983  
FXUS61 KBOX 221055  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TAUNTON MA  
655 AM EDT THU JUN 22 2017  
   
SYNOPSIS
 
 
HIGH PRESSURE IN CONTROL TODAY. WARM AND HUMID AIR FOLLOWS FOR  
THE REMAINDER OF THE WEEK INTO THE WEEKEND ALONG WITH THE THREAT  
OF HEAVY RAIN ASSOCIATED WITH THE REMNANTS OF CINDY. THE COLD  
FRONT WILL STALL ACROSS NEW ENGLAND SATURDAY BEFORE MOVING OFFSHORE  
SATURDAY NIGHT. SEASONABLY WARM AND LESS HUMID CONDITIONS SUNDAY  
WILL BE FOLLOWED BY COOLER AND SOMEWHAT UNSETTLED WEATHER FOR  
EARLY NEXT WEEK.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
650 AM UPDATE...  
SKC ACROSS SNE THIS MORNING. PLEASANT SUMMER DAY ON TAP WITH  
SUNSHINE, SEASONABLY WARM TEMPS AND COMFORTABLE HUMIDITY. SOME  
OF THE HI-RES GUIDANCE INDICATING A SEABREEZE MAY DEVELOP ALONG  
THE IMMEDIATE EAST COAST THIS AFTERNOON. IF IT DOES COME  
ONSHORE IT WILL BE CONFINED TO THE IMMEDIATE COASTLINE.  
 
HIGHS UPPER 70S TO LOW 80S GIVEN MIXING UP AROUND H85 WHERE  
TEMPERATURES RANGE AROUND +12C. THE DEEP MIXING ALLOWS FOR  
SURFACE DEWPOINTS TO DROP AROUND THE LOW TO MID 50S, SOME PLACES  
IN THE UPPER 40S. FEW TO SCATTERED LOW CLOUDS PRIOR TO  
INCREASING HIGH CLOUDS TOWARDS EVENING AS SUB-TROPICAL AIR  
BEGINS TO ASCEND ACROSS THE REGION. EXPECT 60 DEGREE SURFACE  
DEWPOINTS SLIP BACK N TONIGHT.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/
 
 
TONIGHT...  
 
REMAINING MILD, BECOMING HUMID, AS THE CHANCE OF SHOWERS INCREASE.  
CONTINUED ASCENT OF SUB-TROPICAL MOISTURE ACROSS THE REGION WITH  
ACCOMPANYING ELEVATED INSTABILITY AND HIGHER K-INDICES, THOUGH  
STRONGER LOW-LEVEL CONVERGENCE AND DEEP LAYER FORCING IS TIED  
MORE CLOSELY WITH THE DEEP LAYER TROUGH DIGGING S OUT OF CANADA  
INTO THE GREAT LAKES REGION. SUBSEQUENTLY, DESPITE LIFT AND COLUMN  
SATURATION, THE BETTER CHANCES OF WET-WEATHER ARE MORE LIKELY N/W.  
EXPECTING SCATTERED LIGHT OUTCOMES WITH THE POSSIBLE RISK OF  
THUNDER. CONTINUED S FLOW, SURFACE DEWPOINTS CONTINUE TO RISE  
CLOSING IN ON 70. ACROSS THE COOLER OCEAN WATERS, MORE THAN  
LIKELY LOW CLOUDS IF NOT FOG AND VISIBILITY ISSUES FOR SE NEW  
ENGLAND. LOWS IN THE MID TO UPPER 60S.  
 
FRIDAY...  
 
WARM, MUGGY DAY WITH THE CHANCE OF SHOWERS AND THUNDERSTORMS. SUB-  
TROPICAL AIR CONTINUING TO SURGE FROM THE SW PUSHING PRECIPITABLE  
WATERS ABOVE 2 INCHES AS REMNANTS OF CINDY ARE STRETCHED N. THIS  
AHEAD OF CYCLONIC FLOW TIGHTENING AS MID-LEVEL ENERGY CONTINUES TO  
PUSH INTO THE GREAT LAKES REGION. FALLING HEIGHTS ALONG WITH LOW-  
LEVEL CONVERGENT FORCING PUSHING INTO S NEW ENGLAND, PRESENTS A  
FAVORABLE ENVIRONMENT IN WHICH PARTIAL CLEARING IS EXPECTED, MORE  
OVER THE INTERIOR NE CONUS, FOR SHOWER AND THUNDERSTORM DEVELOPMENT.  
LOW CLOUDS ALONG WITH VISIBILITY ISSUES ASSOCIATED WITH FOG / MIST  
ARE EXPECTED TO SOCK IN SE NEW ENGLAND BENEATH THE REMNANTS OF A DRY  
CONVEYOR BELT THAT HAD WRAPPED INTO CINDY. LAPSE RATES CONDITIONALLY  
UNSTABLE, MORE MOIST ADIABATIC CONTRIBUTING TO THIN-TALL CAPE IN AN  
ENVIRONMENT OF WEAK SHEAR. GIVEN THE SUB-TROPICAL AIRMASS IN A BROAD  
REGION OF LOW-LEVEL CONVERGENT FORCING AND DESTABILIZING BOUNDARY  
LAYER, EXPECTING MAINLY HEAVY RAINERS. FREEZING LEVELS UP AROUND 15  
KFT WITH PRECIPITABLE WATERS IN EXCESS OF 2 INCHES, EFFICIENT WARM-  
RAIN PROCESSES FORECAST WITH COLLISION / COALESCENCE. SO WITH ANY  
THUNDER WILL GO WITH A MENTION OF HEAVY RAIN. HIGHER CHANCE POPS  
AWAY FROM THE S/E AS HIGHS WARM WELL INTO THE 80S. WHEREVER THE  
BOUNDARY LAYER MIXES OUT IT'LL LIKELY BE BREEZY FROM THE SW WITH  
GUSTS UP TO 25 MPH.  
 
