AP-CT--BOS-CT N Area Forecast Discussion, CT

000

FXUS61 KBOX 151309

AFDBOX

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE TAUNTON MA

909 AM EDT WED JUL 15 2015

.SYNOPSIS...

A COLD FRONT WILL BRING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS

MAINLY THIS AFTERNOON INTO THE EARLY EVENING HOURS. LOCALLY HEAVY

RAINFALL IS POSSIBLE ESPECIALLY TO THE SOUTH OF THE MASSACHUSETTS

TURNPIKE. CANADIAN HIGH PRESSURE PROVIDES DRY AND SLIGHTLY COOLER

THAN NORMAL WEATHER THURSDAY AND FRIDAY. WARMER WEATHER IS LIKELY

NEXT WEEKEND INTO EARLY NEXT WEEK...BUT WITH AN INCREASED RISK FOR

SHOWERS OR THUNDERSTORMS EACH DAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

***SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS MAY RESULT IN SOME

POOR DRAINAGE STREET FLOODING SOUTH OF MA TURNPIKE THIS

AFTERNOON AND EARLY THIS EVENING***

9 AM UPDATE...

VISIBLE SATELLITE IMAGERY AND SURFACE OBSERVATIONS CONFIRM STRATUS

CONTINUES TO BURN OFF AND LIFT INTO A STRATOCU DECK ESPECIALLY

AWAY FROM THE COASTLINE. FRONTAL BOUNDARY HAS ADVANCED AS FAR

SOUTHEAST AS RI /SFZ-SMITHFIELD/...BID AND SOUTHEAST MA WITH GHG

/MARSHFIELD/ ALREADY WITH A WIND SHIFT TO THE N-NW! ALTHOUGH

DESTABILIZATION WILL TAKE PLACE DESPITE WIND SHIFT AS SURFACE DEW

PTS STILL IN THE 60S ON THE COOLER SIDE OF THE BOUNDARY. HOWEVER

THE RACE WILL BE ON BETWEEN DRIER AIR FROM THE NW /ALBANY N WND

G22KT/ AND WARM SOUPY AIRMASS CURRENTLY OVER THE REGION. FRONTAL

BOUNDARY SHOULD SLOW DOWN AS SURFACE WAVE INTENSIFIES OFF THE NJ

COAST. IS THIS REALLY A MID JULY PATTERN?

THIS AFTERNOON AND EARLY EVENING FORECAST WILL HINGE ON CONVECTION

OVER NJ...SPECIFICALLY DOES THIS CONVECTION ROB DEEP MOISTURE AND

INSTABILITY FROM ADVECTING NORTHEAST INTO SOUTHERN NEW ENGLAND?

HALF OF THE MODEL GUIDANCE SAYS YES WHILE THE OTHER HALF OF THE

GUIDANCE INDICATES A SECOND AREA OF CONVECTION FIRING OVER CT/RI

AND SOUTHEAST MA. WILL JUST HAVE TO SEE HOW WELL 12Z MODELS

SIMULATE NJ CONVECTION AND WATCH SATELLITE AND RADAR TRENDS HOUR

BY HOUR. THUS LOW CONFIDENCE FORECAST BUT HIGH IMPACT POTENTIAL

WITH VERY RAINFALL AND LOCALIZED FLOODING IN THE I95 CORIDOR

POSSIBLY. THIS IS WHERE THE GREATER INSTABILITY WILL LIKELY EXIST.

TIMING COULD IMPACT THE LATE DAY COMMUTE. THUS NOT MUCH CHANGE

FROM PREVIOUS FORECAST BUT STAY TUNED FOR ADDITIONAL DETAILS.

PREVIOUS DISCUSSION...

BY LATE MORNING AND ESPECIALLY THIS AFTERNOON A SHORTWAVE WILL

APPROACH FROM THE SOUTHWEST. AT THE SAME TIME...A COLD FRONT WILL

BE DROPPING DOWN FROM THE NORTHWEST. THIS WILL RESULT IN SCATTERED

SHOWERS AND A FEW THUNDERSTORMS TO INCREASE IN AREAL COVERAGE LATE

THIS MORNING AND ESPECIALLY THIS AFTERNOON. BULK OF ACTION WILL BE

SOUTH OF THE MA TURNPIKE FROM MID AFTERNOON INTO THE EARLY EVENING

HOURS.

