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000
FXUS61 KBOX 232018
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
418 PM EDT WED JUL 23 2014

.SYNOPSIS...
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A COLD FRONT WILL APPROACH THE REGION TONIGHT TRIGGERING SCATTERED
SHOWERS AND THUNDERSTORMS. A FEW STRONG THUNDERSTORMS ARE
POSSIBLE WEST OF THE CENTRAL HILLS. SHOWERS WILL LIKELY LINGER
INTO THURSDAY SOUTHEAST OF THE BOSTON TO PROVIDENCE CORRIDOR. HIGH
PRESSURE BUILDS WITH DRIER WEATHER FOR FRIDAY AND SATURDAY. AN
APPROACHING WARM FRONT SUNDAY WILL BRING MORE HUMID UNSETTLED
WEATHER FOR THE EARLY PART OF NEXT WEEK.
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&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...

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* A FEW STRONG TO SEVERE STORMS POSSIBLE LATE THIS AFTERNOON INTO
  THE EVENING HOURS *

415 PM MESO-UPDATE...

CONTINUING TO MONITOR FOR THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS LATE THIS AFTERNOON INTO THE EVENING HOURS.
CURRENTLY THE COLD FRONT HAS JUST PUSHED THROUGH ITHACA NY UP TO
MONTPELIER VT...AND WILL CONTINUE A EASTWARD PROGRESSION TOWARDS
SOUTHERN NEW ENGLAND THROUGH THE REMAINDER OF THE DAY. OVER THE
NEXT FEW HOURS...BELIEVE A FEW ISOLATED SHOWERS AND THUNDERSTORMS
WILL POP- UP /JUST LIKE THEY ARE IN MOHAWK VALLEY REGION/. THEN
EXPECT A MORE BROKEN LINE SEGMENT TO MOVE THROUGH BY THE EVENING
HOURS AS THE FRONT MOVES CLOSER TO THE REGION.

LOOKING AT SPC MESO ANALYSIS...SB CAPE VALUES HAVE REACHED TO 2500
J/KG WITH NOT MUCH IN THE TERMS OF EFFECTIVE SHEAR FOR SOUTHERN NEW
ENGLAND. RAP 0-6 KM BULK SHEAR VALUES HAVE INCREASED
SLIGHTLY...AND ARE NOW 15-20 KTS. AS OF 20Z...THE STRONGER WIND
SHEAR AND UPPER LEVEL JET DYNAMICS ARE STILL SITUATED ACROSS
UPSTATE NEW YORK WHICH IS ALSO WHERE THE DEEP LAYER MOISTURE IS
LOCATED PER THE K-INDEX. HENCE WHY THE STORMS ARE SUSTAINING
THEMSELVES.

OVERVIEW AND INTO TONIGHT...

A COLD FRONT WILL PASS ACROSS THE NORTHEAST EARLY THIS EVENING AND
INTO THE EARLY OVERNIGHT HOURS. ALTHOUGH WE ARE CURRENTLY LACKING
MOISTURE AND SHEAR AS MENTIONED ABOVE...RAP GUIDANCE SHOWS THAT
BOTH OF THESE PARAMETERS WILL INCREASE CLOSER TO 00Z. THEREFORE
BELIEVE THAT SHOWERS AND STRONGER THUNDERSTORMS WILL DEVELOP AND
OVERSPREAD THE REGION AS THE FRONT PUSHES CLOSER TO SOUTHERN NEW
ENGLAND.

THROUGHOUT THE EVENING HOURS...THE MAIN CONCERN IS THE AMOUNT OF
INSTABILITY WITH LACK OF SOLAR HEATING BY THE LATE EVENING HOURS.
CURRENT THINKING THOUGH IS THAT SINCE THE ATMOSPHERE HAS NOT BEEN
WORKED OVER AND THE GUIDANCE SHOWS LINGER ELEVATED INSTABILITY
OVERNIGHT BELIEVE THAT THE THUNDERSTORM POTENTIAL WILL LINGER TIL
ABOUT MIDNIGHT. BY THEN THE STORMS WILL ENTER THE THE EASTERN
PORTION OF THE AREA WHICH IS BEING INFLUENCED BY THE ADVECTING
MARITIME AIR FROM TODAYS GUSTY SOUTHWEST WINDS.

STILL CANNOT RULE OUT THE POTENTIAL FOR SEVERE WEATHER BUT HAVE
INCREASING CONFIDENCE THAT AT LEAST STRONG STORMS WILL DEVELOP LATE
THIS AFTERNOON INTO THE EVENING HOURS. AFTER DISCUSSING WITH SPC
DECIDED TO ISSUE A WATCH FOR THE LOCATIONS THAT HAVE THE BEST
POTENTIAL TO SEE THE BEST MOISTURE/INSTABILITY AND SHEAR OVERLAPPING
ONE ANOTHER. THE MAIN THREATS ARE DAMAGING WINDS AND LOCALIZED
FLOODING AS PWATS CONTINUE TO INCREASE ABOVE 1.8 INCHES.
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&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...