FRIDAY NIGHT...  
 
WET, MUGGY, MILD. AN ANOMALOUS SETUP ATTRIBUTABLE TO THE REMNANTS OF  
CINDY. ROUGHLY A +4-5 STANDARD DEVIATION (SD) OF H85 MOISTURE FLUX  
AND +3 SD OF PRECIPITABLE WATERS WHICH EXCEED RECORD HIGHS RECORDED  
AT CHATHAM MA WHICH AVERAGE AROUND 2 INCHES BUT ARE FORECAST AROUND  
2.25 INCHES. WILL NEED TO CLOSELY MONITOR ANY FOCUSING MECHANISMS  
WHICH CAN PUT THE SQUEEZE ON THE ATMOSPHERE AND POSSIBLY YIELD A  
PREDECESSOR RAINFALL EVENT.  
 
NOTING INCREASING LOW-LEVEL WINDS PER TIGHTENING PRESSURE GRADIENT  
AHEAD OF MID-LEVEL TROUGHING ACROSS THE GREAT LAKES, CONVERGENTLY  
FOCUSED IN AND AROUND THE S-SHORELINE OF S NEW ENGLAND AHEAD OF A  
SWEEPING COOL FRONT. TIGHTENING BAROCLINIC ZONE. INDICATIONS OF  
HEIGHT FALLS WITHIN THE MID-LEVELS ASSOCIATED WITH WEAK TROUGHING  
SIGNATURES CONTRIBUTING TO THE CONVERGENCE OF SUB-TROPICAL AIR.  
THIS AS EARLIER DAYTIME CONVECTION WILL LIKELY SHIFT S/E AHEAD OF  
SAID COOL FRONT. THIS IN COMBINATION WITH TROPICAL ENERGY AND SOME  
DIFFLUENT MOTIONS ALOFT, CAN'T RULE OUT A POTENTIAL PREDECESSOR  
RAINFALL EVENT. DIFFICULT TO NAIL DOWN AT THIS TIME AS TO EXACTLY  
WHERE BUT FEEL THERE IS A RISK TO S NEW ENGLAND AROUND THE SATURDAY  
AM TIMEFRAME.  
 
LOOKING AT CHANCE TO LIKELY POPS FOR POSSIBLE WIDESPREAD RAIN WITH  
EMBEDDED HEAVIER SHOWERS AND THUNDERSTORMS. HEAVY RAIN THREAT PER  
EFFICIENT WARM-RAIN PROCESSES STILL EXISTS AND WILL CONTINUE TO  
MENTION. AGAIN, FOCUS OF HEAVY RAIN REMAINS UNCERTAIN WITH RESPECT  
TO POTENTIAL FLOODING THREATS.  
 
SURFACE DEWPOINTS WELL INTO THE 70S, A MUGGY AND HUMID AIRMASS FOR  
CERTAIN, OFF THE COOLER OCEAN WATERS ESPECIALLY TO THE S/E, LIKELY  
DEALING WITH FOGGY CONDITIONS OVERNIGHT INTO THE MORNING HOURS.  
COULD SEE VISIBILITY DOWN TO A QUARTER MILE OR LESS AT TIMES.  
 

 
   
LONG TERM /SATURDAY THROUGH WEDNESDAY/
 
 
HIGHLIGHTS...  
 
* SCT SHOWERS AND ISOLD T-STORMS SAT, MAINLY SOUTH OF THE PIKE  
* SEASONABLY WARM AND LESS HUMID SUNDAY  
* COOLER WITH SHOWERS POSSIBLE AT TIMES EARLY NEXT WEEK  
 
OVERVIEW...  
 
