Tuesday, February 27, 2007

Major winter storm becoming more likely

The storm potential is looking better and better for Thursday Night through Friday Night. The latest NWS zone forecast has added the enhanced wording, "heavy snow accumulation" for Thursday Night AND "moderate snow accumulation" for Friday! One thing will be certain with this storm: very high QPF, maybe even higher than the Valentine's Day storm earlier this month.

Confidence levels:
>0.50" QPF ... 95%
>1.00" QPF ... 90%
>2.00" QPF ... 50%
>1.0" Snow ... 95%
>6.0" Snow ... 75%
>12.0" Snow ... 45%
>0.10" Icing ... 85%
>0.25" Icing ... 65%
>0.50" Icing ... 40%

If we get a colder solution with this storm (going with 15:1 snow ratios), we could get two feet easily. This will not happen, but with 12:1 snow ratios Thursday Night, before the change over, we could pick up a quick 6 inches of snow, and then a quarter inch of icing on top.

Special Weather Statement:

Special Weather Statement


SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TAUNTON MA
339 PM EST TUE FEB 27 2007

CTZ002>004-MAZ002>024-026-NHZ011-012-015-RIZ001>008-280930-
HARTFORD CT-TOLLAND CT-WINDHAM CT-WESTERN FRANKLIN MA-
EASTERN FRANKLIN MA-NORTHERN WORCESTER MA-CENTRAL MIDDLESEX MA-
WESTERN ESSEX MA-EASTERN ESSEX MA-WESTERN HAMPSHIRE MA-
WESTERN HAMPDEN MA-EASTERN HAMPSHIRE MA-EASTERN HAMPDEN MA-
SOUTHERN WORCESTER MA-WESTERN NORFOLK MA-SOUTHEAST MIDDLESEX MA-
SUFFOLK MA-EASTERN NORFOLK MA-NORTHERN BRISTOL MA-
WESTERN PLYMOUTH MA-EASTERN PLYMOUTH MA-SOUTHERN BRISTOL MA-
SOUTHERN PLYMOUTH MA-BARNSTABLE MA-DUKES MA-NANTUCKET MA-
NORTHERN MIDDLESEX MA-CHESHIRE NH-EASTERN HILLSBOROUGH NH-
WESTERN AND CENTRAL HILLSBOROUGH NH-NORTHWEST PROVIDENCE RI-
SOUTHEAST PROVIDENCE RI-WESTERN KENT RI-EASTERN KENT RI-
BRISTOL RI-WASHINGTON RI-NEWPORT RI-BLOCK ISLAND RI-
INCLUDING THE CITIES OF...HARTFORD...WINDSOR LOCKS...UNION...
VERNON...PUTNAM...WILLIMANTIC...CHARLEMONT...GREENFIELD...
ORANGE...BARRE...FITCHBURG...FRAMINGHAM...LOWELL...LAWRENCE...
GLOUCESTER...CHESTERFIELD...BLANDFORD...AMHERST...NORTHAMPTON...
SPRINGFIELD...MILFORD...WORCESTER...FOXBORO...NORWOOD...
CAMBRIDGE...BOSTON...QUINCY...TAUNTON...BROCKTON...PLYMOUTH...
FALL RIVER...NEW BEDFORD...MATTAPOISETT...CHATHAM...FALMOUTH...
PROVINCETOWN...VINEYARD HAVEN...NANTUCKET...AYER...JAFFREY...
KEENE...MANCHESTER...NASHUA...PETERBOROUGH...WEARE...FOSTER...
SMITHFIELD...PROVIDENCE...WEST GREENWICH...WARWICK...BRISTOL...
NARRAGANSETT...WESTERLY...NEWPORT...BLOCK ISLAND
339 PM EST TUE FEB 27 2007

...A POTENTIALLY SIGNIFICANT WINTER STORM MAY AFFECT INTERIOR
SOUTHERN NEW ENGLAND THURSDAY NIGHT AND FRIDAY...

SNOW IS EXPECTED TO OVERSPREAD SOUTHERN NEW ENGLAND THURSDAY
NIGHT...AS LOW PRESSURE FORMS OVER THE MID ATLANTIC REGION.

SEVERAL INCHES OF SNOW MAY ACCUMULATE BY DAYBREAK FRIDAY...MAINLY TO
THE NORTHWEST OF THE PROVIDENCE TO BOSTON INTERSTATE 95 CORRIDOR.
CLOSER TO THE COAST...SNOW SHOULD MIX WITH OR CHANGE TO RAIN BY
SUNRISE FRIDAY AFTER A FEW INCHES OF ACCUMULATION.

