National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBOX 221935
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
335 PM EDT WED MAY 22 2013

.SYNOPSIS...
A STALLED FRONT ACROSS SOUTHERN NH AND NORTHEAST MASS WILL MOVE
NORTH AS A WARM FRONT TONIGHT. WARM HUMID SHOWERY WEATHER
CONTINUES THURSDAY AND FRIDAY WITH SCATTERED STRONG THUNDERSTORMS
POSSIBLE. COOLER AND LESS HUMID CONDITIONS ARE EXPECTED FOR THIS
HOLIDAY WEEKEND AS HIGH PRESSURE BUILDS ACROSS THE NORTHEAST.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
THROUGH 00Z...
PARAMETERS SUCH AS THE C-B SIGNIFICANT SEVERE ARE FOCUSSED ON
EASTERN NY AND EXTEND INTO FRANKLIN AND CHESHIRE COUNTIES. THIS
AREA EXPANDS INTO HAMPSHIRE AND HAMPDEN COUNTIES MID TO LATE
AFTERNOON BEFORE DIMINISHING. THE MORE GENERAL PARAMETERS SUCH AS
LIFTED INDEX SHOW THE LOWEST VALUES IN THIS AREA AND ARE UNSTABLE
TO MANCHESTER AND METROWEST BOSTON/NORTHERN RI/NORTHERN CT.
PRECIPITABLE WATER VALUES WILL BE NEAR 1.5 INCHES...SUFFICIENT FOR
SOME HEAVY DOWNPOURS. CONTINUE TO EXPECT SCATTERED TSTMS IN THIS
LATTER AREA WITH LOCALLY HEAVY DOWNPOURS. THE BEST SEVERE
POTENTIAL WILL BE IN WESTERN MASS AND SOUTHWEST NH. SVR TSTM
WATCH 210 IS IN EFFECT FOR THE WESTERN HALF OF OUR FORECAST AREA.

TONIGHT...
UPPER RIDGE SHIFTS EAST OF US...TURNING WINDS INTO A SOUTHWEST
FLOW. THIS SHOULD MOTIVATE THE SURFACE FRONT TO MOVE NORTH AS A
WARM FRONT TONIGHT. THE EASTERLY MARINE SURFACE FLOW OVER THE
MERRIMACK VALLEY AND METRO BOSTON WOULD THEN BECOME SOUTHERLY AND
BRING IN WARMER MORE HUMID SURFACE AIR.

CONVECTIVE PARAMETERS REMAIN UNSTABLE OVERNIGHT...WHILE SUNSET
SHOULD WORK TOWARD STABILIZING THE AIRMASS A TAD. OVERALL POPS
WILL DIMINISH...BUT WITH A LINGERING CHANCE OF THUNDER. THE
GREATEST RISK WILL BE ACROSS THE CT VALLEY AND CENTRAL HILLS WITH
LESS OF A RISK ALONG THE COAST. TEMPS ARE A BLEND OF MOS.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
THURSDAY...
SURFACE LOW PRESSURE MOVES OUT OF THE GREAT LAKES AND UP THE ST
LAWRENCE VALLEY. MEANWHILE THE SUPPORTING UPPER TROUGH DIGS OVER
THE GREAT LAKES AND TURNS THE UPPER FLOW OVER US PAST SOUTHWEST
AND TOWARD SOUTH. THIS WILL SLOW DOWN THE PROGRESS OF THE SURFACE
COLD FRONT AND KEEP NEW ENGLAND IN THE WARM HUMID UNSETTLED
AIRMASS. CONVECTIVE PARAMETERS REMAIN UNSTABLE WITH PREFERENCE FOR
THE CENTRAL HILLS/CT VALLEY/BERKSHIRE EAST SLOPE REGIONS. WILL
NEED TO MONITOR FOR POTENTIAL SEVERE WEATHER. ALSO...PRECIPITABLE
WATER VALUES ARE FORECAST TO INCREASE TO BETWEEN 1.5 AND 1.75
INCHES WHICH INCREASES THE LIKELIHOOD OF HEAVY DOWNPOURS.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
HIGHLIGHTS...

