Area Forecast Discussion
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000
FXUS61 KBOX 300603
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
103 AM EST FRI JAN 30 2015

.SYNOPSIS...
A CLIPPER LOW PRESSURE WILL MOVE INTO THE GREAT LAKES TONIGHT
WITH A SECONDARY LOW DEVELOPING ALONG THE SOUTHERN NEW ENGLAND
COAST AND INTENSIFYING OVER THE GULF OF MAINE FRIDAY INTO FRIDAY
EVENING BRINGING WITH IT A PERIOD OF SNOW FOR THE FORECAST AREA.
BLUSTERY AND VERY COLD CONDITIONS ARE EXPECTED THIS WEEKEND.
WATCHING FOR THE POTENTIAL OF NOREASTERS NEXT WEEK...ONE POSSIBLE
SUNDAY NIGHT INTO MONDAY AND ANOTHER POSSIBLE WEDNESDAY NIGHT
INTO THURSDAY. LOW CONFIDENCE ON BOTH.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
1 AM UPDATE...
AREAS OF LIGHT SNOW OVERSPREADING SNE...BUT SOMEWHAT STEADIER
PRECIP WILL BE MOVING IN FROM THE WEST OVERNIGHT. VSBYS UPSTREAM
GENERALLY 1-2SM SO MAINLY LIGHT SNOW. NO CHANGES TO PREVIOUS
FORECAST. ACCUM BY MORNING WILL BE AN INCH OR 2 IN THE WEST WITH A
COATING TO LESS THAN AN INCH IN THE EAST.

PREVIOUS DISCUSSION...
00Z ALY SOUNDING STILL VERY DRY IN LOW LEVELS SO DESPITE LIGHT
REFLECTIVITY MOVING ACROSS SNE...PRECIP IS MOSTLY ALOFT. NAM
SHOWS LOW LEVELS MOISTENING 03-06Z. EXPECT LIGHT SNOW DEVELOPING
03-06Z WESTERN HALF NEW ENG AND 06-10Z IN THE EAST.

LATEST NAM/RAP ARE SLIGHTLY COOLER IN THE LOW LEVELS AND WITH
GENERALLY LIGHT WINDS NOT ALLOWING MUCH ADVECTION OF WARMER SFC
TEMPS AWAY FROM THE ISLANDS...EXPECT A MIX OF RAIN/SNOW TO BE
CONFINED TO CAPE/ISLANDS TOWARD DAYBREAK...WITH MOSTLY RAIN ON
THE ISLANDS WHERE SOUTHERLY WINDS WILL BE A BIT STRONGER.

AN INCH OR TWO IS POSSIBLE BY DAYBREAK ACROSS CT/WESTERN-CENTRAL
MA TO A DUSTING TO LESS THAN AN INCH OVER RI AND EASTERN MA.

CALM WINDS AND RADIATIONAL COOLING HAS ALLOWED TEMPS TO FALL TO
UPPER TEENS TO LOWER 20S ACROSS PORTION OF SE COASTAL MA AND CAPE
COD/MVY. TEMPS WILL RISE QUICKLY INTO THE 30S ON THE ISLANDS WHEN
S WINDS INCREASE. NOTE BID IS 34 WITH A S WIND 10 KTS.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
*** PLOWABLE SNOWFALL LIKELY FOR MUCH OF NORTH-NORTHEAST MA ***

FORECAST WAS BASED ON A MODEL BLEND GIVEN GOOD CLUSTERING AMONGST
THE MODELS REGARDING THEIR MASS FIELDS...QPF AND THERMAL.

AMPLIFYING NORTHERN STREAM TROUGH TAKES ON A NEGATIVE TILT LATE FRI
AND THEN EVOLVES INTO A CLOSED MID LEVEL OVER SOUTHERN NEW ENGLAND.
THIS STRONG FORCING ALOFT RESULTS IN PARENT LOW OVER NY STATE
FADING/FILLING AND GIVING WAY TO CYCLOGENESIS ALONG OR JUST OFF THE
SOUTHERN NEW ENGLAND COAST FRI. THIS ROBUST MID/UPPER TROUGH RESULTS
IN SECONDARY LOW PRES DEEPENING TO ABOUT 985 MB OVER THE WESTERN
GULF OF MAINE 12Z SAT. IN ADDITION THE MID/UPPER LOW CAPTURES THE
SURFACE CYCLONE AND PULLS IT BACK BRIEFLY TOWARD EASTERN MA
COASTLINE LATE FRI NIGHT INTO SAT. THIS SLOWS THE SYSTEM DOWN AND
RESULTS IN A ROBUST COMMA-HEAD DEVELOPING FRI NIGHT OVER NORTHEAST
MA POSSIBLY WESTWARD INTO WORCESTER COUNTY.

