FXUS61 KBUF 041151
AFDBUF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
651 AM EST FRI DEC 4 2009
.SYNOPSIS...
LAKE EFFECT SNOW WILL DEVELOP TO THE EAST OF BOTH LAKES ERIE AND
ONTARIO TODAY WITH THE GREATEST IMPACT OFF LAKE ERIE INTO THE METRO
BUFFALO AREA. COLD AIR ACROSS THE LAKES WILL MAINTAIN AREAS OF LAKE
EFFECT SNOW FOR TONIGHT...BUT HIGH PRESSURE BUILDING DURING THE
WEEKEND WILL WEAKEN THE LAKE SNOW POTENTIAL.
&&
.NEAR TERM /THROUGH TONIGHT/...
A LAKE EFFECT SNOW WARNING REMAINS IN PLACE ACROSS NORTHERN ERIE
COUNTY WHERE A SIGNIFICANT AMOUNT OF WET SNOW IS EXPECTED TODAY INTO
THIS EVENING. LESSER AMOUNTS OF SNOW WILL BE FOUND ACROSS THE
SURROUNDING COUNTIES AND ALSO EAST OF LK ONTARIO. FIRST...A LOOK AT
THE OVERALL SYNOPTIC PATTERN.
A DEEP...BROAD BASED H5 TROUGH OVER THE UPPER GREAT LAKES WILL
REMAIN IN PLACE THROUGH TONIGHT AS H85 TEMPS WILL LOWER FROM ABOUT
-8C TO -10/-12C. WHILE A DEEP CYCLONIC FLOW WILL BE FOUND OVER THE
REGION TODAY...SFC BASED HIGH PRESSURE WILL BUILD ACROSS THE UPPER
OHIO VALLEY TONIGHT. THIS WILL WEAKEN THE LOW LEVEL FLOW ACROSS OUR
REGION WHICH WILL HELP TO WEAKEN THE LAKE EFFECT.
WHILE THERE IS LITTLE IF ANY DOUBT THAT NORTHERN ERIE WILL GET SNOW
TODAY...THERE ARE STILL MAJOR ISSUES THAT COULD WORK AGAINST
SIGNIFICANT SNOW AMOUNTS. THE BIGGEST PROBLEM IS THE LACK OF
MOISTURE IN THE DENDRITIC SNOW CRYSTAL GROWTH AREA. MOISTURE
PROFILES FROM BUFKIT NAM DISPLAYS AND CROSS SECTIONS FROM THE NAM...
GFS AND RUC ARE IN AGREEMENT THAT THERE IS A LACK MOISTURE TO
WORK WITH ABOVE 750MB. THIS MAY BE MOST EASILY VIEWED BY LOOKING
AT THE 00Z KBUF SOUNDING...WHICH SHOWS A CAP AROUND 9K FT. WHILE
MODEL SOUNDINGS CAN BE DISPUTED AND FLAWED...THIS IS RAW DATA...
WHICH JUST SO HAPPENS TO MATCH UP WELL WITH THE SCENARIO PAINTED
BY MOST OF THE GUIDANCE PACKAGES.
THE DENDRITIC SNOW GROWTH AREA IS SHOWN TO BE NEAR THE TOP OF THE
CAP...AND THE NAM SUGGESTS THAT THIS SMALL AREA WILL ACTUALLY SHRINK
AND POSSIBLY DISAPPEAR ALTOGETHER FOR A PERIOD THIS AFTERNOON. IF
THIS WERE TO VERIFY...THEN THE LAKE SNOWS WOULD MIX WITH AND CHANGE
TO RAIN FOR SEVERAL HOURS.
THE FACT THAT THE CAP WILL UNDER 8-9K FT WILL ALSO WORK AGAINST
SERIOUS CONVECTION. YES...LAKE EFFECT CAN CERTAINLY FORM WITH A CAP
OF THIS HEIGHT...BUT SIGNIFICANT SNOWS ARE USUALLY FOUND IN BANDS
WITH A DEEPER PROFILE. FOR WHAT ITS WORTH...LAKE INDUCED CAPES WILL
AVERAGE LESS THAN 500 J/KG.
