369 FXUS61 KBOX 220936 AFDBOX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 434 AM EST FRI FEB 22 2013 .SYNOPSIS... BLUSTERY CONDITIONS CONTINUE TONIGHT...WITH THE CHANCE FOR SOME LIGHT OCEAN EFFECT SNOWFALL ON CAPE COD AND POSSIBLY NANTUCKET. DRY WEATHER THEN PERSISTS TOMORROW INTO TOMORROW NIGHT. A SIGNIFICANT COASTAL STORM IS LIKELY THIS WEEKEND WITH A HIGH PROBABILITY FOR HEAVY PRECIPITATION. HOWEVER PRECIPITATION TYPE...SNOWFALL AMOUNTS AND WHERE THE RAIN/SNOW LINE SETS UP IS HIGHLY UNCERTAIN AT THIS TIME RANGE. A DRYING TREND IS LIKELY EARLY NEXT WEEK BUT MAY BE SHORT LIVED AS AN ACTIVE WEATHER PATTERN COULD DELIVER ANOTHER WINTER STORM TUE AND/OR WED OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 100 AM UPDATE... RADAR IMAGERY HAS SHOWN SOME SCT SNOW SHOWERS MOVING ACROSS THE OUTER CAPE AND TOWARDS ACK. SURFACE OBS IN CHATHAM HAVE REPORTED SNOW AND NOTICED IT ON WEBCAMS AS WELL. BELIEVE VERY LITTLE ACCUMULATION WILL OCCUR...NO MORE THAN AN INCH AS THERE ARE A NUMBER OF LIMITING FACTORS TO KEEP THE OCEAN EFFECT SNOW MACHINE GOING. ONE BEING THE RIDGE OVER THE UPPER OHIO VALLEY ALREADY BEGINNING TO BUILD IN ACROSS THE REGION. NOTICE MID-LEVEL TEMPS ARE ALREADY STARTING TO WARM. GUSTY WINDS ARE SLOWLY DIMINISHING THIS EVENING AS PRESSURE GRADIENT IS RELAXING FROM EXITING SHORTWAVE TOWARDS THE NORTHERN ATLANTIC. PREVIOUS DISCUSSION... FORECAST REMAINS ON TRACK FOR MUCH OF THE OVERNIGHT. 320 DEG WINDS ACROSS THE EAST COAST/CAPE/ISLANDS IS NOT QUIET IDEAL FOR OCEAN EFFECT SNOW BUT BELIEVE THAT WINDS WILL SLOWLY SHIFT MORE OF A 340-360 DEG WINDS. ALTHOUGH CONCERNING THING STILL IS THE WAA MOVING THROUGH THE MID LEVELS. REGARDLESS WILL KEEP THE CHANCE ACROSS THE OUTER CAPE AND ACK. INCREASED MINS A FEW DEGREES AS GUSTY WINDS OVERNIGHT WILL NOT ALLOW FOR TEMPS TO REACH MAX RADIATIONAL COOLING. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... TOMORROW... INVERTED RIDGE OF FROM HIGH PRES CENTERED IN QUEBEC WILL BE CRESTING OVER THE AREA DURING THE DAY FRI. ANY REMAINING OCEAN EFFECT SNOWS SHOULD GRADUALLY COME TO AN END THROUGH THE MORNING ALTHOUGH CLOUDS MAY LINGER A BIT LONGER UNTIL THE FETCH DISCONNECTS. OTHERWISE...EXPECTING A PARTLY CLOUDY TO PARTLY SUNNY DAY AS SOME MID AND HIGH CLOUDS BEGIN TO APPROACH FROM A FRONTAL SYSTEM /ASSOCIATED WITH THE POTENTIAL WEEKEND STORM/ BEGINS TO MOVE OVER FROM THE SW. TEMPERATURES ARE EXPECTED TO BE RIGHT AROUND TO SLIGHTLY BELOW SEASONABLE NORMS FOR THIS TIME OF YEAR. TOMORROW NIGHT... RIDGE OF HIGH PRES CONTINUES ITS SLIDE TO THE E DURING THE OVERNIGHT. THIS ALLOWS FOR SOME WEAK RETURN S-SW FLOW AND LOW-MID LVL WARM ADVECTION OVERNIGHT. AT THIS TIME...IT APPEARS ANY LIFT ASSOCIATED WITH THE APPROACHING WARM FRONT SHOULD STAY TO THE SW THROUGH 12Z...SO HAVE CONTINUED THE MOSTLY DRY FORECAST. OTHERWISE...WITH CLOUDS GRADUALLY INCREASING AND WARMING MID LVL TEMPS...EXPECT OVERNIGHT MINS TO BE A BIT MORE MILD...GENERALLY