532
FXUS61 KBOX 212334
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
734 PM EDT TUE APR 21 2026
WHAT HAS CHANGED
NO SIGNIFICANT CHANGES.
KEY MESSAGES
- SCATTERED SHOWERS WED AND THU. SOME WET SNOW POSSIBLE WED
MORNING IN THE HIGHER ELEVATIONS, THEN A THUNDERSTORM WITH
SMALL HAIL POSSIBLE THU.
- MAINLY DRY AND SEASONABLE FRI THROUGH THE WEEKEND, THEN
PATTERN LOOKS TO TURN MORE UNSETTLED NEXT WEEK.
DISCUSSION
KEY MESSAGE 1...SCATTERED SHOWERS WED AND THU. SOME WET SNOW
POSSIBLE WED MORNING IN THE HIGHER ELEVATIONS, THEN A
THUNDERSTORM WITH SMALL HAIL POSSIBLE THU.
YOU KNOW IT'S APRIL IN SOUTHERN NEW ENGLAND WHEN YOU HAVE TO
REFER TO YOUR WINTER WEATHER AND CONVECTIVE FORECAST PROCEDURES
ON THE SAME DAY.
BROAD NW FLOW ALOFT DOMINATES AS UPPER LOW OVER MARITIMES DROPS
SOUTHWARD TOWARD GULF OF MAINE WED AND THU. THIS WILL HELP
SUPPRESS A WEAK SHORT WAVE AND SURFACE LOW APPROACHING FROM THE
LOWER GREAT LAKES WHICH EVENTUALLY PASSES OFF NJ COAST AND SOUTH
OF NEW ENGLAND WED. THERE IS ENOUGH LOW LEVEL MOISTURE
CONVERGENCE TO BRING SCATTERED SHOWERS TO SOUTHERN NEW ENGLAND
LATE TONIGHT INTO WED MORNING, ESPECIALLY FOR WESTERN MA AND
MUCH OF CT WHICH ARE CLOSER TO THE BETTER LIFT AND MOISTURE
CONVERGENCE. WE ALSO CAN'T RULE OUT SOME WET SNOW ACROSS THE
HIGHER ELEVATIONS AT ONSET DUE TO MARGINAL TEMPERATURE PROFILES
BUT AT MOST THERE SHOULD ONLY BE A COATING ON THE GRASS.
KIND OF AN INTERESTING SETUP FOR THU AND GUIDANCE MAY BE
UNDERPLAYING CONVECTIVE POTENTIAL A BIT, SOMETHING TYPICAL IN
THESE SITUATIONS WITH COLD AIR ALOFT AND CLOSED LOW LURKING
NEARBY. THERE'S ENOUGH CYCLONIC FLOW COUPLED WITH DAYTIME
HEATING AND AMPLE MOISTURE TO AT LEAST GENERATE DIURNALLY DRIVEN
CLOUDS AND PERHAPS A FEW SHOWERS. CERTAINLY SEEING SOME SIGNALS
IN THE HIGH-RES MODELS FOR A FEW LOW-TOPPED SHOWERS OR
THUNDERSTORMS, ESPECIALLY IN EASTERN MA WHERE THERE SHOULD BE
ADDITIONAL SUPPORT FROM POTENT MID LEVEL SHORT WAVE ROTATING
THROUGH ALONG WITH MINIMAL LOWER LEVEL INSTABILITY. SMALL HAIL
OR GRAUPEL IS POSSIBLE SHOULD CORES GROW TALL ENOUGH GIVEN
PRESENCE OF COLD AIR ALOFT.
KEY MESSAGE 2...MAINLY DRY AND SEASONABLE FRI THROUGH THE
WEEKEND, THEN PATTERN LOOKS TO TURN MORE UNSETTLED NEXT WEEK.