ON THE OTHER SIDE OF THE ARGUMENT IS A SET OF SOLUTIONS SHOWN BY THE
LOCALLY RUN 6KM MESOSCALE MODELS HERE IN BUF WHICH STILL SUGGEST
THAT A WELL DEFINED PLUME OF LAKE EFFECT SNOW WILL SET UP FROM NEAR
BUFFALO AND EXTEND UP ACROSS NRN ERIE COUNTY TO NW GENESEE COUNTY.
GIVEN THE FACTS OUTLINED ABOVE WITH THE CAP AND LACK OF MID LEVEL
MOISTURE...THIS PCPN PATTERN SHOWN BY THE 6KM MODELS IS BECOMING
MORE AND MORE SUSPECT. IT SHOULD ALSO BE NOTED THAT PCPN AT 09/10Z
WAS MUCH MUCH LESS IMPRESSIVE IN COVERAGE AND INTENSITY THAN WHAT
WAS BEING DEPICTED BY THESE LOCALLY RUN MODELS.
AN ENSEMBLE OF MESOSCALE SOLUTIONS FROM SURROUNDING OFFICES IS
SIMILAR IN ITS PLACEMENT AND QPF TO THE FOUR 6KM RU HERE AT
BUFFALO...BUT AGAIN...AM NOT CONFIDENT OF THIS SOLUTION.
GIVEN THE VARIOUS DISCREPANCIES IN THE GUIDANCE PACKAGES...WILL ONLY
MAKE MINOR TWEAKS TO THE FORECAST SNOW BAND AND CONTINUE WARNINGS AND
ADVISORIES ACROSS THE NIAGARA FRONTIER. SNOWFALL AMOUNTS OF 5 TO 10
INCHES WILL REMAIN IN PLACE FOR PARTS OF NRN ERIE COUNTY THROUGH
THIS EVENING WITH 4 TO 8 INCHES POSSIBLE ALONG THE SURROUNDING EDGES
OF SOUTHERN NIAGARA...SW ORLEANS AND WRN GENESEE COUNTIES.
OFF LK ONTARIO...A VERY SIMILAR PROBLEM WILL EXIST AS THE CAP WILL
BE AT OR BELOW 9K FT WITH ONLY MARGINAL AMOUNTS OF MOISTURE IN THE
SNOW CRYSTAL GROWTH AREA. LAKE INDUCED CAPES OFF LK ONTARIO WILL BE
UNDER 300 J/KG THROUGH TONIGHT. AN ADDITIONAL PROBLEM FOR THIS
ACTIVITY WILL BE A HIGHER AMOUNT OF SHEAR IN THE PROFILE...AND A
SUGGESTION THAT THE WINDS BACK TO A POINT WHERE THERE COULD BE A
MUCH SHORTER FETCH OF LAKE MOISTURE AVAILABLE.
WILL GENERALLY GO WITH HIGH LIKELY POPS FOR THE EASTERN LAKE ONTARIO
TODAY AND TONIGHT...BUT ACCUMS WILL BE LIMITED TO JUST A FEW INCHES.
AGAIN...THE LOCALLY RUN 6KM MODELS ARE MORE IMPRESSED FOR HIGHER
SNOWFALL AMOUNTS...BUT THE FUNDAMENTALS DO NOT SUPPORT IT.
ELSEWHERE...TODAY AND TONIGHT WILL FEATURE PARTLY TO MOSTLY CLOUDY
SKIES WITH SOME FLURRIES NEAR SEASONABLE TEMPERATURES.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
THE DEEP UPPER TROUGH AND CLOSED LOW OVER THE UPPER GREAT LAKES TO
JAMES BAY WILL STALL DURING THE WEEKEND. A WEAK RIDGE OF SURFACE
HIGH PRESSURE FROM THE UPPER OHIO VALLEY TO EASTERN NEW YORK AND A
COASTAL LOW WILL DISRUPT THE LAKE EFFECT ALTHOUGH SOME WEAKER LAKE
SNOWS WILL CONTINUE SATURDAY AND SATURDAY NIGHT. PARTIAL SUNSHINE IS
EXPECTED OUTSIDE THE AREAS OF LAKE SNOW AND CLOUDS ON SATURDAY WITH
MORE WIDESPREAD SUNSHINE EXPECTED ON SUNDAY.