IN THE MID 20S TO NEAR AROUND 30. && .LONG TERM /SATURDAY THROUGH THURSDAY/... HIGHLIGHTS... * SIGNIFICANT COASTAL STORM LATE SAT INTO MIDDAY SUN * POTENTIAL FOR DAMAGING HEAVY WET SNOW ACROSS PORTIONS OF THE REGION * HIGHEST RISK FOR HEAVIEST SNOW NORTH OF MA TURNPIKE * SOUTH OF MA PIKE THERE IS STILL THE RISK FOR SOME SIGNIFICANT SNOW DETAILS... A VERY TRICKY FORECAST LATER SATURDAY INTO SUNDAY FOR MUCH OF THE REGION. OUR CONFIDENCE IN HEAVY WET SNOW IS HIGHEST NEAR AND NORTH OF THE MA TURNPIKE AND AWAY FROM THE IMMEDIATE COAST. LOWEST CONFIDENCE INCLUDES AREAS SOUTH OF THE TURNPIKE AND IMMEDIATE COAST PLAIN...WHERE MUCH OF THAT REGION WILL BE ON THE CUSP BETWEEN MAINLY RAIN VS. HEAVY WET SNOW. TIMING...PRECIPITATION WILL OVERSPREAD THE REGION FROM WEST TO EAST DURING THE DAY SATURDAY. THE BRUNT OF THE STORM WILL OCCUR SATURDAY NIGHT INTO MIDDAY SUNDAY...BEFORE PRECIPITATION TAPERS OFF. THE GENERAL IDEA IS THAT LOW PRESSURE WILL DEVELOP OFF THE MID ATLANTIC COAST ON SATURDAY...THEN TRACK NEAR THE BENCHMARK SATURDAY NIGHT/SUNDAY. THERMAL PROFILES ON MOST MODELS SUPPORT MAINLY A SNOW EVENT GENERALLY ALONG AND NORTH OF THE MA TURNPIKE AND AWAY FROM THE IMMEDIATE COAST. BOTH THE GFS/NAM SHOW THE POTENTIAL FOR A MID LEVEL DEFORMATION ZONE DEVELOPING ACROSS PORTIONS OF THE REGION SAT NIGHT. INITIALLY THIS MAY OCCUR ACROSS INTERIOR MA AND INTO SOUTHERN NH...RIGHT WHERE THE MODELS SHOW THE 700 MB WINDS CONVERGING ON THE BACK BENT WARM FRONT. MODELS TEND TO UNDER DO QPF IN THESE MID LEVEL DEFORMATION ZONES...SO AS WE GET CLOSER TO THE EVENT TRYING TO PINPOINT THIS AXIS WILL BE CRUCIAL IN WHERE THE HEAVIEST SNOW OCCURS. BASED ON ALL OF THIS...WE WENT AHEAD AND ISSUED A WINTER STORM WATCH FOR ALL OF WESTERN/CENTRAL AND NORTHEAST MA AS WELL AS SOUTHERN NH. THE POTENTIAL FOR 6+ INCHES OF SNOW EXISTS IN THIS REGION WITH PERHAPS UP TO A FOOT IN SOME LOCALES WHERE BANDING SETS UP. WE ARE CONCERNED BECAUSE THIS WILL BE A WET SNOW WHICH COULD RESULT IN DOWNED TREE LIMBS/SCATTERED POWER OUTAGES. AS WE MENTIONED...AREAS SOUTH OF THE MA TURNPIKE AND ALONG THE IMMEDIATE COAST THERE IS MORE UNCERTAINTY. THERMAL PROFILES ARE SO SENSITIVE AND THIS WILL MAKE A BIG DIFFERENCE BETWEEN A COLD RAIN AND HEAVY WET SNOW. THERE ARE FEW SCENARIOS THAT COULD UNFOLD...SUCH AS SNOW DEVELOPING...THEN CHANGING TO A PERIOD OF RAIN...AND GOING BACK TO SNOW AS THE LOW INTENSIFIES AND HEIGHTS CRASH. THE CLOSER ONE GETS TO THE MA TURNPIKE...PROBABILITIES FOR HEAVY WET SNOW WILL INCREASE. THE 00Z MODELS HAVE TRENDED COLDER...SO WE DO THINK THERE WILL BE AT LEAST SOME SNOW ACCUMULATION NOT TOO FAR AWAY FROM THE SOUTH COAST. ITS POSSIBLE LATER SHIFTS MAY HAVE TO EXPAND THE WINTER STORM WATCH FURTHER SOUTH INTO PORTIONS OF CT/RI AND SOUTHEAST MA...BUT FELT THERE WAS PLENTY OF TIME TO DO THIS GIVEN THE UNCERTAINTY. THE IMMEDIATE NORTHEAST MA COAST INCLUDING BOSTON IS ALSO A VERY TRICKY FORECAST. MOST OF THE PTYPE