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Dec 8-10 LES Potential

ayuud

By ayuud,
in Upstate New York/Pennsylvania

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ayuud

ayuud

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AS WAS MENTIONED AT THE START OF THIS SECTION...THIS WILL NOT BE A

`CLASSIC` EVENT. EXCELLENT ON STATION RESEARCH AND PATTERN

RECOGNITION ACKNOWLEDGES THE NEED FOR A CLOSED H5/85 LOW IN THE

VCNTY OF THE UPPER GREAT LAKES/SOUTHERN ONTARIO IN ORDER TO PRODUCE

A PROLONGED LOW SHEARED FEED OF COLD AIR OVER EITHER LAKE...AND THIS

WILL NOT BE THE CASE. THAT BEING SAID...THERE WILL CERTAINLY BE AN

IMPACT ACROSS THE BUF/IAG METRO AREAS AND ALSO FROM ART TO THE

THOUSAND ISLANDS...ESPECIALLY SINCE IT WILL LARGELY BE THE FIRST

MAIN EVENT OF THE SEASON. GIVEN SOME OF THE UNCERTAINTIES THOUGH...

WILL HOLD BACK ONE MORE FORECAST CYCLE BEFORE ADVANCING THE CURRENT

LAKE EFFECT WATCHES TO ADVISORIES OR WARNINGS. THIS WILL LIKELY BE

DONE ON THE UPCOMING DAYSHIFT.

NOW...FOR THOSE LAKE EFFECT SNOW JUNKIES...HERE ARE SOME OF THE

THERMODYNAMIC AND STEERING FLOW DETAILS FOR THE UPCOMING EVENT.

FOR LK ERIE...THE SFC WATER TEMP CURRENTLY AVERAGES AROUND 8C. OUR

H85 TEMPS ON FRIDAY WILL BE IN THE VCNTY OF -8C WHICH WILL CERTAINLY

ESTABLISH ENOUGH INSTABILITY FOR LAKE INDUCED PCPN. THESE WATER

TEMPS ARE A SOLID 5 DEG C ABV NORMAL...WHICH IS VERY INTERESTING

BECAUSE IF THEY WERE AT THEIR NORMAL LEVEL OF -5C...THEN THE

INSTABILITY WOULD BE MUCH WEAKER. WE WOULD ESSENTIALLY BE ON THE

CUSP OF NOT HAVING ENOUGH INSTABILITY. GIVEN THE SHALLOWNESS OF THE

LAKE THOUGH...IT IS VERY LIKELY THAT THIS WILL BE A ONE TIME

`BENEFIT` FOR LAKE SNOW AS SFC WATER TEMPS WILL DROP CLOSER TO

NORMAL LEVELS BY THE END OF THE EVENT. IN ANY CASE...LAKE INDUCED

CAPES WILL BE IN THE NEIGHBORHOOD OF 300 J/KG FOR THE HEART OF THE

EVENT ON FRIDAY WHILE THE LAKE INDUCED EL WILL BE AROUND 8K FT.

AGAIN...NOT OVERLY IMPRESSIVE NUMBERS FOR A BIG EVENT.

A MODERATELY SHEARED LOW 230-240 FLOW WILL BE IN PLACE (ANOTHER

LIMITING FACTOR)...WITH THE FLOW PROBABLY CLOSER TO 230 FRIDAY

MORNING WHEN THE BEST ORGANIZED BAND COULD BE IN PLACE. GUIDANCE

PACKAGES OFTEN UNDER ESTIMATE THE THERMALLY INDUCED BACKING OF THE

WINDS EARLY IN THE SEASON...SO AM LEANING MORE TO 230 FLOW RATHER

THAN THE NAM SUGGESTED 240. THE RGEM LOOKS MUCH MORE REASONABLE IN

THIS REGARD...PROBABLY DUE TO ITS SUPERIOR DATA ASSIMILATION

PACKAGE. THIS SHOULD CONCENTRATE THE SNOW BAND NORTH OF BUFFALO (OVR

THE `NORTHTOWNS`) EARLY IN THE DAY WHERE SNOW ACCUM RATES OF 1 TO AS

MUCH AS 2 INCHES PER HOUR SHOULD BE POSSIBLE. FOR WHAT ITS WORTH...

THE ON STATION 6KM MESOSCALE MODELS MIMICK THE RGEM...PARTICULARLY

THE THREE NAM BASE ONES.

