I caught the tail end of a segment on The Weather Network that made me do a double take, so I checked the aviation weather observations for Buffalo, NY:

KBUF 130154Z 25008KT 1/4SM +TSSN FG OVC001 01/M01 A2973 RMK OCNL LTGIC OHD TS OHD MOV NE SNINCR 2/4
KBUF 130054Z 27010G19KT 1/2SM TSSN BR OVC003 01/M01 A2971 RMK OCNL LTGIC OHD TS OHD MOV NE TSB51
KBUF 130045Z 28014G19KT 3/4SM -SN BR BKN003 OVC007 01/M01 A2970

For those of you who can’t decode those, I’ll translate bits of the first one.

KBUF 130154Z 25008KT 1/4SM +TSSN FG OVC001 01/M01 A2973 RMK OCNL LTGIC OHD TS OHD MOV NE SNINCR 2/4

This is a weather observation (METAR) for Buffalo, NY (KBUF) taken at 01:51Z on 13 October 2006 (21:51 on 12 October 2006). At that time, the wind was from the southwest at 8 knots (approx. 15 km/h) with 1/4 of a mile visibility. There was heavy thunder snow and fog. The ceiling was at 100′ above the ground and the temperature was 1C and the dewpoint was -1C (i.e. it’s very humid). There was occasional in-cloud lightning observed overhead, a thunderstorm overhead, moving northeast and the snow was increasing.

Yes. Thunder snow. Heavy thunder snow.

In the 37 years that I’ve lived in Ottawa, I can only remember encountering thunder snow a handful of times and heavy thunder only once or twice.

Wikipedia offers three definitions of thunder snow. One of them is “A lake effect or ocean effect thunderstorm which is produced by cold air passing over relatively warm water, this effect commonly produces snow squalls over the Great Lakes.” Basically, the cold air is coming in from the west along Lake Erie and picking up all this extra moisture from the lake and dumping it in a particularly spectacular manner on Buffalo.

If you look at the weather radar from about the same time, you can see the storm tracking east along Lake Erie and passing overhead Buffalo. Observant people will note a similar pattern heading from Lake Ontario over Kingston. The Kingston METAR and TAF (Terminal Area Forecast) show this:

METAR CYGK 130000Z 25013G27KT 7SM -RA SCT011 OVC020 04/01 A2967 RMK SC4SC4 SLP049=
SPECI CYGK 130042Z 24018G24KT 12SM -RASN BKN011 OVC020 RMK SC5SC3=
METAR CYGK 130100Z 25009G20KT 15SM -RASN FEW011 FEW020 BKN040 03/00 A2969 RMK SC1SC2SC4 SLP056=
METAR CYGK 130200Z 25014G19KT 12SM -RASN FEW020 BKN047 03/M01 A2969 RMK SC2SC5 SLP057=
SPECI CYGK 130224Z 26008KT 15SM SCT047 RMK SC4=

TAF AMD CYGK 122319Z 122303 27012G22KT P6SM FEW006 SCT015
TEMPO 2303 2SM -SHSN BKN006 OVC015
RMK NXT FCST WILL BE ISSUED AT 131145Z=

The first observation taken at 20:00 (0000Z) reports light rain and the wind coming out of the southwest at 24 km/h gusting to 50 km/h. 42 minutes later, a special observation reports similar winds, but now there’s some snow mixed in with the rain. Over the next two hours, they experience similar weather.

The forecast call for pretty much what they’ve been experiencing, with period of light snow showers from 1900 to 2300 Eastern Daylight Time.

At least Ottawa’s forecast is still only showing rain for tomorrow and not a fluffier form of precipitation.