Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 242326 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 726 PM EDT TUE MAR 24 2015 .SYNOPSIS... HIGH PRESSURE OVER THE REGION WILL PROVIDE THE NORTH COUNTRY WITH ANOTHER CHILLY NIGHT TONIGHT UNDER CLEAR SKIES AND LIGHT WINDS. MILDER AIR RETURNS FOR WEDNESDAY AS LOW PRESSURE AND ITS ASSOCIATED WARM FRONT PUSH INTO THE NORTHEAST. THIS SYSTEM WILL BRING PERIODS OF LIGHT RAIN TO THE AREA WEDNESDAY AFTERNOON THROUGH THURSDAY, WITH A TRANSITION TO A MIX OF RAIN AND SNOW THURSDAY NIGHT INTO FRIDAY AS A COLD FRONT TRACKS THROUGH. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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AS OF 726 PM EDT TUESDAY...FORECAST REMAINS IN GREAT SHAPE AND ONLY ADJUSTMENT WAS TO MATCH HOURLY T/TD DATA WITH CURRENT OBSERVATIONAL TRENDS. CLEAR AND QUIET WITH LIGHT WINDS AND SOMEWHAT WARMER TEMPERATURES THE MAIN STORY TONIGHT. PRIOR DISCUSSION FOLLOWS... ANOTHER QUIET AND CHILLY NIGHT IN ON TAP FOR THE NORTH COUNTRY AS HIGH PRESSURE CENTERED OVER THE REGION THIS AFTERNOON SLOWLY SLIDES EAST TO THE NEW ENGLAND COAST BY WEDNESDAY MORNING. SKIES WILL REMAIN CLEAR WITH ANY LIGHT WINDS TRENDING CALM LEADING TO EXCELLENT RADIATIONAL COOLING. MUCH LIKE LAST NIGHT TEMPERATURES WILL RUN WELL BELOW NORMAL, BUT ON AVERAGE ABOUT 10 DEGREES WARMER IN THE TEENS FOR MOST LOCATIONS, EXCEPT SINGLE DIGITS IN THE ADIRONDACKS AND NORTHEAST KINGDOM.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... AS OF 357 PM EDT TUESDAY...FORECAST REMAINS ON TRACK FOR WEDNESDAY THROUGH THURSDAY NIGHT WITH CONDITIONS TRENDING UNSETTLED AS SEVERAL LOW PRESSURE SYSTEMS BRING PERIODS OF PRECIPITATION TO THE REGION. ON WEDNESDAY WE`LL START THE DAY UNDER CLEAR SKIES AS HIGH PRESSURE WILL BE CENTERED OVER THE VICINITY OF CAPE COD. TO OUR WEST, SHORTWAVE ENERGY AND ASSOCIATED WEAK SURFACE LOW ENTERING INTO THE GREAT LAKES REGION WILL TRACK NORTHEAST THROUGH SOUTHERN ONTARIO AND INTO SOUTHERN QUEBEC DURING THE AFTERNOON AND EVENING HOURS. ATTENDING WARM FRONT LIFTS THROUGH THE NORTH COUNTRY DURING THIS TIME WITH SOME LIGHT WARM PRECIPITATION. WITH SURFACE TEMPERATURES WARMING TO AROUND SEASONAL NORMALS IN THE UPPER 30S AND LOWER 40S, PRECIPITATION WILL FALL MAINLY AS RAIN ALTHOUGH THERE MAY BE A BRIEF WINTRY MIX ACROSS THE HIGHER ELEVATIONS AND EASTERN VERMONT AT THE ONSET. FRONT LIFTS THROUGH THE AREA AND NORTH OF THE CANADIAN BORDER PRETTY QUICKLY LATE WEDNESDAY EVENING AS A STRONG MID-LEVEL JET AND DRY SLOT SHIFT INTO THE REGION SO PRECIPITATION CHANCES WILL WANE THROUGH THE NIGHT BUT WE COULD SEE SOME SPOTTY DRIZZLE HERE AND THERE IN THE WARM SECTOR. WITH A GOOD AMOUNT OF CLOUDS AND WIND AROUND, EXPECT MIN TEMPS WEDNESDAY NIGHT TO RUN RATHER MILD RANGING THROUGH THE 30S. COULD SEE A FEW