ITS NOT OUT OF THE QUESTION THAT WE GET A LITTLE THUNDER WITHIN THE

TWO MAIN BANDS...ALTHOUGH THE THERMODYNAMICS ARE NOT AS IMPRESSIVE

AS I WOULD LIKE TO SEE FOR THIS. WILL INCLUDE A CHC FOR THUNDER IN

THE LATE THURS NIGHT/FRI MORNING GRIDS.

DURING THE COURSE OF FRIDAY AFTERNOON...THE AFOREMENTIONED VIGOROUS

SHORTWAVE WILL SWING ACROS SOUTHERN ONTARIO AND WILL LITERALLY PUSH

THE AXIS OF THE LK ERIE BAND TO THE U.S. SHORELINE (IF NOT ENTIRE

OFF THE LAKE). THIS WILL BODILY MOVE THE STEADIEST SNOW EAST...

ENCOMPASSING THE AREA FROM THE BUF METRO AREA DOWN ALONG THE LAKE

SHORE.

FOR LK ONTARIO...THE SFC WATER TEMPS ARE CURRENTLY NEAR 7/8C. GIVEN

THE SAME -8C H85 AIRMASS...A VERY SIMILAR THERMODYANMIC PROFILE TO

LAKE ERIE WILL BE FOUND OVER THE EASTERN END OF LK ONTARIO. AGAIN...

THIS WILL SUPPORT LAKE INDUCED CAPES OF 300 J/KG AND LI EL`S OF

ABOUT 8 KFT. MEANWHILE...A 230 STEERING FLOW WILL BE IN PLACE

FRIDAY MORNING OVER THE EASTERN END OF THE LAKE. THIS WILL AIM LAKE

INDUCED PCPN OVER NORTHERN JEFFERSON COUNTY...FROM WATERTOWN TO THE

THOUSAND ISLANDS REGION. DUE TO THE SHORTER FETCH FROM THE 230

FLOW...SNOW ACCUMS ARE NOT EXPECTED TO EXCEED AN INCH PER HOUR IN

THIS AREA FOR THE DAYLIGHT HOURS FRIDAY.

ON FRIDAY NIGHT...THE SHORTWAVE WILL PUSH ACROSS THE LOWER GREAT

LAKES. WHILE THIS WILL INITIALLY AID IN THE LOW LEVEL FORCING FOR

INDIVIDUAL CONVECTIVE CELLS...IT WILL ALSO RESULT IN A MUCH MORE

SHEARED ENVIRONMENT WITH GRADUALLY VEERING WINDS. THIS WILL REORIENT

THE ASSOCIATED SINGLE BAND OFF LK ERIE TO THE SOUTH WITH THE

ACTIVITY TRANSITIONING INTO MULTI-BANDS ON A 270-300 FLOW...WHILE

THE SINGLE BAND OFF LK ONTARIO WILL LIKELY REMAIN INTACT WHILE

SETTLING TO THE TUG HILL.

THE MID LEVEL PACIFIC MOISTURE IS FORECAST TO THIN OUT FROM WEST TO

EAST DURING THE COURSE OF FRIDAY NIGHT...AND THIS WILL DIMINISH THE

EFFICIENCY OF LK SNOW PRODUCTION...PARTICULARLY EAST OF LK ERIE

WHERE A SHORTER FETCH WILL ALREADY BE LESSENING SNOW PRODUCTION.

THIS SHOULD NOT COME INTO PLAY AS MUCH FOR THE LAKE ONTARIO BAND AS

A SINGLE PLUME SHOULD STILL BE PRODUCING FAIRLY SIGNIFICANT SNOWFALL

OVER THE TUG HILL.

FOR SATURDAY...THE BASE OF THE H5 TROUGH WILL PUSH EAST TO NEW

ENGLAND WHILE LOW LEVEL RIDGING OVER THE OHIO VALLEY WILL NOSE UP

ACROSS NEW YORK STATE. THE ASSOCIATED SUBSIDENCE INVERSION WILL DROP

THE EQUILIBRIUM LEVEL TO AROUND 5K FT OVER LK ERIE WITH INCREASINGLY

DRIER AIR WORKING ITS WAY DOWN FROM THE MID LEVELS. THIS SHOULD

ENCOURAGE THE LK EFFECT TO TAPER TO FLURRIES ACROSS THE SRN TIER.

OFF LK ONTARIO...FAIRLY WELL ORGANIZED LAKE SNOW SHOULD REMAIN IN

PLACE IN THE VCNTY OF THE TUG ALTHOUGH SNOWFALL RATES WILL BE LESS

IMPRESSIVE AS THE MOISTURE IN THE SNOW PRODUCTION ZONE WILL BE MORE

LIMITED.

