Lake-Effect Snow, Jefferson
- When
- December 6, 12:00 AM EST to December 7, 12:00 AM EST
- Where
- Jefferson forecast zone
- Reported by
- CoCoRaHS
- Coordinates
- 43.999, -76.052 (the zone’s center; the record gives no point)
Lake-Effect Snow in New York, December 6 to 7, 2018
Weak flow over the eastern Great Lakes allowed moisture to pool over Lake Ontario. As a short wave approached, flow increased from the southwest, and pushed moisture on shore to the east of the lake.
Where it happened
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
- Tornadoes
- Tropical storms and surge
- Floods
- Wind
- Hail
- Winter weather
- Heat and drought
- Cold
- Fire, smoke and dust
- Marine and coastal
- Other
The toll
- Deaths
- 0
- Injuries
- 0
- Property damage
- None recorded
- Crop damage
- None recorded
- Events
- 2
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
What happened
The episode as NWS BUF wrote it up.
Weak flow over the eastern Great Lakes allowed moisture to pool over Lake Ontario. As a short wave approached, flow increased from the southwest, and pushed moisture on shore to the east of the lake. Snow was being generated mostly below 7,000 feet due to a strong inversion, however temperatures were still down to -15C beneath this inversion, which is ample to support dendritic snow growth. Flow increased further and became more sheared, which prevented a single dominant band from developing and moving the bands to the east of the lake. Even so, moisture from the shortwave and front combined with the more fanned out accumulations from the lake bands resulted in a widespread snow event east of Lake Ontario and not just on the Tug Hill. Selected snow totals included 26.5 inches in Carthage and 25 inches 6 miles north of Croghan.
What forecasters said that day
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Buffalo, NY wrote its last area forecast discussion before the first event at Dec 5, 8:34 PM EST, 3 hours 26 minutes earlier.
Area forecast discussion, Dec 5, 8:34 PM EST, 3 hours 26 minutes before
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</html>The radar
The national radar mosaic for the moment the first event began.
Event by event
2 lake-effect snow. Local standard time, as filed.
Lake-Effect Snow, Lewis
- When
- December 6, 12:00 AM EST to December 7, 12:00 AM EST
- Where
- Lewis forecast zone
- Reported by
- CoCoRaHS
- Coordinates
- 43.785, -75.449 (the zone’s center; the record gives no point)
What these are
- Lake-Effect Snow
- Heavy snow in bands downwind of a large lake as cold air crosses warmer water.
After NWS Directive 10-1605, the rules offices file Storm Data by.
The same day elsewhere
More
Every storm in New York in 2018Every state in 2018This day in weather historyWarnings in New York, December 2018
Sources
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-30. Each event’s entry at NCEI: 798833, 798836.