AS MID LEVEL TROUGH TRANSITIONS FROM AN OPEN WAVE TO A CLOSED
CIRCULATION FRI NIGHT OVER EASTERN MA A MODEST SNOW BAND WILL LIKELY
DEVELOP. ALSO UNCERTAINTY ON EXACTLY WHERE THESE BANDS SETUP AND
INTENSITY. HOWEVER MODEL CONSENSUS QPF YIELDS 0.5-0.6 INCHES OVER
NORTHEAST MA...POSSIBLY WESTWARD INTO WORCESTER COUNTY. THEREFORE
HAVE UPGRADED TO A WINTER STORM WARNING FOR ESSEX AND MIDDLESEX
COUNTIES. LATER SHIFTS MAY HAVE TO EXPAND THE WARNING WESTWARD INTO
WORCESTER COUNTY PENDING 00Z MODEL TRENDS. GIVEN THE BANDING
SIGNATURE AND MODEL CONSENSUS QPF EXPANDED ADVISORIES INTO SOUTHERN
WORCESTER/NORTHEAST CT/NORTHERN RI INTO NORTHERN BRISTOL COUNTY OF
MA FOR 2-4 INCHES OF SNOWFALL.

THOUGHT PROCESS WAS SNOWFALL MAY FALL JUST SHORT OF WARNING AND/OR
ADVISORY CRITERIA BUT REALIZING ANY ADDITIONAL SNOWFALL WILL BE
PROBLEMATIC REGARDING SNOW REMOVAL ESPECIALLY IN THE URBAN AREAS
THAT RECEIVED 30+ EARLIER THIS WEEK. ALSO ADDITIONAL SNOWFALL MAY
RESULT IN SNOW LOAD/STRESS TO ROOFS. THEREFORE OUR WARNINGS AND
ADVISORIES ARE SOMEWHAT BASED ON IMPACTS TOO.

PTYPE...ALL SNOW MOST OF THE AREA EXPECT SOUTH COAST OF MA AND RI
INCLUDING CAPE COD AND THE ISLANDS WHERE RAIN OR A RAIN/SNOW CHANGES
BACK TO ALL SNOW FRI EVENING.

FOG? MAY NEED TO MONITOR FOR THE POTENTIAL OF WARM/MOIST AIR OVER
THE DEEPER SNOWPACK TO RESULT IN DENSE GROUND FOG. AREAS ACROSS
E/SE MA WHICH SAW CONSIDERABLE AMOUNTS OF SNOW WOULD /CLIMATOLOGICALLY-
SPEAKING/ EXPECT TO BE SOCKED IN CONDITIONS WHEN A WARM/HUMID
AIRMASS SPREADS ACROSS THE REGION. WILL HAVE TO MONITOR CLOSELY.

IN ADDITION TO THE SNOWFALL FRI NIGHT NORTH AND EVENTUALLY NORTHWEST
WINDS WILL INCREASE TO 35 TO 45 MPH AS LOW INTENSIFIES EAST OF MA.
DANGEROUSLY COLD WIND CHILLS OF 10 TO 20 BELOW ZERO IN HIGHER
TERRAIN OF CENTRAL AND W MA...WITH 5 TO 10 BELOW IN THE COASTAL
PLAIN. WIND CHILL ADVISORIES MAY BE NEEDED FOR HIGHER TERRAIN IN
CENTRAL AND W MA. LOOKS BORDERLINE SO DID NOT HOIST ANY HEADLINES
THERE. LATER SHIFTS WILL NEED TO REEVALUATE.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
HEADLINES...

* SNOW ENDS ACROSS EASTERN AREAS EARLY SATURDAY FOLLOWED BY ARCTIC
  HIGH PRESSURE FOR THE REST OF THE WEEKEND
* WATCHING FOR POTENTIAL NOREASTERS NEXT WEEK

AN ACTIVE WEATHER PATTERN WILL CONTINUE ACROSS SOUTHERN NEW ENGLAND.
OCEAN STORM OFF THE MAINE COAST ON SATURDAY WILL EXIT TO THE EAST...
BRINGING AN END TO ANY SNOWFALL ACROSS COASTAL LOCALES SATURDAY
MORNING. IMPROVING CONDITIONS WILL OCCUR DURING THE DAY ON A
BLUSTERY NW WIND FLOW AS A COLD AIRMASS MOVES INTO NEW ENGLAND FROM
CANADA. THIS WILL ENSURE A VERY COLD WEEKEND WITH TEMPS RUNNING WELL
BELOW AVERAGE.

