353
FXUS61 KBOX 041925
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
325 PM EDT SUN MAY 4 2025
SYNOPSIS
AN UNSETTLED WEATHER PATTERN WITH SHOWERS AT TIMES WILL PERSIST
FOR THE FIRST HALF OF THIS 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 /THROUGH TONIGHT/
KEY MESSAGES:
* PERIODS OF SHOWERS TONIGHT, ESPECIALLY ACROSS PARTS OF WESTERN
MA AND CT, WHERE POCKETS OF HEAVY RAINFALL ARE POSSIBLE.
* AREAS TOWARDS THE CAPE/ISLANDS MAY SEE A FEW SHOWERS, BUT DRY
WEATHER WILL PROBABLY DOMINATE MOST OF TONIGHT.
A FRONT WILL BE MEANDERING ACROSS SOUTHERN NEW ENGLAND TONIGHT,
PROVIDING A CONSISTENT FOCUS FOR SHOWERS. A MID LEVEL SHORTWAVE
PASSING OVER, AND A MODEST LOW LEVEL JET INTERSECTING, THIS
FRONT WILL PROVIDE ADDITIONAL LIFT TO TRIGGER PERIODS OF SHOWERS
AS WELL. MOST OF THESE SHOWERS WILL BE LIKELY BE ACROSS THE
WESTERN HALF OF SOUTHERN NEW ENGLAND.
WILL NEED TO MONITOR RAINFALL SHOULD STRONGER OR PERSISTENT
CONVECTION DEVELOP. INSTABILITY IS LIMITED, AND THE LOW LEVEL
JET SHOULD KEEP AND STORMS MOVING ALONG. THAT SHOULD KEEP
RAINFALL AMOUNTS LIMITED TO 0.50-1.00 INCHES. AS DRY AS WE HAVE
BEEN RECENTLY, WE SHOULD BE ABLE TO HANDLE THOSE AMOUNTS.
NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES EXPECTED.
SHORT TERM /MONDAY THROUGH MONDAY NIGHT/
KEY MESSAGES:
* PERIODS OF SHOWERS CONTINUE INTO MONDAY NIGHT
* MUCH COOLER, WITH SLIGHTLY BELOW NORMAL HIGH TEMPERATURES
MONDAY, AND NEAR NORMAL LOW TEMPERATURES FOR MONDAY NIGHT.
JUST A FEW CHANGES TO THE OVERALL SYNOPTIC PATTERN MONDAY INTO
MONDAY NIGHT, BUT SOME OF THESE ARE SIGNIFICANT. THE FIRST BEING
THE LOCATION OF THE PERSISTENT FRONT. THINKING THIS FRONT
FINALLY GETS PUSHED JUST SOUTH OF NEW ENGLAND TOWARDS 8 AM
MONDAY BY THE HIGH PRESSURE MOVING OVER NORTHERN NEW ENGLAND.
THIS WILL LEAD TO COOLER CONDITIONS WITH A PERSISTENT EASTERLY
ONSHORE FLOW NORTH OF THIS FRONT. THE COOLER AIR WILL THEN LEAD
TO A NEAR IDEAL OVERRUNNING PATTERN. THE LOCATION OF THE HIGH
PRESSURE OVER NORTHERN NEW ENGLAND AND A LOW PRESSURE OVER THE
LOWER OH VALLEY SHOULD INCREASE THE LOW LEVEL JET. THUS,
MOISTURE TRANSPORT IS INCREASED, AND STILL LARGELY FOCUSED
ACROSS THE WESTERN HALF OF OUR REGION.
STILL HAVE SOME CONCERNS FOR FLOODING ISSUES, BUT WILL NEED TO
SEE WHAT THE RAINFALL DISTRIBUTION ACTUALLY TURNS OUT TO BE. THE
MORE TIME WE CAN SPREAD OUT THIS RAINFALL OVER, THE BETTER OFF
WE WILL BE. OVERALL RAINFALL TOTALS THROUGH MONDAY NIGHT OF 1-2
INCHES IS MOST LIKELY, WITH UP TO 3 INCHES IN SPOTS. ACROSS THE
EASTERN HALF OF SOUTHERN NEW ENGLAND, THESE TOTALS ARE MOST
LIKELY UP TO AN INCH OF RAINFALL. THESE TOTAL COULD CHANGE WITH
LATER FORECASTS, BUT THAT IS THE CURRENT THINKING.
