Area Forecast Discussion
Issued by NWS Boston, MA

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 170153
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
953 PM EDT SAT AUG 16 2014

.SYNOPSIS...
A WARM FRONT WILL BRING A ROUND OF SCATTERED SHOWERS TO THE AREA
TONIGHT. ASSOCIATED COLD FRONT SWEEPS ACROSS THE REGION SUNDAY
MORNING AND EARLY AFTERNOON WITH ANOTHER ROUND OF SHOWERS AND
POSSIBLY A THUNDERSTORM. HIGH PRES ARRIVES MON WITH DRY BUT COOL
CONDITIONS. UNSETTLED WEATHER MAY RETURN TUE AND WED OF NEXT
WEEK OR MAY STAY SOUTH OF NEW ENGLAND.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...

10 PM UPDATE...

PREVIOUS FORECAST MATCHING UP NICELY WITH CURRENT RADAR AND
SATELLITE TRENDS. THUS LITTLE IF ANY CHANGE WITH THIS FORECAST
UPDATE. STRONG SHORT WAVE TROUGH AND ASSOCIATED JET STREAK
APPROACHING WESTERN NY STATE LATE THIS EVENING. THESE STRONG JET
DYNAMICS MOVE OVER SOUTHERN NEW ENGLAND 06Z-12Z. HOWEVER AS THE
00Z ALY SOUNDING REVEALS PREFRONTAL ENVIRONMENT IS FAIRLY DRY.
THUS SOME OF THE UPSTREAM ACTIVITY WILL WEAKEN/ERODE AS IT
INTERACTS WITH THIS DOWNSTREAM DRY AIR. NEVERTHELESS SCATTERED
SHOWERS AFTER MIDNIGHT AND ESPECIALLY TOWARD DAYBREAK FROM WEST
TO EAST.

OTHER AREA TO WATCH IS CONVECTION BEGINNING FIRE WELL SOUTH OF NEW
ENGLAND. HIGH THETA-E/MOISTURE AND CAPE ACROSS THIS REGION. AS MID
LEVEL TROUGH APPROACHES NEW ENGLAND IT MAY BE ABLE TO
CAPTURE/ADVECT THIS AREA OF INSTABILITY/MOISTURE NORTHWARD TOWARD
THE CAPE AND ISLANDS. THIS MAY RESULT IN SOME EMBEDDED THUNDER
ACROSS THIS AREA TOWARD MORNING. PREVIOUS FORECAST CAPTURES THIS
WELL SO AGAIN NOT MANY CHANGES PLANNED WITH THIS FORECAST UPDATE.
EARLIER DISCUSSION BELOW.
=================================================================
PREVIOUS DISCUSSION...
DRY WEATHER CONTINUES THROUGH THIS EVENING. MOISTURE INCREASES ON
SOUTHWESTERLY WINDS KEEPING OVERNIGHT TEMPERATURES A BIT WARMER
THAN THE PAST FEW NIGHTS. LOW PRESSURE IN ONTARIO THIS AFTERNOON
WILL MOVE EASTWARD INTO NORTHERN NEW ENGLAND TONIGHT. A STRONG
SHORTWAVE APPROACHING SOUTHERN NEW ENGLAND WILL PROVIDE ENOUGH
LIFT FOR SHOWERS TO DEVELOP FROM NORTHWEST TO SOUTHEAST. IN
ADDITION...AN AREA OF MID LEVEL LIFT AND MOISTURE COMBINED WITH
SOME WEAK INSTABILITY MAY BE ENOUGH FOR A FEW SHOWERS ACROSS THE
CAPE AND ISLANDS LATE TONIGHT. A FEW ISOLATED THUNDERSTORMS ARE
POSSIBLE ACROSS RHODE ISLAND AND SOUTHEASTERN MASSACHUSETTS WHERE
MODEST INSTABILITY EXISTS.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
SHOWERS CONTINUE THROUGH THE MORNING AS THE LOW PRESSURE SYSTEM
MOVES INTO NORTHERN NEW ENGLAND AND SHORTWAVE MOVES OFFSHORE.  MID
LEVEL DRY AIR STARTS MOVING IN BEHIND THE SHORTWAVE AND THIS WILL
LIKELY BRING AN END TO MOST OF THE SHOWERS. COLD FRONT STARTS MOVING
INTO THE REGION MID-MORNING AND SLOWLY TRANSLATES ACROSS THE AREA...
MOVING OFFSHORE BY LATE SUNDAY AFTERNOON. THIS AND THE DRIER AIR
WILL START TO CLEAR OUT THE CLOUDS AS WELL...WITH MOSTLY SUNNY SKIES
EXPECTED BY THE END OF THE DAY.  TEMPERATURES SHOULD BE SIMILAR TO
TODAY WITH HIGHS IN THE UPPER 70S TO LOWER 80S.

SUNDAY NIGHT...DRIER AIR AND HIGH PRESSURE BUILDING INTO SOUTHERN
NEW ENGLAND WILL ALLOW TEMPERATURES TO FALL BACK INTO THE 50S
OVERNIGHT.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
HIGHLIGHTS...
*DRIER TO START THE WEEK...BUT INCREASING HUMIDITY TOWARD WEEK/S END
*SLOWLY INCREASING TEMPERATURES TOWARD WEEK/S END
*DIURNAL SHOWERS TOWARDS THE END OF THE WEEK

OVERVIEW...

MODELS ARE IN GOOD AGREEMENT TO BEGIN THE PERIOD...BUT DIVERGE
TOWARDS THE WEDNESDAY THURSDAY TIMEFRAME AS HAS HAPPENED QUITE
OFTEN. THE MAIN OUTLIER IS THE 00Z ECMWF AS IT SHOWS AN UPPER LEVEL
LOW STAYING TOGETHER AND MOVING THROUGH THE NORTHEAST. WITH
ENSEMBLES LIKE THE NAEFS AND ECENS SHOWING DIFFERENTLY...TRENDED
AGAINST THAT FOR THIS PERIOD.