THE SYNOPTIC PATTERN NEXT WEEK WILL FEATURE SHORTWAVES DIVING INTO
THE UPPER MIDWEST AND ACROSS NEW ENGLAND. THIS WILL ALLOW FOR
POTENTIAL NOREASTERS TO DEVELOP. HOWEVER, MUCH WILL DEPEND ON HOW
SHARP THE TROUGHS BECOME...WHETHER THEY BECOME NEGATIVELY TILTED AND
PHASE OR NOT WITH SOUTHERN STREAM ENERGY.

THERE HAVE BEEN MODEL DIFFERENCES FROM BOTH GFS/ECMWF IN TERMS OF
THE STRENGTH AND TRACK OF THE LOWS SO WILL FOLLOW A BLENDED MODEL
APPROACH. THE TIMING OF THESE POTENTIAL SYSTEMS LOOKS TO BE SUNDAY
NIGHT AND MONDAY AND AGAIN WEDNESDAY NIGHT THROUGH THURSDAY. THESE
ARE THE PERIODS TO MONITOR FOR POTENTIAL HIGH IMPACTS TO THE AREA.
WHETHER OR NOT WE RECEIVE SIGNIFICANT ADDITIONAL SNOWFALL OR THESE
OCEAN STORMS MISS US TO THE EAST IS JUST TOO TOUGH TO SAY WITH ANY
DEGREE OF CONFIDENCE. SO STAY TUNED.

FOR THE SUN NIGHT-MONDAY LOW...BOTH THE OPERATIONAL 29.12Z GFS AND
ECMWF RUNS HAVE THE LOW CENTER PASSING JUST OUTSIDE THE BENCHMARK
WHICH WOULD MEAN A GLANCING BLOW TO SOUTHEASTERN NEW ENGLAND...BUT
STILL A PLOWABLE SNOWFALL TO EASTERN AREAS. HOWEVER, A FEW ENSEMBLE
MEMBERS ARE FURTHER NORTHWEST WITH THE LOW TRACK...SO A MORE
SIGNIFICANT IMPACT IS A POSSIBILITY...AS IS NO IMPACT IF THE LOW
WERE TO TRACK EVEN FURTHER OFF SHORE. THE FIRST RUNS OF THE
OPERATIONAL ECMWF FOR THE BLIZZARD OF 2015 DIDN`T SHOW MAJOR IMPACTS
TO NEW ENGLAND UNTIL 72 HR IN ADVANCE OF THE EVENT. WE ARE STILL
OUTSIDE OF THIS WINDOW...SO LOTS CAN CHANGE.

TUESDAY WILL BE A LULL DAY IF THE AFOREMENTIONED LOW IMPACTS NEW
ENGLAND. THEN WE LOOK TO YET ANOTHER POTENTIAL OCEAN STORM MID
WEEK...WITH MODELS CENTERING ON THE WED NIGHT-THU TIMEFRAME. THE
29.12Z OPERATIONAL ECMWF IS AGGRESSIVE WITH THIS LOW...SLAMMING
HEAVY SNOWS OVER THE INTERIOR WITH A SNOW TO RAIN SCENARIO FOR THE
COAST. HOWEVER, THE GFS DOES NOT PHASE THE NORTHERN AND SOUTHERN
STREAMS...SO IS PROGRESSIVE AND SHOWS MINIMAL IMPACTS. SO USED A
MODEL BLEND AND...ONCE AGAIN...TOO EARLY TO BANK ON EITHER A HIT OR
A MISS. CERTAINLY A LOT TO MONITOR CLOSELY IN THE DAYS AHEAD!

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM...THROUGH SATURDAY...MODERATE CONFIDENCE.

THROUGH 12Z...LIGHT SNOW OVERSPREADING THE REGION WITH CONDITIONS
LOWERING TO MVFR/IFR. SNOW MIXING WITH OR CHANGING TO RAIN
CAPE/ISLANDS TOWARD DAYBREAK.

TODAY...MVFR/IFR IN AREAS OF SNOW...WITH RAIN CAPE/ISLANDS.
SNOW TAPERS OFF AND ENDS CT VALLEY TO THE RI COAST DURING THE
AFTERNOON WITH MAINLY MVFR CIGS...BUT PERIODS OF SNOW CONTINUE
CENTRAL AND E MA. GUSTY NW WINDS TO 25 KT DEVELOPING CT VALLEY BY
LATE AFTERNOON.

