10:00 D1 ON IN SERVICE, GOOD MORNING EVERYONE, HEARING WE MIGHT GET SOME SNOW! AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 700 AM EST THU NOV 13 2014 .SYNOPSIS... HIGH PRESSURE WILL RESULT IN DRY AND COOL WEATHER TODAY. FAST MOVING LOW PRESSURE WILL RESULT IN RAIN CHANGING TO TO SNOW NORTHWEST OF THE CAPE COD CANAL BEGINNING LATE TONIGHT INTO EARLY FRIDAY MORNING. POTENTIAL FOR AN INCH OR TWO ESPECIALLY OVER SE NEW ENGLAND WHICH WILL MAKE FOR HAZARDOUS DRIVING CONDITIONS FOR THE FRIDAY MORNING COMMUTE. WEATHER IMPROVES BY MIDDAY FRIDAY AND CONTINUES INTO SATURDAY BUT IT REMAINS UNSEASONABLY COLD. LOW PRESSURE APPROACHING FROM THE SOUTH WILL LIKELY BRING SOME RAIN TO THE COAST AND PERHAPS A WINTRY MIX TO THE INTERIOR SUNDAY NIGHT INTO MONDAY EVENING. THE COLDEST WEATHER OF THE SEASON MAY INVADE THE REGION BY NEXT TUESDAY AND WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 645 AM UPDATE... MAINLY CLEAR SKIES AND CHILLY TEMPERATURES EARLY THIS MORNING. TEMPS WERE IN THE UPPER 20S AND MID 30S IN MOST LOCATIONS...BUT MILDER 40S WERE FOUND ON THE CAPE AND NANTUCKET AS NNW WIND WAS BLOWING OFF THE OCEAN. PLENTY OF SUNSHINE EXPECTED THIS MORNING...BUT WILL SEE A GRADUAL INCREASE IN CLOUDS FROM WEST TO EAST THIS AFTERNOON. PREVIOUS DISCUSSION... WILL KEEP WITH A DRY FORECAST BENEATH CONTINUED INFLUENCE OF HIGH PRESSURE. EXPECTED TO BE A QUIET COOLER-THAN-NORMAL DAY AS CLOUDS THICKEN AND LOWER TOWARDS EVENING. EXPECTING HIGHS ONLY INTO THE MID-TO UPPER- 40S...A FEW AREAS AROUND THE 50-DEGREE MARK ALONG THE S-COAST. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... LOW OFF THE CAROLINAS DEEPENS WITHIN THE PRESENCE OF A POSITIVELY-TILTED TROUGH AXIS AND ATTENDANT MID-LEVEL ENERGY SWEEPING ACROSS THE NE CONUS ALONG WITH A REINFORCING COLD FRONT AND UNDERCUTTING COLD AIRMASS. REINFORCING COLD FRONT AGAINST THE OFFSHORE WAVE LOW WILL RESULT IN AN ENHANCEMENT OF RAIN / SNOW OUTCOMES ACROSS S NEW ENGLAND. STRONGEST FORCING FOCUSES REARWARD OF THE OFFSHORE WAVE LOW WHERE THE COLLOCATION OF DECENT H9-7 ISENTROPIC ASCENT OF THE WARM-MOIST CONVEYER BELT UNDERGOES FRONTOGENTICAL /F-GEN/ LIFT THROUGH A WELL-SATURATED DENDRITIC GROWTH ZONE...IN ADDITION TO DIFFERENTIAL VORTICITY ADVECTION AHEAD OF THE POSITIVELY-TILTED TROUGH. NOTING SOME NEGATIVE EQUIVALENT POTENTIAL VORTICITY COLLOCATED WITH H6-8 F-GEN LIFT SIGNALING SOME FORM OF INSTABILITY SO IN ADDITION TO THE SLANTWISE ASCENT MAY ALSO SEE SOME MINOR CONVECTIVE ELEMENTS /ALBEIT THINKING ISOLATED/ THAT MAY YIELD A GREATER INTENSITY OF SNOWFALL. KEEPING ALL THIS IN MIND...HAVE HIGHEST CONFIDENCE OF INGREDIENTS COMBINING ACROSS SE NEW