378  
FXUS61 KBOX 201436  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
1036 AM EDT WED JUN 20 2018  
   
SYNOPSIS
 
 
DRY WEATHER IS EXPECTED TODAY AS HIGH PRESSURE BUILDS ACROSS  
NEW ENGLAND. SHOWERS ARE LIKELY TONIGHT SOUTH OF THE MASS PIKE  
AS LOW PRESSURE PASSES SOUTH OF NEW ENGLAND. HIGH PRESSURE FROM  
CANADA BRINGS DRY WEATHER THURSDAY AND FRIDAY. A COLD FRONT  
THEM BRINGS A CHANCE OF SHOWERS AT TIMES THIS WEEKEND, FOLLOWED  
BY DRY WEATHER EARLY NEXT WEEK.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
1030 AM UPDATE...  
 
TRENDS IN THE FORECAST REMAIN ON TRACK FOR TODAY. HIGH LEVEL  
CLOUDS CONTINUE TO PUSH INTO THE REGION AHEAD OF APPROACHING  
SHORTWAVE. CONTINUE TO WATCH SEA BREEZE DEVELOPMENT WHICH LOOKS  
TO WASHOUT BY BY THE EARLY AFTERNOON. THIS WILL LEAD TO COOLER  
TEMPS AT FIRST THEN WILL WARM UP BY THE LATE AFTERNOON AS WINDS  
SWITCH TO THE SOUTHWEST.  
 
PREVIOUS DISCUSSION...  
 
HIGH PRESSURE ACROSS NY STATE WILL PUSH SE DURING THE DAY, SO  
EXPECT LIGHT W WINDS TO SHIFT TO SW DURING THE AFTERNOON. MAY  
SEE ENOUGH MIXING ACROSS E COASTAL AREAS TO SEE GUSTS UP TO  
AROUND 20 KT THIS AFTERNOON, MAINLY FROM BOSTON NORTH TO CAPE  
ANN.  
 
CLOUDS WILL INCREASE DURING THE AFTERNOON AS MID AND UPPER  
LEVEL MOISTURE STARTS TO APPROACH AHEAD OF THE NEXT SYSTEM.  
 
EXPECT SEASONABLE TEMPS TODAY, UP TO THE LOWER 80S ACROSS NE  
MASS TO THE CT VALLEY, THOUGH ONLY IN THE MID 70S OR SO ALONG S  
COASTAL AREAS WITH THE ONSHORE WIND.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/
 
 
TONIGHT...  
 
00Z MODEL SUITE REMAINS IN PRETTY GOOD AGREEMENT WITH THE  
APPROACH OF LOW PRESSURE OUT OF MIDDLE APPALACHIANS. NOTED THAT  
THE MODELS ARE TRENDING A BIT FURTHER S WITH THE LOW PRES AS THE  
H5 LONG WAVE TROUGH ACROSS THE NE U.S. INTO LABRADOR AND  
NEWFOUNDLAND TENDS TO FLATTEN AT ITS BASE S OF NEW ENGLAND.  
 
THE LOW MOVES OFF THE NJ COAST AROUND 09Z OR SO WITH A RATHER  
SHARP NORTHERN EXTENT OF THE PRECIP SHIELD. LOOKS LIKE THE BEST  
CHANCE FOR SHOWERS WILL OCCUR ACROSS N CT/RI INTO S COASTAL MASS  
WHERE LIKELY POPS ARE IN THE FORECAST. THE HIGHER QPF AMOUNTS  
AREA ALSO SUPPRESSED TO THE S, SO EXPECT MAYBE 0.1 TO 0.2  
INCHES, POSSIBLY A BIT HIGHER ON THE ISLANDS. LOOKS LIKE  
CONDITIONS SHOULD REMAIN MAINLY DRY, BUT CAN'T RULE OUT A FEW  
BRIEF SHOWERS POSSIBLY AS FAR N AS THE MASS PIKE.  
 
THURSDAY...  
 
