Saturday, September 08, 2012

Moderate Risk For Severe Today

Track Today's Severe Weather With Our Current Weather Page

The potential for a robust severe weather event is pretty high today across the Mid Atlantic and Northeast.  We're under a moderate risk for severe weather today, which means close to a coin flip chance of any one location within 25 miles of you getting severe criteria wind gusts (60 miles per hour).  The biggest threats with today's storms are wind based; although some hail may be possible with the storms working through this afternoon and evening, odds favor wind being the bigger player on the field today thanks to 60-70 mph winds 5000 feet above the ground.

We do have the potential for a few tornadoes today -- especially across Northeastern Pennsylvania, North Jersey, and Southeast New York State -- as wind shear is present (wind direction changing with height) within the robust low level jet and mid level jet coming at us from different directions.

I mentioned the "coin flip" odds today -- the Storm Prediction Center hints at a 45% chance of anyone within 25 miles of a spot getting severe criteria winds...45 does not mean "definite" but it does mean a pretty good shot compared to most severe weather events that usually are in the 15 or 30 percent category.  This will take the form of a squall line that's out to our west this morning and will intensify further as it approaches our region this afternoon.

The brunt of this squall line will pass to our north, however, as the best wind dynamics and energy reside closer to the low pressure center (which will travel through Ontario and into Quebec).  The squall line's "worst of worst" likely occurs between Binghamton, Scranton, Middletown NY, and up to Albany as individual storms in the line move northeast as the line shifts east through the day.   While the "worst of worst" probably occurs to our north, our region may not be spared from the squall as the line moves through between 4 and 8 PM.

West of the city will get in on this first, closer to 4 PM, with the Shore getting in on the line around 8 PM.  The city's timing should be right around dinner (6 PM, give or take a little bit on either side).

Before all of this moves through, there are a few showers along the coast this morning that will continue to push north and northeast.  These are in association with some warm air advection that's pushing up the coast in advance of the line to our west.   Those will clear out over the coming hours, resulting in a relatively "nice" midday with breezy conditions and sun through some clouds.  It will be humid through the day with dew points in the 60's and 70's ahead of the front.  The lull of some sun through clouds will quickly be replaced by the approaching squall late in the afternoon.   Lightning with this approaching squall line may not be a huge issue -- but the wind will be.