000
FXUS61 KBOX 250255
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
1055 PM EDT FRI MAY 24 2013

.SYNOPSIS...
A COLD FRONT WILL MOVE SLOWLY ACROSS EASTERN NEW ENGLAND THIS
EVENING WITH MUCH COOLER AIR BEHIND THE FRONT. LOW PRESSURE WILL
DEVELOP ON THIS FRONT...WITH SHOWERS LINGERING ACROSS THE REGION
THROUGH SATURDAY NIGHT. SOME IMPROVEMENT IS LIKELY SUNDAY AS THE
LOW DEPARTS INTO NORTHERN NEW ENGLAND. HOWEVER MUCH NICER WEATHER
ARRIVES MEMORIAL DAY MONDAY WITH WARM TEMPERATURES AND DRY
CONDITIONS AS HIGH PRESSURE BUILDS SOUTH OF NEW ENGLAND. A WARM
FRONT WILL BRING EVEN WARMER TEMPERATURES BY LATE NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
1045 PM UPDATE...

MAIN AREA OF SHOWERS WAS ACROSS THE WESTERN 2/3RDS OF SOUTHERN NEW
ENGLAND...CLOSER TO THE MID-LEVEL LOW. NO REAL INSTABILITY LEFT
WELL WEST OF A COLD FRONT LYING JUST OFF THE EAST COAST OF MA.
SOME LIGHTNING WELL OFFSHORE FROM THE MID ATLANTIC STATES. THERE
IS A SMALL POSSIBILITY FOR THUNDERSTORMS IN THE VICINITY OF THIS
FRONT FOR A FEW MORE HOURS WHILE THERE IS STILL A LINGERING MID-
LEVEL JET.

PREVIOUS FORECAST LOOKED PRETTY GOOD...BUT DID UPDATE THE GRIDS TO
BRING NEAR-TERM FORECAST IN LINE WITH OBSERVED TRENDS.

PREVIOUS DISCUSSION...

ANOMALOUS UPPER PATTERN UNDERWAY WITH HIGH AMPLITUDE NEGATIVE
TROUGH EVOLVING INTO A CLOSED MID LEVEL LOW OVER LONG ISLAND
TONIGHT...INDUCING CYCLOGENESIS NEAR NANTUCKET. THIS WILL RESULT
IN COMMA HEAD/TROWAL RAINS OVER NY/NJ AND WESTERN NEW ENGLAND TO
PIVOT ACROSS THE REMAINDER OF THE REGION AS THE NIGHT PROGRESSES.
THUS CATEGORICAL POPS FROM MET AND MAV LOOK REASONABLE. HEAVIEST
AND MOST WIDESPREAD RAINS WILL BE FOCUSED ACROSS WESTERN CT/MA
INTO SOUTHWEST NH...THE I-91 CORRIDOR.

STRONG COLD AIR ADVECTION WILL CONTINUE TO OVERSPREAD THE REGION IN
THE POST FRONTAL AIRMASS FROM WEST TO EAST. WELL TEMPS WILL FALL
INTO THE 40S ACROSS MUCH OF THE REGION TONIGHT...MODEL SOUNDINGS
SUGGEST THERE IS ENOUGH BLYR WARMTH TO KEEP PTYPE ALL RAIN EVEN
ACROSS THE HIGHER TERRAIN.

FALLING TEMPS WILL COMBINE WITH GUSTY NW WINDS TO PROVIDE A BIT OF A
WIND CHILL TONIGHT. THIS ALONG WITH SHOWERS BECOMING MORE WIDESPREAD
WILL YIELD NASTY CONDITIONS FOR ANY OUTDOOR ACTIVITIES. THE ONLY
POSITIVE WILL BE TEMPORARY WARMTH AND HUMIDITY ACROSS EASTERN MA.

TEMPS IN THE L70S ALONG WITH DEW PTS IN THE MU60S ACROSS THIS AREA
HAS RESULTED IN SB CAPES OF AROUND 500 J/KG. DESPITE MODEST DEEP
LAYER SHEAR MID LEVEL LAPSE RATES ARE WEAK SO NOT EXPECTING MUCH IN
THE WAY OF DEEP CONVECTION...JUST SOME HEAVY SHOWERS ACROSS EASTERN
MA/RI AND EASTERN CT.

