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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBOX 141815
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
215 PM EDT TUE MAY 14 2013

.SYNOPSIS...
COOL CONDITIONS PERSIST TODAY INTO TONIGHT UNDER THE INFLUENCE OF
HIGH PRESSURE PRIOR TO LOW PRESSURE WHICH WILL BRING THE CHANCE
OF SHOWERS LATE WEDNESDAY INTO WEDNESDAY NIGHT. BEHIND THE
DEPARTING LOW A BRIEF WARM UP INTO THE 70S THURSDAY FOLLOWED BY
TEMPERATURES COOLING BACK TO NEAR NORMAL FRI AND SAT AS COOL
MARITIME HIGH PRES INFLUENCES OUR WEATHER. TEMPERATURES WILL THEN
LIKELY MODERATE LATER IN THE WEEKEND AND ESPECIALLY INTO EARLY
NEXT WEEK AS MARITIME HIGH PRESSURE MOVES WELL OFFSHORE.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
155 PM UPDATE...
BAND OF LIGHT SPRINKLES ACROSS SE AND S COASTAL MA WILL PUSH
OFFSHORE WITH ANOTHER BAND DEVELOPING ACROSS THE CT VALLEY AT
17Z. HAVE ADDED SPRINKLES TO THE GRIDS ACROSS THAT AREA...WHICH
SHOULD PUSH SE WITH THE NW FLOW ALOFT DURING THE AFTERNOON AS THEY
DISSIPATE. WITH WIDE TEMP/DEWPT SPREADS /ON ORDER OF 25 TO 30
DEGS/ WILL BE TOUGH TO GET THIS DOWN TO THE GROUND...BUT CAN NOT
RULE OUT A FEW SPOTS GETTING A LITTLE BIT.

SURFACE RIDGE ACROSS NY STATE WILL SLOWLY BUILD INTO WESTERN AREAS
LATE IN THE DAY. WITH COLD AIRMASS ALOFT AS WELL AS DIURNAL
CLOUDS...TEMPS LIMITED TO THE 50S OR SO THROUGH THE AFTERNOON.
THIS HAS CUT BACK THE POTENTIAL SEA BREEZE DEVELOPMENT...BUT CAN
NOT RULE OUT THE POSSIBILITY OF WINDS BECOMING ONSHORE FOR A FEW
HOURS.

HAVE UPDATED REMAINING GRIDS TO BRING CONDITIONS CURRENT.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
TONIGHT...

WILL SEE CONTINUED INFLUENCE OF HIGH PRESSURE. THIS SHOULD KEEP
WINDS LIGHT AND VARIABLE OVERNIGHT...BECOMING SOUTH-SOUTHWESTERLY
INTO THE MORNING. WITH THE EXPECTATION OF MOSTLY CLEAR CONDITIONS...
PERHAPS MID-HIGH LEVEL CLOUDS INCREASING OVER WESTERN NEW ENGLAND BY
MORNING...ALLOWS THE OPPORTUNITY FOR EFFECTIVE RADIATIONAL COOLING.
POCKETS OF FROST ARE ANTICIPATED WITH LOWS FALLING INTO THE LOW TO
MID 30S...BUT MAINLY IN NORTHWEST AND NORTH-CENTRAL MASSACHUSETTS
AND SOUTHERN NEW HAMPSHIRE WHERE THE GROWING SEASON DOES NOT BEGIN
UNTIL MAY 20TH. THERE WILL BE SOME AREAS OF FROST FURTHER SOUTH
AND EAST...BUT WILL ALLOW THE DAY SHIFT TO EVALUATE AND ISSUE
HEADLINES AS NECESSARY.

WEDNESDAY INTO WEDNESDAY NIGHT...

A DISTURBANCE WILL TRANSLATE ACROSS SOUTHERN CANADA LATE WEDNESDAY
INTO WEDNESDAY NIGHT. THE ACCOMPANYING SURFACE LOW ACROSS QUEBEC
WILL ALSO INCLUDE A TRAILING COLD FRONT WHICH WILL SWEEP ACROSS NEW
ENGLAND AND OFFSHORE AROUND MIDNIGHT THURSDAY.

