Special Weather Statement, NWS Boston/Norton, MA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
1015 AM EDT THU AUG 9 2012

.SYNOPSIS...
MUGGY WEATHER WILL CONTINUE TODAY. MOIST AND UNSTABLE AIR AHEAD OF
A STALLED COLD FRONT MAY BRING SCATTERED SHOWERS AND
THUNDERSTORMS THIS AFTERNOON. LOW PRESSURE PASSING WEST OF NEW ENGLAND
BRINGS ANOTHER CHANCE OF SHOWERS/THUNDERSTORMS FRIDAY AND
SATURDAY. DRIER AND LESS HUMID AIR RETURNS FOR LATE INTO THE
WEEKEND INTO EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
10 AM UPDATE...UPDATED SKY COVER AND DEWPOINTS IN PARTICULAR FOR
THE LATEST TRENDS. DEWPOINTS ARE IN THE MID TO UPPER 60S TO AROUND
70 AND AM NOT EXPECTING THEM TO DROP MUCH IF AT ALL THROUGH THE
DAY. OTHERWISE...THE FORECAST IS ON TRACK.

TODAY...
EXPECT A MOSTLY DRY DAY TODAY AS THERE IS STILL PLENTY OF DRY AIR
ALOFT PER 00Z SOUNDINGS AT NYC AND ALY. HOWEVER CANNOT RULE OUT
THE POTENTIAL FOR SCATTERED SHOWERS/ISOLATED THUNDER AS A FRONTAL
SYSTEM WILL CONTINUE TO PUSH ACROSS WESTERN NEW ENGLAND. BELIEVE
THE BETTER CHANCES WILL OCCUR LATE THIS AFTERNOON. GOOD AMOUNT OF
LOW LEVEL MOISTURE SO DIURNAL CU IS EXPECTED TO DEVELOP. IF
SHOWERS DO DEVELOP THEY DO HAVE THE POTENTIAL TO STRONG...HOWEVER
LOW TO MODERATE CONFIDENCE. EXPECT STORMS TO BE MULTICELLULAR IN
NATURE BUT WITH WEAK LAPSE RATES AND VERY LITTLE SHEAR STORMS WILL
HAVE A HARD TIME MAINTAINING ANY UPDRAFT. STRONG WINDS AND HEAVY
RAIN SEEM TO THE GREATEST TREAT WITH THESE STORMS...LOW PROB OF
SEVERE. WESTERN PORTION OF THE FORECAST AREA HAS THE BEST CHANCE
AS THE DRIVING FORCE...UPPER LEVEL SHORTWAVE...IS STILL ACROSS THE
GREAT LAKES REGION.

TEMPS TODAY WILL WARM TO THE MID TO UPPER 80S...COMBINED WITH
UPPER 70S DEWPOINTS...A MUGGY THURSDAY IS IN STORE. TEMPS MAY BE
COOLER ALONG THE COASTS AS SEA BREEZE DEVELOPMENT IS POSSIBLE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
TONIGHT...
SHOWERS AND ISOLATED THUNDER WILL CONTINUE INTO THE OVERNIGHT
HOURS AS THERE IS GOOD ISENTROPIC LIFT AND MOISTURE ADVECTION
ALONG THE FRONT. EXPECT THE FRONT TO LIFT NORTHWARD AS A WARM
FRONT AS SURFACE LOW OVER THE GREAT LAKES BEGINS TO APPROACH THE
REGION. ONCE AGAIN BELIEVE THAT WESTERN ZONES HAVE THE BEST
OPPORTUNITY TO SEE ANY PRECIP. OVERALL DO NOT EXPECT THE OVERNIGHT
TO BE A WASHOUT.

SOUTHERLY WIND WILL STILL CONTINUE KEEPING THE HIGH DEWPOINTS
ACROSS SNE. THIS AMOUNT OF MOISTURE WITH THE COOLING TEMPS WILL
ALLOW FOR FOG TO DEVELOP. BEST CHANCE FOR DENSE FOG WILL BE ACROSS
THE SOUTH COAST...SINCE THE TEMP DEWPOINT DEPRESSION IS NEAR
ZERO.