ISSUES WILL BE IN THE MID LEVELS OF THE ATMOSPHERE. HOWEVER...DEPENDING ON THE PRECIPITATION RATES AND EXACT WIND DIRECTION COULD MAKE A BIG DIFFERENCE. THE OCEAN IS A LOT COLDER THAN A MONTH AGO...BUT GIVEN THE VERY MARGINAL 925 MB TEMPS THERE STILL COULD BE SOME IMPACT FOR A TIME IN PTYPE. WE INCLUDED ALL OF ESSEX COUNTY IN THE WATCH...BUT LEFT BOSTON OUT FOR NOW. LATER SHIFTS WILL HAVE TO WATCH THIS CLOSELY. EVEN IF THERE IS A PERIOD OF RAIN...DEPENDING ON HOW QUICKLY THE LOW BOMBS OUT THE COLD CONVEYER BELT COULD HIT THIS REGION SUNDAY MORNING. ALL IN ALL...THE BIGGEST CONCERN IS THAT THIS WILL BE A HEAVY WET SNOW WHICH COULD KNOCK DOWN SOME TREE LIMBS AND RESULT IN SCATTERED POWER OUTAGES. WHILE OUR HIGHEST CONFIDENCE IS NEAR AND NORTH OF THE MA TURNPIKE AND AWAY FROM THE IMMEDIATE COAST...AREAS SOUTH OF THE PIKE AND ALONG PORTIONS OF THE COAST ARE STILL AT RISK. IT DOES APPEAR FOR AT LEAST THE IMMEDIATE SOUTH COAST/CAPE/ISLANDS ANY SNOW ACCUMULATIONS SHOULD BE LIMITED. THERE MAY BE THE NEED FOR WIND ADVISORIES ALONG THE FAR SOUTHEAST NEW ENGLAND COAST...BUT SHOULD REMAIN BELOW HIGH WIND CRITERIA. .NEXT WEEK... MONDAY... DEEPENING TROUGH OVER THE CENTRAL CONUS WILL PROMOTE RIDGING OVER THE ERN CONUS. SFC HIGH PRES BUILDS IN FROM THE WEST BEHIND DEPARTING STORM. THERE MAY BE SOME SNOW SHOWERS EARLY IN THE DAY ACROSS THE CAPE AND ISLANDS...OTHERWISE IT WILL BE DRY WITH DIMINISHING WINDS. TUESDAY... MODELS BEGIN TO DIVERGE WITH REGARD TO THE STRENGTH AND PLACEMENT OF A CLOSED MID-LEVEL LOW EJECTING OUT OF THE MEAN TROUGH OVER THE CENTRAL CONUS. FAVORED THE ECMWF/UKMET/CMC OVER THE MORE PROGRESSIVE GFS/GEFS. THIS SOLUTION PLACES MORE EMPHASIS ON MAINTAINING THE MID-LEVEL RIDGE OVER THE ERN CONUS THROUGH 12Z TUE. FOR NOW...EXPECTING INCREASING CLOUDINESS WITH CHC POPS... ESPECIALLY OVER THE INTERIOR. TUESDAY NIGHT AND WEDNESDAY... CLOSED MID-LEVEL LOW AND ASSOCIATED SURFACE REFLECTION EJECTS NORTHEASTWARD TOWARD THE REGION. AS THIS ENERGY APPROACHES THE COASTLINE...SECONDARY CYCLOGENESIS TO THE LEE OF THE APPALACHIANS MAY OCCUR. BOTH THE GEFS/ECENS INDICATE QUITE A BIT OF SPREAD IN THE MID-LEVEL HEIGHT FIELDS...ESPECIALLY TO THE EAST OF THE MEAN TROUGH AXIS...INDICATING DEVIATIONS BETWEEN THE ENS MEAN AND INDIVIDUAL MEMBERS. ALSO...GIVEN THE RECENT PATTERN... PREDICTABILITY IS LOW. SO AT THIS POINT /6-7 DAYS OUT/...ANOTHER STORM SYSTEM MAY IMPACT THE AREA BY MID-WEEK WITH THE POSSIBILITY OF PRECIPITATION TYPE...WIND AND COASTAL FLOOD ISSUES /GIVEN HIGHER TIDES IN CONJUCTION WITH FULL-MOON/. && .AVIATION /09Z FRIDAY THROUGH TUESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW...HIGH CONFIDENCE THROUGH FRIDAY NIGHT. OVERNIGHT...VFR CONDITIONS WILL PREVAIL WHILE SCT MVFR CIGS MAY MOVE ACROSS THE OUTER CAPE AND ACROSS ACK IN SNOW SHOWERS. GUSTY NW WINDS WILL DIMINISH OVERNIGHT AS WINDS WILL SWITCH TO THE NORTH BY THE EARLY MORNING. FRIDAY INTO FRIDAY NIGHT...VFR