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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
717 PM EDT MON APR 20 2015

.SYNOPSIS...
A WIND SWEPT SOAKING RAIN IS EXPECTED THROUGH THIS EVENING...WITH 
EVEN A FEW THUNDERSTORMS POSSIBLE TONIGHT. SCATTERED SHOWERS AND 
ISOLATED THUNDERSTORMS ALONG WITH MILD TEMPS TUESDAY MORNING GIVES 
WAY TO A DRYING TREND DURING THE AFTERNOON. A COLD FRONT WILL
BRING SCATTERED SHOWERS AND PERHAPS EVEN AN ISOLATED THUNDERSTORM
OR TWO WEDNESDAY AFTERNOON AND EVENING. UNSEASONABLY COOL WEATHER
FOLLOWS THURSDAY THROUGH THIS WEEKEND WITH JUST A SPOT SHOWER FROM
TIME TO TIME.

&&

.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...

715 PM UPDATE...

NUMEROUS SHOWERS WITH BRIEF HEAVY RAINFALL HAVE BLOSSOMED OVER THE 
LAST HOUR OR SO ACROSS CT/RI AND SOUTHEAST MA.  SHOULD SEE THESE 
SHOWERS WITH LOCALLY HEAVY RAINFALL WORK INTO NORTH CENTRAL AND 
NORTHEAST MA SHORTLY.  WHILE SIGNIFICANT FLOODING IS NOT 
EXPECTED...NUISANCE POOR DRAINAGE STREET FLOODING IN TYPICALLY PRONE 
LOCATIONS WILL LIKELY OCCUR.
 
THESE HEAVIER SHOWERS WERE BLOSSOMING ON THE NOSE OF THE LOW LEVEL 
JET/DRY SLOT ALLOWING FOR INCREASED INSTABILITY.  GIVEN SHOWALTER 
INDICES DROPPING BELOW ZERO AND SOME ELEVATED CAPE...A FEW EMBEDDED 
THUNDERSTORMS ARE POSSIBLE THIS EVENING.  WE PROBABLY WILL SEE A BIT 
OF A LULL IN THE ACTIVITY SOMETIME LATER THIS EVENING UNTIL THE NEXT 
BATCH OF ACTIVITY DEVELOPING ACROSS THE EASTERN GREAT LAKES/MID 
ATLANTIC TRACKS NORTHEAST. WHILE SEVERE WEATHER IS NOT 
EXPECTED...THIS MAY POSE A HIGHER RISK OF SCATTERED THUNDERSTORMS 
WITH HEAVY RAINFALL TOWARD DAYBREAK.  THIS IS DISCUSSED FURTHER IN 
THE NEXT SECTION.

FINALLY...AREAS OF FOG MAY BECOME LOCALLY DENSE.  BEST CHANCE FOR 
THIS WILL BE LATER THIS EVENING WHEN WILL LIKELY SEE A LULL IN THE 
ACTIVITY AND WINDS DIMINISH A BIT.  CONFIDENCE AND AREAL COVERAGE 
NOT HIGH ENOUGH TO ISSUE A DENSE FOG ADVISORY...BUT LATER SHIFTS 
WILL HAVE TO MONITOR. 

&&

.SHORT TERM /MIDNIGHT THROUGH 6 PM TUESDAY/...
OVERNIGHT...THE WARM FRONT WILL MOVE NORTH OVER SOUTHERN NEW ENGLAND 
AND THE SOUTHERN PARTS OF THE AREA LOOK TO WARM SECTOR DURING THE 
EARLY MORNING HOURS.  THIS WOULD INCLUDE RHODE ISLAND...SOUTHEASTERN 
MASSACHUSETTS...AND POSSIBLY PORTIONS OF NORTHERN CONNECTICUT.  THIS 
WILL NOT ONLY BRING TEMPERATURES UP THROUGH THE NIGHT...BUT WILL 
ALSO ALLOW THE ATMOSPHERE TO FURTHER DESTABILIZE.  

