000 FXUS61 KBUF 181753 AFDBUF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 1253 PM EST TUE NOV 18 2008 .SYNOPSIS... COLD AIR CROSSING LAKES ERIE AND ONTARIO WILL CONTINUE TO PRODUCE SOME SNOW SHOWERS TODAY...WITH THE MOST PERSISTENT LAKE SNOWS FOUND OVER THE FINGER LAKES REGION THROUGH TONIGHT. A WEAK RIDGE WILL THEN BUILD ACROSS THE LOWER GREAT LAKES LATE TONIGHT AND WEDNESDAY... BEFORE A CLIPPER TYPE SYSTEM WILL SPREAD A GENERAL ONE TO TWO INCH SNOWFALL ACROSS WESTERN NEW YORK WEDNESDAY NIGHT AND THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... BOUNDARY LAYER FLOW CONTINUES ON A 360 DEGREE VECTOR OVER MUCH OF THE AREA...WITH MORE OF A 020 VECTOR ACROSS THE EAST END OF LAKE ONTARIO. 850MB TEMPS OF AROUND -13C AND 700MB TEMPS OF AROUND -23C WILL MAINTAIN MODERATE TO EXTREME LAKE INDUCED INSTABILITY TODAY...ALTHOUGH THE INSTABILITY WILL BE TEMPERED BY THE SHORT NORTHERLY FETCH. THIS WILL PROMOTE MULTIPLE BANDS OF SOMEWHAT LESS INTENSE AND LESS FOCUSED LAKE EFFECT TODAY INTO TONIGHT. ACROSS WAYNE AND NORTHERN CAYUGA COUNTIES...THE NNE FLOW HAS A LONGER FETCH ACROSS THE EAST END OF LAKE ONTARIO FROM THE THOUSAND ISLANDS REGION DOWN ACROSS THE EASTERN BASIN...THE LONGEST FETCH ON THE LAKE WITH THIS WIND DIRECTION. IN ADDITION...SEVERAL CONCAVE BAYS ON THE NORTHERN SHORELINE NEAR WOLFE ISLAND ARE SUPPORTING ENHANCED CONVERGENCE AND A FEW MORE DOMINANT BANDING FEATURES WITHIN THE MULTIPLE BAND REGIME. WE RECEIVED A SPOTTER REPORT OF 13 INCHES IN FAIR HAVEN OVERNIGHT...AND THIS HAS BEEN BACKED UP BY CALLS TO LOCAL POST OFFICES. DUE TO THE PREVIOUS SNOWFALL...AND EXPECTED AREA OF ENHANCED TOTALS TODAY HAVE UPGRADED WAYNE AND NORTHERN CAYUGA COUNTIES TO LAKE EFFECT SNOW WARNINGS THROUGH THIS EVENING. EXPECT ADDITIONAL AMOUNTS OF 4-7 INCHES IN PERSISTENT BANDS BETWEEN SODUS BAY AND FAIR HAVEN...BRINGING TOTALS INTO THE 10-15 INCH RANGE IN A FEW SPOTS. ALSO ADDED OSWEGO COUNTY TO THE ADVISORY...MAINLY FOR THE EXTREME WESTERN END OF THE COUNTY AROUND HANNIBAL. ELSEWHERE...EXPECT LOCAL ACCUMS OF 3 TO 5 INCHES IN THE GENESEE VALLEY AND WESTERN FINGER LAKES TODAY...ALTHOUGH THESE AMOUNTS WILL BE VERY LOCALIZED IN AREAS WHICH HAPPEN TO SIT UNDER A BAND FOR AN EXTENDED TIME. ACROSS THE METRO ROCHESTER AREA...EXPECT THE HEAVIEST TOTALS TO SPLIT THE CITY PROPER WITH THE WESTERN AND EASTERN SUBURBS MOST LIKELY TO PICK UP A FEW INCHES. THE REASON FOR THIS IS DUE TO THE MEAN BOUNDARY LAYER FLOW. THE TRAJECTORY FOR A PARCEL OF AIR CROSSING THE CITY OF ROCHESTER TAKES IT OVER POINT PETRE... SHORTENING THE EFFECTIVE