Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 151836
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
236 PM EDT WED APR 15 2015

.SYNOPSIS...
HIGH PRESSURE TODAY PROVIDES DRY WEATHER AND WARMER THAN NORMAL
TEMPERATURES. DRY BUT SEASONABLY COOL WEATHER FOLLOWS THURSDAY.
HIGH PRESSURE MOVES OFFSHORE FRIDAY WITH A PERIOD OF RAIN
POSSIBLE. A COLD FRONT CROSSES THE AREA LATE SATURDAY. WEAK HIGH
PRESSURE FOLLOWS SUNDAY. LOW PRESSURE APPROACHES EARLY NEXT WEEK
WITH THE THREAT OF WIDESPREAD RAIN LATER MARATHON MONDAY INTO
TUESDAY.

&&

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

2 PM UPDATE...
THE FEW BANDS OF CIRRUS CLOUDS THAT WERE FLIRTING ALONG THE S
COAST HAVE PUSHED OFFSHORE...THOUGH STILL SEE A COUPLE OF SPOTS
WITH SOME HIGH CLOUDS HANGING NEAR THE ISLANDS AT 18Z. WITH LARGE
HIGH PRES PUSHING E OUT OF QUEBEC AND THE GREAT LAKES...EXPECT
THESE CLOUDS TO REMAIN S OF THE REGION THROUGH THE REMAINDER OF
THE DAY. HAVE NOTED A FEW DIURNAL CUMULUS CLOUDS HAVE DEVELOPED
ACROSS E MA INTO RI AROUND MIDDAY...BUT SHOULD SEE THOSE DISSIPATE
BY 21Z-22Z.

N-NE WINDS ACROSS EASTERN AREAS AND N-NW WINDS ACROSS THE CENTRAL
AND WEST HAVE PICKED UP...WITH BRIEF GUSTS OVER 25 KT IN THE CT
VALLEY AROUND MIDDAY /NOTED 32 KT GUST AT KBDL AT 17Z/ BUT LOOK TO
BE DIMINISHING ACROSS W MA/N CENTRAL CT AT 18Z. A SEA BREEZE HAS
ACTUALLY KICKED AT KBOS AT 18Z.

CURRENT FORECAST LOOKS ON TRACK...BUT HAVE UPDATED NEAR TERM TO
BRING CONDITIONS CURRENT.

&&

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

WINDS RELAX AS HIGH PRESSURE BUILDS INTO THE REGION. EXPECTING
LIGHT AND VARIABLE WINDS UNDER MOSTLY CLEAR CONDITIONS. SHOULD SEE
DECENT RADIATIONAL COOLING AND THUS HAVE GONE WITH A CONSENSUS
BLEND OF MOS GUIDANCE...DROPPING IT A COUPLE OF DEGREES ESPECIALLY
IN SUSCEPTIBLE LOW-LYING AREAS PRONE TO RADIATIONAL COOLING.
FROST AND FREEZE HEADLINES ARE NOT NECESSARY AT THIS TIME AS THE
GROWING SEASON DOES NOT BEGIN TILL APRIL 21ST FOR LOW- LYING
COASTAL AREAS.

THURSDAY...

HIGH PRESSURE PUSHES E ALLOWING FOR RETURN S-FLOW. MOSTLY CLEAR
FORECAST WITH LOW DEWPOINTS AS TEMPERATURES WARM TO THE 60-DEGREE
MARK. CONTINUED BOUNDARY-LAYER MIXING ALBEIT LIMITED TO H9 BY A
DRY-AIR INVERSION. INFLUENCE OF HIGH PRESSURE SHOULD KEEP WINDS
BELOW THE 25 MPH THRESHOLD...CAN NOT RULE OUT GUSTS UP TO 20 MPH
WITH THE MIX-DOWN OF FASTER MOMENTUM AND DRIER AIR. WILL NEED TO
RE-EVALUATE WITH THE NEXT FORECAST PERIOD WITH RESPECT TO THE
FIRE WEATHER ENVIRONMENT.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
SYNOPTIC OVERVIEW...

