747
FXUS61 KBOX 091059
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOSTON/NORTON MA
659 AM EDT FRI MAY 9 2025
SYNOPSIS
MODERATE TO HEAVY RAIN TODAY AS A STRONG AND SLOW-MOVING LOW-
PRESSURE SYSTEM MOVES THROUGH THE REGION. RAIN GRADUALLY
DIMINISH 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 PM THIS EVENING/
KEY POINTS
* HEAVY RAIN WILL BRING A RENEWED RIVER FLOODING THREAT TO THE CT
RIVER.
* MINOR STREET AND NUISANCE FLOODING MAY ALIGN WITH THE
AFTERNOON/EVENING COMMUTE
VIGOROUS SHORTWAVE TROUGH AND STRENGTHENING SURFACE LOW MOVE THROUGH
THE REGION TODAY, BRINGING ANOTHER SOAKING RAIN AND A RENEWED THREAT
TO RIVER AND STREAM FLOODING. RAIN MOVES IN FROM WEST TO EAST
TODAY, BECOMING MODERATE TO HEAVY AT TIMES THIS AFTERNOON AND
EVENING. A WARM FRONT STALLS ACROSS NORTHERN MA THIS AFTERNOON,
WHICH, COMBINED WITH NE WINDS, CAUSING UPSLOPE FLOW, WILL BRING THE
HEAVIEST PRECIP TOTALS NEAR THE EAST SLOPES OF THE HIGH TERRAIN. THE
LATEST 00Z HREF LPMM SHOWS 1.5 TO 3.0 INCHES OF RAIN ACROSS BOTH THE
EAST SLOPES OF THE BERKSHIRES AND THE WORCESTER HILLS. OUTSIDE, THE
TERRAIN-INFLUENCED AREAS WILL LIKELY SEE 0.5 TO 1.5 INCHES. GIVEN
THE INCREASE IN QPF ACROSS THE WORCESTER HILLS, THE FLOOD WATCH WAS
EXPANDED EAST INTO WORCESTER AND WINDHAM COUNTIES. THE MAIN FLOODING
THREAT REMAINS RIVER AND STREAM FLOODING WITH SEVERAL POINTS ALONG
THE CT RIVER VALLEY GOING INTO MINOR, POSSIBLY EVEN MODERATE FLOOD.
HI-RES GUIDANCE SHOWS SEVERAL HOURS OF RAIN RATES BETWEEN 0.1 TO 0.3
INCHES PER HOUR. WITH MARGINAL INSTABILITY BUILDING TODAY, WEAK
EMBEDDED CONVECTION MAY BOOST RAIN RATES TO 0.5 IN/HR. THESE HEAVY
RAIN RATES ARE EXPECTED TO COINCIDE WITH THE EVENING COMMUTE ON
FRIDAY AFTERNOON, WHICH COULD MAKE TRAVEL HOURS WITH MINOR STREET
FLOODING POSSIBLE AND REDUCED VISIBILITY. WITH THE RAIN AROUND ALL
DAY, HIGH TEMPERATURES RANGE FROM THE LOW 50S IN NORTHERN MA TO THE
LOW 60S IN SOUTHERN MA, RI, AND CT.
SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/
THE WARM FRONT FINALLY MOVES NORTH AS THE SURFACE LOW PRESSURE
OCCLUDES OVER SNE. PRECIP ENDS FROM WEST TO EAST TONIGHT, WITH MUCH
OF THE RAIN OFFSHORE BY MIDNIGHT, WITH ONLY LINGERING SHOWERS INTO
SATURDAY MORNING. LOW CLOUDS, FOG, AND DRIZZLE CONTINUE ACROSS
EASTERN MA AS WINDS SHIFT FROM ENE TO ESE OVERNIGHT. OVERNIGHT LOWS
STAY IN THE MID-40S TO LOW 50S.
LONG TERM /SATURDAY THROUGH THURSDAY/
KEY POINTS:
* LINGERING SHOWERS SAT MORNING, THEN DRYING OUT AND BLUSTERY IN
THE AFTERNOON
* DRY AND SEASONABLE SUNDAY THEN WARMING TREND NEXT WEEK WITH ABOVE
NORMAL TEMPS
* RISK OF SHOWERS INCREASES WED AND THU ALONG WITH INCREASING
HUMIDITY
SATURDAY...