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THURSDAY...

COLD FRONT WILL SLOW DOWN DURING ITS PASSAGE ACROSS SOUTHERN NEW
ENGLAND THURSDAY MORNING. BOTH THE EC AND NAM SHOW A WAVE DEVELOPING
ALONG THE FRONT ALLOWING FOR THE SLOW DOWN WHILE THE GFS SEEMS TO BE
THE OUTLIER ON PUSHING THE FRONT THOUGH BY 12Z. IN FACT THE UPPER
LEVEL TROUGH AXIS IS STILL ACROSS UPSTATE NY BY 12/15Z RESULTING IN
CLOUDS AND THE CONFIDENCE THAT PRECIP WILL LINGER ESP FOR AREAS
SOUTH AND EAST OF THE BOS-PVD CORRIDOR. BELIEVE THAT BY 00Z THE
FRONT AND THE BULK OF THE PRECIP WILL BE OFFSHORE BUT CANNOT RULE
OUT A FEW LINGERING SHOWERS ESP FOR THE CAPE AND THE ISLANDS.
BECAUSE OF THE SLOW DOWN AND THE POTENTIAL WAVE
DEVELOPMENT...CANT RULE OUT THE POTENTIAL FOR EMBEDDED
THUNDERSTORMS DURING THE DAY.

DRIER AIR WILL WORK ITS WAY IN BEHIND THE FRONT RESULTING IN A
COOLER DAY WITH HIGHS WELL BELOW AVERAGE AND CLOSE TO 15 DEGREES
COOLER THEN TODAY. ASIDE FROM THE CLOUDS AND LINGERING PRECIP
CHANCES...SHOULD BE A PLEASANT DAY.
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&&

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

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*/ HIGHLIGHTS...

 - DRY AND SEASONABLE INTO FRIDAY
 - RETURN OF WARM AND MUGGIER CONDITIONS FOR SATURDAY
 - SIGNIFICANT WEATHER SATURDAY NIGHT INTO EARLY NEXT WEEK
 - A RETURN OF DRY AND SEASONABLE WEATHER BY MIDWEEK

*/ OVERVIEW AND MODEL PREFERENCE...

SURPRISING PATTERN AS WE CLOSE OUT THE MONTH OF JULY! AS PRESENT NW
PACIFIC IMPULSE EJECTS E IT COUPLES WITH AN UPPER-LEVEL LOW PARKED
OVER NE CANADA RESULTING IN TROUGH ENHANCEMENT THROUGH THE GREAT
LAKES REGION. SUBSEQUENT DOWNSTREAM RIDGING OVER THE N-ATLANTIC AND
RIDGE STRENGTHENING OVER THE W-CONUS AHEAD OF A PACIFIC IMPULSE
BOTTLED IN THE GULF OF ALASKA...THE ATMOSPHERIC PATTERN BUCKLES.
WITH THE STAGNANT PATTERN IN PLACE...ANOMALOUS CONDITIONS PREVAIL AS
DECENT AGREEMENT AMONG ENSEMBLE MEMBERS SIGNAL A -3 TO -4 SD IN
HEIGHTS/TEMPERATURE/HUMIDITY.

BUT A NOTE OF CAUTION: SIMILAR ENSEMBLE MEMBERS OUT TO D8 AND INTO
EARLY AUGUST ARE EXHIBITING CONSIDERABLE SPREAD WITHIN NAO/PNA
TRENDS. IT IS WITH NO CERTAINTY AS TO HOW THIS PATTERN WILL EVOLVE.
THIS MAKES THE FORECAST OVER THE NE-CONUS DIFFICULT FURTHER OUT IN
TIME AS NEW ENGLAND ESPECIALLY FINDS ITSELF WITHIN THE E-PERIPHERY
OF THE AFOREMENTIONED TROUGH. JUST A SLIGHT WOBBLE OF THE OVERALL
BUCKLED PATTERN E OR W CAN RESULT IN CONSIDERABLE CHANGES IN THE
FORECAST.

FEEL THE DECENT AGREEMENT BETWEEN DETERMINISTIC AND ENSEMBLE MEMBERS
WARRANTS A BLEND OF MODEL GUIDANCE TOWARDS THE FORECAST. WILL HIT ON
THE MAIN POINTS ALONG WITH ANY PREFERRED GUIDANCE IN THE DAILIES
BELOW.

*/ DAY-TO-DAY DETAILS...

THURSDAY NIGHT THROUGH SATURDAY...

