Tuesday, September 18, 2012

Updating Today's Severe Potential

Updates on Severe Potential later today via Facebook and Twitter

For now, we're still under a slight risk for severe weather today -- a three in ten chance that anyone within 25 miles of a given point get winds to 60 mph, with a one in ten chance that anyone in 25 miles of a spot receives a tornado.  There's a lot of wind energy with this potent Fall storm -- and the potential for severe criteria winds is once again high thanks to that potent low level jet of 60-75 mph winds at 5000' that the front will tap into later today.

Timing looks to be between 6 PM west, 2 AM at the Shore with the front as it crosses -- give or take an hour or two on either side...if there's any give or take, it might be on the earlier side of things with the front...in any case, it's a mainly evening threat with the front itself but squally showers and rain will be with us through the day in advance of the final frontal push.  There will be breaks in the activity -- moreso east of Philadelphia than west.  East of the city, you might get into some sun briefly late this morning or early this afternoon. It will be a tease as more rain will come back into your picture over there.

While the front itself may contain the strongest wind gusts as it crosses the region, we can't rule out a few stronger showers developing ahead of the front that provide a bit more bite and some strong wind gusts on their own.  Additionally, because of the differing wind direction ahead of the front, some tornadic development can't be ruled out through the region.  These tornadoes won't be your "Wizard of Oz" style tornadoes and will be EF0, EF1 variety, "weaker" in nature compared to the "classic" Midwestern twisters.  Any tornadic development will likely be short-duration and short track, very similar to the Mount Ephraim or Kent County tornadoes earlier this month.

The NAM (above) shows its placement of the front/squall line for 8 PM tonight -- generally just west of the city by that point.  Most models center the frontal boundary as passing through the city between 8 and 11 PM.  As it passes through, winds should die down quickly after frontal boundary passage and rains will taper off a few hours thereafter.