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