MID LEVEL LOW WILL BE MOVING ACROSS SNE IN THE MORNING WITH DRY SLOT
MOVING UP FROM THE SOUTH. HOWEVER, WRAP AROUND MOISTURE IN THE COMMA
HEAD WILL LIKELY BRING SOME SHOWERS TO THE INTERIOR AND NORTHERN MA
IN THE MORNING. THEN IT SHOULD DRY OUT IN THE AFTERNOON AS THE LOW
MOVES INTO THE GULF OF MAINE WITH DECREASING MOISTURE. HOWEVER,
STRENGTHENING GRADIENT WILL LEAD TO GUSTY W-NW WINDS IN THE
AFTERNOON WITH FORECAST SOUNDINGS SUPPORTING GUSTS TO 25-35 MPH.
BELOW NORMAL TEMPS IN THE UPPER 50S TO MID 60S.
SUNDAY THROUGH THURSDAY...
MAINLY DRY AND SEASONABLE SUNDAY WITH DIMINISHING WIND AS HIGH PRES
BUILDS IN FROM THE NW. THEN A WARMING TREND NEXT WEEK AS THE HIGH
MOVES SOUTH OF NEW ENG AND UPPER LEVEL RIDGING MOVES INTO THE REGION
WITH WARMING TEMPS ALOFT. WARMEST DAY TUE WITH TEMPS POSSIBLY
REACHING LOWER 80S INTERIOR. THE RIDGE SLIDES OFFSHORE BY WED AS
SLOW MOVING UPPER TROUGH APPROACHES FROM THE WEST. HIGHER PWAT PLUME
AHEAD OF THE TROUGH SURGES NORTHWARD WITH 1.5" PWATS MOVING BACK
INTO NEW ENG SO SHOWERS EXPECTED WED AND PROBABLY THU AS WELL AS THE
UPPER TROUGH MOVES OVERHEAD. TEMPS REMAINING ABOVE NORMAL WITH
INCREASING HUMIDITY AS DEWPOINTS POTENTIALLY RISE INTO THE 60S WED
AND/OR THU.
AVIATION /12Z FRIDAY THROUGH TUESDAY/
LOW - LESS THAN 30 PERCENT.
MODERATE - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
12Z TAF UPDATE:
FRIDAY: 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
FRIDAY NIGHT: 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.
KBOS TAF...HIGH CONFIDENCE.
COULD SEE SOME IMPROVEMENT TO IFR/LOW END MVFR THIS AFTERNOON.
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 MOVES IN AFTER 12Z AND WILL BE MODERATE TO
HEAVY AT TIMES. RAIN TAPERS OFF TONIGHT AFTER 06Z WITH CIGS
IMPROVING TO MVFR
OUTLOOK /SATURDAY THROUGH TUESDAY/...
SATURDAY: MAINLY VFR, WITH LOCAL IFR POSSIBLE. BREEZY. CHANCE
SHRA.
SATURDAY NIGHT THROUGH SUNDAY: VFR. BREEZY.
SUNDAY NIGHT: VFR.
MONDAY THROUGH MONDAY NIGHT: VFR. BREEZY.
TUESDAY: VFR.
MARINE
FORECASTER CONFIDENCE LEVELS:
LOW - LESS THAN 30 PERCENT.
MEDIUM - 30 TO 60 PERCENT.
HIGH - GREATER THAN 60 PERCENT.
TODAY THROUGH FRIDAY NIGHT: MEDIUM CONFIDENCE.
LOW PRESSURE SYSTEM WILL BRING RAIN SHOWERS THROUGH FRIDAY NIGHT
AND INCREASING SOUTHEASTERLY WINDS TO THE WATERS THROUGH FRIDAY
NIGHT. SEAS BEGIN TO INCREASE TO 3-6 FEET IN THE OPEN OCEAN
WATERS STARTING LATE TONIGHT AND CONTINUING THROUGH FRIDAY
NIGHT. WINDS REMAIN LESS THAN 25 KT. SLIGHT CHANCE OF
THUNDERSTORMS.
OUTLOOK /SATURDAY THROUGH TUESDAY/...
SATURDAY: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS UP
TO 25 KT. SEAS UP TO 5 FT. CHANCE OF RAIN SHOWERS.
SATURDAY NIGHT: WINDS LESS THAN 25 KT. AREAS OF SEAS
APPROACHING 5 FT.
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: WINDS LESS THAN 25 KT.
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.
SMALL CRAFT ADVISORY FROM NOON TODAY TO 8 PM EDT SATURDAY FOR
ANZ254>256.
SYNOPSIS...KJC/KP
NEAR TERM...KP
SHORT TERM...KP
LONG TERM...KJC
AVIATION...KP
MARINE...KJC/KP
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