CLOSED LOW OVER THE FOUR CORNERS REGION SUPPORTS SPLIT FLOW ACROSS
THE CONUS INTO EARLY THIS WEEKEND. THIS CLOSED LOW EJECTS SEVERAL
PACKETS OF SOUTHERN STREAM MOISTURE NORTHEASTWARD INTO NEW ENGLAND
WITH THE FIRST MOISTURE PLUME ARRIVING FRI. THE NEXT PACKET OF JET
ENERGY AND MOISTURE TARGET SNE EARLY NEXT WEEK. THIS 2ND PRECIP
EVENT MAY BE MORE WIDESPREAD AND ASSOCIATED WITH APPRECIABLE QPF AS
STREAMS MERGE AND FORMS A COASTAL LOW. MEANWHILE THE NORTHERN STREAM
UNDERGOES SOME AMPLIFICATION AS TROUGHING DEVELOPS VICINITY OF
ALASKA WITH DOWNSTREAM RIDGING INTO WESTERN CANADA. THIS RESULTS IN
A MODEST SURGE OF COOL AIR INTO THE NORTHEAST SAT NIGHT AND SUN
MORNING BEHIND A DEPARTING NORTHERN STREAM SHORT WAVE TROUGH/COLD
FRONT.

MODEL/GUIDANCE EVALUATION...

FIRST ITEM OF CONCERN ARE POPS AND QPF FOR FRI. 00Z GFS IS MOST
BULLISH WITH QPF. MEANWHILE ALL OTHER GUIDANCE HAS LIGHTER AMOUNTS
ALONG WITH PRECIP BECOMING FRAGMENTED ESPECIALLY EASTWARD WHICH
SEEMS REASONABLE AS PRECIP ENTERS CONFLUENT FLOW ALOFT OVER NEW
ENGLAND. GEFS POPS FOR 0.05 QPF CAPTURES THIS NICELY WITH POPS
DIMINISHING FROM WEST TO EAST FRI. THUS WILL FOLLOW A NON GFS
SOLUTION HERE YIELDING LESS QPF. NEXT ISSUE IS TIMING OF PRECIP FOR
MARATHON MONDAY. DETERMINISTIC 00Z GFS AND 00Z ECMWF ALONG WITH GEFS
ENSEMBLES IN GOOD AGREEMENT FOR DRY WEATHER MON MORNING WITH
INCREASING CHANCES FOR RAIN IN THE AFTERNOON AND BEYOND. GIVEN GOOD
MODEL AGREEMENT WILL FOLLOW THIS TIMELINE.

DAILY SENSIBLE WEATHER...

THU NIGHT...MILD NIGHT AS RETURN FLOW ADVECTS DEW PTS NEAR 50 ACROSS
THE REGION. ANY RAIN SHOULD HOLD OFF TIL VERY LATE AT NIGHT OR FRI
MORNING.

FRIDAY...HIGH CERTAINTY FOR SCATTERED SHOWERS BUT STILL SOME
UNCERTAINTY REGARDING HOW WIDESPREAD AND ASSOCIATED QPF. DOESN/T
APPEAR AS A WASHOUT GIVEN FAST FLOW ALOFT MAY YIELD RAIN ENDING IN
THE AFTERNOON WITH PARTIAL CLEARING POSSIBLE.

SATURDAY...MILD START AND WARM ADVECTION AHEAD OF APPROACHING SHORT
WAVE AND ATTENDING COLD FRONT SHOULD SUPPORT A WARM AFTERNOON WITH
HIGHS IN THE U60S TO L70S. LEANED TOWARD THE WARMER MOS TEMPS
COMPARED TO COOLER MODEL BLEND TEMPS. SOME UNCERTAINTY REGARDING
POTENTIAL FOR AFTERNOON AND EVENING SHOWERS. BEST INSTABILITY
/STEEPENING LAPSE RATES/ AND FORCING FOR ASCENT APPEARS ACROSS
NORTHERN AND EASTERN MA. THUS HIGHEST POPS ACROSS THIS REGION.

SUNDAY...COOLER AND DRY BEHIND DEPARTING SHORT WAVE AND ATTENDING
COLD FRONT. ALTHOUGH SEASONABLY MILD WITH HIGHS U50S TO L60S...FEW
DEGS ABOVE NORMAL.

EARLY NEXT WEEK INCLUDING MARATHON MONDAY...FAIRLY HIGH CONFIDENCE
IN WIDESPREAD RAIN SOMETIME LATER MONDAY INTO MONDAY NIGHT AND AT
LEAST EARLY TUE. RAIN COULD BE WIDESPREAD IN AREAL COVERAGE ALONG
WITH APPRECIABLE RAINFALL GIVEN GULF MOISTURE...STREAMS MERGING
RESULTING IN A COASTAL LOW TRACKING NEAR OR OVER SOUTHERN NEW
ENGLAND.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH THURSDAY/...HIGH CONFIDENCE.