THINKING A DRY FORECAST PERIOD WITH THE RRQ OF THE UPPER-LEVEL JET
SHIFTING SE. FEEL THE COLD FRONT AND ATTENDANT WAVE LOW WILL REMAIN
OVER THE WATERS. SHOWERS DISSIPATING /IF ANY/ TOWARDS MIDNIGHT AS
DYNAMICS ARE SHUNTED OUT OF THE REGION.

OTHERWISE...HIGH PRESSURE AND LIGHT NW-FLOW SWEEPS ACROSS NEW
ENGLAND FRIDAY /SEA-BREEZES ALONG THE SHORES/ FOLLOWED BY RETURN
BREEZY S/SW-FLOW FOR THE REMAINDER OF THE PERIOD AS THE HIGH SLIDES
E/SE AND LOW PRESSURE BEGINS TO BUILD IN FROM THE W. SEASONABLE WX
INITIALLY...BUT EXPECT THE RETURN OF WARMER/MUGGIER CONDITIONS BY
SATURDAY. LOOKING CLEAR FOR FRIDAY...DIURNAL CUMULUS FOR SATURDAY.

SATURDAY NIGHT INTO EARLY NEXT WEEK...

THE EVOLUTION OF THE TROUGH AND THE PROXIMITY OF ITS E-PERIPHERY ARE
KEYS TO THE FORECAST /AS IS THE OFFSHORE ENHACING RIDGE ACROSS THE N-
ATLANTIC/. THE TRACK TIMING AND MORPHOLOGY OF INDIVIDUAL IMPULSES
THROUGH THE CYCLONIC FLOW WILL ULTIMATELY DETERMINE THE POTENTIAL
OUTCOMES FOR THE REGION.

FOR SATURDAY NIGHT INTO SUNDAY...SEEMINGLY AN INITIAL IMPULSE IS A
FOCUS FOR CONVECTIVE ACTIVITY /PERHAPS A MCS/ WHERE THERMAL/MOIST
AXES AND SUBSEQUENT INSTABILITY CONVERGE AT THE SURFACE AND ALONG
THE NOSE OF A LLJ REAR OF AN ATTENDANT WARM-FRONT. THE MORE ZONAL
REGIME ADVECTS THIS ACTIVITY W-TO-E. NEARLY UNI-DIRECTIONAL SHEAR
PRESENTS A THREAT OF DAMAGING WIND. BUT EARLY IN TIME AND LIKELY
ABUNDANCE OF CLOUD COVER...THREAT MAY BE LIMITED. HINTS OF MID-LEVEL
DRYING AND WAKE SUBSIDENCE? JUST A HUGE MESS. MAY BE LOOKING AT MORE
WIDESPREAD STRATIFORM WITH EMBEDDED THUNDERSTORMS. WHO KNOWS...JUST
A FIRST GUESS. BIGGEST CONCERN IS THE PLUME OF PWATS EXCEEDING 1.5
INCHES AND A POSSIBLE RISK OF FLASH FLOODING. SOME CONFIDENCE OF
THAT AT LEAST.

INTO MONDAY...THE LOW DEEPENS AS IT OCCLUDES OVER THE GREAT LAKES.
ALONG AND AHEAD OF THE COLD FRONT WITHIN WARM/MUGGY/UNSTABLE
CONDITIONS...CONVECTION IS LIKELY WITHIN AN ENVIRONMENT OF DEEP-
LAYER FORCING...BUT IT IS JUST TOO EARLY TO GO INTO DETAIL. MANY
QUESTIONS AS TO WHETHER THE ENVIRONMENT WILL DESTABILIZE BENEATH
STRONG SW-NE UNI-DIRECTIONAL SHEAR. APPEARS ACTIVITY MAY OCCUR IN
THE MORNING ONCE AGAIN FOLLOWED BY MID-LEVEL DRYING AND SUBSIDENCE.
YEESH. AGAIN...LOTS OF UNCERTAINTY. ONLY CONFIDENCE IS WITH SURGING
PWATS IN EXCESS OF 2-INCHES CONINTUING THE POSSIBLE RISK OF FLASH
FLOODING.

A FINAL NOTE...EVALUATING THE 23.0Z AND 23.12Z CIPS ANALOGS...BOTH
PING UPON POTENTIAL CONVECTIVE THREATS SUNDAY AND MONDAY. THE
PROBABILITIES OF SEVERE WEATHER IMPACTS HAVE SLIGHTLY INCREASED WITH
THE 23.12Z ANALOGS /UP TO 70-PERCENT/. SO WHILE THE ABOVE DISCUSSION
CONTAINS A FAIR AMOUNT OF UNCERTAINTY...THE FORECAST STILL WARRANTS
CLOSE MONITORING.

