Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 080816
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
416 AM EDT TUE JUL 8 2014

.SYNOPSIS...
VERY WARM/HOT AND HUMID WEATHER WILL PERSIST THROUGH MID WEEK.
WHILE MUCH OF THE TIME WILL BE DRY...A FEW STRONG HIT AND MISS
THUNDERSTORMS WILL BE POSSIBLE AT TIMES ESPECIALLY ACROSS THE
INTERIOR. SHOWERS OR AN ISOLATED THUNDERSTORM ARE POSSIBLY MAINLY
NEAR THE SOUTH COAST ON THURSDAY. DRY WEATHER WITH LOWER HUMIDITY
WILL ARRIVE BY THE END OF THE WEEK INTO THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
430AM UPDATE....

FORECAST TRENDS REMAINS ON TRACK EARLY THIS MORNING. UPPER LEVEL
SHORTWAVE WHICH TRIGGERED THE SHOWERS AND THUNDERSTORMS OVERNIGHT HAS
MOVED WELL OFFSHORE. THIS HAS ALLOWED FOR THE RADAR TO FINALLY CALM
DOWN WITH JUST A FEW SHOWERS MOVING ACROSS RI AND SOUTHEAST MA.
EXPECT THESE SHOWERS TO MOVE OFFSHORE BEFORE DAWN ALLOWING FOR A
QUIET START TO THE MORNING. DEWPOINTS ARE IN THE MID TO UPPER 60S
ALLOWING FOR MUGGY AIR TO CONTINUE INTO THE EARLY MORNING HOURS.
SOME PATCHY FOG HAS DEVELOPED IN VERY LOCALIZED AREAS BUT DO NOT
BELIEVE THAT DENSE FOG WILL FORM.

TODAY...

UPPER LEVEL TROUGH WILL CONTINUE TO SET-UP ACROSS THE NORTHERN U.S.
TODAY AND INTO TOMORROW. TODAYS FOCUS IS ONCE AGAIN ON THE POTENTIAL
FOR SHOWERS AND THUNDERSTORMS...WHICH COULD BE STRONG TO SEVERE.
HOWEVER THERE ARE A LOT OF PARAMETERS THAT NEED TO LINE UP FOR THIS
TO OCCUR SO OVERALL HAVE A MODERATE CONFIDENCE ON THE FORECAST.

DURING THE DAY...EXPECT HIGH TEMPS TO WARM WELL INTO THE UPPER 80S
TO LOW 90S. ANTICIPATE SLIGHTLY COOLER TEMPS ACROSS THE SOUTH COAST
THANKS TO SW FLOW PUSHING COOLER MARITIMES AIR ON LAND. DEWPOINTS AS
WELL WILL INCREASE INTO THE UPPER 60S INTO LOW 70S KEEPING THE MUGGY
AIR AROUND.

INSTABILITY WILL INCREASE DURING THE DAY TO ABOVE 2000 J/KG WITH 0-
3KM BULK SHEAR VALUES BETWEEN 35-40 KTS. THIS IS SIGNIFICANTLY MORE
SHEAR THEN YESTERDAY. THE ATMOSPHERE SHOULD BE PRIMED TODAY FOR THE
POTENTIAL FOR THUNDERSTORMS BUT THE UNCERTAINTY IS ON THE TRIGGER
POTENTIAL. BELIEVE A FEW ISOLATED SHOWERS MAY DEVELOP LATE THIS
AFTERNOON WHETHER IT IS FROM OROGRAPHIC LIFT OR REACHING THE
CONVECTIVE TEMP. COVERAGE COULD INCREASE CLOSER TO 00Z AS AN UPPER
LEVEL SHORTWAVE WILL MOVE OVER THE REGION AROUND 00Z-06Z. THERE IS
THE POTENTIAL FOR STRONG TO PERHAPS A FEW SEVERE THUNDERSTORMS WITH
STRONG GUSTY WINDS BEING THE MAIN THREAT. BEST REGION FOR THIS TO
OCCUR IS NORTH AND WEST THE BOS TO PVD LINE. PWAT VALUES INCREASE
CLOSER TO 1.5-2 INCHES THROUGH THE EVENING HOURS LEADING TO HEAVY
RAINFALL AND THE POSSIBILITY OF LOCALIZED FLOODING.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
TONIGHT...

