000 FXUS61 KALY 270524 AFDALY AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 1225 AM EST FRI NOV 27 2009 .SYNOPSIS... A COMPLEX STORM SYSTEM WILL IMPACT THE NORTHEAST TONIGHT INTO SATURDAY WITH UNSETTLED WEATHER INCLUDING RAIN...AND SOME SNOW...ESPECIALLY ACROSS THE HIGHER ELEVATIONS...AND BLUSTERY WINDS. THE STORM WILL MOVE INTO THE CANADIAN MARITIMES SATURDAY NIGHT INTO SUNDAY...WITH HIGH PRESSURE BUILDING IN FROM THE SOUTHEAST WITH DIMINISHING WINDS AND TRANQUIL WEATHER. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... A QUICK UPDATE AS TEMPERATURES IN THE HUDSON VALLEY HAVE DROPPED THRU THE OVERNIGHT LOWS. THEREFORE HAVE UPDATED THE LAST HOUR OR TWO AND FLATLINED THEM FOR THE REST OF THE NITE AS THE TEMPS WERE ON OR ONLY ONE DEGREE OFF THE DEWPOINTS AND MANY SITES IN THE HUDSON VALLEY HAVE HAD SOME OFF AND ON FOG. AFTER A PLEASANT THANKSGIVING DAY...LOOKS LIKE THINGS WILL DETERIORATE TONIGHT AS LATEST RADAR IMAGES SHOW PRECIP WAS SLOWLY EDGING ITS WAY INTO THE MOHAWK VALLEY. ALSO...WITH THE CLEAR SKIES IN THE HUDSON VALLEY...TEMPERATURES HAVE PLUNGED TO THE MID 30S IN THE HUDSON VALLEY FROM GLENS FALLS TO POUGHKEEPSIE. A NUMBER OF NON-METAR SITES ACROSS OUR FORECAST AREA WERE IN THE UPPER 30S AS WELL. THE RUC-13 HAD A REASONABLY GOOD HANDLE...AT LEAST FOR STARTERS ...ON THE TEMPERATURE AND TRENDS BUT EVEN IT WAS TOO WARM FOR ALBANY AND POUGHKEEPSIE...SO DID ANOTHER UPDATE TO THE GRIDS FOR THE OVERNIGHT PERIOD. HAVE ALSO INCREASED THE POP FROM LIKELY TO CATEGORICAL OVER THE ADIRONDACKS FOR TONIGHT BASED ON RADAR TRENDS AND FOR CONSISTENCY. THE COOLER TEMPS THUS SEGWAY INTO P-TYPE ISSUES AND HAVE UPDATED WX/SNOW GRIDS USING MOSTLY THE RAIN/SNOW/SFC TOOL WITH A VERY CONSERVATIVE 32 FOR ALL SNOW AND 36 FOR UPPER END OF MIX...AND A FAIRLY DENSE (7 AND 8 TO 1) SNOW RATIO. THESE GIVE THE ADIRONDACKS UP TO AN INCH OVERNIGHT...AND UP TO ANOTHER INCH FOR FRIDAY MORNING BEFORE THINGS WARM UP ENOUGH TO MIX AND THEN TURN IT BACK TO RAIN. A QUICK LOOK AT THE 00Z ALY OBSERVED SOUNDING SHOWS BOTH A TEMPERATURE INVERSION AND DRYING AROUND 760 HPA...WITH A NEAR ADIABATIC LAPSE RATE DOWN TO 920 HPA...THEN NEARLY ISOTHERMAL TO THE SURFACE AT THE TIME OF LAUNCH. SINCE THEN IT HAS COOLED HERE TO 39. IT LOOKS LIKE THINGS MAY BE COOL ENOUGH ALOFT AT LEAST ATTM TO NOT HAVE TO WORRY ABOUT FZRA ISSUES...BUT WILL MAY TO TAKE ANOTHER LOOK AT THIS LATER THIS EVE OR TONIGHT. WE ARE LOOKING AT LOWS AT 32 IN A NUMBER OF SPOTS IN THE ADIRONDACKS...AND 33 TO 36 DEGREES ACROSS MUCH OF THE ADIRONDACKS...CATSKILLS...AND HIGHER ELEVS OF SOUTHERN VT. WE STILL HAVE POPS GOING TO