Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 010203
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
1003 PM EDT SAT APR 30 2016

.SYNOPSIS...
HIGH PRESSURE OVER THE REGION TONIGHT WILL MOVE OFF TO THE EAST
SUNDAY MORNING. LOW PRESSURE MOVING UP THE OHIO VALLEY WILL BRING
TWO BURSTS OF RAIN TO SOUTHERN NEW ENGLAND...ONE ON SUNDAY
AFTERNOON/EVENING AND THE SECOND ON MONDAY. SHOWER CHANCES
CONTINUE ACROSS THE SOUTH COAST ON TUESDAY BEFORE A BRIEF DRYING
TREND ON WEDNESDAY. EXPECT MORE UNSETTLED WEATHER FOR LATE NEXT
WEEK.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
10 PM UPDATE...CLOUDS ARE INCREASING ACROSS THE AREA AS LOW
PRESSURE MOVES INTO THE GREAT LAKES. OTHERWISE...THE WEATHER
REMAINS QUIET ACROSS SOUTHERN NEW ENGLAND. MADE A FEW ADJUSTMENTS
TO THE SKY COVER AND TEMPERATURE FORECAST TO ACCOUNT FOR THE
LATEST TRENDS.

PREVIOUS DISCUSSION...

HIGH PRESSURE LINGERS OVER THE REGION TONIGHT WITH LIGHT WIND AND
DRY AIR. MAIN CONCERN WILL BE HOW QUICKLY THE EVENING CLOUDS
DISSIPATE. THIS WILL DETERMINE HOW MUCH RADIATIONAL COOLING WE GET
BEFORE MID AND HIGH CLOUDS MOVE UP FROM THE SOUTHWEST. IF THE
COOLING PERIOD IS SHORT...MIN TEMPS MAY BE A LITTLE MILDER THAN
FORECAST. CURRENTLY STAYING WITH MIN TEMPS 40-45...WITH ENOUGH
COOLING TIME THE COOLER SPOTS COULD REACH THE UPPER 30S.

EXTRAPOLATION ON THE INCOMING CLOUD SHIELD WOULD BRING THICKER
CLOUDS OVER WESTERN MA/CT AROUND 10 PM TO MIDNIGHT...CENTRAL HILLS
MIDNIGHT TO 2 AM...AND COASTAL PLAIN 2 TO 4 AM.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
UPPER SHORTWAVE AND PROGRESSIVE FLOW WILL FEED FAVORABLE UPPER
DYNAMICS FOR SURFACE SHORTWAVE TO MOVE NORTHEAST ACROSS THE
EASTERN GREAT LAKES. THIS TRACK WILL ALLOW TWO STREAMS OF 1 INCH
PRECIPITABLE WATER TO MOVE ACROSS SOUTHERN NEW ENGLAND...THE FIRST
MOVING ACROSS LATE SUNDAY AND SUNDAY NIGHT.

THE MODELS ALSO SHOW SHORTWAVE ENERGY TRANSFERRING TO THE COAST
DURING SUNDAY NIGHT. THIS WOULD ALLOW FOR A COASTAL LOW TO SPIN
UP...SETTING UP OVERRUNNING ESPECIALLY ACROSS RI/SE MASS. TOTAL
TOTALS WILL ALSO CLIMB HIGH INTO THE 40S. THIS MAY ALLOW EMBEDDED
THUNDER IN THE AREAS OF RAIN SUNDAY NIGHT.

TIMING OF PCPN...ALL MODELS AGREE ON BRINGING PCPN INTO WESTERN
MA/CT SUNDAY MORNING...AND REACHING EASTERN MASS BY EARLY
AFTERNOON. THE MODELS ALSO HINT AT A BREAK IN THE PCPN LATE AT
NIGHT ESPECIALLY ACROSS WESTERN MASS. WITH THE STEADY EAST-
NORTHEAST FLOW ACROSS NEW ENGLAND...SUSPECT CLOUDS/DRIZZLE WILL BE
A FACTOR IF THE RAIN DOES BRIEFLY DIMINISH.

THE NORTHEAST FLOW SHOULD ALSO HOLD MAX TEMPS DOWN DURING SUNDAY.
WATER TEMPERATURES ARE 45-50. WITH WIND COMING OFF THAT WATER IT
WOULD SUGGEST MAX TEMPS WILL BE ONLY A LITTLE HIGHER...AROUND 50
OR THE LOWER 50S...WITH MIN TEMPS IN THE 40S.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
HIGHLIGHTS...