LONG TERM /TUESDAY THROUGH SUNDAY/
KEY MESSAGES:
* SOAKING RAIN EXPECTED TUESDAY THROUGH WEDNESDAY
* SHORT BREAK FROM RAIN THURSDAY WITH BRIEF RIDGING
* COOLER AND UNSETTLED ONCE MORE HEADING INTO THE WEEKEND
DETAILS...
A CLOSED MID-LEVEL LOW CONTINUES TO SIT OVER THE OHIO VALLEY AS
PART OF AN OMEGA BLOCK PATTERN THAT WILL BEGIN TO BREAK GOING
INTO WEDNESDAY AS IT SHIFTS SLOWLY NORTHEAST. AS THIS HAPPENS,
SOAKING RAINS CAN BE EXPECTED ACROSS SOUTHERN NEW ENGLAND DURING
THIS PERIOD. MEAN PWAT VALUES ACROSS THE ENSEMBLES ARE AROUND
1.35-1.40" TUESDAY AFTERNOON, WITH NAEFS GUIDANCE NOTING THAT
PWAT VALUES THROUGH WEDNESDAY MORNING ARE AROUND 2 STANDARD
DEVIATIONS ABOVE NORMAL. IT IS ALSO WORTH NOTING THAT WPC
CURRENTLY HAS SOUTHERN NEW ENGLAND UNDER A MARGINAL RISK FOR
EXCESSIVE RAINFALL ON TUESDAY.
SLIGHTLY DRIER AIR MOVES IN OVERNIGHT INTO WEDNESDAY MORNING,
BRINGING MEAN PWAT VALUES DOWN TO JUST BELOW AN INCH ACROSS
SOUTHERN NEW ENGLAND. A COLD POOL ALOFT, WHICH IS NOTICEABLE
TOWARDS THE 700-500 MB LEVELS, AND MORE FAVORABLE LAPSE RATES
WEDNESDAY AFTERNOON MAY AID IN THE DEVELOPMENT OF SOME
THUNDERSTORMS. WITH THIS COLD POOL SO FAR ALOFT, TEMPERATURES AT
THE SURFACE MAY STILL REACH THE LOW 70S. ENSEMBLE MEAN SURFACE-
BASED CAPE VALUES STILL RANGE QUITE WIDELY BETWEEN THE GEFS AND
THE GEPS, ALONG WITH BOTH ENSEMBLES' PROBABILITIES FOR EXCEEDING
500 J/KG, SO THIS WILL CONTINUE TO BE SOMETHING TO MONITOR.
CLOUDY CONDITIONS ARE ALSO EXPECTED TO PERSIST WITH SIGNIFICANT
MOISTURE ALOFT.
A BRIEF DRY PERIOD LOOKS POSSIBLE THURSDAY AS RIDGING TRIES TO
BUILD IN BEHIND THE EXITING LOW FROM MIDWEEK AND AHEAD OF
ANOTHER SHORTWAVE SINKING DOWN FROM SOUTHERN ONTARIO THROUGH THE
GREAT LAKES. SOME LIGHT SHOWERS BECOME POSSIBLE ONCE MORE
THURSDAY AFTERNOON INTO THE EVENING HOURS AS A FRONT FROM THIS
SHORTWAVE MOVES THROUGH. RAIN CHANCES CONTINUE TO LINGER THROUGH
MUCH OF THE WEEKEND WITH A LOW MOVING UP ALONG THE EAST COAST
AND JUST OFFSHORE TO THE EAST OF THE REGION. BUT ONCE THESE
SHORTWAVES EXIT TO OUR NORTHEAST, WE MAY SEE SOME DRIER
CONDITIONS SUNDAY AS RIDGING STARTS TO BUILD IN.
AVIATION /19Z SUNDAY THROUGH FRIDAY/
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
REST OF TODAY...MODERATE CONFIDENCE
MIX OF MVFR AND VFR CEILINGS ACROSS THE REGION INTO THIS
EVENING. HIT-OR-MISS SHOWERS OVER THE EAST, WITH A MORE
WIDESPREAD RAINFALL MOVING INTO THE WESTERN HALF OF SOUTHERN NEW
ENGLAND. A NEARLY STATIONARY FRONT SHOULD BE LOCATED FROM THE
VICINITY OF BOS, EXTENDING WEST BETWEEN KFIT AND KORH, THEN
EXTENDING FURTHER INTO NY STATE BETWEEN KPSF AND KBAF.
