Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 242340 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 640 PM EST WED DEC 24 2014 .SYNOPSIS... WARM RAIN TONIGHT WILL GIVE WAY TO GUSTY SOUTHWEST WINDS ON CHRISTMAS DAY AS A COLD FRONT SWEEPS THROUGH THE REGION. RUNOFF FROM SNOWMELT AND RAINFALL COULD CAUSE MINOR FLOODING AREA WIDE. WIND GUSTS OF 40 TO 60 MPH ARE FORECAST FOR NORTHERN NEW YORK, WITH GUSTS OF 30 TO 40 MPH IN VERMONT. WINDS WILL TAPER OFF HEADING INTO FRIDAY WITH A DRY FORECAST FRIDAY AND SATURDAY. A WEAK COLD FRONT ON SUNDAY WILL BRING CHANCES FOR RAIN IN THE VALLEYS AND SNOW IN THE HIGHER TERRAIN. && .NEAR TERM /UNTIL 8 AM THURSDAY MORNING/... AS OF 255 PM EST WEDNESDAY...POSITIVELY TILTED 500 MB TROUGH EXTENDS FROM GREAT LAKES TO MISSISSIPPI DELTA WITH SOUTHERLY FLOW ALONG THE EAST COAST OF THE US. SURFACE LOW OVER WESTERN OHIO WITH COLD FRONT TRAILING STRAIGHT SOUTH TO GEORGIA. SOUTHERLY FLOW ALONG EASTERN COAST BRINGING WARM MOIST AIR TO THE REGION WITH SOLID BAND OF RAIN FROM NEW ENGLAND TO GEORGIA ALONG THE COAST. AS NOTED IN PREVIOUS DISCUSSIONS PRECIPITABLE WATER VALUES VERY HIGH FOR THIS TIME OF YEAR, NEAR 3 STANDARD DEVIATIONS ABOVE NORMAL. FORECAST AREA HAS SEEN SEVERAL ROUNDS OF RAIN OVERNIGHT AS LEADING VORT CENTERS EJECT OUT OF TROUGH TO WEST AND ENHANCE PRECIP. MOST PRECIP AMOUNTS THROUGH 18Z A HALF INCH OR LESS WHILE TEMPERATURES IN 40S MELTING SOME SNOW. SOUTHERLY FLOW DEVELOPING ACROSS AREA IN RESPONSE TO SURFACE LOW TO WEST...ALTHOUGH WEAK SURFACE TROUGH OFF NEW ENGLAND COAST BRINGING NE FLOW TO NORTHERN NEW ENGLAND. FORECAST FOR OVERNIGHT IS FOR THE 500MB TROUGH TO SPREAD EAST AND TAKE A NEGATIVE TILT WITH CLOSED LOW TRACKING ON THE CANADIAN SIDE OF THE SAINT LAWRENCE VALLEY. SURFACE LOW TO FOLLOW SUIT WITH TRAILING COLD FRONT MOVING THROUGH FORECAST AREA AROUND 12Z. RAIN CURRENTLY OVER THE REGION ASSOCIATED WITH DEEP TROPICAL MOISTURE TO SOUTH WILL CONTINUE THROUGH EVENING UP TO ABOUT MIDNIGHT THEN AREA WILL ENCOUNTER PERIOD OF LESS PRECIP AS DRIER AIR MOVES IN AND DEEPER MOISTURE IS PUSHED EAST. RAIN CHANCES RENEW AFTER MIDNIGHT AND TOWARD MORNING WITH APPROACH AND PASSAGE OF COLD FRONT. HAVE ADJUSTED FORECAST RAINFALL AMOUNTS DOWNWARD DUE TO IMPACTS OF DRY SLOT. STORM TOTAL QPF RANGES FROM 1/2 INCH IN ST. LAWRENCE VALLEY TO AN INCH IN SOUTHERN ESSEX COUNTY AND SOUTH OF ROUTE 2 IN VERMONT. TIMING OF ARRIVAL OF COLD FRONT WILL BE TOO LATE ON LOW TEMPS TONIGHT, WITH TEMPS REMAINING NEARLY STEADY. TEMPERATURES TO