THE MOST LIKELY SCENARIO TAKES THE LOW PRESSURE CENTER NEAR
PROVIDENCE AND BOSTON FRIDAY AFTERNOON AND EVENING. THIS WILL BRING
MILDER AIR INTO MUCH OF THE REGION...CAUSING AN EVENTUAL CHANGE TO
RAIN AS FAR INLAND AS SPRINGFIELD...WORCESTER AND LAWRENCE LATE
FRIDAY AFTERNOON. HOWEVER...THERE WOULD BE A TRANSITION FROM SNOW TO
SLEET AND FREEZING RAIN BEFORE THE CHANGEOVER TAKES PLACE.

THE CHANGE TO RAIN SHOULD OCCUR MORE QUICKLY FROM PROVIDENCE AND
BOSTON TO THE SOUTH COAST FRIDAY MORNING...RESULTING IN LOWER
SNOWFALL TOTALS.

AS A RESULT...THERE IS THE POTENTIAL FOR SIGNIFICANT ACCUMULATIONS
OF SNOW AND POSSIBLY ICE ACROSS THE INTERIOR. THIS IS ESPECIALLY TRUE
FROM THE ROUTE 2 CORRIDOR IN NORTHERN MASSACHUSETTS INTO SOUTHWEST
NEW HAMPSHIRE...WHERE THE HIGHEST TOTALS ARE CURRENTLY EXPECTED.

THE FRIDAY MORNING COMMUTE MAY BE AFFECTED BY SNOW...OR A COMBINATION
OF SNOW...SLEET AND FREEZING RAIN AWAY FROM THE COAST.

KEEP IN MIND THERE IS UNCERTAINTY AS TO THE TRACK OF THIS POTENTIAL
WINTER STORM. A MORE INLAND TRACK WOULD LESSEN THE POSSIBILITY OF
SIGNIFICANT SNOW AND ICE ACCUMULATIONS IN SOUTHERN NEW ENGLAND...
WHILE A MORE OFFSHORE TRACK WOULD BRING HIGHER SNOWFALL TOTALS ONTO
THE COASTAL PLAIN.

PEOPLE IN SOUTHERN NEW ENGLAND SHOULD STAY TUNED TO NOAA ALL HAZARDS
WEATHER RADIO OR YOUR LOCAL MEDIA FOR LATER FORECASTS ON THIS
DEVELOPING WEATHER SITUATION. YOU CAN ALSO VISIT THE NATIONAL
WEATHER SERVICE TAUNTON WEBSITE AT WEATHER.GOV/BOSTON FOR MORE
INFORMATION.

$$

JWD/MLE



Taunton NWS Area Forecast Discussion:
000
FXUS61 KBOX 271938
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
238 PM EST TUE FEB 27 2007

...BENIGN WEATHER BEFORE A POTENTIALLY SIGNIFICANT SYSTEM IMPACTS
SOUTHERN NEW ENGLAND THU NIGHT AND FRI...

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
FAIRLY SHARP EDGE TO CLOUD DECK ACROSS MERRIMACK VALLEY OF SW NH AND
NE MA AND INTO IMMEDIATE BOSTON AREA THIS AFTERNOON...EVEN ONTO CAPE
COD AS WELL. THIS CLEARING HAS BEEN PUSHING S DURING PAST FEW
HOURS... AND WE EXPECT IT TO EDGE A LITTLE FARTHER S THROUGH EARLY
EVENING BEFORE CLOUDS FILL BACK IN BY MIDNIGHT AS LOW LEVEL MOISTURE
REMAINS HIGH AND BECOMES TRAPPED BENEATH INVERSION.

ELSEWHERE...CLOUDINESS IS LOCKED IN FAIRLY WELL BUT AREA OF LIGHT
SNOW WHICH AFFECTED CT/RI AND ADJACENT PARTS OF WESTERN/CENTRAL MA
HAVE DIMINISHED TO FLURRIES. MUCH OF THIS IS VERY SHALLOW AND NOT
BEING DETECTED WELL BY RADAR...BUT COMPOSITE REFLECTIVITY ON KENX AND
KBOX ARE SHOWING SOME RETURNS IN CLEAR AIR MODE COMING OVER
BERKSHIRES AND INTO NORTHERN CT.