K INDICES INCREASE AND SHOWALTER INDICES DECREASE AND ALONG WITH THE 
TOTAL TOTALS IN THE 50S THIS WILL RESULT IN SOME SURFACE BASED 
INSTABILITY ALONG WITH THE ELEVATED INSTABILITY ALREADY IN PLACE.  
THIS WILL PROVIDE A BETTER CHANCE OF THUNDER EARLY TUESDAY MORNING 
AS THE SHORTWAVE AND ATTENDANT COLD FRONT MOVE THROUGH THE REGION.

EXPECT RAPID CLEARING BEHIND THE FRONT WITH TEMPERATURES SOARING 
INTO THE UPPER 60S TO NEAR 70 MOST LOCATIONS.  WESTERLY WINDS WILL 
ALLOW EVEN THE COASTAL LOCATIONS TO GET IN ON THE WARM 
TEMPERATURES...UNLIKE SATURDAY.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
HIGHLIGHTS...

* SCATTERED SHOWERS WED WITH A LOW RISK OF THUNDER/SMALL HAIL
* SEASONABLY MILD TEMPERATURES WED
* UNSEASONABLY COOL THU-SUN WITH A SPOT SHOWER OR TWO AT TIMES

DETAILS...

TUESDAY NIGHT...

A SHORTWAVE WILL BE APPROACHING FROM THE WEST TUE NIGHT.  MODELS DO 
NOT SHOW MUCH QPF AS INSTABILITY IS RATHER LIMITED.  MAY SEE A FEW 
SPOT SHOWERS ESPECIALLY NORTH OF THE MA PIKE...BUT MUCH OF THE 
NIGHT SHOULD FEATURE DRY WEATHER IN A GIVEN LOCATION. 
LOW TEMPS WILL BOTTOM OUT IN THE 30S TO THE LOWER 40S.

WEDNESDAY AND WEDNESDAY NIGHT...

A FAIRLY STRONG SHORTWAVE AND ASSOCIATED COLD FRONT WILL CROSS THE 
REGION WED AFTERNOON AND EVENING.  HIGH TEMPS SHOULD STILL REACH 
INTO INTO THE UPPER 50S TO MIDDLE 60S AHEAD OF THE FRONT.  WE WILL 
SEE SCATTERED SHOWERS WITH THE FRONT GIVEN DECENT FORCING AND SOME 
MARGINAL INSTABILITY.  MOST LIKELY TIME FRAME IS WED AFTERNOON AND 
EARLY EVENING.  ITS QUITE COLD ALOFT AND MID LEVEL LAPSE RATES ARE 
VERY IMPRESSIVE AROUND 8C/KM!  IF WE CAN MUSTER A FEW HUNDRED J/KG 
OF CAPE...MAY EVEN SEE AN EMBEDDED THUNDERSTORM OR TWO.  CONFIDENCE 
ON THUNDER IS LOW AT THIS POINT...BUT GIVEN COLD POOL ALOFT THERE IS 
AT LEAST THIS RISK FOR SOME GRAUPEL/SMALL HAIL AND PERHAPS EVEN 
GUSTY WINDS IN THE HEAVIEST SHOWERS.  THIS ACTIVITY SHOULD WIND DOWN 
BY WED EVENING. 
 

THURSDAY THROUGH MONDAY...

ANOMALOUS CLOSED UPPER LEVEL LOW SETS UP ACROSS NORTHERN NEW ENGLAND 
AND INTO QUEBEC.  THE RESULT WILL BE BELOW NORMAL HEIGHTS AND COOLER 
THAN NORMAL TEMPS IN SOUTHERN NEW ENGLAND.  OVERALL...HIGH TEMPS 
WILL RANGE FROM THE UPPER 40S TO MIDDLE 50S MUCH OF THE TIME BUT 
SOME MODERATION IS POSSIBLE BY MONDAY.  AS FOR PRECIP CHANCES...THE 
VAST MAJORITY OF THE TIME SHOULD FEATURE DRY WEATHER.  
HOWEVER...GIVEN COLD POOL ALOFT A FEW SPOT SHOWERS WILL BE POSSIBLE 
AT TIMES...ESPECIALLY IN NORTHERN SECTIONS DURING THE AFTERNOON 
HOURS.  LOW RISK FOR EVEN A FEW WET SNOW FLAKES TO MIX IN FOR 
A TIME ACROSS THE HIGHER TERRAIN...BUT WOULD BE OF NO IMPACT.

