717
FXUS61 KBOX 092012
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
412 PM EDT FRI MAY 9 2025
SYNOPSIS
MODERATE TO HEAVY RAIN CONTINUES TODAY AS A STRONG AND SLOW-MOVING
LOW-PRESSURE SYSTEM MOVES THROUGH THE REGION. RAIN GRADUALLY
DIMINISHES TONIGHT INTO SATURDAY. HIGH PRESSURE RETURNS FOR THE
LATTER HALF OF THE WEEKEND INTO EARLY NEXT WEEK. HIGH PRESSURE
HOWEVER IS FORECAST TO MOVE OFFSHORE TOWARDS MIDDLE OF NEXT WEEK
WITH ANOTHER FRONTAL SYSTEM APPROACHING.
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/
* HEAVY RAIN MAY BRING MINOR STREET AND NUISANCE FLOODING DURING THE
EVENING COMMUTE.
* WIDESPREAD RAIN ENDS BY 8 AM SATURDAY.
A SLOW MOVING LOW PRESSURE CENTER MOVES UP THE NORTHEAST COAST THIS
EVENING AND OVERNIGHT JUST AHEAD OF A DIGGING SHORTWAVE TROUGH WHOSE
AXIS MOVES DIRECTLY OVER SOUTHERN NEW ENGLAND. THIS BRINGS WITH IT A
PWAT PLUME APPROACHING 1.5 INCHES WHICH OVER THE COURSE OF THE 24
HOUR PERIOD FROM THIS MORNING TO SATURDAY MORNING SHOULD DROP
ANYWHERE FROM 1 TO 2 INCHES OF RAIN. RAINFALL RATES AREN'T EXPECTED
TO BE EXTREME, BUT GIVEN THE SATURATED GROUND OF LATE, SOME MINOR
URBAN FLOODING IS POSSIBLE THIS AFTERNOON AND EVENING, ESPECIALLY
WHERE DRAINAGE IS POOR. THE HIGHEST QPF IS EXPECTED OVER BOTH
SOUTHERN CT AND IN THE INLAND HIGH TERRAIN OF THE BERKSHIRES AND
WORCESTER HILLS WHERE EASTERLY OROGRAPHIC FLOW WILL HELP BUMP UP
TOTALS. A DRY SLOT BEGINS TO WORK INTO SNE AT 700 MB TOWARD MIDNIGHT
AND EXPAND INTO EASTERN MA BY 12Z; THIS WILL BRING THE WIDESPREAD
RAINFALL TO AN END BY 8 AM. CONCERN FOR ANY ADDITIONAL FLOODING ON
THE CT RIVER HAS DECREASED SIGNIFICANTLY SINCE LAST NIGHT.
SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/
KEY MESSAGES...
* INCREASINGLY DRY WITH SLOWLY DECREASING CLOUDS THROUGH THE DAY.
DRY SLOT WORKS ITS WAY OVERHEAD DURING THE EARLY MORNING BUT
WRAPAROUND MOISTURE RETURNS TO EASTERN MA ON THE BACK SIDE OF THE
LOW WHICH WILL ALLOW FOR THE RESURGENCE OF SOME SCATTERED SHOWERS
THROUGH AT LEAST NOON. OVERCAST SKIES ALSO CONTINUE FOR MUCH OF THE
MORNING, BUT WILL START TO SEE BREAKS OF SUN IN THE AFTERNOON,
LIKELY QUITE CLEAR BY EVENING. AS THE LOW EXITS INTO NOVA SCOTIA NW
WINDS ON THE BACK SIDE WILL BECOME INCREASINGLY GUSTY DURING THE
AFTERNOON AS THE MIXING HEIGHT INCREASES. AFTER SUNSET WINDS WILL
DECREASE SIGNIFICANTLY BUT LIKELY BREEZY ENOUGH TO KEEP US FROM
RADIATING TOO MUCH; LOWS DROP TO NEAR 50F.
LONG TERM /SUNDAY THROUGH FRIDAY/
KEY POINTS:
* DRY AND WARMER SUNDAY WITH CONTINUED WARMING TREND THROUGH
NEXT WEEK.
* TEMPERATURES LEAN ABOVE NORMAL NEXT WEEK.
* MAINLY DRY EARLY NEXT WEEK WITH AN UNSETTLED PATTERN
DEVELOPING MID-WEEK BRINGING PERIODS OF SHOWERS AND HIGHER
HUMIDITY.
DETAILS...
SUNDAY THROUGH EARLY NEXT WEEK:
DRY CONDITIONS EXPECTED SUNDAY AS A SURFACE HIGH BUILDS IN FROM
NORTHWEST. EXPECT NW WINDS 5-12 MPH WITH GUSTS UP TO 20 MPH IN THE
AFTERNOON. HIGHS RANGE IN THE 60S ACROSS SOUTHERN NEW ENGLAND WITH
FEW SPOTS HITTING 70. WITH SUFFICIENT MIXING IN THE AFTERNOON,
SUNDAY WILL BE THE DRIEST DAY WE'VE HAD IN A WHILE, WITH RELATIVE
HUMIDITY VALUES DROPPING THE UPPER 20S TO LOW 30S ACROSS THE
INTERIOR.
