613
FXUS61 KBOX 040750
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
350 AM EDT SUN MAY 4 2025
SYNOPSIS
AN UNSETTLED WEATHER PATTERN WITH SHOWERS AT TIMES WILL PERSIST
FOR THE FIRST HALF OF THE WEEK WITH SOMEWHAT COOLER CONDITIONS.
POCKETS OF HEAVY RAIN WILL BE POSSIBLE AT TIMES WHICH WILL BE
FOCUSED ACROSS PORTIONS OF INTERIOR MASSACHUSETTS AND
CONNECTICUT. DEPENDING ON HOW MUCH RAIN FALLS EARLY THIS WEEK,
WE COULD SEE RISES TO NEAR OR OVER BANKFULL ON LARGER RIVERS AND
SMALLER STREAMS IN INTERIOR SOUTHERN NEW ENGLAND.
NEAR TERM /UNTIL 6 PM THIS EVENING/
KEY MESSAGES...
* RATHER CLOUDY TODAY WITH SCATTERED SHOWERS AT TIMES NW OF I-95
* HIGHS TODAY IN THE 70S...BUT 60S FAR NORTHEAST MA, CAPE/ISLANDS
DETAILS...
ANOMALOUS CLOSED UPPER LEVEL LOW ACROSS THE MIDWEST WILL CONTINUE TO
EJECT PIECES OF SHORTWAVE ENERGY INTO THE MID-ATLANTIC AND NORTHEAST
STATES. HOWEVER...AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL NOSE
INTO EASTERN NEW ENGLAND TODAY AND RESULT IN SOME SUBSIDENCE NEAR
THE COASTAL PLAIN. THE RESULT SHOULD BE RATHER CLOUDY
CONDITIONS...BUT MAINLY DRY WEATHER OUTSIDE PERHAPS A SPOT SHOWER OR
TWO NEAR AND SOUTHEAST OF THE I-95 CORRIDOR TODAY. THERE WILL BE
SOME SCATTERED SHOWERS AT TIMES NORTHWEST OF I-95 ESPECIALLY ACROSS
NORTHWEST MA AND FAR NORTHERN MA...WHERE A LOW LEVEL BOUNDARY WILL
PROVIDE A BIT OF ENHANCED CONVERGENCE. NOT MUCH INSTABILITY AROUND
TODAY...BUT ENOUGH THAT WE CAN NOT RULE OUT A RUMBLE OR TWO OF
THUNDER IN NORTHWEST/NORTH CENTRAL MA. REGARDLESS...NOT EXPECTING
THE ENTIRE DAY TO BE A WASHOUT EVEN IN THESE LOCATIONS WITH JUST
SCATTERED SHOWERS AT TIMES. DESPITE THE ABUNDANCE OF CLOUDS...MILD
START SHOULD BE ENOUGH FOR HIGHS IN THE 70S ACROSS MUCH OF THE
REGION. A BACKDOOR COLD FRONT WILL PROBABLY KEEP AFTERNOON TEMPS
MAINLY IN THE 60S IN NORTHEAST MA AND ONSHORE FLOW WILL DO THE SAME
FOR THE CAPE/ISLANDS.
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/
KEY MESSAGES...
* PERIODS OF SHOWERS TONIGHT & MON ESPECIALLY ACROSS PARTS OF
WESTERN MA & CT WHERE POCKETS OF HEAVY RAINFALL ARE POSSIBLE
* AREAS TOWARDS THE CAPE/ISLANDS MAY SEE A FEW SHOWERS TONIGHT INTO
MON...BUT DRY WEATHER WILL PROBABLY DOMINATE
* MUCH COOLER MON WITH HIGHS MAINLY IN THE 50S ACROSS
CENTRAL/NORTHEAST MA WITH 60S POSSIBLE CT/RI/SE MA
DETAILS...
TONIGHT AND MONDAY...
HIGH PRESSURE OVER QUEBEC WILL SLIDE SOUTHEAST INTO THE MARITIMES
TONIGHT AND MON. THIS WILL SEND A BACKDOOR COLD FRONT TO THE
SOUTHWEST OF OUR REGION AND NOTICEABLY COOLER TEMPS FOR MON. IT ALSO
WILL COMBINED WITH THE ANOMALOUS CLOSED UPPER LEVEL LOW ACROSS
KENTUCKY/OHIO VALLEY AREA TO RESULT IN AN INCREASING SOUTHEAST LLJ
AT 850 MB. IN FACT...THE 850 MB JET IS EXPECTED TO INCREASE TO
BETWEEN 30 AND 40 KNOTS ACROSS PARTS OF WESTERN MA AND CT GIVEN
THEIR CLOSER PROXIMITY TO THE CLOSED UPPER LEVEL LOW. IN
ADDITION...PWATS WILL CLIMB BACK INTO THE 1.25" TO 1.5" RANGE.