FOR THE REMAINDER OF THE REGION COMMA HEAD RAINS WILL CONTINUE TO
BLOSSOM ACROSS NY/PA/NJ AND NYC WILL CONTINUE TO SLOWLY PIVOT NE
INTO WESTERN NEW ENGLAND LATER TODAY.

COLD FRONT WILL CONTINUE TO OOZE EASTWARD INTO EASTERN MA LATE
THIS AFTERNOON/EARLY EVENING. BEHIND THE FRONT GUSTY WNW WINDS
WITH THE INITIAL SURGE OF COOL AIR...THEN RELAXING A BIT.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
SATURDAY...
NOT YOUR TYPICAL START TO MEMORIAL DAY WEEKEND WITH COASTAL LOW
OVER GULF OF MAINE AS MID LEVEL LOW DRIFTS ACROSS SOUTHERN NEW
ENGLAND. HEIGHTS ALOFT CONTINUE TO FALL WHICH RESULTS IN COOLING
FROM TOP DOWN. VERY IMPRESSIVE SYNOPTIC SCALE FORCING VIA MID
LEVEL Q-VECTOR CONVERGENCE. STRONGEST LIFT WILL ONCE AGAIN BE
ACROSS WESTERN SECTIONS OF CT/MA INTO SOUTHWEST NH...I-91
CORRIDOR. MODEL SOUNDINGS SUGGEST LATE IN THE DAY ACROSS THIS AREA
ESPECIALLY THE HIGHER TERRAIN OF MA/NH THAT RAIN MAY MIX OR CHANGE
TO SNOW AT TIMES WHEN PRECIP INTENSITY IS GREATEST. THIS WILL BE
MOST COMMON AT ELEVATIONS GREATER THAN 1KFT AS FREEZING LEVELS
DROP TO THIS LEVEL. SURFACE AND GROUND TEMPS LIKELY TOO WARM FOR
ANY ACCUMULATION BUT MINOR SNOW ACCUMULATION POSSIBLE ON
TREES/POWERLINES. DON/T EXPECT ANY IMPACT JUST SOME DECORATIVE
SNOW POSSIBLE HIGHER TERRAIN.

ELSEWHERE SHOWERS SHOULD BE WIDESPREAD ALONG WITH CHILLY TEMPS IN
THE U40S TO L50S...BUT WILL FEEL MUCH COOLER WITH GUSTY WNW WIND.
EMBEDDED HEAVY SHOWERS POSSIBLE.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
HIGHLIGHTS...

* LOW PRESSURE WILL SLOWLY MOVE OFFSHORE LATE THIS WEEKEND...
  KEEPING SHOWERS AND COOL TEMPERATURES INTO SUNDAY
* FAIR BUT COOL CONDITIONS FOR MEMORIAL DAY...WITH MODERATING
  TEMPS THROUGH THE MID WEEK
* WARM FRONT BY END OF THE WEEK WILL PUSH TEMPS WELL ABOVE AVERAGE

OVERVIEW AND MODEL PREFERENCES...
MEDIUM RANGE MODELS APPEAR IN GOOD AGREEMENT WITH THE SLOW BUT
STEADY MOVEMENT OF H5 CUTOFF LOW AND ASSOCIATED SURFACE SYSTEM
LATE THIS WEEKEND INTO NORTHERN NEW ENGLAND AND THE MARITIMES BY
MEMORIAL DAY. UPPER LEVEL PATTERN EVOLVES OVER TIME AS CUTOFF LOW
REMAINS ACROSS THE EASTERN MARITIMES INTO THE MIDDLE OF NEXT
WEEK...TENDING TO FLATTEN OUT ACROSS THE NORTHERN TIER STATES WITH
BROAD HIGH PRES ACROSS THE SOUTH. WILL SEE A RETURN TO MAINLY DRY
CONDITIONS...THOUGH A WARM FRONT MAY APPROACH BY MID WEEK WITH A
BRIEF PERIOD OF SHOWERS POSSIBLE. THEN...LOOKS LIKE SUMMER WARMTH
WILL PUSH IN BY LATE NEXT WEEK.