SEVERE WEATHER POTENTIAL IS RATHER LOW GIVEN VERY WEAK WIND FIELDS

AND LIMITED INSTABILITY. HOWEVER...WE SHOULD BE ABLE TO MUSTER

CLOSE TO 1000 J/KG OF CAPE. THIS WILL COMBINED WITH PWATS AROUND 2

INCHES TO BRING THE POTENTIAL OF LOCALLY HEAVY RAINFALL AND BRIEF

POOR DRAINAGE STREET FLOODING WITH ANY OF THE STRONGER ACTIVITY.

THE HIGHEST RISK FOR THIS IS AREAS SOUTH OF THE MA TURNPIKE...WHERE

THEY WILL BE CLOSER TO THE SHORTWAVE ALONG WITH BETTER INSTABILITY.

VERY WEAK WIND FIELDS ARE ALSO A CONCERN SINCE ANY ACTIVITY THAT

DEVELOPS WILL HAVE THE POTENTIAL TO MOVE RATHER SLOWLY OVER A

PARTICULAR LOCATION.

WHILE POCKETS OF BRIEF POOR DRAINAGE STREET FLOODING ARE A DECENT

BET...IT REMAINS UNCERTAIN IF AN ISOLATED LOCATION OR TWO ENDS UP

WITH A PERIOD OF MORE SIGNIFICANT URBAN FLOODING. SOME LIMITING

FACTORS FOR THAT ARE THAT LOW LEVEL FORCING IS NOT THAT IMPRESSIVE

AND BETTER INSTABILITY WILL RESIDE TO OUR SOUTH. HOWEVER...SOME OF

OUR MESOSCALE MODELS ARE SHOWING BULLSEYES OF 2 TO 3.50 INCHES OF

RAIN ACROSS PORTIONS OF NORTHERN CT/RHODE ISLAND AND SOUTHEAST MA.

WHILE WE WOULD LIKE TO SEE THE GLOBAL MODELS SHOWING A LITTLE BETTER

SIGNAL TO HAVE MORE CONFIDENCE IN THIS SCENARIO...THERE IS SOME

REASON TO BE CONCERNED. APPEARS WE MAY BE DEALING WITH SOME TYPE OF

SEA BREEZE FRONT OUT AHEAD OF THE MAIN COLD FRONT. IF THIS COMES TO

FRUITION...IT COULD PROVIDE SOME FOCUS FOR A VERY LOCALIZED AREA OR

TWO RECEIVING 2+ INCHES OF RAIN IN AN HOUR OR LESS. NO ACTION WILL

BE TAKEN AT THIS TIME...BUT BASED ON HOW THINGS LOOK LATER THIS

MORNING THE NEXT SHIFT MAY WANT TO ISSUE A SPECIAL WEATHER STATEMENT

OR PERHAPS EVEN A VERY LOCALIZED FLASH FLOOD WATCH IF CONFIDENCE IS

HIGH ENOUGH.

HIGH TEMPS WILL RANGE FROM THE UPPER 70S TO THE MIDDLE 80S AND IT

WILL BE RATHER HUMID.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...

SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS EARLY THIS EVENING

SHOULD COME TO AN END BY LATE EVENING ACROSS THE SOUTHEAST NEW

ENGLAND COAST. THIS THE RESULT OF A FAIRLY STRONG COLD FRONT FOR

JULY STANDARDS PUSHING SOUTHEAST OF THE REGION. MUCH DRIER AND

COOLER AIR WILL WORK INTO THE REGION. LOW TEMPS BY DAYBREAK

THURSDAY WILL BE IN THE MIDDLE TO UPPER 50S ACROSS MUCH OF THE

INTERIOR...TO THE LOWER TO MIDDLE 60S ON THE COASTAL PLAIN.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...

HIGHLIGHTS...

* DRY AND COOLER ON THURSDAY AND FRIDAY

* UNSETTLED WEATHER FOR THE WEEKEND

* WARMING TREND THIS WEEKEND INTO NEXT WEEK

OVERVIEW AND MODEL PREFERENCES...

