000 FXUS61 KALY 091143 AFDALY AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 643 AM EST FRI JAN 9 2009 .SYNOPSIS... WEAK HIGH PRESSURE WILL BUILD INTO THE REGION LATER TODAY AND TONIGHT. ON SATURDAY A LOW PRESSURE SYSTEM WILL MOVE FROM THE OHIO VALLEY TO THE VIRGINIAS...THEN OFF THE NEW JERSEY COAST SATURDAY NIGHT. THIS SYSTEM WILL BRING A MODERATE TO POTENTIALLY HEAVY SNOWFALL...ESPECIALLY SOUTH OF THE CAPITAL REGION. THE STORM SYSTEM WILL QUICKLY DEPART BY SUNDAY MORNING...WITH HIGH PRESSURE BUILDING BACK IN SUNDAY NIGHT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A FAIRLY TRANQUIL DAY EXPECTED TODAY. THERE ARE STILL A FEW VERY NARROW AND MAINLY LIGHT LAKE EFFECT SNOW SHOWERS MOVING ACROSS PORTIONS OF THE EASTERN CATSKILLS EARLY THIS MORNING WITH NW FLOW PERSISTING. WILL MENTION 20-30 POPS ACROSS THIS AREA THIS MORNING WITH ONLY A FEW TENTHS OF A INCH OF ACCUMULATION IN ISOLATED SPOTS. ELSEWHERE WILL MENTION SCATTERED FLURRIES INTO THIS MORNING. INVERSION HEIGHTS ARE FORECAST TO DROP TO AROUND 900 MB TODAY...WHICH SHOULD LIMIT THE INTENSITY AND COVERAGE OF SNOW SHOWERS...HENCE THE LOW POPS. BY THIS AFTERNOON THE ENTIRE AREA SHOULD BE DRY AS HIGH PRESSURE BUILDS IN FROM THE WEST. MOST AREAS WILL SEE AT LEAST SOME SUNSHINE BY THIS AFTERNOON...WITH MOUNTAINOUS AREAS HANGING ONTO CLOUD COVER THE LONGEST. MAX TEMPS SOMEWHAT CHILLY WITH MID TEENS TO LOWER 20S ACROSS THE HIGHER ELEVATIONS AND MID 20S TO LOWER 30S IN THE VALLEYS. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... A WINTER STORM WATCH HAS BEEN ISSUED FOR ULSTER...DUTCHESS AND LITCHFIELD COUNTIES FROM SATURDAY AFTERNOON INTO SUNDAY MORNING... HIGH PRESSURE BUILDING IN SHOULD ENSURE A QUIET NIGHT WITH MAINLY CLEAR SKIES EARLY...AND HIGH CLOUDS INCREASING TOWARDS MORNING. WINDS SPEEDS WILL ALSO BE DECREASING...SO RADIATIONAL COOLING WILL LEAD TO COLD MIN TEMPS. SINGLE DIGITS TO LOWER TEENS EXPECTED FROM THE MOHAWK VALLEY AND SARATOGA REGION SOUTHWARD...WITH LOWER SINGLE DIGITS TO BELOW ZERO TEMPS NORTH. ON SAT...ATTENTION SHIFTS TO THE NEXT STORM SYSTEM THAT WILL BE AFFECTING THE REGION SATURDAY AFTERNOON THROUGH EARLY SUN MORNING. MODELS HAD PREVIOUSLY SHOWN A GREAT DEAL OF SPREAD WITH THIS SYSTEM. THERE ARE STILL SOME DIFFERENCES...BUT OVERALL BETTER AGREEMENT ESPECIALLY BETWEEN THE GFS/NAM WITH REGARDS TO TRACK/QPF. THE ECMWF CONTINUES TO BE THE OUTLIER...WITH A STRONGER SURFACE LOW...GREATER QPF AND A MORE NORTHERLY TRACK. WILL LEAN TOWARDS THE MORE CONSISTENT GFS SOLUTION...ALTHOUGH QPF HAS INCREASED IN LATEST RUN. DESPITE AGREEMENT WITH THE TRACK...THERE ARE STILL TIMING ISSUES BETWEEN NAM/GFS...WITH THE NAM MUCH SLOWER WITH ONSET OF PRECIP. WILL LEAN TOWARDS FASTER GFS...WITH WARM ADVECTION REGIME TYPICALLY RESULTING IN EARLIER ONSET. WILL MENTION LIKELY TO CATEGORICAL POPS SOUTH OF ALBANY FROM SAT AFTERNOON THROUGH 00Z SUNDAY...WITH LIKELY TO CATEGORICAL POPS ACROSS ALMOST THE ENTIRE AREA SAT NIGHT INTO EARLY SUN MORNING. SYNOPTICALLY...THIS STORM WILL BE A FAST-MOVING SYSTEM WITH AN OPEN UPPER LEVEL WAVE. HOWEVER...THE SURFACE LOW IS FORECAST TO DEEPEN AS IT LIFTS NORTHEAST FROM THE OHIO VALLEY...THROUGH THE MID ATLANTIC REGION AND OFF THE NEW JERSEY COAST SAT NIGHT. THIS TRACK FAVORS ALL SNOW FOR PTYPE. A QUICK BUT SIGNIFICANT PERIOD OF ISENTROPIC LIFT ON THE 285 K SURFACE IS FORECAST FROM EARLY EVENING INTO THE OVERNIGHT HOURS. THE FRONTOGENESIS DOES NOT REALLY GET GOING UNTIL THE STORM DEEPENS WELL OFF THE COAST AND IS PAST OUR REGION. HOWEVER...THERE IS SOME OVERLAP OF OMEGA AND FAVORED -12C TO -18C DENDRITIC GROWTH ZONE AS WELL...SO