INTO NEXT WEEK, A MID LEVEL RIDGE MOVES INTO THE REGION. ACCOMPANIED
BY WARMING 850MB TEMPERATURES, THIS WILL BRING WARMING TREND IN
TEMPERATURES FROM THE WEEKEND WITH MAINLY DRY CONDITIONS. ENSEMBLE
GUIDANCE SHOWS TEMPERATURES LEANING ABOVE NORMAL FOR MUCH OF THE
WEEK. THIS PUTS HIGH TEMPERATURES GENERALLY IN THE 70 DEGREE RANGE
MOST DAYS EXCEPT THE CAPE AND ISLANDS IN THE 60S. TUESDAY SHOULD BE
THE WARMEST DAY WITH HIGHS IN THE MID TO UPPER 70S WITH EVEN A SHOT
AT 80S IN SOME SPOTS ACROSS THE INTERIOR.
MID-WEEK THROUGH FRIDAY:
BY MID-WEEK, WE SHIFT TO A MORE UNSETTLED WEATHER PATTERN. ENSEMBLE
GUIDANCE SHOWS A GENERAL CONSENSUS WITH A SLOW MOVING SOUTHERLY
STREAM UPPER TROUGH MOVING ACROSS THE REGION THROUGH FRIDAY. THIS
WILL BRING UP A PLUME OF ABOVE NORMAL MOISTURE (~120-170% OF
NORMAL). UPPER LEVEL SUPPORT WILL BE LIMITED, BUT THERE SHOULD BE
WEAK ASCENT AND SUFFICIENT MOISTURE TO SUPPORT PERIODS OF SCATTERED
SHOWERS WEDNESDAY THROUGH FRIDAY. WITH THE INCREASED MOISTURE,
DEWPOINTS WILL RISE INTO THE UPPER 50S/LOW 60S MAKING IT FEEL MORE
HUMID.
AVIATION /20Z FRIDAY THROUGH WEDNESDAY/
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
18Z TAF UPDATE:
THIS AFTERNOON: HIGH CONFIDENCE
IFR/LIFR CONDITIONS. RAIN CONTINUES TO SPREAD FROM WEST TO EAST
FRIDAY MORNING-EARLY AFTERNOON. EAST WINDS AT 10-20 KNOTS. RAIN
WILL BE MODERATE TO HEAVY AT TIMES
TONIGHT: HIGH CONFIDENCE.
RAIN TAPERS OFF FROM WEST TO EAST, BUT WITH CONTINUED EAST
FLOW, IFR/LIFR CONDITIONS EXPECTED TO CONTINUE.
SATURDAY: HIGH CONFIDENCE.
MVFR WITH LINGERING SHOWERS IN THE MORNING, TURNING VFR WITH
WESTERLY WINDS IN THE AFTERNOON AT 15-25 KNOTS.
SATURDAY NIGHT: HIGH CONFIDENCE.
VFR. W WINDS 5-10 KTS.
KBOS TAF...HIGH CONFIDENCE.
RAIN MOVES IN AROUND 18Z THIS AFTERNOON, AND COULD BE MODERATE
TO HEAVY AT TIMES. IFR/LIFR CONTINUES FRIDAY NIGHT. RAIN SHOULD
END TAPER OFF SATURDAY MORNING.
KBDL TAF...HIGH CONFIDENCE.
IFR/LIFR TODAY. RAIN WILL BE MODERATE TO HEAVY AT TIMES. RAIN
TAPERS OFF TONIGHT AFTER 06Z WITH CIGS IMPROVING TO MVFR.
OUTLOOK /SUNDAY THROUGH WEDNESDAY/...
SUNDAY: VFR. BREEZY.
SUNDAY NIGHT: VFR.
MONDAY THROUGH MONDAY NIGHT: VFR. BREEZY.
TUESDAY: VFR.
TUESDAY NIGHT: VFR. SLIGHT CHANCE SHRA.
WEDNESDAY: SLIGHT CHANCE SHRA.
MARINE
FORECASTER CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MEDIUM - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
TONIGHT: HIGH CONFIDENCE.
LOW PRESSURE SYSTEM WILL BRING RAIN SHOWERS THROUGH TONIGHT AND
INCREASING SOUTHEASTERLY WINDS TO THE WATERS THROUGH TONIGHT.
SEAS BEGIN TO INCREASE TO 4-5 FEET. WINDS REMAIN LESS THAN 25
KT. SLIGHT CHANCE OF THUNDERSTORMS IN THE EVENING.
SATURDAY AND SATURDAY NIGHT: HIGH CONFIDENCE.
W WINDS 15-25 KTS WITH GUSTS TO 30 KTS ON THE OUTER SOUTHERN
WATERS DURING THE AFTERNOON. WINDS DIMINISH OVERNIGHT. SEAS 2-4
FT DURING THE DAY, DIMINISHING TO 2-4 FT BY SATURDAY NIGHT.
OUTLOOK /SUNDAY THROUGH WEDNESDAY/...
SUNDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING 5 FT.
SUNDAY NIGHT THROUGH MONDAY: WINDS LESS THAN 25 KT.
MONDAY NIGHT: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING
5 FT.
TUESDAY THROUGH TUESDAY NIGHT: WINDS LESS THAN 25 KT.
WEDNESDAY: WINDS LESS THAN 25 KT. SLIGHT CHANCE OF RAIN
SHOWERS.
BOX WATCHES/WARNINGS/ADVISORIES
CT...FLOOD WATCH THROUGH SATURDAY MORNING FOR CTZ002>004.
MA...FLOOD WATCH THROUGH SATURDAY MORNING FOR MAZ002>004-008>012-
026.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT SATURDAY FOR ANZ250-
254>256.
SYNOPSIS...KJC/BW
NEAR TERM...BW
SHORT TERM...BW
LONG TERM...MENSCH
AVIATION...BW/MENSCH
MARINE...BW/MENSCH
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