THROUGH 00Z...VFR. N-NW WINDS GUSTING TO 25 KT THROUGH 19Z-20Z
THEN DIMINISHING. E-NE WINDS FROM KBOS SOUTH TO CAPE COD AND THE
ISLANDS IN PLACE...EXCEPT BRIEF SEA BREEZE AT KBOS THAT WILL
BECOME E-NE BY AROUND 21Z.

TONIGHT...VFR SKC. WINDS BECOME LIGHT/VRBL OR CALM AS HIGH PRES
BUILDS OVER.

THURSDAY...VFR. SKC THROUGH MIDDAY...THEN HIGH CLOUDS START TO
MOVE INTO WESTERN AREAS DURING THE AFTERNOON. LIGHT E-SE WINDS
VEER TO S AND INCREASE TO AROUND 10 KT DURING THE AFTERNOON.

KBOS TAF...HIGH CONFIDENCE IN TAF. BRIEF SEA BREEZE SHOULD BECOME
E-NE BY AROUND 21Z.

KBDL TAF...HIGH CONFIDENCE IN TAF.

OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY...

THURSDAY NIGHT...HIGH CONFIDENCE FOR VFR

FRIDAY...MODERATE CONFIDENCE. MAINLY VFR BUT WITH PERIODS OF MVFR IN
SCATTERED RAIN SHOWERS.

SATURDAY...MOST LIKELY VFR WITH A MODEST WEST WIND BECOMING
NORTHWEST.

SUNDAY...MOST LIKELY VFR ALONG WITH DIMINISHING WINDS.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH THURSDAY/...HIGH CONFIDENCE.

THIS AFTERNOON...EXPECT N-NE WINDS GUSTING UP TO 25 KT. SEAS
REMAIN BELOW 5 FT...BUT MAY POSSIBLY SEE BRIEF SWELLS UP TO 5 FT
ACROSS THE FAR SOUTHERN OUTER WATERS.

TONIGHT AND THURSDAY...LIGHT AND VARIABLE WINDS OVERNIGHT AS HIGH
PRES MOVES ACROSS THE WATERS...THEN SHIFTS E ON THURSDAY ALLOWS
FOR RETURN S FLOW THAT BECOMES BRISK WITH GUSTS UP TO 20 KTS
TOWARDS THE END OF THE DAY.

OUTLOOK...THURSDAY NIGHT THROUGH SUNDAY...

THURSDAY NIGHT AND FRIDAY...MODEST WSW WINDS AS HIGH PRES SLIPS
SOUTH OF NEW ENGLAND. STRONGEST WINDS NORTHERN WATERS AND NEAR
SHORE. VSBY MAY LOWER AT TIMES IN PERIODS OF RAIN.

SATURDAY...LOW PRES MOVING ACROSS EASTERN QUEBEC INTO NEW BRUNSWICK
WILL YIELD A MODEST WSW WIND ACROSS THE WATERS. COLD FRONTAL PASSAGE
LATE SAT YIELDS A WIND SHIFT TO THE WNW WITH MODEST WIND GUSTS.

SUNDAY...DIMINISHING WIND AND SEAS AS HIGH PRES CREST OVER NEW
ENGLAND AND NEARBY COASTAL WATERS. DRY WEATHER RESULTS IN GOOD VSBY.

&&

.FIRE WEATHER...
2 PM UPDATE...
NOTED ERROR ON DEWPT AT MARTHAS VINEYARD DUE TO PROBLEMS WITH THE
DEWPT SENSOR AT THE AIRPORT. BACKUP DEWPT SENSOR REPRESENTATIVE OF
REGION...REPORTING 27 DEGREES AT 18Z.

DEWPTS HAVE ACTUALLY RISEN ACROSS SE MA AS WINDS HAVE SHIFTED TO
E-NE THROUGH MIDDAY. ELSEWHERE...DEWPTS REMAIN IN THE TEENS TO
LOWER 20S WITH RH VALUES REMAINING IN THE 15-20 PERCENT. GUSTY
N-NW WINDS BRIEFLY KICKED ON ACROSS THE CT VALLEY INTO N CENTRAL
MA...BUT APPEAR TO BE DIMINISHING AFTER 17Z.

RED FLAG CONTINUES FOR MOST OF MASSACHUSETTS THROUGH THE
AFTERNOON...NOTING SOME BRUSH FIRE REPORTS.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...RED FLAG WARNING UNTIL 7 PM EDT THIS EVENING FOR MAZ002>023-
     026.
RI...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...NOCERA/SIPPRELL
NEAR TERM...EVT
SHORT TERM...SIPPRELL
LONG TERM...NOCERA
AVIATION...SIPPRELL/EVT
MARINE...NOCERA/SIPPRELL/EVT
FIRE WEATHER...STAFF



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