LEFTOVER SHOWERS ALONG S COASTAL AREAS SHOULD PUSH OFFSHORE BY  
MIDDAY, THOUGH THERE IS SOME TIMING ISSUES AMONGST THE MODEL  
SUITE DURING THIS TIMEFRAME. LEANED TOWARD THE SOMEWHAT FASTER  
GFS/GGEM TIMING. SKIES SHOULD BECOME MOSTLY CLEAR DURING THE  
AFTERNOON, THOUGH A FEW CLOUDS MAY LINGER ACROSS CAPE COD AND  
THE ISLANDS.  
 
IT WILL BE A COOLER DAY ON THURSDAY ALONG THE MASS E COAST AS  
WINDS BECOME E-NE BY AROUND MIDDAY OR EARLY AFTERNOON. TEMPS  
THERE WILL ONLY TOP OFF IN THE MID 60S TO LOWER 70S, COOLEST ON  
THE OUTER CAPE AND NANTUCKET, RANGING TO THE LOWER 80S ACROSS  
THE CT VALLEY.  
 

 
   
LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/
 
 
HIGHLIGHTS...  
 
* DRY AND SEASONABLE ON FRIDAY  
* UNSETTLED WEATHER FOR THIS WEEKEND  
* DRY WEATHER EARLY NEXT WEEK  
 
OVERVIEW...  
 
20/00Z GUIDANCE CONTINUES TO SHOW IMPROVED AGREEMENT IN THE MID  
LEVEL PATTERN FROM EARLIER CYCLES. THIS AGREEMENT STILL BREAKS  
DOWN IN SOME OF THE FINER DETAILS SATURDAY NIGHT INTO SUNDAY,  
BUT NOT TO THE POINT WHERE CONFIDENCE IS LOST IN THE OVERALL  
TRENDS.  
 
HIGH PRESSURE SHOULD MOVE OFFSHORE, OPENING THE DOOR FOR A LOW  
PRESSURE TO MOVE THROUGH THE GREAT LAKES INTO THE SAINT LAWRENCE  
VALLEY. THIS TRAJECTORY WILL FORCE BOTH THE WARM AND COLD FRONTS  
OF THIS SYSTEM ACROSS SOUTHERN NEW ENGLAND SOMETIME THIS  
WEEKEND. AT THIS TIME, EXPECTING AN INCREASING RISK FOR SHOWERS  
LATE FRIDAY NIGHT INTO SATURDAY, PEAKING ABOUT SATURDAY EVENING,  
THEN DIMINISHING INTO SUNDAY. A SECONDARY COLD FRONT SHOULD  
CAUSE SHOWERS TO LINGER LATER SUNDAY. THIS WEEKEND STILL DOESN'T  
LOOK LIKE A WASHOUT. ANOTHER HIGH PRESSURE SHOULD RETURN WITH  
DRY WEATHER EARLY NEXT WEEK.  
 
NOT SEEING ANY MAJOR DEVIATIONS FROM NORMAL TEMPERATURES FOR  
THIS PERIOD. PERHAPS A BIT COOLER THAN NORMAL SATURDAY,  
DEPENDING UPON TIMING OF A WARM FRONT AND AMOUNT OF SUNSHINE.  
 

 
   
AVIATION /14Z WEDNESDAY THROUGH SUNDAY/
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH THURSDAY/... HIGH CONFIDENCE.  
 
TODAY...VFR. SEA BREEZE TO START OUT THIS MORNING, BUT LOOKS TO  
WASHOUT BY THE AFTERNOON. SOUTHWESTERLY WINDS WILL PICK UP BY  
THE EARLY AFTERNOON, GUSTS BETWEEN 15-20 KTS.  
 
TONIGHT...MAINLY VFR. MAY SEE BRIEF MVFR VSBYS IN PATCHY FOG  
ALONG S COASTAL TERMINALS AROUND OR AFTER 04Z. SCATTERED -SHRA  
MOVE FROM W-E THIS EVENING S OF THE MASS PIKE. BEST CHANCE  
ACROSS CENTRAL AND NE CT/RI AND S COASTAL MASS WITH BRIEF LOCAL  
MVFR CIGS. W-SW WINDS GUSTING TO 15-20 KT THIS EVENING ACROSS  
CAPE COD. WINDS SHIFT TO LIGHT W-NW ACROSS THE INTERIOR AFTER  
06Z.  
 