TONIGHT THROUGH MONDAY NIGHT...MODERATE CONFIDENCE.
DETERIORATING CONDITIONS WITH VFR TRENDING TO MVFR-IFR
CONDITIONS, WITH AREAS OF LIFR LIKELY DEVELOPING ESPECIALLY
ACROSS CENTRAL AND NORTHEAST MA. PERIODS OF SHOWERS. ALTHOUGH,
THE ENTIRE PERIOD WILL NOT BE A WASHOUT. SHOWERS WILL TEND TO BE
MORE NUMEROUS ACROSS INTERIOR SOUTHERN NEW ENGLAND. NE WINDS
5-10 KT, WITH SOUTHEAST WINDS AT SIMILAR SPEEDS SOUTHEAST NEW
ENGLAND.
KBOS TAF...MODERATE CONFIDENCE. THINKING IFR ARRIVES QUICKLY
AFTER SUNSET WITH E TO NE WINDS AND LOWERING TEMPERATURES.
CONFIDENCE IN THE TIMING IS THE MAIN CONCERN.
KBDL TAF...MODERATE CONFIDENCE.
OUTLOOK /TUESDAY THROUGH FRIDAY/...
TUESDAY: MAINLY MVFR, WITH AREAS IFR POSSIBLE. BREEZY. SHRA,
ISOLATED TSRA.
TUESDAY NIGHT: MVFR/IFR CONDITIONS POSSIBLE. SHRA, ISOLATED
TSRA.
WEDNESDAY: MAINLY VFR, WITH AREAS MVFR POSSIBLE. CHANCE SHRA,
ISOLATED TSRA.
WEDNESDAY NIGHT: VFR. CHANCE SHRA.
THURSDAY: MAINLY VFR, WITH AREAS MVFR POSSIBLE. CHANCE SHRA.
THURSDAY NIGHT: MAINLY VFR, WITH LOCAL IFR POSSIBLE. CHANCE
SHRA.
FRIDAY: MAINLY VFR, WITH AREAS MVFR POSSIBLE. BREEZY. CHANCE
SHRA.
MARINE
FORECASTER CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MEDIUM - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
THROUGH MONDAY NIGHT...HIGH CONFIDENCE.
A BACKDOOR COLD FRONT WILL SHIFT THE WINDS FROM THE SSW TO E OR
NE ACROSS OUR NORTHERN WATERS LATER TONIGHT INTO MONDAY. THE
PRESSURE GRADIENT SHOULD GENERALLY REMAIN WEAK ENOUGH TO KEEP
WINDS AND SEAS BELOW SMALL CRAFT ADVISORY THRESHOLDS THROUGH.
HOWEVER, WE MAY SEE SOME 20+ KNOT GUSTS AT TIMES MON ACROSS THE
WATERS EAST OF MA, SO THERE MAY BE SOME CHOP OUT THERE. THE
OTHER ISSUE WILL BE THE RISK POOR VISIBILITY FROM FOG PATCHES
AT TIMES.
OUTLOOK /TUESDAY THROUGH FRIDAY/...
TUESDAY THROUGH TUESDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP
TO 5 FT. RAIN SHOWERS, ISOLATED THUNDERSTORMS.
WEDNESDAY: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. CHANCE OF
RAIN SHOWERS.
WEDNESDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. SLIGHT
CHANCE OF RAIN SHOWERS.
THURSDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING
5 FT. SLIGHT CHANCE OF RAIN SHOWERS.
THURSDAY NIGHT THROUGH FRIDAY: WINDS LESS THAN 25 KT. SEAS UP
TO 5 FT. CHANCE OF RAIN SHOWERS.
BOX WATCHES/WARNINGS/ADVISORIES
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...NONE.
SYNOPSIS...BELK/HRENCECIN
NEAR TERM...BELK
SHORT TERM...BELK/LOCONTO
LONG TERM...HRENCECIN
AVIATION...BELK/HRENCECIN
MARINE...BELK/HRENCECIN
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