UPPER LEVEL SHORTWAVE WILL MOVE ACROSS THE REGION TONIGHT. BELIEVE
ANY CONVECTION THAT IS ONGOING WILL CONTINUE AS SHORTWAVE WILL KEEP
THE CONVECTION POTENTIAL ALIVE. GUIDANCES INDICATES THAT INSTABILITY
AND EVEN SHEAR VALUES INCREASE SLIGHTLY OVERNIGHT ALLOWING FOR AN
INCREASE IN CONFIDENCE THAT THE POTENTIAL FOR STRONG STORMS MAY
OCCUR. LLJ WILL ALSO INCREASING ALLOWING FOR ANY CONVECTION TO
DEVELOP OR CONTINUE INTO THE OVERNIGHT HOURS. PWAT VALUES DO
INCREASE CLOSER TO 2 INCHES SO ANY STRONG THUNDERSTORMS MAY RESULT
IN LOCALIZE FLOODING.

TOMORROW...

UPPER LEVEL TROUGH WILL CONTINUE TO SPIN OVER THE REGION...BUT WILL
BEGIN TO PUSH OUT OF THE REGION BY THE EVENING HOURS. THIS TROUGH
WILL ROUND A STRONG SHORTWAVE PUSHING A SLOW MOVING COLD FRONT
ACROSS THE REGION. SINCE THE AIRMASS WILL STILL BE WARM AND MUGGY
ANTICIPATE ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WITH THE
POTENTIAL FOR STRONG THUNDERSTORMS TO OCCUR. INSTABILITY VALUES WILL
INCREASE TO 2000 J/KG AND 0-3 KM BULK SHEAR VALUES ARE STILL 25-30
KTS. RIGHT ENTRANCE REGION OF THE JET STREAK WILL ALSO SET UP OVER
THE REGION INCREASING THE LIFT EVEN MORE. ONLY CAVEAT IS THE LACK OF
DEEP LAYER MOISTURE AS DRY AIR DOES MOVE INTO THE REGION. RIGHT NOW
BELIEVE THAT LOCATION SOUTH AND EAST OF A MHT-ORH-BDL LINE HAS THE
BEST CHANCE FOR STRONG TO MAYBE SEVERE WEATHER ON WEDNESDAY. PWAT
VALUES WILL STILL BE HIGH...CLOSE TO 2 INCHES SO HEAVY DOWNPOURS ARE
A MAIN THREAT AS WELL AS GUSTY WINDS AND SMALL HAIL.

&&

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

* A FEW THUNDERSTORMS POSSIBLE WED NIGHT INTO THU
* DRIER AND LESS HUMID AIR RETURNS BY THE END OF THE WEEK

OVERVIEW AND MODEL PREFERENCES...
OVERALL...BOTH OPERATIONAL AND ENSEMBLE MODELS ARE IN FAIR
AGREEMENT THROUGH THE LONG TERM. LONGWAVE TROF WILL BE LIFTING
THROUGH NEW ENGLAND THROUGH THE...AS THE SFC REFLECTION...A COLD
FRONT SLIDES FURTHER OFFSHORE. THE UPPER PATTERN SHIFT FORCES A
ZONAL FLOW ACROSS THE REGION...ALLOWING DRIER AND MORE SEASONAL
AIRMASS TO MOVE INTO PLACE. THEN YET ANOTHER DEEP CUTOFF TRIES TO
DEVELOP THANKS TO SHORTWAVE ENERGY DIVING S FROM N CENTRAL CANADA.
WHILE THERE IS SOME DISAGREEMENT ON WHERE THE CORE OF THIS CUTOFF
ULTIMATELY RESIDES BY THE TIME IT SETTLES NEXT WEEK...THEY ARE ALL
IN AGREEMENT THAT THIS CUTOFF WILL FORM TO OUR W. THEREFORE...WILL
LIKELY SEE ANOTHER ROUND OF SW FLOW AND POTENTIAL FOR UNSETTLED
AND WET CONDITIONS BY NEXT WEEK. GIVEN THE AGREEMENT...ANOTHER
BLEND OF GUIDANCE WILL BE USED AS BASELINE.

