Area Forecast Discussion
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FXUS61 KBOX 210239
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
1039 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/...
1030 PM UPDATE...

NO MAJOR CHANGES TO ONGOING FORECAST THIS EVENING. DID TWEAK THE
NEXT SEVERAL HOURS TO REFLECT THE LATEST OBSERVED TRENDS.

THE MAIN CONCERN OVERNIGHT REMAINS THE POTENTIAL FOR CONVECTION.
LATEST RUNS OF THE HRRR REMAIN BULLISH ON PRE-DAWN THUNDERSTORM
POTENTIAL ACROSS RI AND SOUTHEAST MA...INCLUDING THE CAPE AND
ISLANDS. WILL NEED TO CONTINUE TO MONITOR PROGRESS OF THUNDERSTORM
CLUSTER OVER PA/NY THIS EVENING...SINCE THIS IS WHERE THE ENERGY
WILL COME FROM. NOT EXPECTING SEVERE WEATHER AT THIS TIME. HEAVY
RAINFALL IS NOT OUT OF THE QUESTION THOUGH. DEPENDING ON WHERE
THIS HAPPENS...AND HOW FAST...WE COULD SEE SOME FLOODING ISSUES
LATE TONIGHT. MAINLY EXPECTING NUISANCE FLOODING...BUT COULD BE
MORE IF THE HEAVY RAINFALL OCCURS WITHIN SOME URBAN AREAS...SUCH
AS FALL RIVER AND NEW BEDFORD.

PREVIOUS DISCUSSION...

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 /02Z TUESDAY 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. LULL FROM RAINFALL LIKELY SHORTLY AFTER
MIDNIGHT...WHERE SOME LOCALLY DENSE FOG IS POSSIBLE. ANOTHER
BATCH OF SHOWERS WITH A HIGHER RISK OF THUNDERSTORMS MOVES IN
TOWARD DAYBREAK. E/SE-WINDS DIMINISHING. LLWS LIKELY INTO EARLY
TUESDAY MORNING.

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. CURRENT PLAN IS TO
REPLACE SOME OF THE GALE WARNINGS WITH SMALL CRAFT ADVISORIES
TOWARD MIDNIGHT...WHICH IS RIGHT ON SCHEDULE WITH PREVIOUS
FORECAST. THIS IS FOR WIND GUSTS UP TO 35 KTS THROUGH THIS
EVENING AND INTO THE NIGHT FOR THE OUTER WATERS.

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 UNTIL 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...FRANK/RLG
NEAR TERM...BELK/FRANK
SHORT TERM...RLG
LONG TERM...FRANK
AVIATION...BELK/FRANK/RLG
MARINE...BELK/FRANK/RLG
TIDES/COASTAL FLOODING...



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