FRIDAY...
BEST CHANCE FOR PRECIP TO OCCUR FOR THE SHORT TERM PERIOD. UPPER
LEVEL SHORTWAVE WILL CONTINUE TO ADVANCE TOWARDS THE AREA. THIS
LIFT COMBINED WITH THE AMOUNT OF MOISTURE IN THE ATMOSPHERE WILL
ALLOW FOR SHOWERS TO DEVELOP FROM WEST TO EAST. AGAIN THE BEST
CHANCE TO SEE PRECIP WILL BE ACROSS THE WESTERN ZONES...BUT BELIEVE
PRECIP WILL SPREAD OUT...ESP INTO THE LATE AFTERNOON/EVENING
HORUS. THUNDERSTORMS ARE POSSIBLE ON FRIDAY...BUT DUE TO CLOUD
COVER THERE MAY BE A LACK OF INSTABILITY. SHEAR VALUES AND LAPSE
RATES ARE NOT IMPRESSIVE EITHER. AGAIN MAIN HAZARD LOOKS TO BE
HEAVY RAIN...HOWEVER IF THE SUN DOES PEAK OUT AND CAPE VALUES
INCREASE THEN THE POTENTIAL FOR STRONG WINDS WILL INCREASE.

TEMPS WILL BE COOLER ON FRIDAY AS CLOUD COVER WILL INHABIT MUCH
HEATING. EXPECT TEMPS TO BE IN THE LOW TO MID 80S. SOUTHERLY WINDS
WILL CONTINUE TO INCREASE DEWPOINTS ALLOWING FOR A MUGGY END OF
THE WEEK.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
BIG PICTURE...
VERY ROBUST UPPER TROUGH FOR THIS TIME OF YEAR IS A FACTOR INTO THE
FIRST PART OF THE WEEKEND AND THEN MORE SHORT WAVE TROF ACTION
POSSIBLE MIDDLE OF NEXT WEEK AS TENDENCY FOR LONG WAVE TROF TO RECUR
VICINITY OF THE OH VALLEY.

FRI NIGHT...A NUMBER OF FACTORS POINT TO HIGH LIKELIHOOD OF SHOWERS
AND POTENTIAL FOR LOCALLY HEAVY RAIN.  PWATS NEAR TO ABOVE 2
INCHES...NOSE OF LOW LEVEL JET APPROACHES SE NEW ENGLAND...AT LEAST
MARGINALLY UNSTABLE...AND A HINT OF DIFFLUENCE ALOFT SET THE STAGE
FOR SHOWERS AND EMBEDDED TSTMS WITH POTENTIALLY VERY HEAVY RAIN.
WENT HIGH LIKELY FOR POPS. CONSIDERED CATEGORICAL POPS BUT A FEW TOO
MANY UNCERTAINTIES IN TIMING AND POSITIONING OF MESOSCALE FEATURES.
ADDED THE HEAVY RAIN ATTRIBUTE FROM THE WX TOOL. SUSPECT THAT THERE
MIGHT BE A TROPICAL FEED OF MOISTURE.

SAT...LOOKS LIKE POSSIBLE OCCLUDED FRONT PASSAGE AS MAIN SURFACE LOW
HEADS INTO ONTARIO. THIS SHOULD HELP PROVIDE FOCUS FOR SHOWERS AND
TSTMS. PWATS REMAIN NEAR TO ABOVE 2 INCHES ACROSS REGION AND HEAVY
DOWNPOURS LIKELY WITH PASSING SHOWERS AND TSTMS. VERTICAL SHEAR ALSO
INCREASES AND THINK THERE MAY BE A POTENTIAL FOR A FEW SEVERE TSTMS
DURING SAT AFTERNOON. CONTINUED THE HEAVY RAIN ATTRIBUTE INTO SAT.

SAT NIGHT...LOOKS LIKE DRIER AIR WRAPS AROUND THE SYSTEM AND MOVES
INTO SOUTHERN NEW ENGLAND QUICKLY SAT NIGHT WITH AT LEAST PARTIAL
CLEARING AND LOWERING HUMIDITY.