* SCATTERED SHOWERS ALONG THE SOUTH COAST TUESDAY
* DRY AND SEASONABLE ON WEDNESDAY
* MORE UNSETTLED WEATHER LATE NEXT WEEK INTO THE WEEKEND

OVERVIEW...

OVERALL HAVE A MODERATE TO LOW CONFIDENCE IN THE FORECAST AS
GUIDANCE SPREAD IS SOMEWHAT LARGE IN THE EXTENDED. LARGE RIDGE OVER
THE WEST WILL RESULT IN UPPER LEVEL TROUGH OVER THE EASTERN HALF OF
THE CONUS. SEVERAL WAVES WILL MOVE THROUGH THE FLOW WHICH WILL
EVENTUALLY DEVELOP A CUT-OFF LOW OVER THE GREAT LAKES. WHILE THIS IS
OCCURRING...A POTENT CUT-OFF LOW WILL MOVE OVER THE PACIFIC
SOUTHWEST RESULTING IN AN OMEGA BLOCK OVER THE REGION. DEPENDING ON
THE EXACT PLACEMENT AND STRENGTH OF THE LOW...SOUTHERN NEW ENGLAND
COULD BE IN FOR AN ACTIVE WET PATTERN FOR THE SECOND HALF OF THE
WEEK. THIS PATTERN LOOKS TO STAY THROUGH THE WEEKEND AS ATLANTIC
RIDGE CONTINUES TO STRENGTHEN STALLING THE PATTERN ACROSS THE CONUS.

DAILIES...

MONDAY...MODERATE CONFIDENCE.

POTENT SHORTWAVE WILL MOVE THROUGH THE FLOW PUSHING A LOW PRESSURE
SYSTEM TO THE WEST OF SOUTHERN NEW ENGLAND. HOWEVER APPEARS THAT A
SECONDARY LOW WILL DEVELOP AND SLIDE JUST SOUTH OF THE REGION. BOTH
OF THESE SYSTEMS WILL RESULT IN SHOWERY WEATHER FOR THE FIRST HALF
OF MONDAY. COULD SEE A RUMBLE OF THUNDER ESP ACROSS THE SOUTH COAST
AS BOTH THE GFS AND EC SHOW LI/S BELOW 0 AND TT ABOVE
50S...INDICATING ELEVATED INSTABILITY. DEPENDING ON HOW THE LOWS AND
THEIR ASSOCIATED FRONTS INTERACT...CANNOT RULE IT OUT.

AS THE SHORTWAVE MOVES EASTWARD A COLD FRONT WILL SWING THROUGH
PUSHING DRY AIR ACROSS THE REGION MONDAY AFTERNOON INTO THE EVENING.
CLOUDS WILL LINGER DURING THE OVERNIGHT KEEPING TEMPS IN THE 40S.

TUESDAY INTO WEDNESDAY...MODERATE CONFIDENCE.

SURFACE COLD FRONT WILL STALL SOUTH OF THE REGION MONDAY NIGHT INTO
TUESDAY. A WAVE OF LOW PRESSURE WILL MOVE ALONG THE FRONT BRINGING
ANOTHER ROUND OF SHOWERS TO THE REGION...ESP ACROSS THE SOUTH COAST.
LOW CONFIDENCE ON HOW FAR NORTHWARD THE PRECIP SHIELD WILL GET AS
HIGH PRESSURE MOVES INTO NORTHERN NEW ENGLAND. GUIDANCE IS STILL
STRUGGLING WITH THIS WAVE AS THE NAM BRINGS PRECIP CLOSE TO THE
NH/MA BORDER...THE GFS KEEPS IT CONFINED TO THE SOUTH COAST AND THE
EC IS IN BETWEEN.

THIS WAVE OF LOW PRESSURE WILL MOVE OFFSHORE BY LATE TUESDAY
RESULTING IN A MOSTLY PLEASANT WEATHER DAY ON WEDNESDAY. PERHAPS IT
IS THE PICK OF THE WEEK? SOUTHWESTERLY FLOW ALOFT WILL DOMINATE
ACROSS THE AREA AHEAD OF DIGGING UPPER LEVEL TROUGH/CUT OFF LOW.
HOWEVER LARGE TEMPERATURES SPREAD AMONGST THE GUIDANCE THANKS TO
ONSHORE FLOW AS INDICATING BY THE EC. GFS KEEPS THE FLOW MORE OF A
SOUTHWEST DIRECTION...BUT THIS IS WHERE GUIDANCE SPREAD IS LARGE.

