Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 250840
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
440 AM EDT WED MAR 25 2015

.SYNOPSIS...
HIGH PRESSURE MOVES OFFSHORE TODAY ALLOWING MORE SEASONABLE AIR TO
RETURN TO NEW ENGLAND. A WARM FRONT MOVES ACROSS NEW ENGLAND
TONIGHT BRINGING A PERIOD OF RAIN...FOLLOWED BY
CLOUDS/DRIZZLE/FOG. ANOTHER AREA OF RAIN MOVES THROUGH ON
THURSDAY. A COLD FRONT SWEEPS ACROSS THE REGION THURSDAY NIGHT
WITH SHOWERS. A SECOND COLD FRONT WILL BRING COLDER TEMPERATURES
LATER FRIDAY INTO THIS WEEKEND. ANOTHER FAST MOVING FRONT WILL
PUSH ACROSS THE REGION SUNDAY NIGHT INTO MONDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THROUGH 8 AM...
HIGH PRESSURE CENTERED OVER NEW ENGLAND WITH CLEAR SKIES ACROSS
THE REGION. PER SATELLITE THE NEAREST CIRRUS WAS LOCATED IN
WESTERN NY/WESTERN PA AT 2 AM. THIS WILL MOVE EAST AT A PACE THAT
WILL BRING IT INTO SOUTHERN NEW ENGLAND AROUND SUNRISE. FAIR SKIES
AND LIGHT WINDS WILL ALLOW COOLING TEMPERATURES THROUGH SUNRISE
WITH DEW POINTS IN THE TEENS AND LOWER 20S ALLOWING AN EXPECTED
RANGE OF MORNING LOWS IN THE MID TEENS TO MID 20S.

TODAY...
INCREASING HIGH CLOUDS MORNING AND MIDDAY BUT PLENTY OF SUN
THROUGH THAT SKY COVER. SO EXPECT TEMPERATURES TO RECOVER FROM THE
CHILLY START. TEMPS ALOFT THROUGH 18Z WOULD SUPPORT MAX SFC TEMPS
IN THE 40S.

SOUTHERLY LOW LEVEL JET REMAINS TO OUR WEST AT 18Z BUT SHIFTS INTO
SOUTHERN NEW ENGLAND BY 00Z. SO EVEN WITH INCREASING CLOUDS THE
WEATHER SHOULD REMAIN DRY THROUGH ALMOST ALL OF THE DAY. COULD BE
A CHANCE OF INITIAL LIGHT SHOWERS IN WESTERN MASS/CT AROUND 5 PM.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
TONIGHT...
PRIME ZONE OF WARM ADVECTION LIFT MOVES THROUGH DURING THE FIRST
HALF OF THE NIGHT AND THEN MOVE EAST OF US AFTER MIDNIGHT. THE
WARM ADVECTION THEN REACHES THE SURFACE AND SHOULD PROVIDE FOR
WARMING TEMPS OVERNIGHT...A DECIDED NON-DIURNAL TREND. WE HAVE
ADJUSTED HOURLY TEMPS TO REFLECT THIS. THE WARM ADVECTION...WITH
DEW POINTS RISING ABOVE FREEZING TO AROUND 40...SHOULD BRING AREAS
OF FOG AS IT RIDES OVER THE SNOWPACK. WITH NEARSHORE WATER TEMPS
IN THE 30S...THE HIGHER DEW POINT AIR MOVING ASHORE ALONG THE
SOUTH COAST MAY ALSO BE SUFFICIENTLY CHILLED TO CREATE AREAS OF
FOG.

THURSDAY...
COLD FRONT STARTS THE DAY EXTENDING FROM NORTHERN VERMONT TO THE
OHIO VALLEY. THIS AXIS HAS A NORMAL COMPONENT TO THE UPPER FLOW
BUT IS NOT FAR FROM BEING PARALLEL. THE FRONT WILL BE SUPPORTED
BY A 155 KNOT UPPER JET OVER THE GREAT LAKES WITH RIGHT ENTRANCE
REGION OVER ILLINOIS/INDIANA. SURPRISE...A WAVE OF LOW PRESSURE
DEEPENS IN THIS LOCATION AS IT MOVES UP THE FRONT. THIS WILL BRING
A STRONG LOW LEVEL SOUTHWEST JET UP TOWARD NEW ENGLAND WHICH
SHOULD GENERATE ANOTHER PERIOD OF RAIN OVER OUR AREA BY
AFTERNOON. ACTUALLY IT/S A TOUGH CALL FOR RAIN VS SHOWERS...THE
PATTERN LOOKS STRATIFORM BUT TAKES PLACE AHEAD OF AN ADVANCING
COLD FRONT. BASED ON THE LOW LEVEL JET AND RESULTING LIFT WE WILL
GO STRATIFORM AT THIS TIME...BUT COULD BE MORE LIKE PERIOD OF RAIN
RATHER THAN A LONG SOAKING RAIN. STABILITY PARAMETERS LOOK
FAVORABLE FOR CONVECTION WITH TOTALS IN THE LOWER 50S AND TQ 17 TO
18. THE COOLING BY THE SNOWPACK MAY MAINTAIN A STABLE LAYER AT THE
SURFACE...BUT ELEVATED INSTABILITY MAY BE ENOUGH TO SET OF
ISOLATED OR WIDELY SCATTERED THUNDER DURING THE AFTERNOON AND
EVENING.