SO IN AN NUTSHELL...THIS SETUP IS FAVORABLE FOR PERIODS OF SHOWERS
TONIGHT AND MONDAY. WHILE THESE SHOWERS MAY IMPACT MUCH OF THE
REGION AT TIMES...THEY WILL BE MOST NUMEROUS AND MORE INTENSE
FURTHER BACK INTO THE INTERIOR ESPECIALLY WESTERN MA AND CT. THIS IS
WHERE THE STRONGEST FORCING/HIGHEST PWAT PLUME IS ACROSS OUR
REGION...SO SOME OF THESE SHOWERS MAY CONTAIN POCKETS OF HEAVY
RAINFALL. MEANWHILE...AREAS TOWARDS THE CAPE AND ISLANDS MAY SEE A
FEW SHOWERS AT TIMES THE MAJORITY OF THIS TIME FRAME WILL BE DRY
GIVEN THEIR FURTHER DISTANCE FROM THE FORCING. TEMPERATURES WILL BE
NOTICEABLE COOLER ON MON BEHIND THE BACKDOOR COLD FRONT. HIGHS WILL
MAINLY BE IN THE 50S ACROSS CENTRAL AND NORTHEAST MA WITH SOME 60S
POSSIBLE IN PARTS OF CT/RI/SE MA.
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/
KEY MESSAGES:
* PROLONGED CLOUDY WEATHER, ONSHORE FLOW AND STEADY RAIN MON
NIGHT THRU TUE NIGHT, WITH EMBEDDED DOWNPOURS POSSIBLE.
HEAVIEST RAIN TOTALS LOOKING MORE LIKELY IN INTERIOR SOUTHERN
NEW ENGLAND.
* RISES ON LARGER RIVERS AND SMALLER STREAMS IN INTERIOR
SOUTHERN NEW ENGLAND POSSIBLE EARLY TO MID NEXT WEEK,
POSSIBLY TO FLOOD STAGE IF HIGHER RAINFALL TOTALS MATERIALIZE.
* FEW SHOWERS POSSIBLE WED BUT NOT AS WIDESPREAD AS MON- TUE.
* DRYING OUT THURS, BUT TURNING UNSETTLED AND QUITE A BIT COOLER
LATE WEEK/WEEKEND?
DETAILS:
MONDAY NIGHT THROUGH TUESDAY NIGHT:
ENSEMBLES CONTINUE TO POINT TO SOUTHERN NEW ENGLAND BEING
POSITIONED BETWEEN A SLOW-MOVING UPPER LOW OVER THE OHIO VALLEY
AND A 1030 MB SFC ANTICYCLONE OVER THE CANADIAN MARITIMES. AN
ENHANCED STREAM OF MOISTURE OF SUBTROPICAL ORIGIN IS PROGGED TO
BE ADVECTED NORTHWARD, ALONG WITH SOUTHEASTERLY ONSHORE.
ALTHOUGH THE TIMING OF RAIN PARTICULARLY IN EASTERN NEW ENGLAND
IS STILL A BIT UNCERTAIN, THE EXPECTED LARGE-SCALE PATTERN IS
ONE THAT FAVORS A PROLONGED PERIOD OF OVERCAST AND RAIN AND
COOLER THAN NORMAL HIGHS/MILDER THAN NORMAL LOWS. THOUGH IT MAY
NOT BE RAINING THE ENTIRE PERIOD OF TIME, CATEGORICAL POPS
REMAIN ADVERTISED GIVEN THIS FORECAST PATTERN, WHICH HAS STAYED
PRETTY CONSISTENT IN RECENT NWP RUNS.