THERE IS ONE FLY IN THE OINTMENT.  WE WILL HAVE TO WATCH A MORE 
SIGNIFICANT LOW PRESSURE SYSTEM SAT NIGHT/SUN.  MOST OF THE MODEL 
GUIDANCE KEEPS THAT SYSTEM WELL TO OUR SOUTH.  THE 12Z ECMWF IS A 
BIT CLOSER THEN THE REST OF THE GUIDANCE...BUT EVEN THAT WOULD KEEP 
US DRY.  AGAIN...ODDS STRONGLY FAVOR KEEPING THIS SYSTEM SOUTH OR 
OUR REGION GIVEN ANOMALOUS CLOSED LOW SITTING JUST TO OUR NORTH.

&&

.AVIATION /23Z MONDAY THROUGH SATURDAY/...
FORECASTER CONFIDENCE LEVELS...

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

.SHORT-TERM /THROUGH TUESDAY/...

TONIGHT...IFR TO LIFR CONDITIONS CONTINUE. NUMEROUS SHOWERS WITH 
HEAVY RAINFALL EXPECTED WITH PERHAPS AN ISOLATED THUNDERSTORM THIS 
EVENING.  LULL IN ACTIVITY LIKELY LATER THIS EVENING...WHERE SOME 
LOCALLY DENSE FOG IS POSSIBLE.  ANOTHER BATCH OF SHOWERS WITH A 
HIGHER RISK OF THUNDER MOVES IN TOWARD DAYBREAK. E/SE-WINDS 
DIMINISHING. LLWS LIKELY TO START.

TUESDAY...CONDITIONS IMPROVING TO VFR BY MIDDAY. COLD FRONT
MOVES THROUGH WITH WINDS SHIFTING W/SW.

KBOS TAF...MODERATE CONFIDENCE. CONCERNED ABOUT A PERIOD OF ONE HALF 
MILE OR LESS VISIBILITY OVERNIGHT BUT TIMING UNCERTAIN.  IT MIGHT 
AFFECT THE MORNING PUSH.  ALSO LOW RISK OF A THUNDERSTORM BETWEEN 8 
AND 12Z.

KBDL TAF...MODERATE CONFIDENCE.  CONCERNED ABOUT A PERIOD OF ONE 
HALF MILE OR LESS VISIBILITY OVERNIGHT BUT TIMING UNCERTAIN.  LOW 
RISK OF AN ISOLATED THUNDERSTORM
 
OUTLOOK...TUESDAY NIGHT THROUGH SATURDAY...

TUE NIGHT...HIGH CONFIDENCE IN MAINLY VFR CONDITIONS DESPITE THE 
RISK FOR A SPOT SHOWER OR TWO.

WED...MODERATE CONFIDENCE.  A COLD FRONT WILL BRING A ROUND OF 
SCATTERED SHOWERS MAINLY WED AFTERNOON/EARLY EVENING.  LOW RISK FOR 
EVEN A FEW RUMBLES OF THUNDER AND PERHAPS SMALL HAIL/GRAUPEL WITH 
THE HEAVIEST SHOWERS.

THU/FRI/SAT...HIGH CONFIDENCE. MAINLY VFR DESPITE THE RISK FOR A 
BRIEF DIURNALLY DRIVEN SHOWER OR TWO.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH TUESDAY/...

HIGH CONFIDENCE.  GALE WARNINGS REMAIN IN PLACE FOR ALL THE WATERS 
OUTSIDE BOSTON HARBOR AND NARRAGANSETT BAY.  THIS IS FOR WIND GUSTS 
UP TO 40 KTS THROUGH THIS EVENING AND INTO THE NIGHT FOR THE OUTER 
WATERS.  FOLLOWING THE EXPIRATION OF THE WARNING...SMALL CRAFT 
ADVISORIES WILL LIKELY BE NEEDED FOR SEAS GREATER THAN 5 FEET...IF 
NOT A FEW LINGERING GUSTS TO 25 KTS. 