CATEGORICAL ACROSS THE ENTIRE REGION BY MIDNIGHT. SNOW AMTS UP TO 1 INCH ARE MOSTLY ACROSS HAMILTON AND NORTHEASTERN HERKIMER CO...ALONG WITH A VERY SMALL AREA IN GREENE CO...WITH LIGHT DUSTING AMTS POSSIBLE OVER THE REST OF THE ADIRONDACKS AND NORTHERN CATSKILLS INCLUDING THE HILLTOWN AREA OF EASTERN SCHOHARIE/WESTERN ALBANY COUNTIES. PREVIOUS NEAR TERM DISCUSSION...ISSUED AT 430 PM...FOLLOWS. HAPPY THANKSGIVING TO ALL...WITH MILD WEATHER AND EVEN SOME SUN ACROSS THE FCST AREA LATE THIS AFTERNOON WITH WEAK HIGH PRESSURE MOVING OFF THE MAINE COAST. THE WATER VAPOR LOOP WITH H500 HEIGHTS OVERLAYED FROM THE NAM80 DEPICTS A PROGRESSIVE UPPER LEVEL TROUGH OVER THE MS RIVER VALLEY...AND EAST OF THE ROCKIES. SHORT WAVE ENERGY IS MOVING THROUGH THE BASE OF TROUGH WITH A COASTAL/OCEAN LOW FORMING OFF THE MID ATLANTIC COAST. THE CLOSED/CUTOFF LOW TO THE HIGH AMPLITUDE LONGWAVE TROUGH IS MOVING ACROSS MI. THE UPPER TROUGH WILL BECOME NEGATIVELY TILTED OVER THE NEXT 12 HOURS OR SO ...AND WILL TRY TO CAPTURE THE COASTAL LOW. THE PHASING BETWEEN THE UPSTREAM SHORT WAVE ENERGY AND THE COASTAL LOW APPEARS IT WILL OCCUR A LITTLE TOO LATE WITH THE LATEST TRENDS OF THE DETERMINISTIC MODELS AND THE ENSEMBLES TO IMPACT THE FCST WITH HVY PCPN /RAIN AND SNOW/...AS THE WARM CONVEYOR BELT WILL BE CUTOFF...WITH ERN NEW ENGLAND IMPACTED THE MOST IN TERMS OF QPF. HOWEVER...A VERY INTENSE CYCLONE WILL MATERIALIZE BY FRIDAY AFTERNOON IN THE GULF OF MAINE. STRONG GUSTY WINDS MAY BECOME PROBLEMATIC FRI NIGHT INTO SATURDAY...WHICH WILL BE DISCUSSED IN MORE DETAIL IN THE SHORT TERM. OVERNIGHT...SOME -RA WILL MOVE IN FROM THE SOUTH AND WEST DUE TO THE UPPER LOW APPROACHING FROM THE WEST. THE CYCLONIC VORTICITY ADVECTION AND WEAK ISENTROPIC LIFT WILL FOCUS THE LIGHT RAIN. SOME MOISTURE WILL ALSO BE CREEPING UP FROM THE COASTAL WAVE. WE MAY END UP IN THE VOID OR NULL ZONE FOR A WHILE...IN TERMS OF THE PCPN EVOLVING. WE INCREASED THE POPS TO CATEGORICAL VALUES AFTER MIDNIGHT. MIN TEMPS WILL BE OF THE WET BULB VARIETY WITH MINS IN THE MID 30S TO L40S. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... TOMORROW...RAPID CYCLOGENESIS OCCURS WITH THE COASTAL LOW PASSING EAST OF CAPE COD AND INTO THE GULF OF MAINE. THE LOW DEEPENS AND INTENSIFIES TO 975-980 HPA. MOST OF THE FCST AREA GETS INTO THE STRONG DEFORMATION ZONE OF THE CYCLONE. THE H850 TEMPS COOL DOWN BELOW ZERO QUICKLY IN THE MORNING...BUT IT IS UNCERTAIN HOW COLD THE BOUNDARY LAYER TEMPS WILL GET. WE ARE EXPECTING SOME WET SNOW OVER THE ADIRONDACKS PRIOR TO NOONTIME DUE TO THE STRONG DYNAMICAL LIFT...AND LATENT HEAT OF FUSION /MELTING