BESIDES THE ABOVE, EVEN THOUGH IT HAS BEEN RATHER DRY, THIS
SLOW- MOVING NORTHERLY- ADVECTING STREAM OF SUBTROPICAL MOISTURE
INFUSING STEADY RAIN WITH EMBEDDED DOWNPOURS AT TIMES IS A
SYNOPTIC AND MESOSCALE ANALOG PATTERN WHICH COULD LEAD TO SOME
AREAS SEEING SOME FAIRLY GOOD HEAVY RAIN FOOTPRINTS FROM
TRAINING OF STEADY RAINS. WHILE THIS IS WELCOME, TOO MUCH OF IT
OVER A LONG PERIOD OF TIME COULD HOWEVER CAUSE HYDROLOGIC
CONCERNS. GREATEST FORECAST QPF IS OVER INTERIOR SOUTHERN NEW
ENGLAND NORTH AND WEST OF I-95, AND THERE ARE QUITE A FEW QPF
BULLSEYES INDICATING POSSIBLE EMBEDDED CONVECTIVE- ENHANCED RAIN
RATES. RIVER STAGE FORECASTS OFF THE MMEFS WEBSITE USING GEFS-
BASED QPF SHOWS SOME RIVERS IN THE CT BASIN RISING CLOSE TO
MINOR FLOOD STAGE EARLY TO MID NEXT WEEK. RISES ON SMALLER
CREEKS AND STREAMS COULD ALSO OCCUR. THOUGH IT'S FAR FROM A
CERTAINTY, IT IS SOMETHING THAT WILL NEED TO BE MONITORED AS WE
MOVE THROUGH EARLY NEXT WEEK.
HIGHS ON TUESDAY IN THE LOWER TO MID 60S, WITH LOWS MONDAY AND
TUESDAY NIGHTS IN THE 40S TO MID/UPPER 50S.
WEDNESDAY:
UPPER LOW THEN BEGINS TO FILL/WEAKEN AND PULL EASTWARD THROUGH
SOUTHERN NEW ENGLAND. THIS MAY BRING SHOWERS OF A MORE
INSTABILITY/COLD-POOL-ALOFT TYPE REGIME WHERE NOT EVERYONE MAY
SEE SHOWERS. TEMPS DO WARM BACK INTO THE UPPER 60S TO LOW 70S
DESPITE A COLD POCKET OF AIR ALOFT, SO THAT MAY ALSO BRING THE
RISK FOR EMBEDDED THUNDERSHOWERS BEFORE THE LOW PULLS FURTHER
EAST.
LATE NEXT WEEK INTO EARLY WEEKEND:
LOOKS AS THOUGH WE DO GET INTO BRIEF RIDGING ALOFT AND DRIER
WEATHER FOR THURSDAY. UNFORTUNATELY LATEST GUIDANCE INDICATES
THIS COULD BE SHORT-LIVED, AS ANOTHER DIGGING SHORTWAVE TROUGH
ALOFT FROM ONTARIO MOVES IN FOR FRI. SOME OF THE INTERNATIONAL
GUIDANCE SOLUTIONS CLOSE THIS LOW OFF INTO AN UPPER LOW WITH
RATHER ANOMALOUSLY COLD LOW LEVEL TEMPS (850 MB TEMPS DOWN TO -2
TO -4C!) FOR FRI INTO SAT. PRECIP CHANCES ARE STILL UNCERTAIN
AND WILL DEPEND ON THE EXACT PLACEMENT OF THIS UPPER FEATURE.
ALTHOUGH WE'VE NOW GONE A TOTAL OF 8 CONSECUTIVE WEEKENDS WITH
MEASURABLE RAIN AT LEAST IN THE BOSTON AREA, AND IT IS POSSIBLE
ANY SHOWERS REMAIN FAR ENOUGH OFFSHORE, IT'S THIS TYPE OF
PATTERN WHICH IS NOT WHAT YOU WANT TO SEE TO BREAK THAT STREAK.
AVIATION /08Z SUNDAY THROUGH THURSDAY/
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
06Z TAF UPDATE:
THROUGH 12Z SUNDAY: LOW CONFIDENCE.
CEILINGS/VISBYS CURRENTLY ARE IN IFR RANGE IN THE INTERIOR
AFTER YESTERDAY'S THUNDERSTORMS WITH WEAK/CALM WINDS, WITH VFR
OVER THE SOUTHEAST TERMINALS. INTERIOR TERMINALS SHOULD REMAIN
MVFR-IFR THROUGH THE OVERNIGHT. CATEGORIES OVER THE CAPE AND
ISLANDS ARE NOW LESS CERTAIN AS GUID HAS BEEN STUBBORN IN
INDICATING STRATUS AND FOG THAT JUST HASN'T DEVELOPED. TRENDED
THINGS HERE MORE TOWARDS MVFR LEVELS AS WE MOVE THROUGH EARLY
SUN AM. WINDS TO BECOME SOUTHERLY AROUND 5-10 KT.