AT SOME POINT THE COLD FRONT SHOULD PUSH E BEHIND WHICH DRIER AND
COOLER AIR WRAPPING INTO THE OCCULUSION SHOULD PREVAIL RESULTING IN
SEASONABLE CONDITIONS FOR THE REGION. WHETHER THIS OCCURS ON TUESDAY
OR WEDNESDAY...JUST TOO UNCERTAIN.
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&&

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

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

SHORT TERM /THROUGH THURSDAY/...

GENERALLY MODERATE CONFIDENCE ON FORECAST.

THROUGH 22Z...GENERALLY VFR.

AFTER 22Z INTO TONIGHT...MVFR CIGS AND VSBYS IN VICINITY OF SCT
TSTMS AHEAD OF A COLD FRONT. A FEW TSTMS MAY BRIEFLY LOWER
CIGS/VSBYS TO IFR LEVELS. ALSO...A FEW TSRA MAY PRODUCE STRONG
WIND GUSTS. THERE IS ALSO A MODERATE POTENTIAL FOR IFR CIGS
FORMING TONIGHT ACROSS THE CAPE AND ISLANDS.

THURSDAY...GENERALLY MVFR CIGS AND VSBYS TO START IN ANTICIPATED
RAIN OR SHOWERS. CONDITIONS WILL BE IMPROVING FROM NW TO SE
THROUGH MUCH OF THE DAY. EXCEPT ALONG AND SE OF A PYM-UUU LINE
WHICH MAY STAY IN LOWER CLOUDS THROUGH MUCH OF
THURSDAY...IMPROVING LATE.

KBOS TAF...HIGH CONFIDENCE. VFR THROUGH MOST OF THE DAY. TSTMS
POSSIBLE AFT 00Z TO THE N AND W OF BOS AND CLOSER TO THE AIRFIELD
ITSELF BY 03Z.

KBDL TAF...HIGH CONFIDENCE IN TAF. TSTMS POSSIBLE AFT 22Z. ANY
TSTMS COULD CONTAIN STRONG WIND GUSTS.

OUTLOOK...THURSDAY NIGHT THROUGH MONDAY...

THURSDAY NIGHT THROUGH SATURDAY...HIGH CONFIDENCE.

VFR. -RA MOVES OUT THURSDAY NIGHT UNDER NW FLOW. LIGHT WINDS AND
MOSTLY CLEAR ON FRIDAY /SEA-BREEZES ALONG THE SHORES/. SCT-BKN 5 KFT
CIGS SATURDAY WITH BREEZY S/SW WINDS.

SATURDAY NIGHT THROUGH MONDAY...LOW CONFIDENCE.

PERIODS OF RA/TSRA. MIX OF MVFR-IFR CONDITIONS...WORST OF WHICH
ANTICIPATED DURING OVERNIGHT PERIODS AND +RA. CONTINUED BLUSTERY
S/SW WINDS.
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&&

.MARINE...
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FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH THURSDAY/...MODERATE CONFIDENCE.

THE SW FLOW WILL STRENGTHEN AHEAD OF A COLD FRONT TO PRODUCE GUSTS
APPROACHING 25 KT ACROSS MANY OF THE NEAR SHORE WATERS...THEREFORESCA
IS STILL IN EFFECT. SEAS MAY APPROACH 5 FEET EAST OF CAPE ANN THIS
EVENING. OTHERWISE WILL NEED TO MONITOR FOR AREAS OF FOG THAT MAY
DEVELOP ALONG THE SOUTH COASTAL WATERS TONIGHT.

OUTLOOK...THURSDAY NIGHT THROUGH MONDAY...

THURSDAY NIGHT THROUGH SATURDAY...HIGH CONFIDENCE.

TRANQUIL BOATING WEATHER. SOME SHOWERS MAY LINGER ALONG THE SE OUTER-
WATERS THURSDAY NIGHT...BUT SHOULD BE GOOD AFTER MIDNIGHT. HIGH
PRESSURE AND LIGHT NW-FLOW FRIDAY /SEA-BREEZES ALONG THE SHORES/.
WINDS VEER S/SW OVERNIGHT AND BECOME BREEZY DURING THE DAY SATURDAY.

SATURDAY NIGHT THROUGH MONDAY...LOW CONFIDENCE.

WEATHER TURNING SOUR. INCREASE S/SW WINDS AHEAD OF A STRONG LOW OVER
THE GREAT LAKES REGION WILL RESULT IN SIGNIFICANT WAVE HEIGHTS OVER
THE S-WATERS ESPECIALLY. SHOWERS/THUNDERSTORMS ANTICIPATED SOME OF
WHICH COULD BE STRONG.
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&&

.BOX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
     ANZ230>237-251.
     SMALL CRAFT ADVISORY UNTIL 8 AM EDT THURSDAY FOR ANZ250-254.
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&&

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