Area Forecast Discussion
Issued by NWS Boston, MA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KBOX 200819
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
419 AM EDT MON OCT 20 2014

.SYNOPSIS...
HIGH PRESSURE WILL SLIDE TO THE SOUTH OF THE REGION TODAY KEEPING
THE WEATHER QUIET. A LONG DURATION COASTAL STORM WILL BRING
PERIODS OF RAIN TUESDAY THROUGH THURSDAY WITH LINGERING SHOWERS
FRIDAY AS THE STORM SLOWLY PULLS AWAY FROM NEW ENGLAND. DRY AND
MILD WEATHER IS EXPECTED NEXT WEEKEND.

&&

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

4 AM UPDATE...

THICK CIRRUS HAS MOVED OVER THE REGION AS OF 400 AM. THIS HAS
LIMITED SOME RADIATIONAL COOLING ACROSS THE INTERIOR ESP ACROSS
NORTHEASTERN MASS. THESE CLOUDS WILL QUICKLY FILTER IN AND OUT OF
THE REGION ALLOWING FOR TEMPS TO DROP..AS NOTICED ACROSS CT. PLUS
WITH  HIGH PRESSURE MOVING OVERHEAD...WINDS WILL DECOUPLE AND
TEMPERATURES WILL DROP VERY QUICKLY. SEVERAL SITES ACROSS WINDHAM
AND TOLLAND COUNTIES IN CT HAVE DROPPED BELOW 32F. WHERE MANY OTHER
SITES ARE AT OR NEAR FREEZING SO WILL CONTINUE TO FROST/FREEZE
HEADLINES FOR THIS MORNING AS TEMPS MAY DROP ANOTHER COUPLE DEGREES
BETWEEN NOW AND DAWN.

TODAY...

WEAK RIDGING IN THE MID-LEVELS WILL MOVE OVER THE REGION WHILE AT
THE SURFACE HIGH PRESSURE PASSES TO THE SOUTH. THIS ALLOWS FOR QUIET
WEATHER AND TEMPS TO MODERATE CLOSE TO AVERAGE.  BUFKIT SOUNDINGS
SHOW MIXING WILL REACH ABOVE 900 MB RESULTING IN SOUTHWEST WINDS TO
INCREASE NEAR 15 MPH DURING PEAK HEATING. OTHERWISE A MIX OF SUN AND
CLOUDS IS EXPECTED THROUGHOUT THE DAY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...

TONIGHT AND TOMORROW...

LOW PRESSURE SYSTEM WILL BEGIN TO DEVELOP ACROSS THE GREAT LAKES
OVERNIGHT. THIS PUTS THE REGION IN MORE OF A SOUTHWEST FLOW AND
BEGIN TO MOISTEN THE COLUMN. ANTICIPATE CLOUDS TO BE ON THE INCREASE
OVERNIGHT LIMITING THE POTENTIAL FOR RADIATIONAL COOLING. THEREFORE
KEPT TEMPS IN THE LOW TO MID 40S...WARMER ALONG THE SOUTH COAST
THANKS TO THE SW FLOW.

SW LLJ WILL BEGIN TO INCREASE CLOSER TO DAYBREAK AND WITHIN THE SW
WAA FLOW...SHOWERS WILL DEVELOP IN THE MORNING HOURS. THE BEST SHOT
WILL BE ACROSS THE CAPE AND ISLANDS AND PERHAPS THE COASTAL
PLAIN...ALIGN WITH THE LOCATION OF THE LLJ. THERE IS A SLIGHT CHANCE
FOR SOME THUNDER OVER THE SOUTHEASTERN WATERS AND EVEN THE CAPE AND
ISLANDS ON TUESDAY WITH CAPE VALUES NEAR 500 J/KG COMBINED WITH
STEEP LAPSE RATES AND LI VALUES BELOW 0. BECAUSE OF THIS AND THE
INCREASING LLJ HAVE INSERTED ISO THUNDER INTO THE FORECAST.

UPPER LEVEL LOW WILL BECOME CUTOFF OVER THE EASTERN GREAT LAKES
DURING THE DAY...AND WILL DOMINATE THE REGION FOR THE REMAINDER OF
THE WEEK. ALTHOUGH THE MAIN SHORTWAVE/LIFT WILL BE AWAY FROM THE
REGION...THERE IS STILL THE POTENTIAL FOR A FEW SHOWERS TO DEVELOP
ACROSS THE WESTERN ZONES. RIGHT NOW HAVE THE HIGHER CONFIDENCE THAT
THE CAPE AND THE ISLANDS WILL SEE THE BEST CHANCE FOR RAINFALL ON
TUESDAY.