EXPECTING SCATTERED TO WIDESPREAD SHOWERS ALONG AND AHEAD OF THE
COLD FRONT...FORCED BY NOT ONLY THE FRONT ITSELF...BUT ALSO BY A
BROAD ENHANCEMENT OF WEST-SOUTHWESTERLY FLOW WITH THE AFOREMENTIONED
DISTURBANCE /COULD SEE A MIX-DOWN OF MOMENTUM DURING THE DAY WITH
BOUNDARY LAYER MIXING UP AROUND 3 KFT RESULTING IN WEST-SOUTHWEST
GUSTS OF AROUND 25 MPH/. WILL SEE MODEST WARM-MOIST ADVECTION ALOFT
RESULTING IN PWATS AROUND AN INCH WITH AN ISOLATED CHANCE OF THUNDER
WITH TOTAL-TOTALS AND K-INDICES EXCEEDING 50 AND 30 THRESHOLDS...
RESPECTIVELY. ALSO CAN NOT RULE OUT AN ISOLATED HEAVY DOWNPOUR
WITH THE SHOWERY WEATHER EXPECTED.

WEST-NORTHWEST FLOW BEHIND THE FRONT WILL RESULT IN QUICK CLEARING
OF ENERGY OFFSHORE BY MORNING. THE BROADER LOW OVER SOUTHERN CANADA
WILL THOUGH USHER MID-HIGH LEVEL CLOUDS SOUTH ACROSS THE REGION.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
SYNOPTIC OVERVIEW/MODEL GUIDANCE AND UNCERTAINTY...

00Z MODEL GUIDANCE INCLUDING ENSEMBLES /GEFS AND ECENS/ ARE IN VERY
GOOD AGREEMENT ON THE LARGE SCALE FLOW ACROSS THE CONUS...WHICH
MAINLY FEATURES A SPLIT FLOW REGIME. GIVEN STREAMS REMAIN SEPARATE
NOT EXPECTING ANY SIGNIFICANT PRECIPITATION THIS PERIOD. THUS
MAINLY DRY WEATHER PREVAILS. AS FOR TEMPERATURES...GOOD MODEL
AGREEMENT ON THE WARMEST DAY OF THE WEEK BEING THU BEHIND INITIAL
FRONTAL PASSAGE...AS COOLER AIRMASS LAGS WELL TO THE NORTHWEST
WITH SECONDARY FRONT SLATED FOR FRI. MARITIME AIRMASS BEHIND THIS
FRONTAL PASSAGE FRI AND SAT WILL YIELD A LARGE TEMP GRADIENT
ACROSS THE REGION. WARMEST READINGS OVER THE CT RVR VALLEY AND
COOLEST OVER EASTERN MA. OVERALL TEMPS WILL BE NEAR NORMAL FRI-
SAT. FORECAST UNCERTAINTY BECOMES AN ISSUE BY SUN AND MON OF NEXT
WEEK AS THE GFS AND SEVERAL GEFS MEMBERS BEGIN TO DIVERGE FROM THE
REST OF THE MODEL PACK...AS THE GFS AND GEFS UNDERCUTS MORE JET
ENERGY INTO THE EVOLVING EAST COAST/WESTERN ATLC RIDGE. THE GFS
MAY BE SUFFERING FROM CONVECTIVE FEEDBACK ISSUES DURING THIS TIME
PERIOD WITH 6 HR QPF VALUES OF 2+! GIVEN THE LACK OF SUPPORT FROM
THE 12Z ECENS/00Z UKMET AND ECMWF WILL RESTRICT POPS TO SLIGHT
CHANCE SUN/MON.

DAILY SENSIBLE WEATHER DETAILS...

THU...