WENT ALONG WITH BLEND OF PREVIOUS FORECAST...00Z ECMWF/12Z GFS AND
WPC GUIDANCE FOR THIS PACKAGE...WHICH SHOWED GOOD CONTINUITY AND
CONSISTENCY OVER THE LAST FEW RUNS. NOTED THAT THE 00Z EC /AND
SINCE THEN...THE 12Z/ OP RUNS HAVE COME MORE IN LINE WITH THE GFS
IN EJECTING THE SURFACE LOW ACROSS THE REGION FASTER THAN THEIR
PREVIOUS RUNS...AND BOTH ARE NEARLY IDENTICAL IN PUSHING SYSTEM
INTO MAINE AND THE MARITIMES LATE THIS WEEKEND INTO THE HOLIDAY.

DETAILS...

SATURDAY NIGHT-SUNDAY...AS H5 LOW MOVES ACROSS E MA SAT NIGHT...
THE NW FLOW BEHIND COMBINED WITH THE COLD POOL ALOFT WILL BRING
MIGHTY CHILLY AIR INTO THE REGION ESPECIALLY ACROSS S NH/W MA.
WITH WRAPAROUND RAINFALL MOVES IN ACROSS INTERIOR AREAS...ALONG
WITH THIS COLDER AIR...WE HAVE MENTIONED THE POSSIBILITY OF /YES/
MIXED RAIN/SNOW SHOWERS ACROSS THE HIGHER TERRAIN OF THE
MONADNOCKS/E SLOPES OF THE BERKSHIRES POSSIBLY DOWN INTO THE
MOUNT WACHUSETT REGION OF N WORCESTER COUNTY SAT NIGHT.
GRANTED...GROUND HAS WARMED UP SO NOT EXPECTING MUCH IN THE WAY OF
ACCUMULATION...BUT COULD SEE SOME ON GRASSY AND SOME UNTREATED
SURFACES. LOWS WILL DROP TO THE MID-UPPER 30S EVEN AS FAR S OF
INTERIOR SE MA/N RI/NE MA...RUNNING 10 TO 15 DEGS BELOW SEASONAL
NORMS.

AS FOR ANY CONVECTION...HAVE REMOVED MENTION FOR NOW BUT WOULD NOT
BE SURPRISED TO HEAR A FEW ISOLD RUMBLES AS PRECIP AND UPPER LEVEL
SYSTEM START TO SHIFT NE.

ON SUNDAY...LEFTOVER SHOWERS WILL END FROM S-N DURING THE DAY.
CLOUDS WILL REMAIN FOR MOST OF THE DAY AS NW WINDS PICK UP. EXPECT
GUSTS UP TO 30-35 MPH ESPECIALLY ACROSS CENTRAL AND WESTERN AREAS.
WILL REMAIN COOL WITH HIGHS ONLY IN THE 50S TO AROUND 60...AGAIN
10-15 DEGREES BELOW NORMAL. SKIES SHOULD BEGIN TO CLEAR SUN NIGHT
AND IT WILL REMAIN RATHER CHILLY.

MONDAY...LOOKS LIKE THE HOLIDAY WEATHER IS SALVAGED AS HIGH PRES
BUILDS OUT OF EASTERN ONTARIO AND WESTERN QUEBEC. WILL STILL SEE
SOME GUSTY W-NW WINDS...UP TO 20-25 MPH...BUT IT WILL BE MILDER.
HIGHS ARE FORECAST TO REACH THE MID 60S TO AROUND 70.

TUESDAY-WEDNESDAY...ANOTHER NICE DAY ON TUESDAY AS HIGH PRES
STARTS TO RECENTER OFF THE MID ATLC COAST. WINDS START TO BACK TO
SW BY LATE IN THE DAY. HIGHS MAINLY IN THE LOWER-MID 70S...THOUGH
ONLY IN THE 60S ALONG THE S COAST. BY TUESDAY NIGHT...WILL SEE
SOME CLOUDS INCREASE AS A WARM FRONT APPROACHES. HAVE BROUGHT IN
LOW CHANCE POPS FOR WED/WED NIGHT AND MAY EVEN SEE A FEW
THUNDERSTORMS AS WARM FRONT WORKS ACROSS.