SNOW RATIOS WILL LIKELY EXCEED CLIMO VALUES OF 12.5 TO 1. USED MAINLY 14 TO 1 RATIOS THROUGH THE EVENT. HEAVIEST QPF OF 0.50 TO 0.75 FORECAST ACROSS ULSTER...DUTCHESS AND LITCHFIELD WHERE THE WINTER STORM WATCH HAS BEEN ISSUED. BASED ON EXPECTED SNOW RATIOS...THIS IS WHERE SNOW ACCUMULATIONS OF 7 OR MORE INCHES IS EXPECTED TO FALL. ADVISORIES MAY EVENTUALLY BE NEEDED FOR THE MOHAWK VALLEY AND CAPITAL REGION SOUTHWARD THROUGH GREEN...COLUMBIA AND BERKSHIRE COUNTIES...WHERE 3 TO 7 INCHES IS POSSIBLE. AT THIS TIME ONLY LIGHT SNOWFALL AMOUNTS EXPECTED ACROSS THE SOUTHERN ADIRONDACKS. SNOW SHOULD START TO DIMINISH AROUND OR SHORTLY AFTER SUNRISE FROM WEST TO EAST ACROSS THE AREA. DRY CONDITIONS EXPECTED SUNDAY AFTERNOON. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... REGION REMAINS UNDER A LONG WAVE TROUGH THROUGH THE PERIOD. THE PATTERN IS EXPECTED TO AMPLIFY BY MID WEEK AS ARCTIC AIR PLUNGES SOUTHWARD AND A DEEP BROAD TROUGH COVERS THE CONUS EAST OF THE ROCKIES. ON THURSDAY 850 MB TEMPERATURES ACROSS THE LOCAL AREA ARE FORECAST TO DROP TO -20 TO -25 DEGREES CELSIUS. THE LOW WHICH WILL BRING SNOW TO THE REGION OVER THE WEEKEND WILL HEAD NORTHEAST UP THE NEW ENGLAND COAST SUNDAY NIGHT AND WEAK SURFACE RIDGING WILL BUILD IN. THE HIGH`S VISIT WILL BE BRIEF AS MORE ENERGY DIVES INTO THE LONG WAVE TROUGH AND SPINS UP ANOTHER LOW PRESSURE SYSTEM WHICH WILL MOVE ACROSS THE REGION EARLY IN THE WEEK. ARCTIC AIR WILL BEGIN TO POUR INTO THE REGION IN THE WAKE OF THIS SYSTEM TUESDAY. HOWEVER...YET ANOTHER LOW PRESSURE SYSTEM WILL SPIN UP AS MORE ENERGY DIVES INTO THE LONG WAVE TROUGH. THIS TIME THE LOW IS FORECAST TO PASS TO OUR SOUTH WEDNESDAY NIGHT OR THURSDAY THEN EVEN COLDER AIR WILL BE USHERED INTO THE REGION. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... VFR CONDITIONS EXPECTED AT TAF SITES THROUGH TAF PERIOD...12Z/SAT. W-NW WINDS 10 TO 15 KNOTS WILL BECOME GUSTY THIS MORNING WITH GUSTS AROUND 25 KNOTS ESPECIALLY AT KALB. THE WINDS WILL DIMINISH FRIDAY EVENING. SCATTERED TO BROKEN STRATOCUMULUS CLOUDS EXPECTED TODAY WITH SKIES CLEARING EARLY THIS EVENING. HIGH LEVEL CIRRUS CLOUDS OVERSPREAD THE REGION LATE TONIGHT IN ADVANCE OF AN APPROACHING LOW PRESSURE SYSTEM. OUTLOOK.... SAT...VFR-MVFR...SNOW OVERSPREADING DURING THE AFTERNOON. SAT NIGHT...MVFR-IFR IN SNOW. SUN...IMPROVING CONDITIONS WITH SNOW ENDING. SUN NIGHT...VFR...NO SIG WX. MON...VFR WITH MVFR POSSIBLE...SLIGHT CHC TO CHC SNOW SHOWERS. MON NIGHT-TUE...VFR- MVFR...CHC SNOW. && .HYDROLOGY... FEW...IF ANY...HYDROLOGY RELATED PROBLEMS ARE EXPECTED THROUGH THE WEEKEND AND INTO THE COMING WEEK. SEASONABLE TEMPERATURES INTO EARLY NEXT WEEK WITH AN ARCTIC AIRMASS EXPECTED FOR MID WEEK. ICE WILL FORM AND THICKEN ESPECIALLY EARLY NEXT WEEK AS TEMPERATURES PLUNGE WELL BELOW FREEZING AND IT MAY GET COLD ENOUGH ACROSS THE ADIRONDACKS AND SOUTHERN VERMONT FOR SOME ISOLATED FREEZE UP RIVER ICE JAMS TO FORM BY TUESDAY. HOUSATONIC FLOW HAS HAD ONLY A SLIGHT INCREASE...SO LITTLE IF ANY ICE MOVEMENT MAY BE EXPECTED. SNOW WATER EQUIVALENT DATA FROM FIELD SURVEYS SHOW 3 TO 7 INCHES OF WATER OVER MUCH OF THE ADIRONDACKS...WITH 2 TO 4 INCHES OF WATER IN SOUTHERN VERMONT. OUR INITIAL 08-09 WINTER SPRING FLOOD POTENTIAL OUTLOOK WILL BE ISSUED ON FRIDAY JAN 9TH. FOR DETAILS ON THE RIVERS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY MORNING FOR CTZ001-013. NY...WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SUNDAY MORNING FOR NYZ063>066. MA...NONE. VT...NONE. && $$ SYNOPSIS...JPV NEAR TERM...JPV SHORT TERM...JPV LONG TERM...IAA AVIATION...IAA HYDROLOGY...IAA