FETCH FOR ROCHESTER. ACROSS THE BUFFALO AREA...EXPECT OCCASIONAL SNOW SHOWERS TO CONTINUE WITH THE MOST PERSISTENT ACTIVITY EAST OF THE METRO AREA FROM MEDINA DOWN TO BATAVIA WHERE A FEW INCHES MAY FALL LOCALLY. ANOTHER AREA OF PERSISTENT SNOW WILL CONTINUE FOR A FEW MORE HOURS FROM FORESTVILLE TO JAMESTOWN. THE COLD ADVECTION WILL HOLD MAX DAYTIME TEMPS DOWN TO THE MID 20S TO LOW 30S...THE COLDER SPOTS IN THE SOUTHERN TIER AND TUG HILL REGION. LOWS TONIGHT WILL RANGE FROM THE LOWER 20S ALONG THE LAKE PLAINS TO THE MID TEENS ACROSS THE SOUTHERN TIER AND TUG HILL REGIONS. THE UPPER TROUGH WILL SLIP TO THE EAST TONIGHT AND RIDGING BOTH SURFACE AND ALOFT WILL START TO BUILD IN FROM THE WEST BY WEDNESDAY MORNING...DISRUPTING THE LAKE SNOWS SOUTH OF LAKE ONTARIO. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... A QUICK MOVING SHORTWAVE RIDGE WILL CROSS THE FORECAST AREA DURING THE DAY WEDNESDAY...WITH WARM ADVECTION HELPING TO GENERATE A WEALTH OF CLOUD COVER. WHILE THE BULK OF THE DAY SHOULD BE PRECIPITATION FREE...THERE WILL BE A COUPLE AREAS OF LIGHT SNOW THAT WILL NEED TO BE ADDRESSED. FIRST...THERE WILL BE SOME LINGERING LAKE EFFECT SNOW SHOWERS ACROSS THE FINGER LAKES REGION WEDNESDAY MORNING. THIS ACTIVITY SHOULD TAPER OFF TO FLURRIES BY MIDDAY AS INCREASED SHEAR WITHIN THE NW FLOW WILL COUPLE WITH A SHRINKING DENDRITIC SNOW GROWTH ZONE. SNOW ACCUMS WEDNESDAY MORNING WILL GENERALLY BE AN INCH OR LESS WITHIN THIS AREA. THE OTHER AREA OF LIGHT SNOW WILL BE SYNOPTIC IN NATURE. THE COMBINATION OF ISENTROPIC LIFT FROM THE WARM ADVECTION...AND THE INTRODUCTION OF SOME JET INDUCED LIFT FROM THE UPPER GREAT LAKES COULD PRODUCE SOME LIGHT SNOW/FLURRIES OVER THE EIGHT WESTERN COUNTIES BY LATE AFTERNOON. THE ONSET OF THIS AREA OF LIGHT SNOW HAS BEEN SPED UP FROM CONTINUITY BY ABOUT 3-6 HOURS. WEDNESDAY NIGHT AND THURSDAY WILL THEN BE DOMINATED BY A CLIPPER TYPE SYSTEM THAT WILL DROP FROM THE UPPER GREAT LAKES TO THE NEW JERSEY COAST. A SUPPORTING 130 KNOT H3 JET WITH THE FEATURE WILL CROSS FROM LOWER MICHIGAN TO PENNSYLVANIA...AND THIS WILL PLACE MUCH OF NEW YORK UNDER THE FAVORED LF QUAD (JET EXIT REGION) OF THE JET WHERE THE OVERALL LIFT WILL BE ENHANCED FROM ALOFT. POPS HAVE BEEN RAISED FROM LIKELY TO CATEGORIAL FOR THE BULK OF THE FORECAST AREA AS A RESULT...WITH CHC TO LIKELY POPS FOUND ACROSS THE NORTH COUNTRY. THE RAISING OF THE POPS IS SUPPORTED BY THE GFS...ECMWF AND ALSO BY NEARLY 100 PERCENT OF THE SREF ENSEMBLE MEMBERS. THE PASSING OF THE CLIPPER WILL BRING A GENERAL 1 TO 3 INCH SNOWFALL TO