LONGWAVE TROF OVER THE GT LAKES WILL BE THE MAIN FEATURE IN THE  
EXTENDED PERIOD. POLAR JET WILL BE IN THE VICINITY OF NEW ENG WITH A  
SERIES OF WEAK SHORTWAVES MOVING THROUGH THE FLOW AS THE TROF  
GRADUALLY MOVES INTO NEW ENG EARLY NEXT WEEK. THIS WILL BRING A  
SOMEWHAT UNSETTLED PATTERN INTO THE MIDDLE OF NEXT WEEK WITH  
COOLER TEMPS TRENDING NEAR OR BELOW NORMAL.  
 
DETAILS...  
 
SATURDAY...  
 
COLD FRONT EXPECTED TO STALL ACROSS SNE WITH TROPICAL PWAT PLUME  
EXCEEDING 2" AND HIGH THETA-E AIR REMAINING ACROSS SOUTHERN HALF OF  
THE REGION. SHORTWAVE ASSOCD WITH THE REMNANTS OF CINDY TRACKS NEAR  
OR SOUTH OF NEW ENG AND WILL LIKELY BRING A PERIOD OF SHOWERS AND  
ISOLD T-STORMS WITH BRIEF DOWNPOURS, ESPECIALLY SOUTH OF THE PIKE. A  
FEW SHOWERS MAY EVEN EXTEND INTO NORTHERN MA IN THE MORNING BUT  
TREND SHOULD BE FOR IMPROVING CONDITIONS HERE IN THE AFTERNOON WITH  
DEVELOPING SUNSHINE.  
 
TEMPS ARE TRICKY SOUTH OF THE PIKE WHERE CLOUDS AND SHOWERS MAY HOLD  
TEMPS DOWN. WE UNDERCUT GUIDANCE HERE WITH HIGHS MOSTLY IN THE 70S  
TO NEAR 80 BUT LOW TO MID 80S NE MA. REMAINING RATHER HUMID SOUTH OF  
THE PIKE WITH DEWPOINTS WELL INTO THE 60S TO NEAR 70, BUT EXPECT  
DEWPOINTS DROPPING INTO THE 50S ACROSS NORTHERN AND WESTERN MA IN  
THE AFTERNOON. DRIER AIR WILL EVENTUALLY MAKE ITS WAY TO THE COAST  
SAT NIGHT WITH CLEARING SKIES.  
 
SUNDAY...  
 
THE COLUMN IS CONSIDERABLY DRIER SUNDAY SO EXPECT SUNSHINE MIXING  
WITH DIURNAL CLOUDS. MAINLY DRY CONDITIONS BUT MID LEVEL SHORTWAVE  
TRACKING TO THE NORTH AND WEST MAY BRING A BRIEF SHOWERS TO NW MA.  
SEASONABLE TEMPS IN THE UPPER 70S AND LOWER 80S WITH LOW HUMIDITY AS  
DEWPOINTS WILL BE IN THE 50S.  
 
MONDAY INTO WEDNESDAY...  
 
GT LAKES TROF WILL GRADUALLY MOVE EAST INTO NEW ENG AS A SERIES OF  
SHORTWAVES MOVE THROUGH WITH MID LEVEL TEMPS COOLING THROUGH THE  
PERIOD. 500 MB TEMPS -16 TO -20C. THIS WILL RESULT IN AN UNSETTLED  
PATTERN WITH SHOWERS OR EVEN AN ISOLD T-STORM POSSIBLE AT TIMES, BUT  
LOW CONFIDENCE ON TIMING. TEMPS TRENDING COOLER TO NEAR OR A BIT  
BELOW SEASONABLE NORMALS.  
 

 
   
AVIATION /12Z THURSDAY THROUGH MONDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH FRIDAY NIGHT/...  
 
TODAY...  
VFR. LIGHT WINDS GRADUALLY VEERING S. SEA-BREEZES POSSIBLE ALONG  
THE IMMEDIATE E-COAST. FEW-SCT CIGS AROUND 6 KFT. INCREASING  
HIGH CLOUDS FROM THE W TOWARDS SUNSET.  
 
TONIGHT...  
CIGS BECOMING SCT TO BKN LOWERING TOWARDS 4-6 KFT WITH SHRA MOVING  
IN, THE BETTER CHANCE OF WHICH WILL BE ACROSS N/W CT AND MA WITH  
A LOW RISK TSRA. INCREASING S WINDS WITH THE THREAT OF MVFR VSBYS  
ALONG THE S COAST.  
 
