CONTEST STATUS - Last update: FRI ... 14-JUL-17 @ 8:30 PM EDT

Winter '17 / '18 - Snowfall Forecast Contests
19th Annual 'Regular Season'
Season starts when the first flakes start a'flyin'

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17th Annual 'Season-total'
Entries accepted between 01-NOV-17 and 30-NOV-17
Verification period: 01-DEC-17 through 31-MAR-18

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Winter '16 / '17 - Snowfall Forecast Contests
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18th Annual 'Regular Season'
FINAL results here
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16th Annual 'Season-total'
FINAL results here

Friday, February 9, 2007

LES is More


Big time lake effect snow event along the windward shore of Lake Ontario this past week with historic snowfalls recorded at some stations.

The observed conditions @ Watertown, NY on February 4 are of particular interest.

METAR KART 041756Z AUTO 28014G18KT M1/4SM +SN FZFG VV001 M12/M14
METAR KART 041856Z AUTO 27012G31KT M1/4SM +SN FZFG VV001 M11/M13
SPECI KART 041942Z AUTO 25015G33KT M1/4SM +SN FZFG M11/M13
METAR KART 041956Z AUTO 27019G31KT M1/4SM +SN FZFG M11/M13
SPECI KART 042014Z AUTO 26017G29KT M1/4SM +SN FZFG VV001 M11/M13
SPECI KART 042051Z AUTO 26016G24KT M1/4SM +SN FZFG M11/M13
METAR KART 042056Z AUTO 27012G22KT M1/4SM +SN FZFG M11/M13

From 1756z until 2056z...there was considerable falling or blowing snow. Visibility was frequently reduced to less than 1/4 SM. The wind frequently gusted to above 35 MPH (30 KTS). These observations depict near-blizzard conditions from lake-effect snow. Had these conditions lasted a little while longer...they would have meet the three hour threshold for a blizzard.

The theta diagram shown below shows deep layer instability from the surface up to ~750 mb.

The SkewT-logP diagram shows the vertical temperature profile is nearly dry adiabatic from the surface to ~750 mb...moist adiabatic from the LCL near 900 mb...and deep moisture in the column up to ~700 mb. With such an unstable sounding and cold temperatures aloft...it/s surprising there were no reports of +TSSN. Also note the low tropopause height near 350 mb (~25K')


More interesting and extreme LES obs from Buffalo, NY
SPECI KBUF 032210Z 24029G38KT 0SM R23/0600V2200FT +SN FZFG BLSN VV001 M08/M09
[...]
SPECI KBUF 032359Z 24032G40KT 0SM R23/1800VP6000FT +SN FZFG BLSN SCT004 BKN015 OVC040 M09/M12

Zero visibility although runway visual range reported a low value of 600' (~0.1 SM). Wind gusts to 46 MPH.

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