TONIGHT...MAIN FOCUS FOR AREAS OF SNOW AND MVFR/IFR CONDITIONS
WILL BE ACROSS E MA...WITH VFR CT VALLEY. GUSTY NW WINDS DEVELOP
FROM WEST TO EAST IN THE EVENING WITH GUSTS TO 30-35 KT AFTER
MIDNIGHT.

SATURDAY...LINGERING MVFR/IFR IN AREAS OF LIGHT SNOW ACROSS E MA
AND CAPE/ISLANDS EARLY...OTHERWISE IMPROVING TO VFR WITH CLEARING
SKIES FROM WEST TO EAST. GUSTY NW WINDS TO 35 KT.

KBOS TAF...MODERATE CONFIDENCE. A PERIOD OF IFR IN SNOW POSSIBLE

KBDL TAF...MODERATE CONFIDENCE.

OUTLOOK /SATURDAY NIGHT THROUGH MONDAY/...

SATURDAY NIGHT-SUNDAY...HIGH CONFIDENCE. VFR. NW WINDS GUSTING TO
25-35 KNOTS SATURDAY...HIGHEST ALONG THE COAST. LIGHTER WINDS
SUNDAY.

SUNDAY NIGHT-MONDAY...LOW CONFIDENCE. LOW PRES DEVELOPS S OF THE
REGION...BUT TRACK REMAINS UNCERTAIN. TOO EARLY TO HAVE ANY
CONFIDENCE ON VFR OR IFR THIS PERIOD.

TUESDAY...MODERATE CONFIDENCE. IF LOW IMPACTS THE TERMINALS MONDAY,
CONDITIONS WOULD BE IMPROVING ON TUE.

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

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

SHORT TERM /THROUGH FRIDAY/...HIGH CONFIDENCE.

7 PM UPDATE...NO MAJOR CHANGES.

TONIGHT...INCREASING SOUTHERLY WINDS EXPECTED AHEAD OF LOW PRES
MOVING THROUGH THE GREAT LAKES...BUT WIND GUSTS SHOULD REMAIN BELOW
SCA.

FRIDAY...SOUTHERLY WINDS WILL SHIFT TO W THEN NW DURING FRI
AFTERNOON...WITH GUSTS TO 25-30 KT DEVELOPING ACROSS RI COASTAL
WATERS BY LATE AFTERNOON.

FRI NIGHT...LOW PRES INTENSIFIES OVER WESTERN GULF OF MAINE WITH
WIDESPREAD NNW GALES. SNOW REDUCES VSBY AS WELL.

OUTLOOK /SATURDAY THROUGH MONDAY/...MODERATE CONFIDENCE

SATURDAY NIGHT...WINDS AND SEAS WILL DIMINISH AS LOW PRESSURE
DEPARTS THE AREA.

SUNDAY...EXPECT WINDS TO DIMINISH BUT REMAIN AT SMALL CRAFT
LEVELS...THOUGH SOME GALE GUSTS MAY LINGER ON THE EASTERN OUTER
WATERS EARLY. SEAS WILL SLOWLY SUBSIDE...BUT WILL REMAIN AOA 5 FT
ON THE OUTER WATERS.

SUNDAY NIGHT-TUESDAY...HIGHLY DEPENDENT ON STRENGTH AND TRACK OF
DEVELOPING LOW PRESSURE SOUTH OF THE REGION AND THUS A LOW
CONFIDENCE FORECAST. WORSE CONDITIONS WOULD BE MONDAY WITH SLOW
IMPROVEMENT ON TUESDAY.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER WEATHER ADVISORY UNTIL 6 AM EST SATURDAY FOR CTZ004.
MA...WINTER WEATHER ADVISORY UNTIL 6 AM EST SATURDAY FOR MAZ004-012-
     013-015>019.
     WINTER STORM WARNING UNTIL 6 AM EST SATURDAY FOR MAZ005>007-
     014-026.
RI...WINTER WEATHER ADVISORY UNTIL 6 AM EST SATURDAY FOR RIZ001.
MARINE...GALE WARNING FROM MIDNIGHT TONIGHT TO 6 PM EST SATURDAY FOR
     ANZ230>234-251.
     GALE WARNING FROM 2 AM TO 1 PM EST SATURDAY FOR ANZ236.
     GALE WARNING FROM 9 PM THIS EVENING TO 6 PM EST SATURDAY FOR
     ANZ235-237.
     GALE WARNING FROM 11 PM THIS EVENING TO 6 PM EST SATURDAY FOR
     ANZ250-254-255.
     GALE WARNING FROM 7 PM THIS EVENING TO 6 PM EST SATURDAY FOR
     ANZ256.

&&

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


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