SYNOPTIC SCALE FEATURES REMAIN IN FAIRLY GOOD AGREEMENT THROUGH

THE LONG TERM. THE UPPER LVL VORTEX ACROSS NRN CANADA WILL

ACTUALLY RETROGRADE SOMEWHAT AS IT PHASES WITH ANOTHER WAVE MOVING

OUT OF THE ALASKAN REGION. THIS ORIENTS THE ZONAL FLOW ACROSS THE

NRN CONUS /AND BY PROXY...SNE/ FROM W-E TO MORE OF A SW TO NE

DIRECTION. THIS MEAN-JET IS ON THE PERIPHERY OF A BUILDING

SUBTROPICAL RIDGE ACROSS THE SE CONUS. THIS SHIFT IN THE FLOW

PATTERN ALOFT HAS TWO CONSEQUENCES...IT ALLOWS FOR A CONDUIT OF

SEVERAL WEAK SHORTWAVES WHICH WILL MOVE ACROSS THE REGION FROM

DURING THE EXTENDED AND ALSO ALLOWS MORE DESTABILIZED AIR...AND

POSSIBLY EVEN AN EML FROM THE WRN CONUS TO MOVE ACROSS THE AREA.

THEREFORE...EXPECT THE DRY LATE WEEK PERIOD TO TRANSITION TO A

WETTER AND MORE UNSETTLED PERIOD FROM THE LATTER HALF OF THE

WEEKEND INTO EARLY NEXT WEEK. MODERATING TEMPERATURES ARE EXPECTED

THROUGH THE LONG TERM...STARTING MAINLY BELOW NORMAL THEN TRENDING

ABOVE BY EARLY NEXT WEEK. A BLEND OF GUIDANCE SEEMS REASONABLE

GIVEN THE LARGER SCALE AGREEMENT. SLIGHT ADJUSTMENTS WILL BE MADE

AS NEEDED FOR SENSIBLE WX.

DETAILS...

THU INTO FRI NIGHT...

HIGH PRES BUILDS ACROSS THE REGION THROUGH THE PERIOD WITH MAINLY

DRY WX. TEMPS ON THU WILL BE MAINLY BELOW NORMAL...ESPECIALLY NEAR

THE E COAST WHERE 10-20 KT N-NE WINDS ASSISTED BY SEA BREEZE WILL

KEEP HIGHS ONLY IN THE LOW 70S. WARMER FURTHER W...BUT H85 TEMPS

ARE ONLY ABOUT +12C...WHICH WOULD CORRESPOND TO NEAR OR SLIGHTLY

BELOW NORMAL HIGHS. BY FRI...HIGHS WILL REBOUND A BIT TO NEAR

NORMAL...ALTHOUGH LIGHT FLOW SUGGESTS SEA BREEZES ONCE AGAIN AT

THE COASTLINES.

SAT...

STRONG WAVE/COLD POOL WHICH APPEARS TO BE THE REMNANT OF A NRN

PLAINS MCS WILL BE APPROACHING THE REGION FROM THE W. DEVELOPING

BAROCLINICITY AS IT APPROACHES THE IMPACT ON SRN NEW ENGLAND WILL

BE WHERE THE WARM FRONTAL BOUNDARY ENDS UP. BEST CHANCES APPEAR TO

BE ACROSS THE W...BUT THE INSTABILITY GRADIENT MAINLY TO THE W AND

SW. THEREFORE...EXPECT MOST OF THE CONVECTION TO BE RIGHT TURNING

AWAY FROM THE REGION. STILL...ENOUGH UNCERTAINTY WITH THIS UPDATE

TO INCLUDE A RISK FOR T-STORMS MAINLY IN THE W. HIGHEST RISK IS

HEAVY RAIN THANKS TO MODERATELY HIGH PWATS. IN ANY

CASE...AFTERNOON/EVENING SHOWERS ARE LIKELY EVERYWHERE AS THE

UPPER LVL WAVE CONTINUES IT/S PROGRESSION TO THE E.

SUN INTO MON...