THE STRONG WARM ADVECTION WILL CONTINUE TO BRING RELATIVELY HIGH
DEW POINT AIR...IN THE 40S...ACROSS THE REGION. THIS WILL AID BOTH
FOG FORMATION AND SNOWMELT. PRECIPITABLE WATER VALUES CLIMB TO
AROUND 1 INCH TO 1.5 INCHES...WHICH IS ABOUT 2 SD ABOVE NORMAL.
THIS SUGGESTS POTENTIAL FOR OCCASIONAL HEAVY DOWNPOURS.

950 MB TEMPS 8-10C BROUGHT TO THE SURFACE ISOTHEMALLY WOULD START
TEMPERATURES AT 45-50. ALLOW SOME MINIMAL WARMING DURING THE
MORNING AND POTENTIAL IS THERE FOR MAX TEMPS 50-55.

THURSDAY NIGHT...
THE SURFACE LOW PASSES TO OUR NORTH AND THEN SWINGS THE COLD FRONT
THROUGH SOUTHERN NEW ENGLAND DURING THE NIGHT. LOW CONFIDENCE ON
EXACT TIMING...BUT THE WIND SHIFT SHOULD COINCIDE WITH DIMINISHING
SHOWERS. WE STAYED CLOSE TO BLENDED MODEL GUIDANCE FOR MIN TEMPS
LATE THURSDAY NIGHT.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
HIGHLIGHTS...

* BLUSTERY AND BELOW AVERAGE TEMPS FOR THE WEEKEND
* WEAK DISTURBANCE POSSIBLE ON MONDAY

MODEL GUIDANCE...

OVERALL AMPLIFIED TROUGH PATTERN WILL CONTINUE WITH 00Z GUIDANCE IN
GOOD AGREEMENT. STILL SOME TIMING/INTENSITY ISSUES FOR UPCOMING
SYSTEMS. DEEP TROUGH AXIS WILL MOVE OVERHEAD SAT INTO EARLY SUNDAY
FOLLOWED BY A QUICK MOVING RIDGE. BY LATE SUNDAY INTO MONDAY ANOTHER
SHORTWAVE WILL MOVE INTO SOUTHERN NEW ENGLAND. GUIDANCE IS SPLIT ON
THIS SYSTEM AS THE GFS IS MORE AMPLIFIED COMPARED TO THE EC.
OTHERWISE...MIDDLE OF NEXT WEEK LOOKS TO BE A POSSIBLE PATTERN
CHANGE.

DETAILS...

* FRIDAY INTO SATURDAY...MODERATE CONFIDENCE.

DEEP SHORTWAVE WILL DIG FROM THE GREAT LAKES DOWN INTO THE SOUTHEAST
ALLOWING FOR DEEP TROUGH TO SETTLE OVER THE NORTHEAST BY LATE
FRIDAY/SATURDAY. PRIOR TOO THIS SECONDARY COLD FRONT WILL SWEEP
ACROSS THE AREA FROM WEST TO EAST ON FRIDAY PUSHING MOST OF THE
PRECIP OFFSHORE...BUT USHERING COLDER AIR ALOFT. THIS FRONTAL
PASSAGE WILL OCCUR LATE IN THE DAY/EVENING HOURS TO MUCH OF THE
REGION MAY REACH INTO THE MID 40S TO LOW 50S. COULD SEE A FEW POP UP
SHOWERS ALONG THE FRONT AS IT PASSES THROUGH AS THERE IS SOME LINGER
MOISTURE. AM NOT EXPECTING MUCH IN THE WAY OF ACCUMULATIONS.

COLD AIR WILL USHER ACROSS THE REGION FRIDAY NIGHT INTO SATURDAY. AS
UPPER LEVEL TROUGH PUSHES OVERHEAD...COULD SEE SOME SCT SNOW SHOWERS
DURING THE DAY ON SATURDAY. FEEL THESE MAY BE MORE CONVECTIVELY
DRIVEN AS THERE IS SOME MOISTURE IN THE LOW LEVELS AND LAPSE RATES
STEEPEN DURING THE DAY. THEREFOR INSERT SLIGHT CHC POP INTO THE
FORECAST...WITH THE AREA WITH THE BEST CHANCE OF SEEING A SNOW
SHOWER BEING WEST OF I-95. TEMPS OVERNIGHT WILL FALL WELL BELOW
NORMALS WITH LOWS AROUND THE TEENS TO LOW 20S. TEMPS MAY BE SLIGHTLY
COLDER AT WE COULD RADIATE OUT THANKS TO CLEARING SKIES AND LIGHT
WINDS ACROSS THE INTERIOR.