EFFECTS COOLING DOWN THE COLUMN DUE TO THE MODERATE TO HVY PCPN/. HOWEVER...THIS WILL LIKELY AMOUNT TO AN INCH OR TWO. ELSEWHERE...WE ARE EXPECTING PERIODS OF RAIN FOCUSED BY THE LOW-MID LEVEL DEFORMATION ZONE. THE H850-700 PARTIAL THICKNESSES ARE BELOW 1540 METERS DURING THE DAY...BUT THE 1000-850 VALUES ARE STILL ABOVE 1310 METERS. THEREFORE...THE PREDOMINANT PTYPE DURING THE DAY WILL BE RAIN. WE FOLLOWED A GFS/GEFS/ECMWF SCENARIO HERE AND THROUGHOUT. THE QPF IS MUCH LOWER WITH A DRY SLOT IMPACTING THE HUDSON RIVER VALLEY VIA THE GFS/NAM. THE WINDS WILL SHIFT TO THE W/NW DURING THE AFTERNOON AND WILL INCREASE BY THE EARLY EVENING...AS THE LOW LEVEL HORIZONTAL PRESSURE GRADIENT INCREASES BETWEEN THE CYCLONE...AND HIGH PRESSURE NEAR THE LOWER MS RIVER VALLEY. THE PCPN WILL START TO TRANSITION TO SNOW AT ALL LOCATIONS AT 1500 FT AGL AND GREATER BY 00Z. TEMPS WILL SLIGHTLY FALL...OR BE STEADY THROUGHOUT THE DAY...WITH PEAK READINGS IN THE M30S TO M40S. FRIDAY NIGHT...WE HAVE WAITED TO ISSUE A POSSIBLE WIND ADVISORY HERE...SINCE THEY ARE NOT ISSUED BEYOND THE FIRST TWO PERIODS. THANKS FOR THE COLLABORATION WITH THE NEIGHBORING OFFICES. THE LOW LEVEL WIND FIELDS STRENGTHEN WITH H925 WINDS VIA THE GFS OF 35-45 KTS. THE NAM IS A LITTLE WEAKER WITH 30-40 KTS. THE H850 WINDS ARE 45-60 KTS AS THE LOW BEGINS TO OCCLUDE NEAR THE MAINE COAST. THE BEST MOMENTUM TRANSFER AT NIGHT OFF THE GFS/NAM BUFKIT SOUNDINGS WOULD BE 35-40 KTS FROM 2.5 KFT AGL. FOR NOW...WE HAVE GUSTS MENTIONED TO 39 KTS /45 MPH/ JUST SHY OF MARGINAL WIND ADVISORY CRITERIA. THE SITUATION IS SOMEWHAT SIMILAR TO CASES IN THE CURRENT COOL SEASON HIGH WIND STUDY IN CSTAR...BUT THE SYSTEM LOCATION...AND MORE IMPORTANTLY THE TIMING OF THE MIXING OF THE STRONG WINDS TO SFC IS NOT IDEAL. IN TERMS OF THE SNOWFALL...WE CONCUR WITH THE HPC GRAPHICS...AND HAVE 1-3 INCHES OCCURRING OVER THE SRN ADIRONDACKS...SRN GREENS...AND BERKSHIRES OVERNIGHT. AN INCH OR SO OVER THE HELDERBERGS...ERN CATSKILLS...AND TACONICS. THE CAPITAL REGION...LAKE GEORGE REGION...MOHAWK RIVER VALLEY...MAY RECEIVE A COATING TO POSSIBLY AN INCH. TOTAL SNOW ACCUMULATIONS OVER THE SRN GREENS AND DACKS WILL BE IN THE 2-4 INCH RANGE. SATURDAY...WIND WILL BE THE MAIN CONCERN. BLUSTERY CONDITIONS WILL CONTINUE...AND BETTER MIXING MAY OCCUR FROM 2-3 KFT AGL...WITH WIND GUSTS MARGINALLY APPROACHING ADVISORY CRITERIA OF 46-57 MPH. THE WIND FIELDS START TO WEAKEN BY 18Z WITH THE STACKED OCCLUDED CYCLONE MEANDERING OVER THE GULF OF ST LAWRENCE. THE BETTER CHANCE OF VERY STRONG WINDS MAY BE EAST OF THE REGION OVER ERN NEW ENGLAND. SCT UPSLOPE SNOW SHOWERS WILL