AREAS TOUCH THE FREEZING MARK SO SOME SLICK SPOTS ON THE ROADWAYS COME THURSDAY MORNING ARE POSSIBLE. BREAK IN THE ACTION IS SHORT LIVED AS WE PROGRESS INTO THURSDAY WITH A SECOND STRONGER TROUGH DIGGING INTO THE GREAT LAKES. SURFACE LOW PRESSURE DEVELOPS IN RESPONSE OVER THE OHIO/TENNESSEE RIVER VALLEY AND TRACKS NORTHEAST TO THE GULF OF MAINE BY EARLY FRIDAY MORNING. PRECIPITABLE WATER VALUES RISE TO AROUND 0.75-1" THURSDAY WITH GOOD FORCING AND LIFT INDICATING A WIDESPREAD RAINFALL EVENT WITH AMOUNTS LIKELY EXCEEDING A HALF INCH. SURFACE COLD FRONT SHIFTS THROUGH THURSDAY NIGHT WITH A TRANSITION TO A MIX OF RAIN AND SNOW THROUGH PRECIPITATION WILL BEGIN TO TAPER OFF AFTER MIDNIGHT. LIGHT ACCUMULATIONS OF A DUSTING TO AN INCH ARE POSSIBLE WITH LOWS FALLING BACK INTO THE UPPER 20S TO LOWER 30S. WITH THE EXPECTED RAINFALL AND 36-48 HOURS OF ABOVE FREEZING TEMPERATURES WE`LL LIKELY SEE SOME MELTING OF THE SNOWPACK WHICH MAY RESULT IN SOME ICE MOVEMENT, ESPECIALLY IN OUR SOUTHERN RIVERS. FOR MORE ON THAT SEE OUR HYDRO SECTION BELOW. && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 326 PM EDT TUESDAY...SNOW SHOWERS CONTINUE IN LINGERING MOISTURE BEHIND COLD FRONT AS POSITIVELY TILTED UPPER TROUGH AND ASSOCIATED VORT PROVIDE LIFT FRIDAY. AS THE TROUGH MOVES ACROSS THE NORTH COUNTRY FRIDAY NIGHT, SNOW SHOWERS WILL DIMINISH, WHILE AT THE SURFACE RIDGE OF HIGH PRESSURE BUILD OVER THE CENTRAL GREAT LAKES REGION. THIS WILL KEEP THE NORTH COUNTRY IN CHILLING NW FLOW. THIS WILL RESULT IN FALLING TEMPERATURES THROUGHOUT THE DAY ON FRIDAY AND FRIDAY NIGHT MINS IN THE SINGLE DIGITS TO TEENS. COME SATURDAY MORNING, GFS LAGS BEHIND ECMWF WITH RESPECT TO PROGRESSION OF UPPER TROUGH AND KEEPS SNOW SHOWERS OVER THE REGION. BUT WITH GFS PWATS AROUND A TENTH OF AN INCH DO NOT EXPECT MORE THAN PARTLY TO MOSTLY CLOUDY SKIES, WHICH BOTH MODELS SUPPORT WITH SECONDARY VORT MOVING OVER THE AREA. SATURDAY MAX TEMPS REFLECT THE COLD AIR ADVECTION FROM NORTHERLY FLOW, REACHING THE M20S-L30S. CLEARING SURFACE HIGH PRESSURE, DRY AIR AND RIDGING ALOFT, AS DEPICTED BY BOTH GFS AND ECMWF, WILL ALLOW TEMPERATURES SUNDAY MORNING TO FALL INTO THE SINGLE DIGITS TO MID TEENS. BUT AS THE SURFACE RIDGE SHIFTS EASTWARD, SW FLOW WILL RETURN AND BRING A WARMING TREND. MAX TEMPS REACH THE M30S-L40S AHEAD OF THE NEXT SYSTEM THAT APPROACHES MONDAY. MODELS DIFFER ON EVOLUTION OF THIS SYSTEM, SO SOMETHING TO KEEP AN EYE ON FOR THE BEGINNING OF THE WORK WEEK. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... THROUGH 00Z THURSDAY...VFR SKC CONDITIONS INTO THE OVERNIGHT. THOUGH VFR INTO WEDNESDAY, INCREASING SOUTH/SOUTHEAST WINDS & WIND SHEAR, WITH DEVELOPING RAIN IN LATTER PART OF TAF PERIOD. HIGH PRESSURE WILL STILL CONTRIBUTE TO CLEAR SKIES AND LIGHT SURFACE WINDS OVERNIGHT. HIGH THEN SHIFTS EAST BY THE PRE-DAWN HOURS, RESULTING IN SOUTHEAST FLOW WHICH STEADILY INCREASES THROUGH WEDNESDAY. EXPECT SOUTHEAST WINDS 10-12 KTS WITH GUSTS UP TO 20-22 KTS BY THE AFTN HOURS. BASED ON OBS ACROSS THE OHIO VALLEY, GUIDANCE CEILING PROGS LOWERING TO MVFR BY 20Z LOOKS OVERDONE. THEREFORE, KEPT CEILINGS IN THE VFR CATEGORY BETWEEN 20-22Z WITH VCSH DUE TO WARM FRONTAL RAIN/PRECIP. WIND FIELDS INCREASE TO SOUTH AROUND 40 KTS LATE IN THE TAF PERIOD. GIVEN STRENGTH OF WARM ADVECTION, LLWS IS POSSIBLE CLOSER TO 00Z THURSDAY, BUT IS MORE CONDITIONAL ON IF SURFACE GUSTS CAN BE MAINTAINED. OUTLOOK 00Z THURSDAY THROUGH SUNDAY... 00Z THURSDAY - 12Z FRIDAY...VFR DETERIORATING TO PERIODS OF MVFR WITH BRIEF IFR FLIGHT CONDITIONS UNDER RAIN/SNOW SHOWERS AS A LOW PRESSURE SYSTEM BRINGS A GOOD CHANCE FOR MEASURABLE PRECIP TO THE REGION. POSSIBLE BREAK IN PRECIPITATION THURSDAY MORNING. 12Z FRIDAY - 00Z SUNDAY...MIX OF VFR AND MVFR WITH SCATTERED SNOW SHOWERS POSSIBLE. 00Z SUNDAY - 00Z MONDAY...VFR CONDITIONS UNDER RIDGE OF HIGH PRESSURE. && .HYDROLOGY... AS OF 320 PM EDT TUESDAY...THE PRIMARY HYDRO ISSUE IS THE POTENTIAL FOR ICE BREAKUP AND SUBSEQUENT ICE JAMS. PERIOD OF ABOVE FREEZING TEMPERATURES WILL RELEASE SNOW MELT, AND WHEN COMBINED WITH THURSDAY RAINFALL WILL PRODUCE WITHIN BANK RISES ON RIVERS. RAIN THAT ARRIVES WITH WARM AIR ADVECTION WEDNESDAY NIGHT WILL BE ABSORBED BY COLD SNOWPACK WITH LITTLE IMPACT ON RIVERS. SOUTH WINDS AND INCREASING DEWPOINTS WILL BEGIN MELT SOME SNOW ON THURSDAY, WITH HYDRO FORECAST MODELS SHOWING THREE QUARTERS TO AROUND AN INCH OF SNOWMELT ALONE THROUGH FRIDAY MORNING. RAINFALL ARRIVING LATE THURSDAY AND THURSDAY NIGHT IS THE SECOND FACTOR IN ICE BREAKUP POTENTIAL. SOME UNCERTAINTY, AS ALWAYS, INTRODUCED BY SPREAD IN MODEL RAINFALL FORECAST. GFS LEADING THE WAY WITH A HALF INCH OR MORE IN 18Z-24Z THURSDAY TIMEFRAME, AND QPF INCORPORATED IN RIVER FORECASTS ARE NEARER THE GFS SOLUTION. FORECAST RIVER RISES OF 4 TO 6 FEET WOULD BE SUFFICIENT TO BREAK UP OUR EXISTING RIVER ICE THAT IS 1 TO 1.5 FEET THICK. EVEN SCALING BACK PRECIP FORECASTS TO SOME OF THE LESSER AMOUNTS IN NAM AND ECMWF WILL PRODUCE RISES UP TO 3 FEET WHEN COMBINED WITH SNOWMELT RUNOFF, WHICH IS MARGINALLY ABLE TO BREAK UP OUR ICE COVERAGE. MAIN THREAT FOR ICE BREAKUP AND JAMS IS IN VERMONT FROM THE WINOOSKI BASIN SOUTHWARD, AS WELL AS ESSEX COUNTY NY. && .EQUIPMENT... AS OF 307 PM EDT TUESDAY...KTYX IS OPERATIONAL AND HAS RETURNED TO SERVICE. TECHNICIANS RECEIVED AND INSTALLED THE REPLACEMENT PARTS TODAY. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...LAHIFF NEAR TERM...JMG/LAHIFF SHORT TERM...LAHIFF LONG TERM...KGM AVIATION...KGM/LOCONTO HYDROLOGY...HANSON EQUIPMENT...WFO BTV

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