FRIDAY...  
SCT TO BKN LOW-END VFR CIGS, MORE OVC ACROSS SE NEW ENGLAND, AS  
S/SW WINDS INCREASING 10 TO 15 KTS SUSTAINED WITH GUSTS UP TO 25  
KTS. INCREASING AREAL COVERAGE OF SHRA/TSRA WITH EMBEDDED THREATS  
OF +RA. TEMPO MVFR/IFR VSBYS WITH ANY RA/+RA WHILE LIKELY MVFR/IFR  
VSBYS WILL PLAGUE THE S-COAST TOWARDS EVENING.  
 
FRIDAY NIGHT...  
BKN TO OVC MVFR/IFR CIGS WITH AREAS OF IFR/LIFR FG TOWARDS SE NEW  
ENGLAND TERMINALS. SHRA/TSRA CONTINUE WITH EMBEDDED THREATS OF +RA.  
THERE IS ALSO THE LOW RISK OF LLWS IMPACTS ACROSS THE CAPE AND  
ISLANDS.  
 
KBOS TERMINAL...SEA-BREEZE MAY DEVELOP THIS AFTERNOON BUT  
CONFIDENCE NOT HIGH. IT COULD REMAIN JUST OFFSHORE. VFR FOR THE  
ENTIRE TAF PERIOD. INCREASING CIGS DURING THE EVENING HOURS,  
LOWERING INTO FRIDAY MORNING.  
 
KBDL TERMINAL...HIGH CONFIDENCE. VFR THROUGHOUT.  
 
OUTLOOK /SATURDAY THROUGH MONDAY/...  
 
SATURDAY...MODERATE CONFIDENCE.  
MVFR AND LOCALIZED IFR IN SCT SHOWERS AND ISOLD T-STORMS, ESPECIALLY  
SOUTH OF THE PIKE WITH IMPROVING CONDITIONS, MAINLY VFR NORTH OF THE  
PIKE.  
 
SUNDAY...HIGH CONFIDENCE. MAINLY VFR.  
 
MONDAY...HIGH CONFIDENCE.  
MAINLY VFR CIGS WITH A FEW SHOWERS POSSIBLE IN THE INTERIOR.  
 

 
   
MARINE
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH FRIDAY NIGHT/...  
 
HIGH PRESSURE TODAY. LIGHT WINDS VEERING THOUGH THE DAY BECOMING  
S OVERNIGHT, INCREASING INTO FRIDAY WITH SUSTAINED WINDS 10 TO  
15 KTS AND GUSTS UP TO 25 KTS. THIS WILL PUSH SEAS 5 TO 6 FEET  
AND REQUIRE SMALL CRAFT ADVISORIES. WITH A COLD FRONT SWEEPING  
DOWN FROM THE N AS THE REMNANTS OF TS CINDY ADVECT N FROM THE S,  
WILL LIKELY SEE THE RETURN OF MIST / FOG CONDITIONS RESULTING  
IN LOW VISIBILITY DOWN TO A QUARTER MILE OR LESS AT TIMES.  
 
OUTLOOK /SATURDAY THROUGH MONDAY/...  
 
SATURDAY...MODERATE CONFIDENCE.  
SOME GUSTY W/SW WINDS EARLY SAT, POSSIBLY NEAR SCA THRESHOLDS SHOULD  
DIMINISH IN THE AFTERNOON. SEAS UP TO 5-6 FT OVER THE SOUTH COASTAL  
WATERS.  
 
SUNDAY AND MONDAY...HIGH CONFIDENCE.  
WINDS SHOULD GENERALLY REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS  
THROUGH THE PERIOD. LINGERING 5 FT SEAS OVER THE SOUTH COASTAL  
WATERS WILL SUBSIDE SUN NIGHT.  
 

 
   
TIDES/COASTAL FLOODING
 
 
ASTRONOMICAL TIDES ARE RATHER HIGH THIS WEEKEND DURING THE NIGHT TIME  
CYCLES. BOSTON HAS A 12.4 FT HIGH TIDE AROUND MIDNIGHT SAT NIGHT AND  
12.2 FT JUST AFTER MIDNIGHT SUN NIGHT. FORTUNATELY, OFFSHORE WINDS  
ARE FORECAST WITH MINIMAL OR NO SURGE SO DO NOT ANTICIPATE ANY  
ISSUES.  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...NONE.  
RI...NONE.  
MARINE...SMALL CRAFT ADVISORY FROM 8 PM FRIDAY TO 8 AM EDT SATURDAY FOR  
ANZ232>235-237.  
SMALL CRAFT ADVISORY FROM 2 PM FRIDAY TO 8 AM EDT SATURDAY FOR  
ANZ250-254>256.  
 

 
 

 
SYNOPSIS...KJC/SIPPRELL  
NEAR TERM...KJC/SIPPRELL  
SHORT TERM...SIPPRELL  
LONG TERM...KJC/SIPPRELL  
AVIATION...KJC/SIPPRELL  
MARINE...KJC/SIPPRELL  
TIDES/COASTAL FLOODING...  
 
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