CONTINUED WITH A  MODEL AND ENSEMBLES BLEND FOR THIS PORTION OF THE
FORECAST UNTIL GUIDANCE DIFFERENCE GETS RESOLVED.

THURSDAY AND BEYOND...LOW TO MODERATE CONFIDENCE.

THIS IS A VERY LOW CONFIDENCE FORECAST THROUGHOUT THE LONG TERM
PERIOD DUE TO THE LARGE MODEL SPREAD AND RUN TO RUN VARIABILITY.
THIS UNCERTAINTY IS AMPLIFIED BY THE MODELS FORECASTING CUTOFF
LOWS...WHICH IS AN ITEM THEY ALL HAVE A LOWER THAN AVERAGE SKILL AT
FORECASTING.

FOR TEMPERATURES THURSDAY-SATURDAY USED A MODEL BLEND. FOR NOW
FORECASTING A MORE ACTIVE WET PATTERN WITH TEMPERATURES NEAR OR
BELOW AVG FOR HIGHS...AND ABOVE AVG FOR LOWS.

&&

.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/...HIGH CONFIDENCE.

THROUGH TONIGHT...VFR. ONSHORE SEA BREEZE WINDS AROUND 10 KNOTS
DIMINISHING THIS EVENING.

SUNDAY AND SUNDAY NIGHT...RAIN MOVES INTO W MA/CT BETWEEN 11-14Z
SUNDAY REACHING THE EAST COAST BETWEEN 15-18Z. INITIAL VFR IN
LIGHT RAIN DETERIORATES TO MVFR CIGS/VSBYS IN RAIN SUNDAY EVENING
WITH AREAS OF IFR.

KBOS TERMINAL...HIGH CONFIDENCE IN TAF.

KBDL TERMINAL...HIGH CONFIDENCE IN TAF.

OUTLOOK /MONDAY THROUGH THURSDAY/...

MONDAY...OVERALL HIGH CONFIDENCE WITH MVFR/IFR CONDITIONS IN
PERIODS OF RAIN.

TUESDAY...VFR WITH MODERATE CONFIDENCE OF MVFR ACROSS THE SOUTH
COAST IN -SHRA.

WEDNESDAY...MODERATE CONFIDENCE. MAINLY VFR WITH LIGHT WINDS.

THURSDAY...LOW CONFIDENCE. MVFR/IFR WITH WIDESPREAD RA.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH SUNDAY NIGHT/...HIGH CONFIDENCE.

HIGH PRESSURE OVERHEAD TONIGHT AND SUNDAY WILL KEEP WINDS BELOW 20
KNOTS AND SEAS BELOW 5 FEET. RAIN MOVES IN FROM WEST TO EAST
DURING SUNDAY...ENTERING THE WATERS LATE MORNING OR EARLY
AFTERNOON. LOWERING VSBYS IN RAIN AND FOG DURING THE
AFTERNOON/EVENING.

SUNDAY NIGHT...EAST-NORTHEAST WINDS WILL INCREASE WITH SPEEDS
AROUND 20 KNOTS. BEST CHANCE WILL BE ALONG THE WATERS NEAR CAPE
ANN/NORTH SHORE. THE INCREASING WINDS WILL BUILD SEAS DURING THE
NIGHT WITH 5 FOOT HEIGHTS ON THE OUTER WATERS. A SMALL CRAFT
ADVISORY MAY BE NEEDED. REDUCED VSBYS IN RAIN AND PATCHY FOG.

OUTLOOK /MONDAY THROUGH THURSDAY/...

MONDAY...LOW CONFIDENCE ON WINDS DUE TO UNCERTAINTY IN TRACK OF
LOW PRES. ROUGH SEAS...ESPECIALLY EASTERN WATERS. VSBYS REDUCED AT
TIMES IN RAIN AND FOG.

TUESDAY...MODERATE CONFIDENCE. LIGHT WINDS BUT LEFTOVER ROUGH
SEAS WILL SLOWLY SUBSIDE. -SHRA ACROSS THE SOUTHERN WATERS TUESDAY
MORNING.

WEDNESDAY AND THURSDAY...LOW CONFIDENCE WIND FORECAST. LOW
PRESSURE TO THE SOUTH MAY RESULT IN WINDS BEING MORE EASTERLY THAN
WHAT IS CURRENTLY FORECAST.

&&

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

&&

$$
SYNOPSIS...WTB/DUNTEN
NEAR TERM...WTB/DUNTEN/RLG
SHORT TERM...WTB
LONG TERM...DUNTEN
AVIATION...WTB/DUNTEN
MARINE...WTB/DUNTEN


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