INITIAL FRONTAL BOUNDARY AND DEEP LAYER MOISTURE OFFSHORE EARLY THU.
DEEP WESTERLY FLOW SETS UP ACROSS THE REGION WHICH WILL SUPPORT LOTS
OF SUNSHINE AND WARM TEMPS. BUFKIT MODEL SOUNDINGS INDICATE DEEP
BLYR MIXING AND GUSTY WEST WINDS WHICH WILL FAVOR WARM TEMPS RIGHT
TO THE COAST. 850 TEMPS ABOUT +9C BUT MODEL SOUNDINGS SUGGEST MIXING
UP TO 750 MB ALONG WITH SUPER ADIABATIC LAPSE RATES. THUS HIGHS WELL
INTO THE 70S TO PERHAPS NEAR 80 IN A FEW SPOTS. COOLER ALONG THE
SOUTH COAST WITH WSW WINDS.

FRI INTO SAT...

LOW PRES MOVES INTO THE MARITIMES WITH DRY COLD FRONTAL PASSAGE
EARLY IN THE DAY. SHALLOW COOL MARITIME AIRMASS INVADES THE REGION
THIS PERIOD...BUT STRONG MAY SUNSHINE WILL STILL WARM TEMPS CLOSE TO
NORMAL BOTH DAYS...ALTHOUGH SLIGHTLY COOLER SAT. DRY WEATHER AND
FAIRLY LIGHT WINDS PREVAIL.

SUN INTO MON...

AS MENTIONED ABOVE ALL MODELS BUILD EAST COAST/WESTERN ATLC RIDGE
DURING THIS PERIOD. HOWEVER THE 00Z GFS AND SEVERAL MEMBERS OF THE
GEFS APPEARS TO BE THE ONLY MODEL UNDERCUTTING JET ENERGY INTO THE
RIDGE WHICH YIELDS A FRONTAL WAVE ENTERING NEW ENGLAND. GIVEN THE
GFS DOESN/T HAVE SUPPORT FROM ANY OF THE OTHER MODEL GUID WILL
FOLLOW THE DRIER AND WARMER ECENS/ECMWF AND UKMET THIS PERIOD.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH WEDNESDAY NIGHT/...

TONIGHT...HIGH CONFIDENCE. VFR. NW WINDS GUSTING TO AROUND 20 KT
MAINLY ACROSS CENTRAL AND EASTERN AREAS THROUGH MID AFTERNOON...
THEN SHOULD DIMINISH AS RIDGE BUILDS IN TONIGHT.

WEDNESDAY...MODERATE TO HIGH CONFIDENCE. VFR MOST OF THE DAY. MAY
SEE PATCHY MVFR CIGS/VSBYS MOVE INTO CT VALLEY LATE IN THE DAY.
SCT SHOWERS MOVE IN FROM W-E DURING THE DAY AS WARM FRONT
APPROACHES.

WEDNESDAY NIGHT...MODERATE CONFIDENCE. CIGS/VSBYS LOWERING TO MVFR
WITH POCKETS OF IFR CONDITIONS IN SCT-WIDESPREAD SHOWERS AND FOG.
S-SW WINDS MAY GUST TO 25 KT EARLY BEFORE WIND SHIFT. LOW
CONFIDENCE OF ISOLD THUNDER. CONDITIONS IMPROVE ACROSS WESTERN
AREAS AFTER MIDNIGHT ON W-NW WINDS.

KBOS TERMINAL...HIGH CONFIDENCE IN VFR CONDITIONS THROUGH WED.
LOW CONFIDENCE ON SEA BREEZE DEVELOPMENT...MAY FOR A COUPLE OF
HOURS PRIOR TO 22Z WHEN MAX HEATING ENDS IF N-NW WINDS RELAX
ENOUGH.

KBDL TERMINAL...HIGH CONFIDENCE IN TAF.

OUTLOOK...THURSDAY THROUGH SATURDAY...

HIGH PROBABILITY FOR VFR/DRY WEATHER AND FAIRLY LIGHT WINDS.
-- End Changed Discussion --

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /UNTIL WEDNESDAY NIGHT/...