REMAIN ABOVE FREEZING IN THE 40S OVERNIGHT WITH SOUTH WINDS 10 TO 20 MPH CONTINUING SNOWMELT. && .SHORT TERM /8 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 255 PM EST WEDNESDAY...SURFACE AND UPPER LOW AT 12Z THURSDAY OVER SOUTHWEST QUEBEC. SURFACE WINDS INCREASE IN RESPONSE TO DEEPENING SURFACE LOW NEARBY AND SOUTHWEST CHANNELING IN SAINT LAWRENCE VALLEY. BUFKIT FORECAST SOUNDS SHOW STEEP INVERSION OVERNIGHT TONIGHT WASHES OUT AND BOUDNARY LAYER BECOMES WELL MIXED AFTER 12Z THURSDAY. SUSTAINED 25 KTS AND GUSTS TO 50 KTS POSSIBLE ST. LAWRENCE VALLEY DURING THE DAY CHRISTMAS DAY AND DOWNSLOPE ENHANCEMENT ALSO POSSIBLE IN WESTERN CLINTON COUNTY ON NORTHEAST SLOPES OF THE ADIRONDACKS. LESSER WINDS OF 20 TO 30 KTS IN THE ADIRONDACKS INTO WESTERN CHAMPLAIN VALLEY. HIGH WIND WARNING AND WIND ADVISORY TO CONTINUE AS ISSUED...WARNING FOR THE ST. LAWRENCE VALLEY AND WEST CLINTON COUNTY AND ADVISORY FOR WESTERN CHAMPLAIN VALLEY AND NORTHERN ADIRONDACKS. TEMPS ALL OVER THE PLACE ON THURSDAY WITH SOME COLD AIR ADVECTION COOLING THINGS OFF IN THE ADIRONDACKS WHILE DOWNSLOPE MAY CONTINUE SOME WARMTH IN WESTERN CHAMPLAIN VALLEY. LOW DEPARTS TO NORTHEAST THURSDAY NIGHT AND BROAD RIDGE OVER EASTERN US WILL CREATE GENERALLY WESTERLY LOW LEVEL FLOW WITH NEAR NEUTRAL TEMPERATURE ADVECTION. UPSHOT IS NOT SIGNIFICANT COOLING BEHIND THE CHRISTMAS DAY COLD FRONT. WESTERLY FLOW WILL PICK UP MOISTURE OFF THE GREAT LAKES AND EXPECT CONSIDERABLE CLOUDINESS TO PERSIST THROUGH THE WEEKEND. TEMPERATURES TO RUN 5-10 DEGREES ABOVE NORMAL THROUGH THE PERIOD. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 230 PM EST WEDNESDAY...OVERALL VERY QUIET EXTENDED FCST PERIOD WITH LARGE SCALE SYNOPTIC PATTERN FEATURING MID/UPPER LVL RIDGE ALONG THE EAST COAST BREAKING DOWN...WITH A FAST/PROGRESSIVE CONFLUENT FLW DEVELOPING BY EARLY NEXT WEEK. MEANWHILE...ACRS THE CONUS...A MID/UPPER LVL RIDGE WL DEVELOP ALONG THE WEST COAST...WITH SHARP TROF OVER THE INTER-MOUNTAIN WEST...WITH SEVERAL DISTURBANCES EJECTING FROM TROF INTO THE CENTRAL/EASTERN CONUS. ALL MODELS ARE STRUGGLING WITH TIMING OF INDIVIDUAL S/W`S AND AMOUNT OF MOISTURE INTERACTION ASSOCIATED WITH SUB TROPICAL JET...ESPECIALLY TWD THE MIDDLE PART OF NEXT WEEK. CRNT TRENDS HAVE BEEN FOR THE ECMWF TO COME IN LINE WITH THE GFS IN THIS FAST PROGRESSIVE PATTERN...WITH LITTLE AMPLIFICATION AND SYSTEMS SUPPRESSED TO OUR SOUTH. THIS IS ALSO SUPPORTED BY THE 12Z GEM AND THE 12Z GFS ENSEMBLE MEMBERS. ITS SEEMS LATELY EURO DOES BETTER IN HIGHLY