Monday January 16, 2012

Wintry Mix tonight

Updated:
10:00 P.M. Monday January 16, 2012

Welcome to Kingston Snows!!

School Forecast For:
Tuesday January 17, 2012
Two-Hour Delay Cancellation Early Dismissal
70%
40%
0%

9:50PM Update

A batch of heavy snow moved through between 8PM and 9:30PM dropping a full inch of snow in Kingston. This alone represents nearly double Kingston's total forecast snowfall for the night.
With a second similar batch timing to move through between 12AM and 2AM, it is not unreasonable to anticipate total snowfall in the 2 to 3 inch range. Sleet and freezing rain after 3am will prevent additional accumulations. Temperatures will rise above freezing with a change to rain around 6AM.The change in probability is to reflect 2 to 3 inches of snow, but with the accumulations tapering off around 3AM, that gives around 6 hours to clear roads in the event of a delay.Ice accumulation should not be a factor.


7:00PM Update

I am currently monitoring the temperature trends. Currently in Kingston we're at 29 degrees, which is a whole 4 degrees above the forecast temperature for 7PM. This has been the case for at least the last hour or so. Temperatures are only expected to rise tonight, although I expect they may fall some once precipitation initially begins to cool the atmosphere. But the current 29 is still not reassuring, especially with how Thursday's storm turned out. I will monitor this through 10PM and post a final word no later than 10PM. Based on the current forecast I have upped the chances of a delay to 60%.


Previous Update

A low pressure system will approach from the west this evening. This will spread a round of precipitation into the area tonight into Tuesday. Temperatures will gradually rise overnight and through Tuesday afternoon.

Snow will develop between 8PM and 11PM, possibly mixing with sleet at times. Snow accumulations of up to half an inch or so are forecast.

By 2AM, we should transition over to mainly freezing rain and sleet. Accumulations will be limited once we transition over, as sleet does not accumulate nearly as much as snow. No significant ice accumulations are expected.

Sleet and freezing rain should persist until around 5AM when the temperature rises above the freezing mark. At this point we should transition over to plain rain.

Rain will continue throughout most of the afternoon and possibly linger into the early evening. The high on Tuesday will be around 44 degrees.

Based on this forecast and the timings, I have decided to increase the probabilities. A delay is probable, but not yet categorical.

With tonight's mix of precipitation, the type will partially depend on intensity: heavier precipitation will result in more wintry precipitation, while lighter precipitation will allow for more in the way of freezing rain and rain. The probabilities above take this into consideration.

A winter weather advisory is in effect from 10PM tonight through 10AM Tuesday. I will have a brief post by 10PM tonight with any updates.

Next Update:
By 10PM.

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