12Z MODELS INDICATE LITTLE CHANGE IN OVERALL PATTERN TONIGHT INTO
WED MORNING. A SERIES OF WEAK MID LEVEL SHORT WAVES WILL MOVE
THROUGH REGION...IN CONCERT WITH A WEAK SURFACE LOW WHICH WILL
PROVIDE SOME ADDED LOW LEVEL CONVERGENCE...ESPECIALLY TO RI AND SE
MA AS IT TRACKS JUST S OF NEW ENGLAND. WHILE ANY LIFT IS CERTAINLY
WEAK...IT WILL BE ABLE TO ACT UPON A NEARLY SATURATED AIRMASS AND
PRODUCE SCATTERED FLURRIES OVER MOST OF REGION...ESPECIALLY ALONG
AND S OF MASS TURNPIKE. WE MAY SEE SOME BRIEFLY HEAVIER SNOW SHOWERS
GIVE A DUSTING OF SNOW TO LOCATIONS NEAR S COAST AND ISLANDS
OVERNIGHT...GENERALLY WHERE NAM/GFS SHOW A FEW HUNDREDTHS OF
QPF...BUT CONFIDENCE ON THAT OCCURRING IS LOW.

HIGH PRESSURE WILL BEGIN TO BUILD INTO SOUTHERN NEW ENGLAND WED.
SUBSIDENCE AND DRYING WILL BRING CLEARING TO CT VALLEY TOWARD MIDDAY
AND TO COASTAL PLAIN WED AFTERNOON. MOSTLY CLEAR SKIES EXPECTED WED
NIGHT AS RIDGE BUILDS OVERHEAD.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
POTENTIALLY POTENT STORM SYSTEM TO AFFECT SOUTHERN NEW ENGLAND
THURSDAY NIGHT INTO FRIDAY. ALL 12Z GLOBAL/REGION MODELS AS WELL AS
THE GFS ENSEMBLE ARE IN GOOD AGREEMENT WITH BRINGING A STRONG
PRIMARY LOW UP INTO THE GREAT LAKES STATES THURSDAY. SECONDARY LOW
PRESSURE WILL THEN FORM AT THE TRIPLE POINT OVER THE MID ATLANTIC
STATES THURSDAY NIGHT. THIS SECONDARY LOW IS REASONABLY WELL-PROGGED
BY THE MODELS THE MOVE QUICKLY ACROSS SOUTHERN NEW ENGLAND BY FRIDAY
EVENING.

THIS WILL MEAN A SNOW CHANGING TO MIXED PRECIPITATION/RAIN SCENARIO
FOR ALL OF SOUTHERN NEW ENGLAND...ALL STARTING THURSDAY NIGHT. THIS
COULD POTENTIALLY BE A PRETTY BIG QPF EVENT AS LOW LEVEL JET
DYNAMICS LOOK QUITE GOOD THURSDAY NIGHT INTO FRIDAY. ATLANTIC
MOISTURE WILL QUICKLY BE TRANSPORTED NORTHWARD BY THIS LOW LEVEL JET
ON FAIRLY STEEP THETA SURFACES. THIS WILL AID IN THE FORMATION OF
HEAVY PRECIPITATION DURING THURSDAY NIGHT INTO FRIDAY.

PRECIP TYPE IS THE BIG QUESTION HERE. WE'RE FAIRLY CERTAIN ALL OF
SOUTHERN NEW ENGLAND WILL START AS SNOW THURSDAY NIGHT AS THE COLUMN
SHOULD BE COLD ENOUGH. HOWEVER...THE LOW TRACK AND INTENSITY OF THE
SOUTHERLY LOW LEVEL JET SHOULD ALLOW FOR A PRETTY QUICK CHANGE TO
MIXED PRECIPITATION AS WELL AS PLAIN RAIN FROM SOUTH TO NORTH BY
EARLY FRIDAY MORNING.

OMEGA VALUES COULD BE HIGH ENOUGH THAT ALL AREAS SEE A PRETTY GOOD
THUMP OF SNOW BEFORE THE CHANGEOVER. NORTHERN ZONES WILL SEE THE
MOST SNOW...QUITE POSSIBLY WINTER STORM WARNING CRITERIA...BY
SOMETIME FRIDAY MORNING BEFORE THE PRECIP CHANGES OVER TO RAIN/SLEET
OR FREEZING RAIN. FURTHER SOUTH...AT LEAST A FEW INCHES OF SNOW
WILL BE POSSIBLE ALONG THE I-95 CORRIDOR BEFORE THE CHANGEOVER.