CONDITIONS AND VARIABLE WINDS EXPECTED AS HIGH PRESSURE MOVES OVER THE REGION. HIGH LEVEL CLOUDS WILL START TO MOVE IN AHEAD OF APPROACHING SYSTEM. KBOS TAF...HIGH CONFIDENCE IN TAF. KBDL TAF...HIGH CONFIDENCE IN TAF. OUTLOOK...SATURDAY THROUGH MONDAY... SATURDAY... CIGS LOWERING GRADUALLY INTO SATURDAY NIGHT TO IFR. LIFR POSSIBLE ALONG THE S/SE COASTLINE TERMINALS. RA/SN OVERSPREADING TERMINALS. ANY AREAS WITH SN LIKELY TO SEE IFR VSBYS. E/SE FLOW GRADUALLY INCREASING. SUNDAY... IFR CIGS WITH MVFR VSBYS FOR AREAS IN RA...IFR VSBYS WITH SN. INCREASING E/NE WINDS WITH GUSTS UP TO 40 KTS DURING THE DAY ACROSS E/SE MA AND E RI. WINDS DIMINISH AND CONDITIONS GRADUALLY IMPROVE INTO SUNDAY NIGHT. MON...MODERATE CONFIDENCE FOR IMPROVING CONDITIONS...MVFR-VFR. && .MARINE... HIGH CONFIDENCE ON TRENDS TODAY THOUGH FRIDAY NIGHT. GUSTY WINDS GRADUALLY SHIFT TO THE N DURING THE OVERNIGHT HOURS TONIGHT. EXPECT SOME OF THESE TO REACH GALE FORCE ESPECIALLY ON THE EASTERN OUTER WATERS...CURRENT GALE WARNINGS LOOK GOOD SO NO CHANGES MADE. OTHERWISE...SMALL CRAFT CONDITIONS FOR ALL WATERS THROUGH THE OVERNIGHT HOURS. HIGH PRES DURING THE DAY TOMORROW WILL ALLOW WINDS AND SEAS TO SLACKEN TO BELOW SMALL CRAFT THRESHOLDS BY TOMORROW NIGHT. ASIDE FROM WIND AND HEADLINE ISSUES...SOME OCEAN EFFECT SNOW AND RAIN SHOWERS ARE POSSIBLE FOR THE EASTERN WATERS DURING THE OVERNIGHT HOURS TONIGHT. OUTLOOK...SATURDAY THROUGH MONDAY... SATURDAY... COASTAL LOW DEVELOPING OFF THE DELMARVA PENINSULA TOWARDS THE 40N/70W BENCHMARK. INCREASING E/SE FLOW WILL RESULT IN INCREASING WAVES OVER ALL WATERS. GALES MAY OCCUR LATE IN THE PERIOD OVER THE S/SE WATERS. WAVE HEIGHTS BY THIS TIME FRAME 8 TO 10 FEET OVER S OUTER WATERS. SUNDAY... COASTAL LOW DEEPENING AS IT DEPARTS EAST OF THE 40N/70W BENCHMARK. GALE E/NE WINDS OVER E/SE WATERS ANTICIPATED. WAVES 12 TO 14 FEET ANTICIPATED. SOME DIMINISHING IS EXPECTED LATE IN THE PERIOD. MON...IMPROVING CONDITIONS WITH HIGH PRES BUILDING INTO NEW ENGLAND FROM THE WEST. && .TIDES/COASTAL FLOODING... MODERATE PROBABILITY OF MINOR COASTAL FLOODING EASTERN MA SHORELINE SUN MORNING TIDE CYCLE. IF STRONGEST WINDS AND SURGE COINCIDE WITH TIDE CYCLE THEN A RISK OF MODERATE COASTAL FLOODING IS POSSIBLE ALONG WITH BEACH EROSION. STILL LOTS OF UNCERTAINTY ON EXACT STORM TRACK WHICH WILL BE CRITICAL TO COASTAL FLOOD THREAT. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR ANZ231>234. SMALL CRAFT ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR ANZ230-236. SMALL CRAFT ADVISORY UNTIL 7 AM EST THIS MORNING FOR ANZ235- 237. GALE WARNING UNTIL 6 AM EST EARLY THIS MORNING FOR ANZ250-254. SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR ANZ251. SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR ANZ255- 256. && $$ SYNOPSIS...DUNTEN/SIPPRELL NEAR TERM...DUNTEN SHORT TERM...DUNTEN LONG TERM...FRANK AVIATION...DUNTEN/SIPPRELL MARINE...DUNTEN/SIPPRELL TIDES/COASTAL FLOODING...DUNTEN