DETAILS...

WED NIGHT INTO THU...
CURRENT TIMING OF THE FINAL COLD FRONT HAS IT SLIDING ACROSS SRN
NEW ENGLAND SLOWLY...MAINLY BETWEEN 00Z AND 12Z THU. AHEAD OF THE
FRONT...HIGH DWPTS IN THE UPPER 60S TO AROUND 70 STILL SUPPORT
500-800J/KG OF ML CAPE COINCIDENT WITH REMAINING 40 KT OF 0-6KM
SHEAR. THEREFORE...NOT OUT OF THE QUESTION THAT SOME CONVECTIVE
ACTIVITY MAY CONTINUE INTO THE OVERNIGHT HOURS ESPECIALLY S OF THE
MASS PIKE AND ALONG THE WATERS. HIGH SHEAR MAY PROMOTE GUSTY WINDS
OR HAIL AS WELL. THE MAIN FLY IN THE OINTMENT IS DRYING IN THE MID
LVLS WHICH MAY PRECLUDE CONVECTION SOMEWHAT...SO FOR NOW MOST POPS
ARE CHANCE OR BELOW. THE KEY MAY BE ANYTHING THAT FORMS DURING THE
AFTERNOON/EVENING WED WHICH WOULD BE WITHIN A MOIST COLUMN AND IS
HELD TOGETHER BY THE SHEAR.

BY THU...THE THREAT FOR SHOWERS OR AN ISOLATED STORM MAY LINGER
UNTIL THE FRONT IS ABLE TO PUSH FURTHER OFFSHORE. THEREFORE...HAVE
GRADUALLY LOWERING POPS THROUGH THE DAY. STILL WARM ON THU LIKELY
AS THE MID LVL TEMPS ARE LIKELY TO BE SLOW TO CHANGE. SO WILL
CONTINUE WITH HIGHS ABOVE NORMAL.

FRI AND SAT...
HIGH PRES MOVES IN FROM THE W AS W-E ZONAL FLOW DEVELOPS ALOFT.
THIS NW FLOW WILL ALLOW THE PERSISTENT HUMIDITY EARLY THIS WEEK TO
FINALLY BREAK WITH DWPTS BEING ALLOWED TO FALL INTO THE LOW-MID
50S. H85 TEMPS EACH DAY RANGE AROUND +12 TO +14C...WHICH SUGGEST
HIGHS NEAR SEASONAL NORMALS OR IN THE LOW-MID 80S.

SUN INTO MON...
A GRADUALLY DEVELOPING CUTOFF TO THE W WILL YIELD INCREASING
RETURN FLOW THROUGH THE PERIOD. THEREFORE...EXPECT INCREASING
HUMIDITY AND COLUMN MOISTURE THROUGH THE PERIOD...AS WELL AS
WARMER TEMPERATURES. ENSEMBLES SUGGEST THAT BY MON...PWATS MAY
APPROACH 2 STD DEVIATIONS FROM NORMAL. ALTHOUGH THERE ARE SOME
DISAGREEMENTS ON EXACTLY HOW IT TURNS OUT. BY SUN...WARM FRONT
WILL MOVE INTO NRN NEW ENGLAND YIELDING THE POSSIBILITY OF SHOWERS
OR POSSIBLY AN ISOLATED RUMBLE OF THUNDER. THE HIGHER THREAT LOOKS
TO BE MON INTO TUE...AS ANOTHER SLOW MOVING COLD FRONT APPROACHES
FROM THE W...IN WHAT COULD BE A MOISTURE RICH AND POTENTIALLY
UNSTABLE AIRMASS.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH WEDNESDAY/...