ALL IN ALL...FRIDAY MORNING'S RUSH HOUR LOOKS TO BE QUITE MESSY
EVERYWHERE...AS A PLETHORA OF PRECIP TYPES WILL BE POSSIBLE. WE'RE
STILL 2.5 TO 3 DAYS OUT FROM THIS EVENT...SO ANY CHANGE IN LOW TRACK
WILL MAKE A DIFFERENCE IN PRECIP TYPES AND TIMING OF ONSET AND
CHANGEOVER. WENT WITH CAT POPS FOR ALL AREAS LATE THURS NITE AND FRI.

WILL HAVE TO WATCH LOW LEVEL WINDS DURING THE DAY ON FRIDAY FOR THE
SOUTH COAST/CAPE/ISLANDS. USUALLY THE STRONG SOUTHERLY LLJ WON'T MIX
DOWN DUE TO THE COLD OCEAN WATERS...BUT THIS WILL HAVE TO BE WATCHED
NONETHELESS.

THE STEADY PRECIP CUTS OFF BY LATE IN THE DAY FRIDAY AS THE MAIN
MECHANISMS FOR FORCING MOVE OFFSHORE. THERE STILL COULD BE SOME
LIGHT PRECIP FRIDAY NIGHT AND SATURDAY AS PRIMARY LOW ATTEMPTS TO
MOVE THROUGH.


&&

.AVIATION /19Z-18Z/...
18Z TAFS KEEP LOWEST CEILINGS /MVFR/ OVER KBAF/KORH/KBDL TERMINAL
AREAS INTO WED MORNING BEFORE LIFTING TO VFR TOWARD MIDDAY.
ELSEWHERE VFR CEILINGS WILL PERSIST THROUGH TONIGHT...WITH AREAS OF
MVFR CEILINGS ESPECIALLY NEAR CAPE COD AND ISLANDS. VFR CEILINGS
EXPECTED TO PREVAIL THROUGH MIDDAY WED.

SCATTERED FLURRIES ARE EXPECTED TONIGHT ALONG AND S OF MASS TURNPIKE
BUT WERE ONLY INCLUDED IN KHYA/KACK TAFS WHERE CONFIDENCE IS HIGHEST.
IT IS ALSO POSSIBLE THAT BRIEFLY HEAVIER SNOW SHOWERS WILL AFFECT
THESE TERMINALS 06Z-12Z WED WITH VSBY 4-5SM...BUT PROBABILITY ON THAT
OCCURRENCE IS LOW.

LIGHT AND VARIABLE WINDS EXPECTED THROUGHOUT REGION INTO
WED...THOUGH WE SHOULD SEE MORE OF A LIGHT W/NW COMPONENT WED
MORNING AS WEAK LOW PRESSURE HEADS OFFSHORE.

OUTLOOK 18Z WED TO 12Z THU... VFR. CLEARING IS EXPECTED TO TAKE HOLD
LATE WED AFTERNOON AND WED EVENING AS HIGH PRESSURE BUILDS INTO NEW
ENGLAND WITH PREVAILING NW WINDS 10KT OR LESS.

&&

.MARINE...
WE EXTENDED SMALL CRAFT ADVISORY FOR SEAS ON OUTER SE WATERS THROUGH
MIDNIGHT...AS SOUTHERLY SWELL KEEPS SEAS A BIT HIGHER THAN WHAT 12Z
WAVEWATCH INDICATES. OTHERWISE LIGHT WINDS AND FLAT SEAS EXPECTED
THROUGH WED NIGHT AS A RIDGE OF HIGH PRESSURE BUILDS INTO SOUTHERN
NEW ENGLAND.

LOW PRESSURE WILL APPROACH FROM THE SOUTHWEST ON THURSDAY NIGHT AND
MOVE JUST NORTH OF THE LOCAL WATERS DURING THE DAY ON FRIDAY. THIS
WILL MEAN BUILDING WINDS AND SEAS THURSDAY NIGHT AND FRIDAY. GALE
FORCE WINDS WILL BE POSSIBLE...ESPECIALLY ON OUTER WATERS DURING
THIS TIME FRAME. SOUTHWESTERLY/WESTERLY WINDS BEHIND THE SYSTEM
FRIDAY NIGHT THROUGH THE WEEKEND WILL LIKELY BE IN THE SMALL CRAFT
RANGE.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL MIDNIGHT EST
TONIGHT FOR ANZ254-255.

&&

$$

SHORT TERM...JWD
LONG TERM...EKSTER
AVIATION...JWD
MARINE...JWD/EKSTER

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