THURSDAY-FRIDAY...MUCH WARMER AIR WORKS IN DURING THIS TIMEFRAME.
ANY LEFTOVER SCT SHOWERS/TSTMS WILL PUSH OUT OF THE REGION DURING
THU...WITH MORE HUMIDITY WORKING IN AS WELL. EXPECT HIGHS BOTH
DAYS MAINLY IN THE 80S...EXCEPT COOLER ALONG THE S COAST.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...

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

OVERVIEW...MODERATE CONFIDENCE TONIGHT AND SAT.

TONIGHT...COLD FRONT JUST EAST OF THE MASS E COAST AT 03Z WILL
STALL LATER TONIGHT AS A LOW PRESSURE DEVELOPS ALONG IT. EXPECTING
IFR CONDITIONS ALONG E COASTAL AREAS...WITH VFR CONDITIONS
LOWERING TO AREAS OF MVFR AS SHOWERS DEVELOP FROM W-E AS UPPER
LEVEL REFLECTION MOVES SLOWLY INTO THE REGION.

SAT...
WIDESPREAD SHOWERS OVER WESTERN NEW ENGLAND PIVOTS INTO EASTERN
NEW ENGLAND DURING THE AFTERNOON. SNOW MAY MIX IN WITH THE RAIN
ACROSS THE HIGHER TERRAIN OF WESTERN MA AND SOUTHWEST NH. NW
WINDS MAY GUSTS TO 25 KT. IFR CONFINED TO SOUTHEAST MA WITH MVFR
ELSEWHERE.

KBOS TERMINAL...MODERATE CONFIDENCE IN TAF. VFR CONDITIONS WILL
LOWER TO MVFR AND EVENTUALLY IFR CIGS WITH VFR-MVFR VSBYS IN SCT
SHOWERS. SAT...SHOWERS BECOME MORE WIDESPREAD DURING THE AFTERNOON
AND WINDS INCREASE UP TO 25 KT.

KBDL TERMINAL...MODERATE CONFIDENCE IN TAF. LOW CIGS AND SHOWERS
EXPECTED TONIGHT AND SATURDAY. MAINLY MVFR CIGS AND VFR-MVFR VSBYS
MAINLY IN SHOWERS. WNW WINDS UP TO 25 KT EARLY TONIGHT AND
POSSIBLY UP TO 30 KT SAT WITH MVFR CONTINUING.

OUTLOOK...SATURDAY NIGHT THROUGH WEDNESDAY...

SATURDAY NIGHT-SUNDAY...LOW TO MODERATE CONFIDENCE. UNSETTLED
PATTERN WITH VARIABLE CONDITIONS FROM VFR TO MVFR-IFR CONDITIONS
IN SHRA/FOG. LOW PROB OF ISOLD TSTM SAT NIGHT. PRECIP TAPERS OFF
FROM S-N DURING SUNDAY WITH GENERAL VFR CONDITIONS BY LATE SUNDAY
THOUGH VFR CIGS LINGER SUNDAY NIGHT. MAY SEE PATCHY MVFR-IFR VSBYS
IN PATCHY FOG SUN NIGHT.

MONDAY-TUESDAY...HIGH CONFIDENCE. VFR. LOW CONFIDENCE ON SEA
BREEZE DEVELOPMENT. MAY SEE PATCHY FOG WITH MVFR-IFR VSBYS LATE
MON NIGHT-EARLY TUE MORNING.

WEDNESDAY...MODERATE CONFIDENCE. MAINLY VFR. MAY SEE CLOUDS/SCT
SHOWERS MOVE IN AHEAD OF WARM FRONT WITH LOCAL MVFR CONDITIONS.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

TONIGHT...LARGE S SWELLS CONTINUE ON THE SOUTHERN RI AND MA
WATERS. OTHERWISE A SLOW WIND SHIFT TO WEST WITH FRONTAL PASSAGE.
WNW WINDS MAY GUSTS UP TO 20 KT AS LOW PRES DEVELOPS NEAR
NANTUCKET. SHOWERS BECOME MORE WIDESPREAD AS THE NIGHT PROGRESSES.
FORECAST CONFIDENCE MODERATE.