THE CLOSED LOW OVER ONTARIO WILL OPEN AND EJECT TO THE EAST ON
SUNDAY BUT A BROAD UPPER TROUGH IN A QUASI ZONAL FLOW WILL REMAIN
OVER THE UPPER GREAT LAKES AND NORTHEASTERN STATES. A SHORT WAVE IN
THIS UPPER FLOW WILL BRING A GENERAL AREA OF PRECIP ON MONDAY WITH
MOSTLY A MIX OF RAIN AND SNOW DURING MONDAY AFTERNOON.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
THE WEAK TROUGH IN THE QUASI ZONAL FLOW WILL MOVE EAST AND THE
SURFACE LOW WILL DISSIPATE OVER NEW ENGLAND DURING MONDAY NIGHT.
LIGHT SNOW WILL PERSIST MONDAY NIGHT AND TRANSITION TO MIXED
RAIN/SNOW DURING TUESDAY AFTERNOON...AND BACK TO SNOW TUESDAY NIGHT.
A FOUR CORNERS LOW DURING TUESDAY WILL MOVE ACROSS THE PLAINS AND
SPREAD INTO THE NORTHEASTERN STATES ON WEDNESDAY. THE QUANDARY
HEREIN IS THE TEMPERATURE AHEAD OF THIS SYSTEM. BOTH 00Z GFS AND
ECMWF SHOW STRONG WARM ADVECTION AT 850MB WITH TEMPS RISING TO +6C
BY 18Z ON WED AS PER GFS...AND TO +6C TO +8C AS EARLY AS 12Z BY
ECMWF. SURFACE TEMPS ARE SIMILARLY DIFFICULT AS THE GFS KEEP TEMPS
BELOW FREEZING THROUGH 15Z WED...THE ECMWF SHOWS AN EARLY WARMING
WITH SURFACE TEMPS ALREADY IN THE 40S BY 12Z WED. IT LOOKS THAT
THERE WILL BE A PERIOD OF PREDAWN SNOW CHANGING OVER TO RAIN DURING
THE DAYLIGHT HOURS OF WEDNESDAY...THAN BACK TO SNOW DURING THE
EVENING AND OVERNIGHT AS COLDER FOLLOWS THIS LOW...WILL GO WITH THE
TEMP TRENDS GIVEN BY THE GFS FOR NOW...BUT EXPECT THIS TO CHANGE IF
THE TREND IS TOWARD THE ECMWF SOLUTION.
GIVEN THE TRACK OF THIS LOW AND ITS DEEPENING CHARACTER...STRONG
WINDS WILL DEVELOP AHEAD OF THE LOW ON WEDNESDAY...DIMINISH SOME AS
THE LOW PASSES WED EVENING...THEN INCREASE AGAIN WED NIGHT AND
CONTINUE STRONG THROUGH THURSDAY. THE MODEL WINDS SHOW GALES ON THE
LAKES AND THE POTENTIAL FOR WIND ADVISORY ON THE LAND. ALSO...THE
COLD AIR TRAILING THE LOW WILL BE SUFFICIENTLY COLD FOR LAKE EFFECT
ON THURSDAY WITH 850MB TEMPS FALLING TO THE MINUS TEENS AND EVEN
CLOSE TO -20C BY THURSDAY NIGHT.
HIGH AND LOW TEMPS DURING THIS PERIOD WILL VARY FROM LOWS GENERALLY
IN THE MID 20S EACH NIGHT WITH HIGHS IN THE MID TO UPPER 30S TUESDAY
AND WEDNESDAY...EVEN WARMER ON WED IF ECMWF IS RIGHT...AND COOLER
WITH LOW TO MID 30S ON THURSDAY.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
LAKE EFFECT PROCESSES WILL AFFECT A LARGE PORTION OF WESTERN AND
NORTH CENTRAL NEW YORK IN SOME FORM OR ANOTHER THROUGH THIS EVENING
AS BANDS OF WET LAKE EFFECT SNOW WILL EXTEND INLAND OFF BOTH LAKES
ERIE AND ONTARIO. THIS WILL DIRECTLY IMPACT OPERATIONS AT KBUF WHERE
SIGNIFICANT DELAYS WILL BE POSSIBLE. LESSER OPERATIONAL PROBLEMS
WILL BE POSSIBLE AT ALL OF THE OTHER SITES.