THE WARM FRONT WILL MAKE A SLOW ATTEMPT AT PROGRESSING NE AS THE

UPPER LVLS TEND TOWARD RIDGING FOLLOWING THE FIRST WAVE PASSAGE ON

SAT. WITH MODERATE PWAT AIR /AVERAGING AROUND 1.5 INCHES/ AND THE

SLOW MOVING /POSSIBLY EVEN STALLING/ FRONT IN THE

VICINITY...SUSPECT THAT IN SPITE OF THE UPPER LVL RIDGE...THE RISK

FOR DIURNALLY DRIVEN CONVECTIVE SHOWERS/STORMS ARE POSSIBLE EACH

DAY. THE T-STORM RISK WILL DEPEND MOSTLY ON WHERE THE FRONT STALLS

/LATEST GFS ACTUALLY PUSHES IT BACK W AS A BACKDOOR COLD FRONT ON

MON/. WILL GO WITH MAINLY -SHRA...BUT INCLUDE A LOW END CHANCE OF

T-STORMS AS WELL. ALTHOUGH H85 TEMPS INCREASE TO NEAR +15C BY THIS

POINT...ACTUAL TEMPS WILL BE DEPENDENT ON CLOUD COVER AND FRONTAL

BOUNDARY MOVEMENT.

TUE AND WED...

AFTER A BRIEF PERIOD IN THE WARM SECTOR POSSIBLE A SECONDARY

UPPER LVL WAVE WILL APPROACH FROM THE W WITH AN ASSOCIATED COLD

FRONT. THIS WILL HAVE TO BE WATCHED AS GUIDANCE INDICATES THE

POSSIBILITY OF A REMNANT EML AND FAIRLY DESTABILIZED COLUMN WITH

WARM LOW LVL TEMPS AND REASONABLY HIGH MOISTURE. STILL TIMING

ISSUES AND OVERALL COLUMN STATIC STABILITY TO WORK OUT...BUT THIS

PERIOD MAY NEED TO BE WATCHED.

&&

.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...

FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT.

MODERATE...30 TO 60 PERCENT.

HIGH...GREATER THAN 60 PERCENT.

SHORT TERM /TODAY AND TONIGHT/...

9 AM UPDATE...NOT MUCH CHANGE FROM 12Z TAFS. VFR AWAY FROM THE

COASTLINE WITH SLOWLY IMPROVING CONDITIONS ALONG THE COAST.

GREATEST RISK FOR HEAVY AFTERNOON SHOWERS AND THUNDERSTORMS WILL

BE ACROSS CT/RI AND SOUTHEAST MA. EARLIER DISCUSSION BELOW.

TODAY...MODERATE CONFIDENCE.

CONDITIONS ARE ALREADY IMPROVING TO VFR AND EXPECT THIS TREND TO

CONTINUE AWAY FROM THE SOUTH COAST THIS MORNING. LOW CLOUDS WITH

MAINLY MVFR /ALTHOUGH PERIODIC IFR NOT OUT OF THE QUESTION/ MAY

HANG IN MOST OF THE DAY ESPECIALLY S OF A WST-TAN-PYM LINE.

OTHERWISE...AFTERNOON SHOWERS AND THUNDERSHOWERS POSSIBLE

ESPECIALLY THIS AFTERNOON AND ESPECIALLY AT TERMINALS S OF THE

MASS PIKE. LOCALLY HEAVY RAINFALL WITH BRIEF IFR CONDITIONS

POSSIBLE.

TONIGHT...HIGH CONFIDENCE IN TRENDS...LOWER CONFIDENCE IN EXACT

TIMING.

EVENING MVFR/IFR CONDITIONS IN LEFTOVER FOG/SHOWERS/T-STORMS WILL

GRADUALLY GIVE WAY TO CLEARING AND IMPROVING CONDITIONS DURING THE

OVERNIGHT HOURS WITH VFR EXPECTED PRETTY MUCH EVERYWHERE BY 04Z

OR MIDNIGHT LOCAL. WINDS WILL BE SHIFTING MAINLY TO THE N...WITH

GUSTS 20-30 KT POSSIBLE ESPECIALLY ACROSS E MA AND RI LATE.

KBOS TERMINAL...HIGH CONFIDENCE FOR VFR NOW THAT LOW CLOUDS HAVE

CLEARED. SCATTERED SHOWERS AND PERHAPS AN ISOLATED THUNDERSTORM

WILL BE IN THE VICINITY OF THE TERMINAL THIS AFTERNOON.

KBDL TERMINAL...EXPECT SOME IMPROVEMENT FROM THE MVFR CIGS LATER

THIS MORNING. SCATTERED SHOWERS AND PERHAPS AN ISOLATED

THUNDERSTORM WILL BE IN THE VICINITY OF THE TERMINAL THIS

AFTERNOON.