RAIN EXPECTED TO CONTINUE WITH STEADY RAIN COMING TO AN END LATE 
THIS EVENING AND TURNING MORE SHOWERY THROUGH MIDDAY TUESDAY.  A FEW 
ISOLATED RUMBLES OF THUNDER ARE POSSIBLE THIS EVENING...WITH A 
BETTER CHANCE EARLY TUESDAY MORNING.  VISIBILITIES MAY BE LIMITED AT 
TIMES.

OUTLOOK...TUESDAY NIGHT THROUGH SATURDAY...

TUESDAY NIGHT AND WEDNESDAY...HIGH CONFIDENCE.  MODEST WEST TO 
SOUTHWEST FLOW EXPECTED AHEAD OF A COLD FRONT...BUT SPEEDS SHOULD 
REMAIN BELOW SMALL CRAFT THRESHOLDS.  A FEW SHOWERS WED AFTERNOON 
AND EVENING WITH A LOW RISK OF AN ISOLATED THUNDERSTORM WITH SMALL 
HAIL.

THURSDAY THROUGH SATURDAY...HIGH CONFIDENCE.  MODEST WESTERLY FLOW AS 
A RESULT OF CLOSED LOW PRESSURE ACROSS QUEBEC.  ENOUGH COLD 
ADVECTION OVER THE WATERS WILL BE PRESENT TO GENERATE PERIODS OF 25 
KNOT WIND GUSTS.  MARGINAL SCA SEAS EXPECTED ACROSS THE OUTER-WATERS 
AT TIMES...BUT WITH GOOD VISIBILITY.

&&

.TIDES/COASTAL FLOODING...
EAST TO SOUTHEAST WINDS WILL INCREASE THROUGH TONIGHT. GUIDANCE
CONTINUES TO TRACK STRONGEST WINDS ACROSS NEW ENGLAND EARLY THIS
EVENING...BEFORE HIGH TIDE OCCURS ALONG THE SOUTH COAST /AROUND
03Z/ AND EAST COAST /ABOUT 06Z/. THIS RESULTS IN WINDS BEGINNING
TO SLACKEN AS HIGH TIDE APPROACHES. ALSO SYSTEM IS FAIRLY
PROGRESSIVE SO DURATION OF ONSHORE WINDS IS LIMITED.
 
ESTOFS CONTINUES TO BE MORE ROBUST AND REALISTIC THAN ETSS WITH 
SURGE VALUES 1.0-1.5 FT AT THE TIME OF HIGH TIDE. SEAS ALSO BUILDING 
TO 10-15 FT JUST OFFSHORE. THIS SHOULD BE SUFFICIENT TO GENERATE 
AREAS OF MINOR COASTAL FLOODING AND SPLASH OVER. THUS WILL CONTINUE 
WITH A COASTAL FLOOD ADVISORY FOR THESE LOCATIONS DURING THIS 
EVENING AND EARLY TUE MORNING HIGH TIDES. 
 
WINDS DO NOT LOOK STRONG ENOUGH AT THE TIME OF HIGH TIDE FOR A 
MODERATE COASTAL FLOOD EVENT.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...COASTAL FLOOD ADVISORY FROM MIDNIGHT TONIGHT TO 4 AM EDT 
     TUESDAY FOR MAZ007-015-016-019-022-024.
     COASTAL FLOOD ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR MAZ020-
     021.
RI...COASTAL FLOOD ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR RIZ002-
     004>007.
MARINE...GALE WARNING UNTIL MIDNIGHT EDT TONIGHT FOR ANZ231>235-237-251.
     SMALL CRAFT ADVISORY UNTIL 4 AM EDT TUESDAY FOR ANZ230-236.
     GALE WARNING UNTIL 4 AM EDT TUESDAY FOR ANZ250-254>256.

&&

$$ 
SYNOPSIS...RLG/FRANK 
NEAR TERM...FRANK 
SHORT TERM...RLG 
LONG TERM...FRANK 
AVIATION...FRANK/RLG 
MARINE...RLG/FRANK
TIDES/COASTAL FLOODING...STAFF

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