THIS GENERAL PROCESS WILL CONTINUE SATURDAY NIGHT AS RIDGING AT ALL

LEVELS WILL BUILD ACROSS THE LOWER LAKES. WARMING ALOFT (H85 -4C)

SHOULD CEASE THE LAKE EFFECT OFF LK ERIE ALTOGETHER BY THIS

TIME...WHILE THE SNOWS EAST OF LK ONTARIO WILL TAPER OFF TO LIGHT

SNOW SHOWERS AND FLURRIES WITH LITTLE/IF ANY ADDITIONAL ACCUM.

FOR THE SECOND HALF OF THE WEEKEND...STRONG HIGH PRESSURE WILL WORK

ACROSS PENNSYLVANIA WHILE OUR H85 TEMPS WILL MODERATE TO BETWEEN

ZERO AND +2C. THIS WILL PROMOTE ABUNDANT SUNSHINE REGIONWIDE...

INCLUDING EAST OF BOTH LAKES WHERE THE FRESH SNOW COVER WILL MAKE

FOR A VERY BRIGHT MIDDAY. SFC TEMPS WILL MODERATE BACK TO NEAR

NORMAL LEVELS AFTER MORE THAN TWO DAYS OF COLDER THAN NORMAL MERCURY

LEVELS.

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OSUmetstud

OSUmetstud

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I'm kinda wishing I was at the old house in Riverside (NW Buffalo) for this one. It's starting to become more likely this is more of a northtowns event than a southtowns event. Another main limiting factor I've noticed is that the mesoscale models are putting very little lift through snow crystal growth layer..much of the omega is found below it.

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ayuud

ayuud

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I'm kinda wishing I was at the old house in Riverside (NW Buffalo) for this one. It's starting to become more likely this is more of a northtowns event than a southtowns event. Another main limiting factor I've noticed is that the mesoscale models are putting very little lift through snow crystal growth layer..much of the omega is found below it.

the microcast kept showing a mix around the lakeshore,do you think will see a mix for a while on Friday?

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ayuud

ayuud

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...LAKE EFFECT SNOW WATCH REMAINS IN EFFECT FROM LATE TONIGHT

THROUGH LATE FRIDAY NIGHT...

* LOCATIONS...EASTERN LAKE ONTARIO REGION MAINLY FROM THE TUG

HILL NORTHWARD ACROSS JEFFERSON AND NORTHERN LEWIS COUNTY.

* TIMING...LATE THURSDAY NIGHT THROUGH EARLY SATURDAY MORNING.

* ACCUMULATIONS...1 TO 3 INCHES TONIGHT...3 TO 5 INCHES

FRIDAY...AND 3 TO 6 INCHES FRIDAY NIGHT...LEADING TO STORM

TOTALS OF 7 TO 14 INCHES IN THE MOST PERSISTENT LAKE SNOWS.

Snowman.gif
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LakeEffectKing

LakeEffectKing

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I might post a map tonight....but a 230-240 flow can be prolific for NE of L. Ontario, IF the L. Erie band can establish a convergence zone over L. Ontario prior to the north shore frictional convergence zone becoming established. However in most cases, we see a "double" band off Ontario....one near or north of ART (with the north shore convergence zone), and another (originating from the left over vertical circulation cells and ice crystal seeding from L. Erie) coming in the extreme NW part of Oswego Co. and plowing into the Tug. The orographic lift will ultimiately benefit the Tug region, regardless of the band(s) structure off Ontario.

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OSUmetstud

OSUmetstud

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I might post a map tonight....but a 230-240 flow can be prolific for NE of L. Ontario, IF the L. Erie band can establish a convergence zone over L. Ontario prior to the north shore frictional convergence zone becoming established. However in most cases, we see a "double" band off Ontario....one near or north of ART, and another coming in the extreme NW part of Oswego Co. and plowing into the Tug. The orographic lift will ultimiately benefit the Tug region, regardless of the band(s) structure off Ontario.

u can see a hint of a double banding structure on the 12z wrf I just posted. I hope the winds have just a little more westerly component..

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LakeEffectKing

LakeEffectKing

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u can see a hint of a double banding structure on the 12z wrf I just posted. I hope the winds have just a little more westerly component..

Yeah, L. Ontario's E-W orientation keeps those bands from "getting together" in a sharply cyclonic flow. The rare occasions where there is CCA on a 230 flow with neutral or slightly anticyclonic flow provides a better opportunity for the unification of Erie-Ontario bands.

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