* SUNDAY...HIGH CONFIDENCE.

SUNDAY IS A TRANSITION DAY AS DEEP TROUGH BEGINS TO PULL OFFSHORE
AND UPPER LEVEL RIDGE MOVES INTO THE REGION. TEMPS ON SUNDAY WILL
WARM INTO THE LOW TO MID 40S...WHICH IS STILL SEVERAL DEGREES BELOW
AVERAGE. EXPECT MOSTLY CLEAR SKIES IN THE MORNING BUT THEY WILL
BEGIN TO CLOUD UP DURING THE AFTERNOON AS THE NEXT SYSTEM APPROACHES
FROM THE WEST.

MONDAY INTO TUESDAY...LOW CONFIDENCE.

NEXT UPPER LEVEL DISTURBANCE WILL IMPACT SOUTHERN NEW ENGLAND LATE
SUNDAY INTO MONDAY. STILL A GOOD AMOUNT OF SPREAD AMONGST THE
GUIDANCE WITH THE EC KEEPING THE SYSTEM TO THE NORTH WHILE THE GFS
BRINGS THE SYSTEM OVER SNE. CONTINUED TO KEEP PRECIP IN THE FORECAST
FOR NOW WITH THIS SYSTEM. SURFACE LOW ACROSS THE GREAT LAKES WILL
PASS JUST NORTH OF SNE...DRAGGING ASSOCIATED COLD FRONT WITH IT.
TEMPS AT THE ONSET LOOK TO BE COOL THEN WARM UP DURING THE DAY ON
MONDAY PRIOR TO FRONTAL PASSAGE. THIS MAY CAUSE P-TYPE ISSUES...BUT
BECAUSE THIS IS SEVERAL DAYS AWAY WILL NEED TO REEVALUATE. FRONT
WILL PASS THROUGH LATE MONDAY WITH HIGH PRESSURE AND COOLER TEMPS IN
ITS WAKE FOR TUESDAY.

&&

.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
FORECASTER CONFIDENCE LEVELS...

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

HIGH CONFIDENCE THROUGH WEDNESDAY...THEN SOME UNCERTAINTY ON
EXACT TIMING OF LOWER CIGS/VSBYS WITH RAIN LATE WED INTO WED
EVENING.

THROUGH 12Z/8 AM...HIGH CONFIDENCE. VFR CLR. LIGHT/VRBL OR CALM
WINDS.

TODAY...VFR. CLOUDS LOWER AND THICKEN DURING THE AFTERNOON/EVENING.
MVFR CIGS/VSBYS DUE TO RAIN MAY ENTER THE CT RIVER VALLEY BETWEEN
21Z AND 00Z THIS EVENING.

TONIGHT...CONDITIONS LOWERING TO MVFR WITH AREAS OF IFR DUE TO
LOW CIGS/RAIN/FOG. RAIN TAPERS OFF AFTER MIDNIGHT BUT IFR/LIFR DUE
TO LOW CIGS/FOG/DRIZZLE THROUGH SUNRISE.

THURSDAY...ANOTHER AREA OF RAIN MOVES IN FROM THE SOUTHWEST. MIXED
MVFR/IFR CIGS/VSBYS IN RAIN AND FOG. LOCALLY HEAVY DOWNPOURS
POSSIBLE THURSDAY NIGHT AS A COLD FRONT SWINGS THROUGH. LOW
CONFIDENCE FOR ISOLATED THUNDERSTORMS LEADING THE FRONT THURSDAY
EVENING/NIGHT. BEST CHANCE FOR THUNDER WOULD BE ACROSS RI AND
SOUTHEAST MASS.

KBOS TAF...HIGH CONFIDENCE THRU 00Z TODAY THEN SOME UNCERTAINTY
ON EXACT TIMING OF LOWERING CONDITIONS.

KBDL TAF...HIGH CONFIDENCE THRU 21Z TODAY THEN SOME UNCERTAINTY
ON EXACT TIMING OF LOWERING CONDITIONS.

OUTLOOK...FRIDAY THROUGH SUNDAY...MODERATE TO HIGH CONFIDENCE

FRIDAY THROUGH SATURDAY...MVFR CONDITIONS IMPROVING TO VFR FROM WEST
TO EAST ON FRIDAY. COULD SEE ISO/SCT MVFR CIGS ALONG COLD FRONT ON
FRIDAY AND AGAIN DIURNALLY DRIVEN ON SATURDAY.

