765 
FXUS61 KBOX 110836
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
336 AM EST FRI JAN 11 2013

...UPDATES TO THE NEAR- AND SHORT-TERM FORECASTS...

.SYNOPSIS...

SHOWERS ALONG WITH POCKETS OF FREEZING RAIN WILL ACCOMPANY AN AREA
OF LOW PRESSURE SLIDING SOUTH OF NEW ENGLAND LATE TODAY INTO
SATURDAY. UNSEASONABLE MILD WEATHER WILL FOLLOW SUNDAY INTO
MONDAY. A COLD FRONT WILL CROSS THE REGION LATE MONDAY INTO MONDAY
NIGHT WITH THE RETURN OF MORE SEASONABLE TEMPERATURES. A WAVE OF
LOW PRESSURE MAY BRING SOME RAIN OR WINTRY PRECIPITATION TO THE
REGION TUESDAY INTO WEDNESDAY. 

&&

.NEAR TERM /UNTIL 6 AM SATURDAY/...

AS HIGH PRESSURE DOMINATES WITH AN UPPER LEVEL RIDGE AXIS MOVING 
ACROSS NEW ENGLAND...CLOUD COVER THICKENS IN ADVANCE OF AN 
APPROACHING DISTURBANCE EJECTING NORTHEASTWARD FROM THE CENTRAL 
PLAINS. THE INHIBITION OF ABUNDANT SUNSHINE WILL CONSEQUENTIALLY 
KEEP A COOLER AND DRIER AIRMASS ACROSS THE REGION WITH MAX TEMPS 
AROUND THE UPPER 30S TO LOW 40S. 

TOWARDS THE EVENING WITH FALLING HEIGHTS AND BETTER DYNAMIC 
FORCING...PRECIPITATION SHOULD BEGIN TO OVERSPREAD THE REGION 
RESULTING IN A TOP-DOWN MOISTENING OF THE ATMOS PROFILE. WITH THAT 
BEING SAID THERE ARE SEVERAL CONCERNS TOWARDS THE POTENTIAL OF 
FREEZING RAIN. 

ONE IS THE POTENTIAL FOR A COLD AIR DAMMING SETUP. DURING PREVIOUS 
EVENTS EARLIER THIS SEASON...BOTH NEAR- AND SHORT-TERM GUIDANCE 
FAILED IN CONTRIBUTING A MORE NORTHERLY COMPONENT OF FLOW TO THE SFC 
WINDS...RATHER MORE EASTERLY. WHILE THE PROXIMITY AND NATURE OF THE 
DEPARTING SFC HIGH IS NOT CHARACTERISTIC OF A COLD AIR DAMMING 
SETUP...THE H975-H925 AGEOSTROPHIC FLOW EXHIBITS A DECENT DRAINAGE 
PATTERN AT THE SFC THROUGH NORTHERN AND CENTRAL NEW ENGLAND /20-30 
KTS NORTHEASTERLY PER 11.0Z NAM AND GFS...THE NAM WITH A SLIGHTLY 
MORE NORTHERLY COMPONENT/. THOUGH THE FETCH OF AGEOSTROPHIC WINDS AT 
H975 ORIGINATE FROM ALONG THE SHORELINE OF MAINE. 

TWO IS THE IMPACT OF EVAPORATIVE COOLING PROCESSES. AT ONSET... 
DEWPOINTS ARE FORECASTED TO BE IN THE UPPER 20S ACROSS A MAJORITY OF 
INTERIOR NEW ENGLAND. WITH TOP-DOWN MOISTENING...THERE IS THE 
EXPECTATION OF SFC TEMPS COOLING TOWARDS THE WET-BULB...AND 
CONSEQUENTIALLY FOR AREAS ACROSS INTERIOR NEW ENGLAND...THE WET BULB 
VALUE MAY BE AT OR BELOW FREEZING. 

THREE IS THE FACT THAT THERE IS ALREADY DECENT SNOWPACK ON THE 
GROUND FOR INTERIOR PORTIONS OF MA AND SOUTHERN NH PER COOPERATIVE 
OBSERVER OBSERVATIONS THIS MORNING. THIS SUBSEQUENTLY SHOULD KEEP A 
SURFACE COLD AIR MASS IN PLACE. IN ADDITION...WITH THE ABUNDANCE OF 
MOISTURE...THERE IS A CONCERN FOR DENSE FOG. 