BECAUSE OF THE RETURN FLOW AND THAT SOUTHERN NEW ENGLAND IS IN WARM
AIR ADVECTION SIDE OF THE SYSTEM...TEMPS WILL WARM INTO THE UPPER
50S TO MID 60S.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...

HIGHLIGHTS...

* PERIODS OF RAIN OF VARYING INTENSITY EXPECTED THROUGH THU AS A
  COASTAL STORM STALLS SOUTH OF NEW ENG
* LINGERING SHOWERS FRIDAY BUT SLOWLY IMPROVING CONDITIONS
* MAINLY DRY AND MILD WEATHER NEXT WEEKEND

OVERVIEW...
GUIDANCE IN EXCELLENT AGREEMENT ON EVOLUTION OF THE COASTAL STORM
THAT DEVELOPS OFF THE MID ATLC COAST TUE NIGHT BEFORE FINALLY
PULLING AWAY FROM NEW ENG FRI/FRI NIGHT. TIGHT CLUSTERING AMONG THE
MODELS ON THE TRACK OF THE STORM WHICH STALLS S OF NEW ENG FOR A
TIME AS IT GETS CAPTURED UNDER THE MID LEVEL CIRCULATION.  DESPITE
THE GOOD AGREEMENT ON THE MASS FIELDS THERE ARE DIFFERENCES IN THE
TIMING AND PLACEMENT OF QPF DURING THE PERIOD. SO WHILE CONFIDENCE
IS HIGH THAT PERIODS OF RAIN WILL AFFECT THE REGION THROUGH AT LEAST
THU...THERE IS STILL UNCERTAINTY ON WHERE/WHEN HEAVIEST RAIN WILL
FALL. STRONG WINDS AND COASTAL FLOODING WILL NOT LIKELY BE
SIGNIFICANT FACTOR IN SNE AS CORE OF LOW LEVEL JET EXPECTED TO
REMAIN TO THE NORTH.  USED A BLEND OF AVAILABLE GUIDANCE FOR
POPS/QPF TO ACCOUNT FOR MODEL VARIATION IN THESE FIELDS.

DAILIES...

TUESDAY NIGHT THROUGH THURSDAY...
WHILE WE EXPECT PERIODS OF RAIN TO AFFECT SNE DURING THIS
TIME...CONFIDENCE IS BELOW AVERAGE ON EXACT TIMING AND LOCATION OF
HEAVIER RAINFALL.  MODELS ARE SIGNALING A POSSIBLE DRY SLOT MOVING
UP FROM THE SOUTH TUE NIGHT INTO EARLY WED WHICH MAY RESULT IN
LIGHTER PRECIP DURING THIS TIME. HEAVIEST RAIN MAY BE DURING WED
NIGHT THU AS MID LEVEL LOW LIFTS N INTO REGION WITH INCREASING QG
FORCING AND POTENTIAL FOR MORE CONVECTION ASSOCD WITH COOLING TEMPS
ALOFT.  USING A BLEND OF AVAILABLE GUIDANCE YIELDS RAINFALL OF 1-3
INCHES WITH HIGHEST AMOUNTS ACROSS NE MA INTO S NH.  WINDS DO NOT
APPEAR TO BE A SIGNIFICANT FACTOR FOR SNE AS CORE OF LOW LEVEL JET
WILL REMAIN TO THE NORTH. A PERIOD OF GUSTY NE WINDS COULD AFFECT
COASTAL NE MA LATE TUE NIGHT/WED BUT CONFIDENCE IS LOW.

WITH STRONGEST WINDS LIKELY N OF THE REGION...THE THREAT FOR COASTAL
FLOODING REMAINS LOW AS SEAS AND STORM SURGE WILL NOT LIKELY BE HIGH
ENOUGH TO CAUSE PROBLEMS.  HOWEVER...THE RISK CONTINUES FOR COASTAL
BEACH EROSION WITH WAVE ACTION OVER SEVERAL HIGH TIDE CYCLES.

FRIDAY...
COASTAL STORM WILL BE EAST OF CAPE COD BY FRI MORNING AND SLOWLY
LIFTING N TOWARD NOVA SCOTIA DURING THE DAY.  WHILE CONDITIONS
SHOULD BE IMPROVING...SCT SHOWERS WILL LIKELY CONTINUE UNDER
LINGERING COLD POOL ALOFT WITH MID LEVEL LOW JUST E OF THE REGION.

SAT AND SUN...
LOOKS MAINLY DRY NEXT WEEKEND. COLD FRONTAL PASSAGE SOMETIME LATE
SAT/SAT NIGHT COULD BRING A FEW SHOWERS. SAT WILL  LIKELY BE THE
MILDEST DAY OF THE WEEKEND WITH MAXES WELL INTO THE 60S...THEN
COOLER SUN BEHIND THE COLD FRONT.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH MONDAY/...HIGH CONFIDENCE.