* SCATTERED SHOWERS AND THUNDERSTORMS FRIDAY
* COOLER AND LESS HUMID FOR THE WEEKEND

CONFIDENCE LEVEL/MODEL GUIDANCE...MODERATE CONFIDENCE IN OVERALL
FORECAST. 00Z MODELS CONTINUE TO SLOW DOWN THE ELONGATED TROUGH
MOVING ACROSS THE EASTERN HALF OF THE CONUS. THERE IS STILL SOME
TIMING DIFFERENCES ON WHEN THE SYSTEM WILL PUSH THROUGH THE
NORTHEAST. REGARDLESS APPEARS THAT ELONGATED TROUGH WILL MOVE INTO
NEW ENGLAND EVENTUALLY BECOMING A CUTOFF LOW BY THE WEEKEND. THIS
LOW WILL EVENTUALLY MOVE INTO THE MARITIMES BY THE BEGINNING OF
THE WORK WEEK AS HIGH PRESSURE MOVES IN. HAVE HIGH CONFIDENCE THAT
PRECIP WILL OCCUR ON FRIDAY AND COOLER TEMPS WILL DOMINATE THE
REGION FOR THE WEEKEND. LOW CONFIDENCE IN FORECAST AFTER TUES.

DETAILS...

THURSDAY NIGHT INTO FRIDAY...
UPPER LEVEL TROUGH WILL PUSH THROUGH THE EASTERN GREAT LAKES
REGION EVENTUALLY PUSHING A COLD FRONT THROUGH SOUTHERN NEW
ENGLAND. MODELS CONTINUE TO SLOW THE TIMING OF THE FRONT DOWN...SO
BELIEVE THAT IT MOVE THROUGH SOMETIME ON FRIDAY. BECAUSE OF THE
MODEL DIFFERENCE HAVE LOW CONFIDENCE IN TIMING.
REGARDLESS...BELIEVE THAT SHOWERS AND THUNDERSTORMS WILL MOVE
THROUGH WITH TEMPS NEAR AVG. CANNOT RULE OUT A FEW STRONG
THUNDERSTORMS ESPECIALLY ACROSS REGIONS SOUTH OF THE I-84
CORRIDOR. MODELS INDICATE SOME INSTABILITY WITH ABOUT 25KTS OF
SHEAR. PWAT VALUES OF OVER 1.5 INCHES LEADS FORECASTER TO BELIEVE
THAT HEAVY DOWNPOURS IS THE MAIN THREAT...BUT WITH FALLING HEIGHTS
AS COLD FRONT APPROACHES...SMALL HAIL AND GUSTY WINDS IS NOT OUT
OF THE QUESTION. ANY CHANCE FOR STRONG STORMS TO DEVELOP WILL
DIMINISH AFTER SUNSET AS DIURNAL HEATING IS LOST.

WEEKEND...TRICKY FORECAST IS PLAYING OUT FOR THE WEEKEND. MODELS
HAVE INDICATED THAT THE ELONGATED TROUGH WILL CUT OFF OVER THE MID
ATLANTIC AND SLOWLY ROTATE OVER NEW ENGLAND FOR THE WEEKEND. THIS
WILL ALLOW FOR MUCH COOLER AIR...WELL BELOW AVG AND EVEN HAS
SLOWED DOWN THE TIMING OF PRECIP. BELIEVE THAT PRECIP MAY LINGER
INTO SAT...BUT HAVE LOW CONFIDENCE THAT PRECIP WILL OCCUR ON
SUNDAY. FOR NOW HAVE CONTINUED WITH THE SLOW DOWN TREND IN THE
FORECAST. EXPECT HIGHS REACHING INTO THE MID TO UPPER 60S WITH
LOWS DROPPING INTO THE MID TO UPPER 30S. IF SKIES CLEAR OUT AS
THIS COLD POOL SITS OVER US...THERE IS A POSSIBILITY THAT
FROST/FREEZE HEADLINES MAY BE NEEDED AS THE ENTIRE REGION IS
OFFICIALLY IN THE GROWING SEASON.

MONDAY AND BEYOND...SURFACE HIGH PRESSURE WILL BE IN CONTROL FOR
THE FIRST HALF OF NEXT WEEK. THIS WILL HELP TEMPS REACH SEASONAL
CONDITIONS. APPEARS THAT THERE IS LIMITED MOISTURE KEEPING THE
FORECAST DRY...HOWEVER CANNOT RULE OUT A SPOT SHOWER OR TWO...ESP
IF SEA BREEZES DEVELOPS.

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.

OVERVIEW...MODERATE CONFIDENCE IN TIMING OF CEILINGS AND CONVECTION.

THIS AFTERNOON/EVENING...
CIGS BELOW 1000 FEET LINGER ALONG THE EAST COAST...LIFTING TO 1500
TO 2500 FEET IN THE COASTAL PLAIN AND VFR IN THE CT VALLEY. EXPECT
CLOUDS ALONG THE COAST WILL BE TOUGH TO BREAK ESPECIALLY WHERE
WINDS LINGER OUT OF THE EAST. FOG LINGERS AT ACK AND IFR/LIFR
CONDITIONS EXPECTED THROUGH THE AFTERNOON.