THE GENERAL PATTERN SHOWS A STRONG JET ENTERING THE PACIFIC
NORTHWEST ALLOWING FOR A RELAXING FROM THE PREVIOUS HIGH AMPLITUDE
PATTERN TO A MORE ZONAL ONE FOR THE BEGINNING OF THE WEEK. THE END
OF THE WEEK SEES AN ATMOSPHERIC WAVE TRAIN ENTER THE STATES FOR A
CHANGE BACK TO A HIGHER AMPLITUDE PATTERN. OUR REGION SHOULD SEE
DIURNAL SHOWERS TOWARDS THE END OF THE WEEK AS THE FLOW IS STILL A
COOLING FLOW COMING IN FROM CANADA.

DAILIES...

MONDAY THROUGH WEDNESDAY...CONTINUING DRY AIR AND COOL TEMPERATURE
ANOMALIES OVER THE REGION WITH FLOW IN FROM THE NORTHWEST BEHIND THE
SLOWLY DEPARTING UPPER LEVEL LOW. THIS ALLOWS HIGH PRESSURE TO MOVE
INTO THE REGION FOR LATE MONDAY THROUGH LATE WEDNESDAY. MAY ALSO
SEEN EARLY MORNING FOG DURING THIS PERIOD WITH TD DEPRESSIONS LESS
THAN 5F.

THURSDAY THROUGH SATURDAY...PERIODS OF COOLING NIGHT TIME
TEMPERATURES AND WARMING DAY TIME TEMPERATURES ALLOW FOR DIURNAL
SHOWERS IN THE AFTERNOON. A LACK OF CAPE AND SHEAR DURING THIS
PERIOD ALLUDES TO JUST SHOWERS RATHER THAN THUNDER. HOWEVER...WITH
BUILDING HIGH PRESSURE OVER THE SOUTHEASTERN STATES...BELIEVE WEAK
SHORTWAVES WILL BEGIN TO MOVE TOWARDS NEW ENGLAND. TT/S ALSO BEGIN
TO INCREASE TO ABOVE 40 ON FRIDAY SHOWING INCREASING MID LEVEL
MOISTURE. PRECIP AMOUNTS LOOK VERY MINIMAL DURING THIS PERIOD WITH
PWATS BASICALLY NORMAL. HOWEVER MID LEVEL LAPSE RATES ABOVE 6C/KM
MAY HELP KEEP STORMS GOING.

&&

.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM...THROUGH SUNDAY NIGHT...

TONIGHT...MODERATE CONFIDENCE. SCATTERED SHOWERS POSSIBLE AFTER
06Z FROM WEST TO EAST WITH A SECONDARY AREA OF SHOWERS POSSIBLE
CAPE/ISLANDS. LOW RISK OF MVFR CIGS WITH SHOWERS. VERY LOW
PROBABILITY OF ISOLATED -TSRA OVER THE SOUTH COAST. SW WINDS
CONTINUE.

SUNDAY...SOME UNCERTAINTY REGARDING TIMING OF SHOWERS/ISOLD TSTMS.
APPEARS BEST CHANCE WILL BE IN THE MORNING AND EARLY AFTERNOON
MAINLY ACROSS RI AND EASTERN MA...WITH LOWER CHANCES WESTWARD.
SOME IMPROVEMENT DURING THE AFTERNOON FROM WEST TO EAST AS FRONT
EXITS THE REGION. MAINLY VFR WITH SCATTERED MVFR CONDITIONS IN
SHOWERS AND POSSIBLY ISOLATED -TSRA ACROSS RI AND EASTERN MA 12Z-
20Z.

SUNDAY NIGHT...VFR.

KBOS TERMINAL...HIGH CONFIDENCE IN TAF. LOWER CONFIDENCE IN TIMING
OF ISOLATED TSRA/SHRA.

KBDL TERMINAL...HIGH CONFIDENCE IN TAF.

OUTLOOK...MONDAY THROUGH THURSDAY...

MONDAY...HIGH CONFIDENCE. VFR. POSSIBLE SEA BREEZES ALONG THE
COASTLINES.

TUESDAY...MODERATE CONFIDENCE. VFR EXCEPT LOCAL MVFR CONDITIONS
ACROSS THE SOUTH COAST IN SCATTERED SHOWERS.

WEDNESDAY...MODERATE CONFIDENCE. VFR.

THURSDAY...MODERATE CONFIDENCE. VFR EXCEPT FOR ANY DIURNAL SHOWERS
WHERE MVFR IS POSSIBLE.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

HIGH CONFIDENCE. MOSTLY QUIET BOATING WEATHER IS EXPECTED DURING THE
DAY.  THERE IS A LOW PROBABILITY OF SCATTERED SHOWERS TONIGHT INTO
SUNDAY MORNING.  SOUTHWESTERLY WINDS ARE EXPECTED THROUGH SUNDAY
AFTERNOON.  A COLD FRONT WILL MOVE ACROSS THE WATERS LATE SUNDAY
AFTERNOON...SHIFTING WINDS FROM THE SOUTHWEST TO THE WEST.

OUTLOOK...MONDAY THROUGH THURSDAY...HIGH CONFIDENCE.

MONDAY THROUGH THURSDAY...WINDS AND SEAS BELOW SCA CRITERIA.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...RLG/99
NEAR TERM...KJC/NOCERA/RLG
SHORT TERM...RLG
LONG TERM...99
AVIATION...KJC/RLG/99
MARINE...RLG/99



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