ALL OF WESTERN NEW YORK...WITH AMOUNTS LEANING TOWARDS THE LOWER END OF THAT RANGE FOR MOST OF JEFFERSON AND LEWIS COUNTIES. AS THE CLIPPER WEAKENS AND MOVES OFFSHORE THURSDAY NIGHT...COLDER AIR IN ITS WAKE WILL ONCE AGAIN TEAM UP WITH A CYCLONIC FLOW OVER THE WIDE OPEN LAKES TO PRODUCE MORE LAKE EFFECT SNOW. WHILE SNOW SHOWERS WILL INITIALLY BE FAIRLY WIDESPREAD ACROSS THE REGION EARLY THURSDAY NIGHT...THE LAKES SNOWS WILL BECOME CONCENTRATED OVER THE WESTERN SOUTHERN TIER (MINUS ALLEGANY COUNTY) AND FROM MONROE AND ORLEANS COUNTIES EAST TO SYRACUSE. && .LONG TERM /FRIDAY THROUGH MONDAY/... TEMPERATURES WILL GENERALLY REMAIN BELOW NORMAL DURING THIS PERIOD...ALTHOUGH READINGS WILL TREND BACK TOWARDS NORMAL SUNDAY AND MONDAY. THIS MAY PROVE TO BE MISLEADING THOUGH WHEN IT COMES TO WHAT WE CAN EXPECT FOR THE REMAINDER OF NEXT WEEK. BEFORE DELVING INTO THAT...LETS LOOK AT THE DETAILS THROUGH THE WEEKEND. A DEEP LONGWAVE TROUGH WILL REMAIN OVER EASTERN CANADA ON FRIDAY WITH H85 TEMPS OF -15C BEING FOUND ACROSS MOST OF OUR FORECAST AREA. THIS WILL LIKELY RESULT IN THE COLDEST DAY OF THE SEASON AS SFC TEMPERATURES WILL STRUGGLE TO MAKE IT UP TO THE FREEZING MARK. TEMPS ACROSS THE WRN SOUTHERN TIER WILL PROBABLY BE IN THE MID/UPPER 20S. NEEDLESS TO SAY...THE COLD AIR AT THIS TIME OF YEAR WILL BE ACCOMPANIED BY SCATTERED LAKE EFFECT SNOW SHOWERS WITH THE MAIN AREAS OF CONCERN BEING OVER CHAUTAUQUA COUNTY AND ALSO FROM WAYNE TO OSWEGO COUNTY. SCATTERED LAKE EFFECT SNOW SHOWERS WILL CONTINUE FRIDAY NIGHT... WITH AGAIN THE MOST WIDESPREAD ACTIVITY BEING FOUND SOUTHEAST OF BOTH LAKES. A RIDGE WILL THEN BUILD ACROSS THE LOWER GREAT LAKES SATURDAY AND SUNDAY. AT THIS POINT...THE BULK OF THAT TIME LOOKS TO BE DRY BUT ONE SHOULD NEVER TRUST WARM ADVECTION. IN THE WAKE OF THE RIDGE ON SUNDAY...WARM ADVECTION PROCESSES COULD GENERATE SOME SPRINKLES OR FLURRIES. MOISTURE SPREADING NORTHWARD FROM THE OHIO VALLEY AHEAD OF A FRONTAL SYSTEM COULD THEN PRODUCE SOME LIGHT RAIN OR SNOW FOR LATER SUNDAY NIGHT INTO MONDAY. LOOKING FURTHER AHEAD AT THE BULK OF NEXT WEEK...THERE IS A HUGE DISPARITY BETWEEN THE OPERATIONAL RUNS OF THE GFS AND ECMWF WHICH WILL LIKELY HAVE HUGE IMPLICATIONS FOR THE OVERALL TREND OF NEXT WEEKS WEATHER. THE 00Z RUN OF THE OPERATIONAL GFS IS SUGGESTING A PACIFIC FLOW ACROSS THE COUNTRY WITH RIDGING CROSSING THE OHIO VALLEY AND OUR REGION...WHICH WOULD SEND TEMPS ABOVE NORMAL. ON THE OTHER HAND...THE ECMWF DEVELOPS A DEEP LOW OVER THE UPPER GREAT LAKES MONDAY NIGHT AND TUESDAY WITH ANOTHER LONGWAVE TROUGH SETTING UP OVER EASTERN CANADA AND THE GREAT LAKES REGION. THE LATTER PATTERN IS SUPPORTED BY THE MAJORITY OF THE GEFS MEMBERS AS A LONGWAVE TROUGH IS DEPICTED OVER EASTERN CANADA. RATHER THAN BEING TRUE COLD AIR THOUGH...THE SOLUTION FROM THE GEFS ALSO SUGGESTS THAT THE AIR WITHIN THE TROUGH WILL BE MAINLY PACIFIC IN NATURE. STAY TUNED. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... NORTH WINDS CONTINUE TO PRODUCE WIDESPREAD LAKE EFFECT SNOW SHOWERS SOUTH OF LAKES ERIE AND ONTARIO TODAY...AND THIS WILL CONTINUE THROUGH THE EVENING. EXPECT VFR TO DROP PERIODICALLY TO IFR/LIFR AS SNOW SHOWERS CROSS ALL OF THE WESTERN 4 TERMINALS...ALTHOUGH TIMING OF THE REDUCTION OF VISIBILITY WILL BE IMPOSSIBLE GIVEN THE NATURE OF THE LAKE EFFECT ACTIVITY. TONIGHT AS FLOW GRADUALLY BACKS MORE TO THE NORTHWEST...THIS SHOULD CARRY LAKE EFFECT AWAY FROM KIAG-KBUF-KROC WITH CONDITIONS RETURNING TO VFR. AT KJHW OCCASIONAL LAKE EFFECT SNOW SHOWERS WILL LINGER LONGER INTO THE EVENING BEFORE RIDGING AND SUBSIDENCE BUILDS IN AND SQUELCHES LAKE EFFECT SNOW. AT KART...EXPECT VFR CONDITIONS TO PREVAIL THROUGH THE PERIOD. OUTLOOK... WEDNESDAY...GENERALLY VFR EXCEPT MVFR IN LIMITED SNOW SHOWERS TO THE LEE OF THE LAKES. WEDNESDAY NIGHT AND THURSDAY...MVFR/IFR IN AREAS OF LIGHT SNOW. FRIDAY AND SATURDAY...LOCAL IFR LAKE EFFECT SNOW SOUTHEAST OF THE LAKES. SUNDAY...VFR. && .MARINE... STRONG HIGH PRESSURE CENTERED OVER THE CENTRAL PLAINS WILL CONTINUE TO HELP TO PRODUCE NORTH TO NORTHWEST WINDS OF 10 TO 20 KNOTS ACROSS BOTH LAKES TODAY. THESE WINDS...IN COMBINATION WITH THE COLD AIR IN PLACE...WILL HELP TO BUILD WAVES AS HIGH AS 5 FEET ALONG THE SOUTH SHORE OF LK ONTARIO BETWEEN THIRTY MILE POINT AND MEXICO BAY. WILL THUS RAISE A SMALL CRAFT ADVISORY FOR THAT AREA TODAY THROUGH 21Z. THE REMAINING NEARSHORE AREAS WILL GENERALLY HAVE WAVES OF 2 TO 4 FEET...WHICH WILL SUBSIDE DURING THE COURSE OF TONIGHT AS THE SFC PRESSURE GRADIENT WILL RELAX SOMEWHAT. THIS WILL ESPECIALLY BE THE CASE OVER LAKE ERIE. FOR WEDNESDAY...A RIDGE WILL CROSS THE LOWER GREAT LAKES AND THIS WILL RESULT IN LIGHT WINDS AND MINIMAL WAVES. INCREASING SOUTHWESTERLIES LATE WEDNESDAY NIGHT WILL BUILD THE WAVES BACK TO NEAR SMALL CRAFT CRITERIA ON LAKE ERIE. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ003-006-013-014. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR NYZ004-005. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR LOZ042>044. && $$ SYNOPSIS...RSH NEAR TERM...HITCHCOCK/WCH SHORT TERM...RSH LONG TERM...RSH AVIATION...HITCHCOCK MARINE...RSH