TODAY: MODERATE CONFIDENCE.
GRADUAL IMPROVEMENT IN CATEGORIES WITH MORE OF AN MVFR-VFR LOOK
IN THE INTERIOR. IF STRATUS DEVELOPS AS FORECAST OVER THE SOUTH
COAST/CAPE AND ISLANDS, WE SHOULD SEE MORE SLOWER/DELAYED
EROSION BUT IT MAY OTHERWISE STAY VFR. RAIN SHOULD HOLD OFF MOST
OF THE DAY, WITH HIT-OR-MISS SHOWERS OVER THE INTERIOR. WINDS
MAINLY SOUTHERLY AROUND 5-10 KT; IT'S A MORE DIFFICULT WIND
FORECAST FOR BOS AND BED WITH POTENTIAL FOR NE WINDS AROUND 5-10
KT TO DEVELOP AFTER 17Z.
TONIGHT AND MONDAY: MODERATE CONFIDENCE.
DETERIORATING CONDITIONS WITH VFR TRENDING TO MVFR-IFR WITH
PERIODS OF SHOWERS, STRATUS AND PERHAPS SOME MIST/FOG TONIGHT,
WITH NOT MUCH OPTIMISM FOR IMPROVEMENT INTO MONDAY. NE WINDS
5-10 KT, WITH SOUTHEAST WINDS AT SIMILAR SPEEDS SOUTHEAST NEW
ENGLAND.
KBOS TAF...MODERATE CONFIDENCE. IFR CEILINGS TO TREND VFR BY
EARLY SUNDAY MORNING. TOUGH WIND FORECAST WITH POSSIBLE PERIOD
OF NE WINDS DEVELOPING AFTER 17Z.
KBDL TAF...MODERATE CONFIDENCE.
OUTLOOK /MONDAY NIGHT THROUGH THURSDAY/...
MONDAY NIGHT: MVFR/IFR CONDITIONS POSSIBLE. BREEZY. SHRA.
TUESDAY: MAINLY MVFR, WITH AREAS IFR POSSIBLE. SHRA.
TUESDAY NIGHT: MVFR/IFR CONDITIONS POSSIBLE. CHANCE SHRA.
WEDNESDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. CHANCE SHRA.
WEDNESDAY NIGHT: VFR. SLIGHT CHANCE SHRA.
THURSDAY: MAINLY VFR, WITH AREAS MVFR POSSIBLE. CHANCE SHRA.
MARINE
FORECASTER CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MEDIUM - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
TODAY THROUGH MONDAY...HIGH CONFIDENCE.
A BACKDOOR COLD FRONT WILL SHIFT THE WINDS FROM THE SSW TO E OR NE
ACROSS OUR NORTHERN WATERS LATER TODAY AND ACROSS OUR OTHER WATERS
TONIGHT INTO MON. THE PRESSURE GRADIENT SHOULD GENERALLY REMAIN WEAK
ENOUGH TO KEEP WINDS/SEAS BELOW SMALL CRAFT ADVISORY THRESHOLDS
THROUGH MON. HOWEVER...WE MAY SEE SOME 20+ KNOT GUSTS AT TIMES
ESPECIALLY ON MON ACROSS OUR NORTHERN WATERS SO THERE MAY BE SOME
CHOP OUT THERE. THE OTHER ISSUE WILL BE THE RISK FOR FOG PATCHES AT
TIMES.
OUTLOOK /MONDAY NIGHT THROUGH THURSDAY/...
MONDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING
5 FT. CHANCE OF RAIN SHOWERS.
TUESDAY THROUGH TUESDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP
TO 5 FT. RAIN SHOWERS.
WEDNESDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING
5 FT. CHANCE OF RAIN SHOWERS.
WEDNESDAY NIGHT THROUGH THURSDAY: WINDS LESS THAN 25 KT. AREAS
OF SEAS APPROACHING 5 FT. SLIGHT CHANCE OF RAIN SHOWERS.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...NONE.
SYNOPSIS...FRANK/LOCONTO
NEAR TERM...FRANK
SHORT TERM...FRANK
LONG TERM...LOCONTO
AVIATION...LOCONTO
MARINE...FRANK/LOCONTO
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page