FOR WESTERN NEW YORK...LAKE EFFECT PRECIPITATION IS IN THE PROCESS
OF BECOMING BETTER ORGANIZED OVER LAKE ERIE. THIS BAND WILL THEN
EXTEND ACROSS NORTHERN ERIE COUNTY AND PORTIONS OF THE NIAGARA
FRONTIER. AS A RESULT...IFR CIGS AND VSBYS ARE EXPECTED AT KBUF FOR
THE BULK OF THIS MORNING WITH MVFR CONDITIONS AT KIAG. THESE
CONDITIONS WILL ONLY IMPROVE SLIGHTLY DURING THE MIDDAY AND
AFTERNOON AS THE LAKE EFFECT PRECIPITATION WILL BECOME MIXED WITH
RAIN AND SHOULD BECOME LESS ORGANIZED.
AT KJHW...GENERALLY VFR CONDITIONS WILL BE IN PLACE TODAY WHILE THE
LOWER LAKE EFFECT CLOUDS AND ASSOCIATED PCPN WILL REMAIN TO ITS
NORTH.
AT ROC...EXPECT VFR CONDITIONS TO DETERIORATE TO MVFR AS LAKE EFFECT
STRATO-CU AND ITS ASSOCIATED SNOWFALL OFF LK ERIE WILL EXTEND ACROSS
THE SITE. CONDITIONS WILL THEN LIKELY FLUCTUATE BETYWEEN VFR AND
MVFR THROUGH THE AFTERNOON.
EAST OF LAKE ONTARIO...AT KART...LAKE EFFECT SNOW WILL DEVELOP JUST
TO THE SOUTH OF KART AND LIFT NORTH. THIS WILL LIKELY RESULT IN
CONDITIONS DETERIORATING TO AT LEAST MVFR WITH IFR VSBYS POSSIBLE.
CONDITIONS WILL THEN RETURN TO VFR DURING THE COURSE OF THIS
EVENING.
GENERALLY VFR CONDITIONS ARE EXPECTED ACROSS THE REGION TONIGHT...
ALTHOUGH A FEW HOURS OF MVFR CIGS/VSBYS COULD BE FOUND IN THE
VICNITY OF KBUF IN WEAKENING LAKE EFFECT.
OUTLOOK...
SATURDAY...VFR.
SUNDAY...VFR WITH OCCASIONAL SNOW SHOWERS EAST OF LK ONTARIO.
MONDAY...VFR WITH SOME AFTERNOON RAIN AND SNOW.
TUESDAY...MVFR IN SCATTERED SNOW SHOWERS.
&&
.MARINE...
SMALL CRAFT ADVISORIES FOR THE EASTERN SHORES OF LAKES ERIE AND
ONTARIO WILL BE EXPANDED TO INCLUDE ALL NEARSHORE WATERS THIS
AFTERNOON AND EVENING AS SOUTHWESTERLY WINDS INCREASE. WINDS AND
WAVES WILL DIMINISH TONIGHT AND REMAIN LIGHT THROUGH SATURDAY
EVENING...THEN BECOME WESTERLY AND INCREASE TO 15 TO 20 KNOTS ON
BOTH LAKES DURING SUNDAY. A MUCH STRONGER WIND EVENT IS EXPECTED TO
DEVELOP LATER NEXT WEEK.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW ADVISORY UNTIL 6 PM EST THIS EVENING FOR
NYZ001-002-011.
LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THIS EVENING FOR
NYZ010.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EST THIS EVENING FOR LEZ040-
041.
SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 1 AM
EST SATURDAY FOR LOZ042-043.
SMALL CRAFT ADVISORY UNTIL 4 AM EST SATURDAY FOR LOZ044-
045.
&&
$$
SYNOPSIS...WCH
NEAR TERM...RSH
SHORT TERM...WCH
LONG TERM...WCH
AVIATION...RSH
MARINE...WCH