MEANWHILE AN AREA OF TSTMS MOVES IN FROM EASTERN NY WITH BRIEF
CIGS 500-1000 FEET AND VSBYS 1-3 MILES WHERE THEY MOVE OVERHEAD.
BRIEF STRONG WINDS AND HAIL POSSIBLE WITH THESE STORMS IN THE CT
VALLEY THIS AFTERNOON/EVENING.

TONIGHT...LOW TO MODERATE CONFIDENCE.
SHOWERS/TSTMS DIMINISH IN INTENSITY BUT SCATTERED PRECIPITATION
LINGERS OVERNIGHT. THE WARM HUMID AIRMASS AND WET GROUND WILL
GENERATE MORE FOG WITH VSBYS 1-3 MILES IN GENERAL AND BELOW 1 MILE
IN THE COASTAL PLAIN.

THURSDAY...LOW TO MODERATE CONFIDENCE.
CONTINUED UNSETTLED WEATHER. FOG AND LOW CLOUDS WILL SLOWLY LIFT
DURING THE MORNING. THE TAFS MAY BE TOO FAST IN LIFTING
CIGS/VSBYS. SCATTERED SHOWERS/TSTMS WILL REGENERATE DURING THE DAY
WITH MORE STRONG STORMS IN THE CT VALLEY AND CENTRAL HILLS.

KBOS TERMINAL...LOW TO MODERATE CONFIDENCE IN TRENDS AND CEILINGS.

KBDL TERMINAL...LOW TO MODERATE CONFIDENCE IN TIMING OF CONVECTION
THROUGH THE PERIOD. COULD SEE BRIEF IFR IN AN AREA OF TSRA.
POTENTIAL FOR HAIL OR WIND GUSTS TO 50 KNOTS IN ISOLATED TSTMS.

OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY...

THURSDAY NIGHT INTO FRIDAY...LOW CONFIDENCE. MODERATE CONFIDENCE
ON SEA BREEZE DEVELOPMENTS. VERY UNSETTLED PATTERN WITH
VARIABILITY BETWEEN VFR CONDITIONS AND MVFR/IFR CONDITIONS IN
SHRA/TSRA/FOG. IMPROVING CONDITIONS LATE FRIDAY NIGHT INTO
SATURDAY MORNING.

SATURDAY-SUNDAY...HIGH CONFIDENCE. VFR.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.

HIGH CONFIDENCE THROUGH THURSDAY.
A FRONT IS STALLED ACROSS THE EASTERN WATERS WITH EAST WINDS TO
THE NORTH AND SOUTHWEST WINDS TO THE SOUTH. THIS FRONT WILL SHIFT
NORTH TONIGHT WITH ALL WATERS TURNING TO SOUTHWEST WINDS.
SOUTHWEST WINDS WILL INCREASE OVERNIGHT AND THURSDAY WITH
POTENTIAL FOR 25 KNOTS ON THURSDAY. THIS WIND WILL CAUSE BUILDING
SEAS THROUGH THE PERIOD WITH 5-8 FOOT SEAS ON THE SOUTHERN EXPOSED
WATERS AND POSSIBLY THE EASTERN OUTER WATERS.

EXPECT LOW VSBYS IN FOG AND LOCALLY HEAVY SHOWERS. ISOLATED
THUNDERSTORMS ARE ALSO POSSIBLE.

OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY...

FRIDAY...MODERATE TO HIGH CONFIDENCE. COLD FRONT WILL BE SLOW TO
CLEAR THE WATERS...SO EXPECT SW WINDS IN PLACE FOR A PORTION OF
THE DAY BEFORE SHIFTING TO W-NW ACROSS THE EASTERN WATERS.

THE WEEKEND...MODERATE CONFIDENCE. SEAS WILL REMAIN ABOVE SCA FOR
MOST OF THE WEEKEND ESP FOR THE OUTER WATERS. GUSTY NW BEHIND THE
FRONT WILL BRING GUSTS CLOSE TO GALE FORCE SAT INTO SAT NIGHT.
EXPECT BOTH SEAS AND WIND TO SLOWLY SUBSIDE THROUGHOUT THE DAY
ON SUNDAY.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM THURSDAY TO 6 AM EDT FRIDAY FOR
     ANZ232>234.
     SMALL CRAFT ADVISORY FROM 10 AM THURSDAY TO 6 AM EDT FRIDAY
     FOR ANZ230-231-236-251.
     SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 6 AM EDT FRIDAY
     FOR ANZ235-237.
     SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 AM EDT FRIDAY
     FOR ANZ250.
     SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ254>256.
-- End Changed Discussion --

&&

$$
SYNOPSIS...WTB/DUNTEN
NEAR TERM...WTB/DUNTEN
SHORT TERM...WTB
LONG TERM...DUNTEN
AVIATION...WTB/DUNTEN
MARINE...WTB/DUNTEN