AMPLIFIED/CLOSED SYSTEMS WHILE GFS TENDS TO BE BETTER IN THE FAST PROGRESS FLW PATTERNS ACRS THE CONUS. THIS WL SUPPORT BLW AVERAGE CHCS FOR PRECIP...WITH TEMPS RETURNING CLOSE TO NORMAL BY EARLY NEXT WEEK. WEAK SFC LOW PRES TRACKS ACRS THE NORTHERN GREAT LAKES ON SAT INTO SUNDAY...AND WL PUSH A COLD FRNT THRU OUR CWA. THIS SFC CONVERGENCE COMBINED WITH WEAK RIBBON OF ENHANCED 850 TO 500MB RH AND WEAK 5H VORTICITY WL PRODUCE A PERIOD OF RAIN SHOWERS LATE SAT NIGHT INTO SUNDAY AS WE ARE WELL ESTABLISHED IN THE WARM SECTOR AGAIN...BEFORE ENDING AS A BRIEF PERIOD OF MAINLY MTN SNOW SHOWERS ON SUNDAY MORNING. MODERATE LLVL CAA DEVELOPS BEHIND FRNT ON SUNDAY WITH PROGGED 85H TEMPS DROPPING TO NEAR -10C BY 00Z MONDAY AND BTWN -13C AND -15C BY 00Z TUESDAY. MOISTURE IS VERY LIMITED SO NOT EXPECTING MUCH QPF...MAYBE A FEW FLURRIES IN THE MTNS...WITH LLVL CAA SQUEEZING OUT REMAINING MOISTURE IN THE COLUMN ON SUNDAY NIGHT INTO MONDAY. SFC RIDGE BUILDING FROM THE GREAT LAKES INTO NORTHERN NY FROM TUES INTO WEDS...WL KEEP FCST MAINLY DRY WITH NEAR NORMAL TEMPS. DEPENDING UPON THE TIMING OF INTER-MOUNTAIN WEST TROF AND ASSOCIATED SFC LOW PRES...I HAVE CARRIED SOME CHC POPS TWD THE MIDDLE OF NEXT WEEK. && .AVIATION /23Z WEDNESDAY THROUGH MONDAY/... THROUGH 00Z FRIDAY...ACTIVE PERIOD WITH SIGNIFICANT AVIATION IMPACTS OVER THE NEXT 12-18 HOURS. LOW CEILINGS, PERIODS OF MIST, LOW- LEVEL WIND SHEAR AND THEN A SHARP COLD FRONTAL PASSAGE WITH GUSTY WINDS/ACCOMPANYING TURBULENCE. LIGHT RAIN WITH VFR TO IFR CEILINGS/VISIBILITIES WILL CONTINUE TO LIFT NORTHEAST OVER THE NEXT COUPLE OF HOURS. PRECIPITATION THEN BECOMES MORE SHOWERY UNTIL THE COLD FRONT ARRIVES, WITH CEILINGS/VISIBILITIES IN THE VFR/MVFR RANGE. IN SPITE OF A DIMINISHING SNOWPACK, A CONTINUED RISK OF MIST WILL EXIST AFTER INITIAL STEADIER RAIN. LOW-LEVEL WIND SHEAR ABOVE STRONG INVERSION DURING THIS PERIOD, AS CXX AND TYX WIND PROFILER SHOWS WINDS AT 2 KFT NEAR 40 KTS AND LIKELY TO INCREASE ANOTHER 5-10 KTS. SURFACE WINDS SOUTHEAST UNDER 10 KNOTS, THOUGH A BIT STRONGER AT RUT AND PBG. COLD FRONTAL PASSAGE TIMING AROUND 08Z AT MSS, SLK PBG BTV 10-11Z AND AFTER 12Z FOR MPV AND RUT. EXPECT A PERIOD OF MODERATE TO POSSIBLY HEAVY RAIN WITH THE FRONT. A SHARP, GUSTY WIND SHIFT FROM SOUTHEAST TO WEST-SOUTHWEST WITH GUSTS IN THE 30 TO 45 KT RANGE (HIGHEST AT MSS). CEILINGS VFR/MVFR WITH PRECIPITATION MORE FAVORED AT MPV AND SLK BEHIND FRONT. OUTLOOK 00Z FRIDAY THROUGH SUNDAY... GUSTY WINDS WL CONT ON THURS AFTN...WITH VALUES