THURSDAY...VFR. ANY LEFTOVER -SHRA ALONG S COASTAL AREAS MOVE  
OFFSHORE BY MID MORNING, THOUGH MAY LINGER UNTIL MIDDAY ACROSS  
CAPE COD AND THE ISLANDS. N-NW WINDS SHIFT TO E-NE BY AROUND  
MIDDAY, WITH SOME GUSTS TO 20 KT ALONG E COASTAL TERMINALS  
POSSIBLE.  
 
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. ONGOING SEA BREEZE LOOKS  
TO WASHOUT BETWEEN 16-19Z.  
 
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.  
 
OUTLOOK /THURSDAY NIGHT THROUGH SUNDAY/...MODERATE CONFIDENCE.  
 
THURSDAY NIGHT THROUGH FRIDAY: VFR.  
 
FRIDAY NIGHT: VFR. SLIGHT CHANCE SHRA.  
 
SATURDAY: MAINLY VFR, WITH AREAS MVFR POSSIBLE. SHRA LIKELY.  
 
SATURDAY NIGHT: MAINLY VFR, WITH LOCAL IFR POSSIBLE. CHANCE  
SHRA, ISOLATED TSRA.  
 
SUNDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. CHANCE SHRA.  
 

 
   
MARINE
 
 
FORECASTER CONFIDENCE LEVELS...  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
SHORT TERM /THROUGH THURSDAY/...HIGH CONFIDENCE.  
 
TODAY AND TONIGHT...LIGHT W WINDS EARLY TODAY SHIFT TO SW, UP  
TO 15-20 KT ON THE EASTERN WATERS LATE TODAY. MAY SEE GUSTS UP  
TO 25 KT LATE THIS AFTERNOON INTO THIS EVENING ON THE EASTERN  
OUTER WATERS, WHERE SEAS MAY BRIEFLY BUILD UP TO 4 FT. SMALL  
CRAFT ADVISORY HAS BEEN ISSUED. WINDS MAY GUST UP TO 20 KT ON  
THE LOWER END OF NARRAGANSETT BAY INTO BUZZARDS BAY WITH LOCALLY  
CHOPPY SEAS THIS AFTERNOON. REDUCED VISIBILITY IN SHOWERS AND  
PATCHY FOG TONIGHT MAINLY ACROSS THE SOUTH COASTAL WATERS.  
 
THURSDAY...N-NW WINDS EARLY THU WILL SHIFT TO E-NE BY MIDDAY  
THU WITH GUSTS UP TO 20 KT POSSIBLE. LEFTOVER REDUCED VISIBILITY  
ALONG S COASTAL WATERS THROUGH MIDDAY THU, THEN IMPROVING.  
 
OUTLOOK /THURSDAY NIGHT THROUGH SUNDAY/...MODERATE CONFIDENCE.  
 
THURSDAY NIGHT THROUGH FRIDAY: WINDS LESS THAN 25 KT.  
 
FRIDAY NIGHT: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING  
5 FT. CHANCE OF RAIN SHOWERS.  
 
SATURDAY: WINDS LESS THAN 25 KT. SEAS LOCALLY APPROACHING 5 FT.  
RAIN SHOWERS LIKELY.  
 
SATURDAY NIGHT: WINDS LESS THAN 25 KT. LOCAL ROUGH SEAS. RAIN  
SHOWERS LIKELY, WITH ISOLATED THUNDERSTORMS.  
 
SUNDAY: WINDS LESS THAN 25 KT. AREAS OF ROUGH SEAS. SLIGHT  
CHANCE OF RAIN SHOWERS.  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...NONE.  
RI...NONE.  
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 10 PM EDT  
THIS EVENING FOR ANZ250.  
 

 
 

 
SYNOPSIS...BELK/EVT  
NEAR TERM...DUNTEN/EVT  
SHORT TERM...EVT  
LONG TERM...BELK  
AVIATION...BELK/EVT  
MARINE...BELK/EVT  
 
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