WITH THE FORECAST...LEANED TOWARDS MODEL 2M TEMPS...INCORPORATING A 
BLEND OF WRF MODEL SOLNS COUPLED WITH A BIAS CORRECTED IN-HOUSE 
VERSION OF THE 11.0Z NAM. FOR THOSE AREAS WHERE DEWPOINTS WERE AT OR 
BELOW 32 DEGREES...BUMPED SFC TEMPS DOWN A DEGREE TO INVOKE THINKING 
OF EVAPORATIVE COOLING PROCESSES TOWARDS THE WET-BULB. 

IN SUMMARY...EXPECTING FREEZING RAIN TO IMPACT HIGHER ELEVATIONS AND 
INTERIOR VALLEYS ACROSS WESTERN MASSACHUSETTS INTO SOUTHERN NEW 
HAMPSHIRE...THE REMAINDER OF THE REGION REMAINING AS PLAIN RAIN. 
UPDATES WILL LIKELY BE NEEDED AS THE EVENT EDGES CLOSER AND WE GET A 
BETTER HANDLE ON SFC TEMPS...BUT FOR THE TIME BEING...THE PRESENT 
THINKING IS ICE ACCUMULATIONS UP TO A TENTH OF AN INCH WILL IMPACT 
THE AFOREMENTIONED LOCATIONS FROM LATE FRIDAY INTO SATURDAY MORNING. 
HAVE ISSUED A FREEZING RAIN ADVISORY ACCORDINGLY. 

&&

.SHORT TERM /SATURDAY/... 

WITH THE SFC LOW PRES SKIRTING TO THE S/E OF THE SOUTHERN SHORELINE 
OF NEW ENGLAND...A STRONGER EASTERLY FLOW PERSISTS TO ALLOW ANY 
FURTHER LOCATIONS AT OR BELOW FREEZING TO WARM ACCORDINGLY. A WEAK 
INVERTED TROUGH FROM THE DEPARTING LOW WILL BECOME THE FOCUS FOR LOW-
LVL CONVERGENCE AND CONSEQUENTIALLY SOME LIGHT SHOWERY WX / DRIZZLE. 
THIS ACTIVITY IS EXPECTED TO MAINLY IMPACT EASTERN NEW ENGLAND WHILE 
GRADUALLY CLEARING TO THE WEST. MAX TEMPS INTO THE MID-UPPER 40S.

THE ABUNDANCE OF MOISTURE WILL REMAIN A CONCERN FOR THOSE AREAS
WITH DECENT SNOW PACK. THE WARMER MORE MOIST AIR WILL HAVE THE
PROPENSITY OF CONDENSING OUT AS DENSE FOG FOR THOSE AREAS WITH
SIGNIFICANT SNOW PACK AND LITTLE TO NO WIND. HEADLINES MAY BE
NECESSARY FOR THE EARLY AND LATER PORTIONS OF SATURDAY.

&&

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

HIGHLIGHTS...

* CLOUDY/DREARY WEATHER EXPECTED ON SAT
* UNSEASONABLY MILD TEMPERATURES SUN INTO PART OF MON
* A FEW SHOWERS POSS LATE SUN INTO MON BUT NOT A WASHOUT
* CHILLIER AIR ARRIVES TUE-WED AND PERHAPS EVEN SOME WINTRY WEATHER

DETAILS...

SATURDAY... 
THE BULK OF THE STEADY PRECIPITATION WILL BE OVER BY 
DAYBREAK SAT.  HOWEVER...AN ABUNDANCE OF CLOUDS ALONG WITH A FEW 
LINGERING SHOWERS...DRIZZLE/FOG WILL BE A POSSIBILITY AT LEAST FOR 
THE FIRST PART OF THE DAY ALONG THE COASTAL PLAIN.  HIGH TEMPS ARE 
TRICKY AS AN ABUNDANCE OF CLOUDS/LIGHT SURFACE WINDS WILL LIKELY 
KEEP THE AREA IN AN INVERSION.  THEREFORE...FEEL GUIDANCE NUMBERS 
ARE PROBABLY TOO HIGH.  FOR NOW WILL GO WITH HIGHS MAINLY IN THE 
40S...BUT ITS POSSIBLE PORTIONS OF THE INTERIOR DO NOT REACH 40.  