SUN...LOOKS DRY ALTHOUGH SUSPICIOUS THAT THERE MIGHT BE ISOLATED OR
WIDELY SCT SHOWERS/TSTMS DURING THE LATE AFTERNOON AS THE TROF AXIS
AND ASSOCIATED COOL POOL SWEEPS INTO THE REGION.

SUN NIGHT THRU TUE MORNING...LOOKS TO BE DRY WITH TEMPS NEAR OR A
TAD HIGHER THAN NORMAL.

TUE AFTERNOON...MODELS HINT AT LOWERING HEIGHTS AND AN AIR MASS THAT
IS BECOMING MARGINALLY UNSTABLE. PUT IN SLIGHT CHANCE TO LOW CHANCE
OF TSTMS IN INTERIOR SECTIONS.

WED...SOME DISPARITY IN OPERATIONAL MODELS BY THIS POINT SO
CONFIDENCE IS FAIRLY LOW. 00Z GFS RUN BRINGS FAIRLY AMPLIFIED
SHORT WAVE TROF THRU NEW ENGLAND WITH A SURFACE LOW REFLECTION
THAT TRANSLATES FROM THE MID ATLC REGION TO THE GULF OF MAINE.
THIS SOLUTION DOES NOT SEEM TO BE SUPPORTED VERY WELL BY OTHER
MODELS OR ENSEMBLES...AT LEAST THUS FAR. HOWEVER...ALL MEDIUM
RANGE MODELS DEPICT A VIGOROUS SHORT WAVE MOVING ACROSS THE
CANADIAN/USA BORDER AND APPROACHING NORTHERN NEW ENGLAND. NEW 00Z
ECMWF ACTUALLY CLOSES THIS UPPER LOW OFF OVER THE GULF OF MAINE
AFT WED. FOR NOW...SEEMS WISE TO HAVE A CHANCE OF SHOWERS/TSTMS
FOR WED.

&&

.AVIATION /14Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
  LOW...LESS THAN 30 PERCENT
  MODERATE...30 PERCENT TO 60 PERCENT
  HIGH...GREATER THAN 60 PERCENT

TODAY THROUGH FRIDAY...MODERATE CONFIDENCE. MVFR/IFR VSBY/CIGS
WILL GRADUALLY BURN OFF THRU MID MORNING. EXPECT MAINLY VFR WITH
SOUTHERLY WINDS TODAY...WITH SEA BREEZE DEVELOPMENT LIKELY. LOW CHANCE
FOR WESTERN ZONES TO SEE MVFR CONDITIONS IN SHRA/TSRA. ONCE AGAIN
MVFR/IFR IN FOG AND STRATUS DEVELOPMENT TONIGHT. BECOMING MAINLY
VFR FRIDAY WITH PERIODS OF MVFR/IFR CONDITIONS IN TSRA/SHRA.

KBOS TAF...MODERATE CONFIDENCE. BECOMING VFR AROUND OR SHORTLY
AFTER 13Z. SEA BREEZE LIKELY DEVELOPING BY 15Z. TIMING AND EXTENT
OF FOG AND STRATUS DEVELOPMENT A LITTLE UNCERTAIN. MOST LIKELY
WILL SEE MVFR CONDITIONS DEVELOP AFT ABOUT 02Z WITH POSSIBLY IFR
CIGS IN ROUGHLY THE 08Z-12Z TIME FRAME. SCT SHRA/TSRA LIKELY FRI
AFTERNOON.

KBDL TAF...MODERATE CONFIDENCE. BECOMING VFR AROUND OR SOON AFT
13Z WITH A LIGHT SOUTH WIND DEVELOPING IN THE AFTERNOON.
SHOWERS/SCATTERED TSTMS DEVELOPING MID AFTERNOON WITH POTENTIAL
FOR BRIEF MVFR CIGS/VSBYS. EXPECT FOG TO DEVELOP TONIGHT DROPPING
SITE TO MVFR AND PROBABLY IFR DURING THE EARLY MORNING HOURS. LOW
CONFIDENCE ON TIMING. MODERATE PROB IN SHRA/TSRA ON FRIDAY
LOWERING CIGS AND VSBYS TO MVFR/IFR.

OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...

FRIDAY NIGHT-SATURDAY...MODERATE CONFIDENCE.
WIDESPREAD MVFR CIGS AND VSBYS EXPECTED WITH
AREAS OF IFR CIGS AND VSBYS IN SOME OF THE SHOWERS AND SCT TSTMS.
TSTMS DURING SAT AFTERNOON MAY CONTAIN LOCALLY STRONG WIND GUSTS.
SAT NIGHT...MODERATE CONFIDENCE. BECOMING VFR.
SUN THRU MON...MODERATE TO HIGH CONFIDENCE. GENERALLY VFR.
ISOLATED SHOWER OR TSTM POSSIBLE NORTHERN INTERIOR DURING SUN
AFTERNOON.

&&

.MARINE...
HIGH CONFIDENCE. QUIET BOATING WEATHER EXPECTED. EXPECT SOUTH TO
SOUTHWEST WINDS AND SEAS TO REMAIN BELOW SCA CRITERIA. LOW TO
MODERATE PROBABILITY OF PATCHY...POSSIBLY DENSE...FOG DEVELOPING
ON THE SOUTHERN WATERS TONIGHT.

OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...

MODERATE CONFIDENCE
SUFFICIENT S WIND TO BUILD SEAS TO 5 TO 6 FT ALONG EXPOSED S COAST
WATERS...ALTHOUGH WAVEWATCH MAY BE A FOOT OR TWO OVERDONE. SCT TSTMS
SAT AFTERNOON OR EARLY EVENING MAY CONTAIN LOCALLY STRONG WIND
GUSTS. SEAS GRADUALLY SUBSIDE DURING EARLY NEXT WEEK.

&&

.HYDROLOGY...
STRONG CHANCE OF LOCALIZED STREET FLOODING FRI NIGHT AND SAT WITH
POSSIBILITY OF HIGHLY LOCALIZED FLASH FLOODING. AS NOTED
ABOVE...SEE A RISK OF A TROPICAL FEED AIDED BY A LOW LEVEL JET IN
AT LEAST A MARGINALLY UNSTABLE AIR MASS. BEST DYNAMICS REMAIN WELL
W AND N OF REGION...BUT COULD ENCOUNTER SERIOUSLY EXCESSIVE RAFL
IN ANY MESOSCALE BANDS THAT MAY SET UP.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...AIR QUALITY ALERT UNTIL 10 PM EDT THIS EVENING FOR MAZ009-011.
NH...NONE.
RI...NONE.
MARINE...NONE.

&&

SYNOPSIS...DUNTEN/THOMPSON
NEAR TERM...RLG/DUNTEN/THOMPSON
SHORT TERM...DUNTEN
LONG TERM...THOMPSON
AVIATION...DUNTEN/THOMPSON
MARINE...DUNTEN/THOMPSON
HYDROLOGY...

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TAUNTON MA
448 AM EDT THU AUG 9 2012