1025 AM UPDATE...
EXPECT WINDS AND SEAS BELOW SMALL CRAFT CRITERIA THIS AFTERNOON
AND EVENING.

PREVIOUS DISCUSSION...
HIGH PRESSURE WILL LINGER INTO EARLY WEDNESDAY WILL RESULT IN
BOTH WINDS AND SEAS TO REMAIN BELOW SMALL CRAFT ADVISORY
THRESHOLDS. CONCERNS RETURN MIDDAY WEDNESDAY INTO WEDNESDAY NIGHT
AS SOUTHERLY FLOW INCREASES WITH GUSTS UP TO AROUND 25 KTS AHEAD
OF A COLD FRONT WHICH WILL SWEEP ACROSS THE WATERS AROUND MIDNIGHT
THURSDAY INTO THURSDAY MORNING. THE LONG- DURATION OF SOUTHERLY
FLOW WILL CHURN SEAS WITH WAVE HEIGHTS OF AROUND 6 TO 8 FEET ALONG
THE OUTER WATERS.

WITH INCREASING RECREATION ON THE INNER BAYS AND HARBORS...AND
SOME UNCERTAINTY AS TO THE STRENGTH OF WIND GUSTS...HAVE BEGUN
SMALL CRAFT ADVISORIES DURING THE EARLY AFTERNOON HOURS ON
WEDNESDAY. SHOULD SEE HEADLINES DROP OFF FOR THE INNER WATERS
AROUND MIDNIGHT THURSDAY...BUT CONTINUING FOR THE OUTER WATERS
INTO THURSDAY ITSELF.

OUTLOOK...THURSDAY THROUGH SATURDAY...

THU...

COLD FRONT OFFSHORE WITH WEST WINDS OVERSPREADING THE AREA. GUSTY AT
TIMES NEAR SHORE WITH GUSTS 20-25 KT POSSIBLE. LEFTOVER SOUTHERLY
SWELLS ON THE OCEAN WATERS. DRY WEATHER AND GOOD VSBY.

FRI INTO SAT...

SECONDARY COLD FRONT MOVES THROUGH EARLY FRI WITH A REINFORCING
SURGE OF COOL/DRY AIR. A DRY FRONTAL PASSAGE EXPECTED. ALTHOUGH
POST FRONTAL WINDS ARE ONLY MODEST. SOUTHERLY SWELLS SLOWLY ERODE.
BY SAT MARITIME HIGH PRES BUILDS OVER THE WATERS...SO FAIRLY LIGHT
WINDS/DRY WEATHER AND GOOD VSBY PREVAIL.

&&

.FIRE WEATHER...
1115 AM LOOK...PREVIOUS DISCUSSION REMAINS VALID.

MINIMUM RELATIVE HUMIDITIES WILL RANGE AROUND 20 TO 25 PERCENT
TODAY...YET WINDS WILL REMAIN LIGHT LIMITING THE FIRE WEATHER
POTENTIAL. THOUGH GREEN-UP CONTINUES...MUCH OF THE REGION REMAINS
BELOW-NORMAL FOR TOTAL RAINFALL OVER THE LAST TWO MONTHS.

RAIN OVER THE PAST WEEKEND...AND FORECASTED RAIN FOR LATE
WEDNESDAY INTO WEDNESDAY NIGHT WILL BE OF HELP TOWARDS THE BELOW-
NORMAL RAINFALL CONDITIONS. YET STILL...THE REGION REMAINS DRY
POSSIBLY CONDUCIVE TOWARDS FUTURE FIRE WEATHER POTENTIAL.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 2 PM WEDNESDAY TO 2 AM EDT THURSDAY
     FOR ANZ230>234-236-251.
     SMALL CRAFT ADVISORY FROM 2 PM WEDNESDAY TO 8 AM EDT THURSDAY
     FOR ANZ235-237-250-254>256.

&&

$$
SYNOPSIS...NOCERA/SIPPRELL
NEAR TERM...NOCERA/SIPPRELL/EVT/THOMPSON
SHORT TERM...SIPPRELL
LONG TERM...NOCERA
AVIATION...NOCERA/SIPPRELL/EVT/THOMPSON
MARINE...NOCERA/SIPPRELL/EVT
FIRE WEATHER...STAFF