OUTLOOK...THURSDAY THROUGH SUNDAY...

THU THROUGH FRI....HIGH CONFIDENCE. MAINLY VFR. NORTHERLY WINDS

APPROACH 20-25 KT ESPECIALLY OVER E MA TERMINALS ON THU...SEA

BREEZES LIKELY WITH WEAKER FLOW ELSEWHERE FRI.

SAT INTO SUNDAY...MODERATE CONFIDENCE.

MAINLY VFR. COULD SEE SCT MVFR IN ISO -SHRA/-TSRA. HIGHEST

CONFIDENCE IS ACROSS WESTERN TERMINALS. SOME FOG POSSIBLE DURING

THE OVERNIGHTS.

&&

.MARINE...

FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT.

MODERATE...30 TO 60 PERCENT.

HIGH...GREATER THAN 60 PERCENT.

SHORT TERM /TODAY THROUGH WEDNESDAY/...

***NORTHEAST WIND GUSTS OF 20 TO 30 KNOTS EXPECTED LATE THIS EVENING

AND INTO THE FIRST HALF OF THURSDAY***

TODAY...MODERATE TO HIGH CONFIDENCE. WEAK PRESSURE GRADIENT WILL

KEEP WINDS BELOW SMALL CRAFT ADVISORY THRESHOLDS. HOWEVER...SMALL

CRAFT ADVISORIES GO INTO EFFECT THIS MORNING FOR OUR SOUTHERN WATERS

FOR 3 TO 6 FOOT SOUTHERLY SWELL. BY LATE AFTERNOON AND EARLY

EVENING...SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL LIKELY

AFFECT THE WATERS NEAR THE SOUTH COAST.

TONIGHT...MODERATE TO HIGH CONFIDENCE. SCATTERED SHOWERS AND

ISOLATED THUNDERSTORMS EXPECTED THIS EVENING ACROSS OUR SOUTHERN

WATERS. IN ADDITION...AREAS OF FOG MAY ALSO REDUCE VISIBILITIES

DURING THE FIRST HALF OF THE NIGHT. OTHERWISE...STRONG COLD FRONT

FOR JULY STANDARDS WILL BRING NORTHEAST WIND GUSTS OF 20 TO 30 KNOTS

BY LATE EVENING. SMALL CRAFT HEADLINES POSTED FOR ALL WATERS EXCEPT

BOSTON HARBOR AND NARR BAY.

OUTLOOK...THURSDAY THROUGH SUNDAY...

THU...HIGH CONFIDENCE.

WITH HIGH PRES APPROACHING FROM THE W...EXPECT N-NE WIND GUSTS

APPROACHING 25 KT AT TIMES THROUGH THE DAY. SEAS WILL REMAIN

ELEVATED...5-6 FT ON THE OCEAN WATERS. THEREFORE...SMALL CRAFT

ADVISORIES WILL BE EXTENDED INTO THU...AND MAY NEED TO LINGER INTO

THU NIGHT UNTIL SEAS ARE ALLOWED TO SUBSIDE.

FRI AND SAT...HIGH CONFIDENCE.

MAINLY QUIET BOATING WEATHER UNDER HIGH PRES. ALTHOUGH A FEW

SHOWERS OR T-STORMS ARE POSSIBLE ON SAT.

SUN...MODERATE CONFIDENCE.

SHOWERS AND STORMS MAY LINGER. WIND DIRECTIONS WILL DEPEND ON THE

LOCATION OF A FRONT BY THIS TIME. HOWEVER...EXPECT WINDS AND SEAS

TO GENERALLY REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...

CT...NONE.

MA...NONE.

RI...NONE.

MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 4 PM EDT

THURSDAY FOR ANZ231>234-250-251.

SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 4 PM EDT

THURSDAY FOR ANZ235-237.

SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 8 PM EDT

THURSDAY FOR ANZ254.

SMALL CRAFT ADVISORY UNTIL 8 PM EDT THURSDAY FOR ANZ255-256.

&&

$$

SYNOPSIS...FRANK/DOODY

NEAR TERM...FRANK/NOCERA/DOODY

SHORT TERM...FRANK

LONG TERM...DOODY

AVIATION...FRANK/NOCERA/DOODY

MARINE...FRANK/DOODY

Delivered by Weather Underground Inc. Wed Jul 15 2015 9:09AM EDT