SUNDAY AND MONDAY... 
SOUTHWEST FLOW ALOFT AND AT THE SURFACE AHEAD 
OF A SLOW MOVING COLD FRONT WILL RESULT IN UNSEASONABLY MILD 
TEMPERATURES.  HIGHS ON SUN SHOULD BE WELL INTO THE 50S ACROSS MOST 
LOCALES AND ITS NOT OUT OF THE QUESTION THAT SOMEONE ACROSS INTERIOR 
RHODE ISLAND/SOUTHEAST MA TOUCHES 60.  ON MONDAY...HIGH TEMPS WILL 
DEPEND UPON THE EXACT TIMING OF THE FRONT.  BEST CHANCE FOR READINGS 
OF 50+ WILL BE ACROSS RHODE ISLAND/SOUTHEAST MA.  SOMEWHAT CHILLIER 
WEATHER WILL FILTER INTO THE REGION SOMETIME LATER MON INTO MON 
NIGHT.

AS FOR PRECIPITATION CHANCES SUN INTO MON WE ARE NOT EXPECTING A 
WASHOUT AND MUCH OF THE TIME WILL PROBABLY END UP DRY.  HOWEVER...A 
PERIOD OF SCATTERED SHOWERS WILL BE POSSIBLE SOMETIME LATE SUN INTO 
MON IN ASSOCIATION WITH THE COLD FRONT.  CERTAINLY NOT EXPECTING A 
LOT OF RAINFALL WITH THIS SYSTEM.

TUESDAY AND WEDNESDAY... 
PLENTY OF UNCERTAINTY IN THIS TIME FRAME.  
THE MODELS HAVE A WAVE OF LOW PRESSURE DEVELOPING ON THE FRONTAL 
BOUNDARY...BUT PLENTY OF UNCERTAINTY ON THE TRACK.  IF THE LOW TAKES 
A NORTHERLY TRACK WE WOULD HAVE MAINLY A RAIN EVENT.  A TRACK 
FURTHER SOUTH WOULD BRING THE POTENTIAL FOR MORE IN THE WAY OF 
ICE/SNOW.  THERE IS EVEN THE POSSIBILITY THAT THE LOW WOULD PASS TOO 
FAR SOUTH AND KEEP OUR WEATHER MAINLY DRY.  GIVEN THAT THE EVENT IS 
5 TO 6 DAYS IN THE FUTURE MEANS WE MAY HAVE TO KEEP ALL OPTIONS AT 
THIS POINT.
 
THURSDAY... 
LOOKS LIKE DRY WEATHER FOLLOWS BEHIND WHAT EVER TRANSPIRES TUE INTO 
WED.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...

NEAR-TERM THROUGH FRIDAY...HIGH CONFIDENCE.

HIGH PRESSURE...LIGHT WINDS...VFR.

LATE FRIDAY INTO SATURDAY...MODERATE CONFIDENCE.

CIGS LOWERING AND THICKENING. BECOMING MVFR-LIFR. ATTENDANT
INCREASING MOISTURE WILL RESULT IN -RA WITH THE POSSIBILITY OF
POCKETS OF -FZRA ACROSS NORTHERN AND CENTRAL INTERIOR NEW ENGLAND
/ESPECIALLY FRIDAY NIGHT/. PRECIP WILL ADVANCE W TO E...LINGERING
OVER E NEW ENGLAND LATE. IN ADDITION...WARMER AIR ACROSS A DENSE
SNOW PACK ALSO ACROSS INTERIOR NEW ENGLAND WILL LIKELY LEAD TO THE
DEVELOPMENT OF DENSE FOG. CONSERVATIVE FORECAST FOR NOW WITH VSBYS
NO LESS THAN 3SM...BUT CAN NOT RULE OUT VSBYS DOWN TO 1/4SM OR
LESS AT TIMES.