BTWN 30 AND 40 KNOTS LIKELY FROM THE SOUTHWEST. CONDITIONS WL SLOWLY IMPROVE TO MVFR TO VFR BY FRIDAY AS SFC HIGH PRES BUILDS INTO THE REGION. NEXT WEAK SYSTEM ARRIVES LATE SAT INTO SUNDAY WITH A CHC OF MAINLY RAIN SHOWERS ALONG WITH MVFR CIGS POSSIBLE AT SLK/MSS/MPV. && .HYDROLOGY... HAVE BACKED OFF ON STORM TOTAL RAINFALL TO A HALF TO ONE INCH ACROSS THE AREA. SNOWMELT TO CONTINUE WITH STRONG SOUTH WINDS OVERNIGHT AND TEMPS STEADY MAINLY IN THE 40S. SNOWPACK HOLDING 1.5 TO 2.5 INCHES OF SNOW WATER EQUIVALENT, AND MUCH OF THE SWE IS FORECAST TO BE RELEASED IN THE UPCOMING MELT EPISODE. ALTHOUGH LESS RAIN FORECAST...COMBINATION OF RAINFALL AND ONGOING SNOWMELT CAN STILL POTENTIALLY CREATE FLOODING. RIVERS AND STREAMS WILL SEE SHARP RISES TO BANKFULL...AND AREAS OF POOR DRAINAGE DUE TO SNOW BLOCKED DITCHES WILL BE SUSCEPTIBLE. SOME UNCERTAINTY REMAINS ON HOW FORECAST RAINFALL PLAYS OUT BUT STILL ENOUGH OF A FLOOD RISK TO CONTINUE FLOOD WATCH. EAST BRANCH AUSABLE AT AUSABLE FORKS NY, OTTER CREEK AT CENTER RUTLAND, AND WINOOSKI AT ESSEX JUNCTION OF PRIMARY CONCERN WITH FORECAST RISES TO NEAR FLOOD STAGE. && .MARINE... A LAKE WIND ADVISORY HAS BEEN ISSUED FOR TONIGHT AND WILL LIKELY NEED TO BE EXTENDED THROUGH CHRISTMAS DAY (THURSDAY). SOUTH WINDS FROM 10 TO 20 KNOTS THIS AFTERNOON WILL GRADUALLY INCREASE TO 15 TO 25 KNOTS THIS EVENING AND THROUGH THE FIRST HALF OF TONIGHT. WINDS WILL PEAK EARLY THURSDAY MORNING FROM 20 TO 30 KNOTS BEFORE TURNING SOUTHWEST AND RETURNING TO 15 TO 25 KNOTS THROUGH THE REMAINDER OF THE DAY ON THURSDAY. WINDS WILL DECREASE FURTHER... BELOW ADVISORY THRESHOLD...THURSDAY NIGHT. WAVES WILL BUILD TO 2 TO 4 FEET THIS EVENING...AND 3 TO 5 FEET EARLY THURSDAY MORNING...BEFORE SUBSIDING BACK TO 1 TO 3 FEET LATER THURSDAY. THE STRONGEST WINDS AND HIGHEST WAVES WILL OCCUR IN THE OPEN WATERS OF LAKE CHAMPLAIN AS WELL AS ALONG OPEN AND SOUTHWARD FACING SHORES. INCREASED CHOP IS EXPECTED ON THURSDAY AS WELL AS WINDS TURN SOUTHWESTWARD. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...FLOOD WATCH THROUGH FRIDAY MORNING FOR VTZ001>012-016>019. NY...HIGH WIND WARNING FROM 6 AM TO 6 PM EST THURSDAY FOR NYZ026- 027-031-087. FLOOD WATCH THROUGH FRIDAY MORNING FOR NYZ026>031-034-035-087. WIND ADVISORY FROM 6 AM TO 6 PM EST THURSDAY FOR NYZ028>030- 034-035. && $$ SYNOPSIS...HANSON NEAR TERM...HANSON SHORT TERM...HANSON LONG TERM...TABER AVIATION...TABER/LOCONTO HYDROLOGY...HANSON MARINE...MUCCILLI

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