BEFORE 12Z...HIGH CONFIDENCE...VFR CONDITIONS SHOULD CONTINUE ACROSS
A GOOD PORTION OF THE AREA. A FEW SITES HAVE LOWERED TO MVFR/IFR FOR
VSBYS DUE TO LOCALIZED PATCHY FOG.

TODAY AND INTO TONIGHT...MODERATE CONFIDENCE.  VFR CONDITIONS WILL
DOMINATE...BUT PERHAPS A BETTER CHANCE OF LOW CLOUDS AND FOG
DEVELOPING ALONG THE SOUTHEAST NEW ENGLAND COAST TONIGHT.  IN
ADDITION...A FEW AFTERNOON AND EVENING STRONG THUNDERSTORMS ARE
POSSIBLE WITH THE BEST SHOT NORTHWEST OF A BOS TO PVD LINE.

WEDNESDAY...MODERATE CONFIDENCE. VFR CONDITIONS ESPECIALLY NORTH AND
WEST OF A MHT-ORH-BDL LINE. SOUTH AND EST OF THE LINE...EXPECT VFR
CONDITIONS WITH LOCALIZED MVFR ON SHOWERS AND THUNDERSTORMS.

KBOS TAF...MODERATE CONFIDENCE IN TAF.

KBDL TAF...MODERATE CONFIDENCE IN TAF.

OUTLOOK...WEDNESDAY THROUGH SATURDAY...

WED NIGHT INTO THU...MODERATE CONFIDENCE.
MAINLY VFR. SHOWERS OR AN ISOLATED THUNDERSTORM POSSIBLE MAINLY
NEAR THE S COAST WITH BRIEF MVFR/IFR CONDITIONS. ALL VFR EXPECTED
BY LATE IN THE DAY THU.

FRI INTO SAT...HIGH CONFIDENCE.
MAINLY VFR.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH WEDNESDAY/...HIGH CONFIDENCE.

PERSISTENT SOUTHWEST FLOW WILL CONTINUE TONIGHT AHEAD OF A SLOW
MOVING COLD FRONT. WINDS MAY GENERALLY BE 15-20 KTS BUT ACROSS THE
NEAR SHORE WATERS OF THE CAPE AND BUZZARD BAY MAY SEE 25KTS SO HAVE
ISSUED A SCA.  OTHERWISE SCA CONTINUES FOR OUTER WATERS FROM THE
LONG SOUTHWEST FETCH RESULTING IN 4 TO 7 FOOT SEAS.

OTHERWISE...MAY SEE AREAS OF FOG DEVELOP TONIGHT WHICH COULD BE
LOCALLY DENSE ACROSS THE SOUTHERN WATERS. IN ADDITION...LOW TO
MODERATE PROBABILITY FOR A FEW STRONG THUNDERSTORMS TO MOVE ACROSS
THE NEAR SHORE WATERS THIS EVENING AND TONIGHT AND AGAIN ON
WEDNESDAY.

OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY.

WEDNESDAY NIGHT INTO THURSDAY...MODERATE CONFIDENCE.
A COLD FRONT WILL BE MOVING OFF THE SRN WATERS WED NIGHT. THIS
MEANS SHOWERS AND AN ISOLATED THUNDERSTORM IS POSSIBLE THROUGH
ABOUT MID DAY THU. OTHERWISE...SEAS WILL GRADUALLY BE DECLINING
THROUGH THE PERIOD FROM ABOUT 5-6 FT ON THE OCEAN WATERS.
THEREFORE...OUTSIDE OF ANY STORMS...SMALL CRAFT ADVISORIES ARE
LIKELY TO BE COMING DOWN INTO EARLY THU.

FRI AND SAT...HIGH CONFIDENCE.
MAINLY QUIET BOATING WEATHER WITH HIGH PRESSURE. WINDS AND SEAS
BELOW SMALL CRAFT THRESHOLDS.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 11 AM EDT
     WEDNESDAY FOR ANZ231>234.
     SMALL CRAFT ADVISORY UNTIL 9 PM EDT WEDNESDAY FOR ANZ235-237-
     254>256.

&&

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



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