SATURDAY NIGHT INTO SUNDAY...VFR CONDITIONS LIKELY.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

HIGH CONFIDENCE TODAY THEN MODERATE CONFIDENCE TONIGHT AND
THURSDAY.

TODAY...LIGHT WINDS BECOME SOUTH THIS AFTERNOON. WINDS AND SEAS
REMAIN BELOW SMALL CRAFT THRESHOLDS. CHANCE OF LIGHT RAIN TOWARD
EVENING.

TONIGHT...SOUTH TO SOUTHWEST WINDS WILL INCREASE TO 20-25 KNOTS.
THIS WILL BUILD SEAS TO 5 FEET ON THE OUTER WATERS AND 3-4 FEET
CLOSER TO SHORE. A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR SOME
OF THE EASTERN WATERS. THE SOUTH WIND WILL TRANSPORT INCREASING
HUMIDITY WITH DEW POINTS AT LEAST IN THE 40S. AS THIS MOVES OVER
38 DEGREE WATER IT MAY GENERATE LOW VSBYS IN FOG ACROSS THE
WATERS...ESPECIALLY SOUTH OF NEW ENGLAND.

THURSDAY AND THURSDAY NIGHT...INCREASING SOUTHWEST WINDS WITH
FREQUENT GUSTS 25-30 KNOTS. THIS WILL BUILD SEAS WITH 5-10 FOOT
HEIGHTS EXPECTED ON THE EXPOSED WATERS INCLUDING RI SOUND. HEIGHTS
ON THE OUTER WATERS COULD REACH 11 TO 13 FEET AT TIMES. VSBYS WILL
REMAIN LOW IN RAIN AND FOG. A COLD FRONT APPROACHES THE WATERS
OVERNIGHT THURSDAY NIGHT.

OUTLOOK...FRIDAY THROUGH SUNDAY...

MODERATE TO HIGH CONFIDENCE FRIDAY. MODERATE CONFIDENCE FRIDAY NIGHT
INTO SUNDAY.

FRIDAY...WINDS SHIFT TO NW DURING THE DAY AS COLD FRONT PASSES.
BUILDING SEAS WILL SLOWLY BEGIN TO SUBSIDE BY FRIDAY NIGHT. GUSTY
WINDS LOW END GALES WILL ALSO BEGIN TO DISSIPATE AS THE FRONT PASSES
THROUGH.

FRIDAY NIGHT INTO SUNDAY...HIGH PRESSURE WILL SLIDE SOUTH OF THE
REGION FRIDAY NIGHT/SATURDAY ALLOWING FOR THE WIND AND SEAS TO BEGIN
TO SUBSIDE. THIS MAY TAKE SOME TIME AS WE COULD SEE LINGERING SCA
WIND GUSTS THANKS TO CAA. SCA MAY BE NEEDED FOR THE WHOLE PERIOD.

&&

.HYDROLOGY...
CONTINUE TO NOTE GOOD AMOUNT OF RAINFALL WILL MOVE ACROSS THE
REGION...AS WELL AS TEMPERATURES RISING TO THE UPPER 40S TO MID
50S ALONG WITH INCREASING DEWPTS /AT LEAST TO THE 40S/ THURSDAY
INTO FRIDAY. THIS WILL COMBINE TO CAUSE SIGNIFICANT SNOW MELT
ACROSS THE REGION.

EXPECT RAINFALL AMOUNTS TO RANGE FROM 0.5 TO 1 INCH ACROSS THE
REGION...POSSIBLY 1.25 IN SPOTS. HIGHEST VALUES WILL BE ACROSS
NORTHERN AND WESTERN MASS AND CT. HOWEVER...WITH MILDER
TEMPS...WILL SEE A BIG WATER RELEASE WITH THE SNOW TO WATER
EQUIVALENT /SWE/ ON ORDER OF 2-5 INCHES. MAY ALSO SEE SOME HEAVIER
DOWNPOURS OVERNIGHT THU INTO FRI MORNING ESPECIALLY IF ANY
CONVECTION DEVELOPS.

COMBINING THE RAPID SNOW MELT WITH THE UPCOMING QPF...MAY SEE 1.5
TO 3 INCHES OF WATER FLOWING INTO AREA RIVERS AND STREAMS. SEVERAL
OF THE MAIN STEM RIVER LEVELS MAY APPROACH ACTION STAGE DURING
FRIDAY...WITH A COUPLE POSSIBLY APPROACHING MINOR FLOOD STAGE.
CURRENT FORECASTS ISSUED BY THE NORTHEAST RIVER FORECAST CENTER
HAVE THE DETAILS.

CONTINUE TO MONITOR FORECAST UPDATES FOR MORE DETAILS ON THIS
EVENT.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO NOON EDT
     THURSDAY FOR ANZ250-254.

&&

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



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