CTZ002>004-MAZ002>024-026-NHZ011-012-015-RIZ001>008-100900-
HARTFORD CT-TOLLAND CT-WINDHAM CT-WESTERN FRANKLIN MA-
EASTERN FRANKLIN MA-NORTHERN WORCESTER MA-CENTRAL MIDDLESEX MA-
WESTERN ESSEX MA-EASTERN ESSEX MA-WESTERN HAMPSHIRE MA-
WESTERN HAMPDEN MA-EASTERN HAMPSHIRE MA-EASTERN HAMPDEN MA-
SOUTHERN WORCESTER MA-WESTERN NORFOLK MA-SOUTHEAST MIDDLESEX MA-
SUFFOLK MA-EASTERN NORFOLK MA-NORTHERN BRISTOL MA-
WESTERN PLYMOUTH MA-EASTERN PLYMOUTH MA-SOUTHERN BRISTOL MA-
SOUTHERN PLYMOUTH MA-BARNSTABLE MA-DUKES MA-NANTUCKET MA-
NORTHERN MIDDLESEX MA-CHESHIRE NH-EASTERN HILLSBOROUGH NH-
WESTERN AND CENTRAL HILLSBOROUGH NH-NORTHWEST PROVIDENCE RI-
SOUTHEAST PROVIDENCE RI-WESTERN KENT RI-EASTERN KENT RI-BRISTOL RI-
WASHINGTON RI-NEWPORT RI-BLOCK ISLAND RI-
448 AM EDT THU AUG 9 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHERN
CONNECTICUT...CENTRAL MASSACHUSETTS...EASTERN
MASSACHUSETTS...NORTHEASTERN MASSACHUSETTS...SOUTHEASTERN
MASSACHUSETTS...WESTERN MASSACHUSETTS...SOUTHERN NEW
HAMPSHIRE...NORTHERN RHODE ISLAND AND SOUTHERN RHODE ISLAND.

.DAY ONE...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

SHOWERS AND THUNDERSTORMS FROM FRIDAY AFTERNOON INTO SATURDAY MAY
CONTAIN VERY HEAVY DOWNPOURS...WITH POTENTIAL FOR LOCALIZED
FLOODING. ALSO...SOME THUNDERSTORMS ON SATURDAY MAY CONTAIN STRONG
WIND GUSTS.

MORE THUNDERSTORMS ARE POSSIBLE FOR THE MIDDLE OF NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME FOR TODAY BUT MAY
BE NEEDED AT TIMES FRIDAY AFTERNOON THROUGH SATURDAY.

ANZ230>237-250-251-254>256-100900-
BOSTON HARBOR-CAPE COD BAY-NANTUCKET SOUND-VINEYARD SOUND-
BUZZARDS BAY-RHODE ISLAND SOUND-NARRAGANSETT BAY-BLOCK ISLAND SOUND-
COASTAL WATERS EAST OF IPSWICH BAY AND THE STELLWAGEN BANK NATIONAL
MARINE SANCTUARY-MASSACHUSETTS BAY AND IPSWICH BAY-
COASTAL WATERS FROM PROVINCETOWN MA TO CHATHAM MA TO NANTUCKET MA
OUT 20 NM-
COASTAL WATERS EXTENDING OUT TO 25 NM SOUTH OF MARTHAS VINEYARD AND
NANTUCKET-
COASTAL WATERS FROM MONTAUK NY TO MARTHAS VINEYARD EXTENDING OUT TO
20 NM SOUTH OF BLOCK ISLAND-
448 AM EDT THU AUG 9 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR MASSACHUSETTS COASTAL WATERS
AND RHODE ISLAND COASTAL WATERS.

.DAY ONE...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

A FEW THUNDERSTORMS DURING SATURDAY AFTERNOON MAY CONTAIN STRONG
WIND GUSTS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

THOMPSON

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TAUNTON MA
101 PM EDT THU AUG 9 2012

MAZ002-003-091800-
EASTERN FRANKLIN MA-WESTERN FRANKLIN MA-
101 PM EDT THU AUG 9 2012

AT 1253 PM EDT NATIONAL WEATHER SERVICE DOPPLER RADAR SHOWED A
THUNDERSTORM NEAR SHELBURNE...OR ABOUT 7 MILES WEST OF
GREENFIELD...MOVING EAST AT 10 MPH.

* SOME LOCATIONS AFFECTED INCLUDE...SHELBURNE...DEERFIELD...
  GREENFIELD AND BERNARDSTON.

FOR YOUR SAFETY...GET INSIDE WHEN THIS STORM APPROACHES. WINDS MAY BE
STRONG ENOUGH TO BRING DOWN SMALL BRANCHES. MINOR STREET FLOODING AND
PONDING OF WATER IN POOR DRAINAGE AREAS IS ALSO POSSIBLE.

DO NOT DRIVE THROUGH FLOODED ROADS.

&&

LAT...LON 4271 7255 4254 7247 4252 7280 4258 7282

WTB