Saturday, May 09, 2009

A Look at Watch #280

The Storm Prediction Center has issued a Severe Thunderstorm Watch that stretches across almost all of New York State. It remains in effect until 7pm tonight. Here is a look at the exact counties it includes. As you can see, Tompkins, Cortland and S. Cayuga are right in the middle of it.

The main threat from this event is going to be damaging winds. Hail will also be possible, and my gut feeling is there will be a tornado somewhere in the watch box. The official probabilities that the SPC has put with the watch:
Probability of 2 or more tornadoes

Low (20%)

Probability of 1 or more strong (F2-F5) tornadoes

Low (5%)

Probability of 10 or more severe wind events

Mod (60%)

Probability of 1 or more wind events > 65 knots

Mod (30%)

Probability of 10 or more severe hail events

Mod (30%)

Probability of 1 or more hailstones > 2 inches

Low (20%)

Combined Severe Hail/Wind
Probability of 6 or more combined severe hail/wind events

High (80%)

Since it is at the top of the hour, the current observations and indicies will not be in for another 20-40 minutes. Looking at the data from noon, though, it is obvious to me that the atmosphere is quickly destabilizing. Also, a pocket of strong winds in the upper atmosphere is beginning to move into Western New York, and will spread over the rest of the state, enhancing the thunderstorms. Storms are going to develop from west to east, and have already begun to fire up across Western New York, Lake Erie and Lake Ontario. These storms should organize into a squall line eventually, which is when the greatest threat for wind damage will be. The highest tornado and hail threat will be just prior to that, when the storms are more individual cells.

Be sure to keep checking back through the afternoon for the latest!

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