LIKELY CONTINUE THROUGH THE MORNING AND DIMINISH BY THE AFTERNOON WITH THE LOW-LEVEL FLOW MORE NW...AND THE H500 CIRCULATION WELL NE OF THE REGION. IT WILL BE A CHILLY DAY WITH MAX TEMPS IN THE MID 30S TO L40S IN THE MTNS...AND L40S TO MID40S IN THE VALLEYS. SATURDAY NIGHT INTO SUNDAY...HIGH PRESSURE WILL NUDGE IN FROM THE SOUTHEAST WITH THE MID LEVEL FLOW BECOMING FLATTER AND ZONAL AHEAD OF THE NEXT WEAK DISTURBANCE APPROACHING FROM THE GREAT LAKES REGION. WE DON/T SEE ANY LAKE EFFECT ISSUES SATURDAY NIGHT...AND HAVE GONE WITH A RELATIVELY DRY FCST DURING THIS TIME FRAME WITH JUST A SLIGHT CHANCE OF A SNOW SHOWER OR FLURRY WELL WEST OF THE HUDSON RIVER VALLEY SAT NIGHT...AND A SLIGHT CHANCE OF SHOWERS ON SUNDAY WITH AN APPROACHING TROUGH OF LOW PRESSURE...AND A COLD FRONT. TEMPS MODERATE ABOVE NORMAL TO CLOSE THE HOLIDAY WEEKEND WITH HIGHS 5-10 DEGREES ABOVE NORMAL. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... MOS AND ECMWF IN CLOSE AGREEMENT CONCERNING THE FIRST SYSTEM...SO WENT WITH MOS GUIDANCE. A COLD FRONT BRINGS GOOD CHANCE POPS FOR THE START OF THE WORK WEEK. PRECIP WILL LIKELY BE MOSTLY RAIN IN THE VALLEYS AND SOUTHERN LOCATIONS...WITH A MIX OF RAIN OR SNOW SHOWERS ELSEWHERE. MAXIMUM TEMPERATURES ARE LIMITED BY CLOUD COVER AHEAD OF THE FRONT...WITH HIGH READINGS EXPECTED TO BE IN ONLY THE 30S IN THE HIGHEST PEAKS...WHERE THE ONSET OF PRECIP WILL ONLY SERVE TO COOL THE COLUMN OF AIR. THE FRONT PULLS THROUGH LATE MONDAY... BUT WE KEEP CHC POPS GOING AS A WESTERLY WIND FLOW BEHIND THE FRONT MAY RESULT IN SOME LAKE-ENHANCED SHOWERS...THOUGH NOTHING OF GREAT CONSEQUENCE. AS WINDS QUIET DOWN...POPS MAX OUT AT SLGT CHC FROM TUE NGT INTO WED NGT. WE WILL HAVE THE GREATEST CHANCE OF SEEING THE STARS TUE NGT...BUT THEN HIGH CLOUDINESS LIFTS IN AHEAD OF LOW PRESSURE FORMING OVER THE DEEP SOUTH...EVEN AS WE SIT UNDER AN AREA OF HIGH PRESSURE. HOWEVER...WHILE SCANT SUNSHINE MEANS LIMITED WARMING ON WEDNESDAY... THE LACK OF A SOURCE OF COLD AIR MEANS THE POTENTIAL FOR JUST ANOTHER MIXED EVENT ON THURSDAY AS THIS LOW REACHES THE MID-ATLANTIC REGION. WHILE BOTH THE GFS AND ECMWF DIFFER IN THE STORM TRACK /ECMWF KEEPS IT WELL INLAND/ AND TEMPERATURE ASPECT WITH THIS SYSTEM...HPC SENDS THE LOW OUT TO SEA WELL TO OUR SOUTH... WHICH...IF ANYTHING...WOULD APPEAR TO LEAN TOWARD THE COLDER SOLUTION OF THE GFS...WHICH...AGAIN...WOULD BE ONLY COLD ENOUGH TO GIVE US A MIXED SCENARIO...INSTEAD OF RAIN. THUS...GMOS REPRESENTS THE BEST COMPROMISE AT THIS TIME. HIGH TEMPERATURES WON'T SHOW TOO MUCH DAY-TO-DAY VARIATION. TUESDAY WILL BE SLIGHTLY THE COLDEST DAY...FRESH BEHIND THE COLD FRONT. BOTH HIGHS AND LOWS WILL AVERAGE VERY CLOSE TO NORMAL. LOW TEMPS WILL BE SUB-FREEZING EVERYWHERE FROM TUESDAY NIGHT ON...WITH SOME UPPER TEENS POSSIBLE ON THE MOUNTAINTOPS. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... IFR CONDITIONS THIS MORNING...ESPECIALLY RIGHT ALONG THE HUDSON RIVER WHERE IDEAL RADIATIONAL FOG HAS RESULTED IN 1/4SM VIS WHICH WILL CONTINUE FOR THE NEXT FEW HOURS. AS SEEN ON THE RADAR MOSAIC...REFLECTIVITIES COVERAGE REMAINS OVER CENTRAL NY AND ADDITIONAL SHOWER ACTIVITY COMING NORTHWARD FROM LONG ISLAND INTO SOUTHERN NEW ENGLAND. AS THIS STORM EVOLVES OFF THE MID ATLANTIC COAST...PRECIPITATION WILL INCREASE IN COVERAGE THROUGH THIS FRIDAY MORNING KEEPING MVFR/IFR CONDITIONS WHICH SHOULD BE MAINLY FROM CIGS. WINDS WILL BECOME MORE PROBLEMATIC LATE TODAY INTO TONIGHT WITH AN INCREASED WEST-NORTHWEST WIND FLOW. WILL INTRODUCE LLWS TONIGHT WITH SFC WIND GUSTS BETWEEN 20-30 KTS TO START. OUTLOOK... FRI OVNGT-SAT NGT...MVFR/IFR...-SHRA CHG TO -SHSNRA. LLWS. WINDY. SUN...VFR. NO SIG WX. MON...MVFR/IFR. -RA/-SN. TUE...VFR/MVFR. CHC -SHRA/-SHSN. && .HYDROLOGY... A STRONG STORM SYSTEM FORECAST TO DEVELOP ACROSS EASTERN NEW ENGLAND...WILL BRING PRECIPITATION TO THE REGION FROM LATE TONIGHT THROUGH SATURDAY MORNING. THERE IS STILL SOME UNCERTAINTY WITH REGARDS TO THE EVOLUTION OF THE STORM AND ASSOCIATED QPF. MODELS HAVE COME INTO SOMEWHAT BETTER AGREEMENT. FORECAST QPF AMOUNTS EXPECTED TO RANGE FROM ONE QUARTER TO AROUND ONE INCH ACROSS THE HSA. THE HIGHEST AMOUNTS OF 0.50 TO 1.00 INCH ARE EXPECTED TO FALL ACROSS PORTIONS OF WESTERN NEW ENGLAND. DEPENDING ON WHEN THE COLDER AIR MOVES IN...SOME OF THE PRECIP MAY FALL AS SNOW...ESPECIALLY ACROSS THE HIGHER ELEVATIONS LATE FRIDAY INTO FRIDAY NIGHT. AT THIS TIME IT APPEARS RISES ON AREA RIVERS WILL BE AROUND 1 TO 2 FEET BUT WILL REMAIN WITHIN THEIR BANKS. THE PRECIPITATION WILL TAPER OFF SATURDAY MORNING...AS THE STORM PULLS AWAY INTO THE CANADIAN MARITIMES. WE HAVE MODELED A NUMBER OF RIVERS SUCH AS THE SMALLER RIVERS OVER SOUTHERN VERMONT AND WESTERN NEW ENGLAND ALONG WITH THE SOMETIMES TROUBLESOME EAST CANADA CREEK. SOME OF THEM SHOW RISES OF ONE TO THREE FEET...BUT NONE GET NEAR FLOOD. WEAK HIGH PRESSURE BUILDING IN WILL RESULT IN DRY CONDITIONS FROM SATURDAY AFTERNOON THROUGH MUCH OF SUNDAY. A COLD FRONT PASSAGE WILL BRING ADDITIONAL SHOWERS WITH MAINLY LIGHT QPF SUNDAY NIGHT THROUGH MONDAY. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...WASULA NEAR TERM...RCK/WASULA SHORT TERM...WASULA LONG TERM...ELH AVIATION...BGM HYDROLOGY...JPV/RCK WWW.WEATHER.GOV/ALBANY