BROAD CYCLONIC FLOW DOMINATES LATER THIS WEEK AND THROUGH THE
WEEKEND AS UPPER LOW MEANDERS AROUND ATLANTIC CANADA. THIS
ESSENTIALLY BLOCKS ANY SYSTEMS APPROACHING OUR AREA FROM THE
PLAINS AND GREAT LAKES AND MAINTAINS DRY WEATHER, ALTHOUGH IT'S
CERTAINLY POSSIBLE THAT WE SEE DIURNAL CLOUDS AND PERHAPS A
BRIEF SHOWER FROM COMBINATION OF DAYTIME HEATING AND COLD AIR
ALOFT. TEMPERATURES SHOULD END UP NEAR OR JUST BELOW AVERAGE
HIGHS FOR LATE APRIL WHICH ARE IN THE UPPER 50S TO LOWER 60S.
THERE ARE SOME SIGNALS IN LONGER RANGE GUIDANCE THAT BLOCKY
PATTERN BREAKS DOWN EARLY NEXT WEEK WHICH ALLOWS A SERIES OF
CLOSED UPPER LOWS TO TRACK THROUGH REGION, EACH BRINGING ROUNDS
OF STEADIER RAINFALL, SO IT'S POSSIBLE WE SEE A RETURN TO A
WETTER PATTERN TOWARD THE MIDDLE OF NEXT WEEK.
AVIATION /00Z WEDNESDAY THROUGH SUNDAY/
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
00Z TAF UPDATE: HIGH CONFIDENCE.
VFR THROUGH EARLY TONIGHT BEFORE MVFR CEILINGS ARRIVE AFTER
MIDNIGHT WITH SCATTERED SHOWERS. MOST LOCATIONS WILL HAVE A FEW
HOURS OF SHOWERS WED MORNING WITH MVFR CEILINGS AND
VISIBILITIES. IT'S POSSIBLE SOME TERMINALS LOWER TO IFR CEILINGS
DURING THE DAY BUT CONFIDENCE WASN'T HIGH ENOUGH TO INCLUDE
THAT YET. SHOWERS COME TO AND END BY WED AFTERNOON BUT MVFR (OR
PERHAPS IFR) CEILINGS SHOULD PERSIST ALL DAY.
LIGHT WINDS WITH COASTAL SEA BREEZES BECOME S/SW TONIGHT AND
WED. MAY SEE A FEW 20-25KT GUSTS WED AFTERNOON, ESPECIALLY
CLOSER TO SOUTH COAST.
OUTLOOK /THURSDAY THROUGH SUNDAY/...
THURSDAY: VFR. BREEZY. SLIGHT CHANCE SHRA, SLIGHT CHANCE TSRA.
THURSDAY NIGHT THROUGH FRIDAY NIGHT: VFR.
SATURDAY THROUGH SATURDAY NIGHT: VFR. SLIGHT CHANCE SHRA.
SUNDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE.
MARINE
FORECASTER CONFIDENCE LEVELS...
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
HIGH CONFIDENCE THROUGH THE WEEKEND.
EXPECTING WINDS AND SEAS TO REMAIN BELOW SCA THROUGH THE WEEKEND.
WEAK LOW PRESSURE PASSES SOUTH OF NEW ENGLAND WED. WE MAY SEE SOME
SOUTHERLY 20KT GUSTS AHEAD OF IT ON SOUTH COASTAL WATERS WED MORNING
ALONG WITH 3-4 FT SEAS, BEFORE WINDS SHIFT TO N/NE AND SUBSIDE LATER
WED AND WED NIGHT.
OVERALL, LIGHT WINDS AND CALM SEAS WILL PREVAIL INTO THE WEEKEND AS
HIGH PRESSURE REMAINS NEAR MARITIMES AND A SERIES OF LOW PRESSURE
SYSTEMS TRACK WEST AND SOUTH OF NEW ENGLAND.
OUTLOOK /THURSDAY THROUGH SUNDAY/...
THURSDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING 5 FT.
SLIGHT CHANCE OF RAIN SHOWERS, SLIGHT CHANCE OF THUNDERSTORMS.
THURSDAY NIGHT THROUGH SATURDAY: WINDS LESS THAN 25 KT.
SATURDAY NIGHT THROUGH SUNDAY: WINDS LESS THAN 25 KT. SLIGHT
CHANCE OF RAIN SHOWERS.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...NONE.
DISCUSSION...JWD
AVIATION...MCMINN/JWD
MARINE...JWD
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