS
IF ANYTHING. IN THAT SCENARIO, IFR WOULD LIKELY RE-DEVELOP BY
MID TO LATE AFTERNOON WITH A CHANCE OF A ISOLATED -SHRA/-DZ.
LIFR RE-DEVELOPS FOR CAPE/ISLAND TERMINALS. NE-EASTERLY WINDS
8-12 KTS. STRONGER WINDS FOR CAPE/ISLANDS THIS MORNING WITH A
FEW GUSTS TO 22 KTS.
TONIGHT...HIGH CONFIDENCE.
IFR/LIFR CONDITIONS DEVELOP ACROSS THE EASTERN TERMINALS
TONIGHT, BECOMING MORE WIDESPREAD AS RAIN OVERSPREADS REGION
FROM WEST TO EAST AFTER 03Z.
THURSDAY...HIGH CONFIDENCE IN TRENDS.
RAIN CONTINUES THROUGH EARLY AFTERNOON WITH IMPROVING CEILINGS
LATE AFTERNOON. LIGHT SE WINDS BECOME WESTERLY LATER IN
AFTERNOON.
KBOS TERMINAL...MODERATE CONFIDENCE IN TAF TIMING. VERY SLOW
IMPROVEMENT TO MVFR LATE IN THE AFTERNOON. THERE IS THE
POTENTIAL FOR IFR CEILINGS TO PERSIST ALL DAY.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK /THURSDAY NIGHT THROUGH SUNDAY/...
THURSDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. BREEZY.
FRIDAY: VFR. BREEZY.
FRIDAY NIGHT THROUGH SATURDAY: VFR.
SATURDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE.
SUNDAY: VFR. BREEZY.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
HIGH CONFIDENCE THROUGH THE END OF THE WEEK.
PRESSURE GRADIENT BETWEEN SLOW-MOVING LOW PRESSURE SE OF THE 40/70
BENCHMARK AND HIGH PRESSURE OVER THE CANADIAN MARITIMES KEEPS E/NE
WINDS IN PLAY THROUGH THE END OF THE WEEK.
NE WINDS MAY APPROACH SCA AROUND CAPE COD WITH 20KT GUSTS. MAIN
ISSUE WILL BE THE LONG FETCH OF NE WINDS RESULTING IN ROUGH
SEAS OF 5 TO 8 FEET ON OUTER WATERS THROUGH THU WHERE SCA
REMAINS POSTED. MAY HAVE TO EXTEND IT INTO RHODE ISLAND AND
BLOCK ISLAND SOUNDS SHOULD CONFIDENCE INCREASE IN LATER
FORECASTS.
OUTLOOK /THURSDAY NIGHT THROUGH SUNDAY/...
THURSDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. SLIGHT
CHANCE OF RAIN SHOWERS.
FRIDAY THROUGH FRIDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP TO
5 FT.
SATURDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING
5 FT. SLIGHT CHANCE OF RAIN SHOWERS.
SATURDAY NIGHT: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING
5 FT. SLIGHT CHANCE OF RAIN SHOWERS.
SUNDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING 5 FT.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT FRIDAY FOR ANZ250-254>256.
DISCUSSION...FT
AVIATION...MENSCH/FT
MARINE...FT
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