BEFORE 12Z...VFR. HIGH LEVEL CIRRUS WITH LIGHT WINDS.

AFTER 12Z...VFR. LIGHT WINDS BACKING TO SW. THIN CLOUDS CONTINUE
THROUGH THE DAY.

TONIGHT AND TOMORROW...VFR MOST OF THE NIGHT. PATCHES OF MVFR
CIGS MOVING NEAR DAY BREAK ACROSS CAPE/ISLAND IN LIGHT RAIN. MVFR
CIGS MAY SPREAD NORTH AND EAST THROUGH THE DAY ON TUESDAY IN
RAIN. LOW CHANCE OF AN ISO THUNDER ACROSS CAPE/ISLAND.

KBOS...HIGH CONFIDENCE IN TAF.

KBDL...HIGH CONFIDENCE IN TAF.

OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY...

TUESDAY NIGHT THROUGH THURSDAY...HIGH CONFIDENCE OVERALL WITH AREAS
OF MVFR/IFR AND PERIODS OF RAIN OF VARYING INTENSITY...BUT LOW
CONFIDENCE ON DETAILS. LOW PROB OF NE WIND GUSTS TO 25 KT ACROSS NE
MA COAST LATE TUE NIGHT/WED.

FRIDAY...MODERATE CONFIDENCE. A MIX OF MVFR/VFR WITH SCT SHOWERS.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /TODAY THROUGH TUESDAY/...HIGH CONFIDENCE.

TODAY...
HIGH PRESSURE BUILDS OVER THE WATERS ALLOWING FOR THE WINDS TO
SLOWLY DIMINISH. WESTERLY WINDS WILL SWITCH TO THE SOUTHWEST BY
THE AFTERNOON. SEAS WILL LINGERING AROUND 5 FEET DURING THE
THE AFTERNOON SO HAVE EXPANDED SCA ACCORDINGLY. WOULD NOT BE
SURPRISED IF IT IS CANCELLED EARLIER.

TONIGHT... HIGH PRESSURE MOVES OFFSHORE. SOUTHWEST WINDS WILL REMAIN
BELOW 25 KTS AND SEAS WILL REMAIN BELOW 5 FEET. LIGHT RAIN MOVES
UP FROM THE MID ATLANTIC COAST LATE AT NIGHT.

TOMORROW...SOUTHWEST FLOW WILL ALLOWING RAIN SHOWERS TO MOVE
ACROSS THE SOUTHEASTERN WATERS. CONDITIONS WILL REMAIN BELOW SCA
BUT THERE IS A LOW PROB FOR AN ISO THUNDERSTORM DURING THE DAY.

OUTLOOK...TUESDAY THROUGH FRIDAY...

TUE NIGHT AND WED...WINDS GENERALLY BELOW SCA...BUT A PERIOD OF NE
WIND GUSTS TO 25-30 KT POSSIBLE OVER NE MA COASTAL WATERS ALTHOUGH
CONFIDENCE IS LOW. LOW PROB WINDS COULD REACH GALE FORCE OVER WATERS
EAST OF CAPE ANN. HIGHEST SEAS 6-9 FT LATE TUE NIGHT/WED OVER NE MA
COASTAL WATERS.

WED NIGHT AND THU...MODERATE CONFIDENCE.  EASTERLY WINDS MAINLY
BELOW SCA WITH LOW PROB OF SCA NE GUSTS OVER NE MA COASTAL WATERS.
HIGHEST SEAS 6-8 FT REMAIN OVER NE MA COASTAL WATERS.

FRI...MAINLY NW WIND GUSTS TO 20 KT WITH LOW PROB REACHING 25 KT.
SCA SEAS OVER EASTERN MA COASTAL WATERS.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR CTZ002>004.
MA...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR MAZ007-015-016-
     019-022-023.
     FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR MAZ005-006-
     009>014-017-018-020-021.
NH...NONE.
RI...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR RIZ002-004-005-
     007.
     FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR RIZ001-003-006.
MARINE...SMALL CRAFT ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR
     ANZ231>234-251.
     SMALL CRAFT ADVISORY UNTIL 3 PM EDT THIS AFTERNOON FOR ANZ250-
     254>256.

&&

$$
SYNOPSIS...KJC/DUNTEN
NEAR TERM...DUNTEN
SHORT TERM...DUNTEN
LONG TERM...KJC
AVIATION...KJC/DUNTEN
MARINE...KJC/DUNTEN


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.