ENGLAND... ESPECIALLY AREAS E/SE OF THE WORCESTER HILLS AND CT-RIVER VALLEY. BULK OF ACTIVITY BEGINS AROUND MIDNIGHT AND CONCLUDES MID-MORNING ON FRIDAY. WITH THE REINFORCING COLD FRONT COLLIDING WITH THE ELEMENTS OF THE OFFSHORE WAVE LOW...AM ANTICIPATING AN INCREASING INTENSITY OF PRECIPITATION W TO E. WITH UNDERCUTTING COLD AIR AND A TOP-DOWN MOISTENING PROFILE UNDERGOING DYNAMIC COOLING...FEEL TEMPERATURES WILL BE QUICK TO FALL BELOW-FREEZING AS FAR E AS THE UPPER-CAPE. SO RAIN INITIALLY...BUT SHOULD QUICKLY CHANGE-OVER TO SNOW /THIS BASED ON AN EVALUATION OF H95-925 TEMPERATURES TO WHICH VALUES AROUND -2C WERE EVALUATED TO BE AROUND THE CAPE COD CANAL BETWEEN 9-12Z/. USED A 36-DEGREE THRESHOLD FOR THE RAIN/SNOW TRANSITION...AND APPLIED A WET-BULB METHODOLOGY TO 2M TEMPERATURES. ONE COULD MAKE THE CASE ABOUT IT BEING WARM AS OF RECENT...AND THAT GROUND TEMPERATURES MAY MAKE IT DIFFICULT FOR SNOW TO ACCUMULATE. BUT CONSIDERING THE NOCTURNAL TIMEFRAME AND EXPECTED INCREASE IN SNOW INTENSITY W TO E...HAVE NO DOUBT IN SEEING SNOW ACCUMULATION. PERHAPS INITIAL RAIN MAKING SURFACES WET MAY COMPLICATE ACCUMULATING SNOWS...BUT UPON INCREASING INTENSITY...SNOW SHOULD STICK. LEANED MORE WITH THE COLDER MODEL GUIDANCE WITH THIS FORECAST WHILE WEIGHTING SURFACE TEMPERATURES CLOSER TO THEIR RESPECTIVE DEWPOINT. FAVORED THE WRF-NMM / CANADIAN / NAM / ECMWF SOLUTIONS. WHILE THE STORM-TOTAL SNOW GRAPHIC IS A BROAD-BRUSH OF FORECAST SNOWFALL AMOUNTS...IN SPECIFICITY...HAVE AROUND 1-INCH ACROSS W- AND CENTRAL-LOCALES OF MA / CT. AROUND 2-INCHES FROM THE WORCESTER HILLS S/E ENCOMPASSING NE CT / MUCH OF RI / E-SE MA...AWAY FROM THE IMMEDIATE SHORE. A LOW PROBABILITY OF POSSIBLY SEEING 3-4 INCHES AROUND THE HIGH-TERRAIN OF E/SE NEW ENGLAND /I.E. NW RI...BLUE HILL/. THERE WILL CERTAINLY BE IMPACTS FOR THE FRIDAY MORNING COMMUTE... ESPECIALLY ALONG THE I-95 CORRIDOR AND SURROUNDING 295 AND 495 BELTWAYS ACROSS E/SE MA AND N RI. BE PREPARED FOR SLICK ROADWAYS AND REDUCED VISIBILITIES IN SNOW. AS THE OFFSHORE WAVE LOW DEEPENS...IN WAKE OF THE REINFORCING COLD FRONT WILL SEE GRADUAL CLEARING AS WINDS INCREASE WITH GUSTS OF AROUND 20-25 MPH ALONG THE SHORELINES AND ADJACENT WATERS. WITH SUNSHINE PEAKING OUT TOWARDS MIDDAY...HIGHS WILL RISE INTO THE UPPER-30S TO LOW-40S. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... HIGHLIGHTS... * DRY BUT UNSEASONABLY COLD AND BLUSTERY FRI NIGHT/SAT * COASTAL RAIN SUN NIGHT/MON WITH RAIN OR WINTRY MIX INTERIOR * COLDEST AIR OF THE SEASON LIKELY INVADES THE REGION BY TUE/WED
Posted on: Thu, 13 Nov 2014 14:57:07 +0000
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