KBOS TAF...HIGH CONFIDENCE IN TAF.

KBDL TAF...MODERATE CONFIDENCE IN TAF. LOW CONFIDENCE ON -FZRA
IMPACTS BUT CAN NOT BE RULED OUT. 

OUTLOOK...SATURDAY NIGHT THROUGH TUESDAY...

SATURDAY NIGHT...MODERATE CONFIDENCE. MVFR-IFR CONDITIONS MAY
HANG ON INTO THE AFTERNOON ESPECIALLY ACROSS THE COASTAL PLAIN IN
LOW CLOUDS/FOG PATCHES.

SUNDAY AND MONDAY...MODERATE CONFIDENCE.  MARGINAL MVFR TO VFR 
CEILINGS EXPECTED.

TUESDAY...LOW CONFIDENCE.  MVFR-IFR CONDITIONS POSSIBLE IN RAIN 
AND/OR SNOW.

&&

.MARINE...

WHILE WINDS HAVE SUBSIDED...SWELL REMAINS ACROSS THE OUTER WATERS
WITH SIGNFICANT WAVE HEIGHTS OF 5 FEET. THIS SHOULD DISSIPATE INTO
THE MORNING HOURS ALLOWING FOR SMALL CRAFT ADVISORIES TO EXPIRE. 

THEREAFTER...SHOWERS WILL BE ON THE INCREASE AS A WAVE OF LOW
PRESSURE SWEEPS EAST ALONG THE SOUTH COAST OF NEW ENGLAND. THERE
IS THE PLAUSIBILITY OF MODEST EASTERLY FLOW TO THE NORTH OF THE
LOW TO GENERATE SIGNIFICANT WAVE HEIGHTS UP TO 5 FEET OVER THE
OUTER WATERS ON SATURDAY...BUT AT THIS PRESENT TIME CONFIDENCE IS
LOW. THEREFORE FOR THE REMAINDER OF THE PERIOD...WINDS AND SEAS
WILL REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS. 

OUTLOOK...SATURDAY THROUGH TUESDAY... 

SUNDAY... 
MODERATE TO HIGH CONFIDENCE THAT WINDS/SEAS REMAIN BELOW SCA
THRESHOLDS. HOWEVER...AREAS OF FOG MAY RESULT IN SOME VISIBILITY
RESTRICTIONS ESPECIALLY DURING THE OVERNIGHT INTO THE MID MORNING
HOURS.

MONDAY AND TUESDAY... 
MODERATE CONFIDENCE.  A COLD FRONT ON MONDAY WILL BE FOLLOWED BY A 
WAVE OF LOW PRESSURE TUE.  COLD ADVECTION AND THE LOW PRESSURE 
SYSTEM WILL BRING A DECENT SHOT FOR SOME SCA WIND GUSTS AND SEAS 
OVER THIS TIME.

&&

.TIDES/COASTAL FLOODING...

FORECAST TIDE LEVELS ARE 11.9 FT TOMORROW MORNING AT 10:13 AM FOR
BOSTON WITH THE FLOOD STAGE AT 12 FT. EXPECT WINDS TO BE LIGHT AND
OFFSHORE AS HIGH PRESSURE WILL BE IN PLACE. HOWEVER STILL CANNOT
RULE OUT THE POSSIBILITY FOR SPLASHOVER ESPECIALLY ACROSS THE
MORE VULNERABLE AREAS.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...

CT...NONE.
MA...FREEZING RAIN ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST 
     SATURDAY FOR MAZ002-004-008-026.
NH...FREEZING RAIN ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST 
     SATURDAY FOR NHZ011-012-015.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST THIS MORNING FOR ANZ250-
     254-255.

&&

$$

SYNOPSIS...FRANK/SIPPRELL
NEAR TERM...SIPPRELL
SHORT TERM...SIPPRELL
LONG TERM...FRANK
AVIATION...FRANK/SIPPRELL
MARINE...FRANK/SIPPRELL
TIDES/COASTAL FLOODING...DUNTEN