SAT...LOW PRES TRACKS FROM NANTUCKET TO GULF OF MAINE. NW WINDS UP
TO 25 KT POSSIBLE ALONG WITH LINGERING S SWELLS SOUTH WATERS OF RI
AND MA. SHOWERS REDUCE VSBY AS WELL. OUTLOOK...SATURDAY NIGHT
THROUGH WEDNESDAY...

OUTLOOK...SATURDAY NIGHT THROUGH WEDNESDAY...

MODERATE CONFIDENCE THROUGH THE PERIOD.

SATURDAY NIGHT-SUNDAY...SURFACE LOW WILL LINGER ACROSS THE EASTERN
WATERS SAT NIGHT...THEN SHIFT SLOWLY NE SUN. SEAS REMAINING ABOVE
5 FT. W-NW WINDS WILL PICK UP...WITH GUSTS UP TO GALE FORCE MAINLY
ON THE SOUTHERN WATERS TO S AND E OF NANTUCKET. KEPT GALE WATCH
GOING THERE. WINDS SHOULD DIMINISH DURING SUN AFTERNOON/NIGHT.

MONDAY...WINDS DIMINISH BELOW SMALL CRAFT. SEAS REMAIN AOA 5 FT
ON THE OUTER WATERS.

TUESDAY...WINDS AND SEAS REMAIN BELOW SMALL CRAFT.

WEDNESDAY...S-SE WINDS MAY SEE SE WINDS PICK UP DURING THE DAY WITH
GUSTS UP TO 20 KT. SEAS MAY APPROACH 5 FT ON THE SOUTHERN WATERS.

&&

.HYDROLOGY...
DISCOUNTED THE GFS AS IT APPEARED AN OUTLIER WITH UP TO 4 INCHES
OF RAIN IN WESTERN MA AND SOUTHWEST NH. MODEL CONSENSUS OF 12Z
NAM/ECMWF AND GEFS SUGGEST WIDESPREAD 0.75-1.00 INCH RAINFALL
ACROSS THE ENTIRE REGION. POSSIBLY UP TO 1.5 INCHES ACROSS I-91
CORRIDOR OF WESTERN CT/MA INTO SOUTHWEST NH GIVEN PROXIMITY TO
COMMA HEAD/TROWAL. GIVEN THIS IS SPREAD OUT INTO SUN MORNING RISK
OF FLOODING IS VERY LOW. THUS NO HEADLINES.

&&

.TIDES/COASTAL FLOODING...
EAST COAST OF MA THIS WEEKEND...

HIGH ASTRONOMICAL TIDES THIS WEEKEND. AT BOSTON...A HIGH TIDE OF
11.9 FT WILL OCCUR TONIGHT AT 11:21 PM AND 12.2 FT EARLY SUNDAY
MORNING AT 12:12 AM. ESTOFS INDICATING UP TO 0.5 FT SURGE WHICH
SEEMS REASONABLE. DESPITE THE LACK OF MUCH WAVE ACTION COULD SEE
SOME MINOR INUNDATION ESPECIALLY WITH THE SAT NIGHT HIGH TIDE.
AGAIN VERY MINOR COASTAL FLOODING POSSIBLE IN THE TYPICALLY PRONE
LOCATION OF EASTERN MA...IE MORRISSEY BLVD IN DORCHESTER.
CONFIDENCE NOT HIGH ENOUGH TO ISSUE A COASTAL FLOOD ADVISORY
ESPECIALLY GIVEN A MARGINAL EVENT. LATER SHIFTS WILL HAVE TO
REEVALUATE THE RISK.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...GALE WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY MORNING FOR
     ANZ235-237-254>256.
     SMALL CRAFT ADVISORY UNTIL 2 PM EDT SATURDAY FOR ANZ235-237-
     250-254>256.

&&

$$
SYNOPSIS...NOCERA/EVT
NEAR TERM...BELK/NOCERA
SHORT TERM...NOCERA
LONG TERM...EVT
AVIATION...BELK/NOCERA/EVT
MARINE...BELK/NOCERA/EVT
HYDROLOGY...NOCERA
TIDES/COASTAL FLOODING...NOCERA

NWS BOX Office Area Forecast Discussion