Thursday, November 20, 2014

Storms not likely Sunday & Monday

Thought so. The convective action that earlier GFS & Euro runs hinted at for Sunday and/or Monday now looks unlikely for southern Virginia. There could be some storms east of the I-95 corridor but that's well out of my chase range, especially for a weak off-season setup. I'll still keep an eye on things but I have no plans to chase at the moment.

Not really a disappointment since I didn't put much stock in the earlier model hints. Now I have my fingers crossed for an early start to the 2015 chase season. Mid-March, anyone?

Monday, November 17, 2014

A Thanksgiving week chase????

Normally I don't pay much attention to convective potential this late in November, especially after extended bouts of Arctic air, but there are hints of SOMETHING possible on Monday 11/24. On both the GFS and Euro there appears to be a high shear / low CAPE setup early next week altho' the two models disagree on timing.

Could there be a late November chase in the cards? I'm not holding my breath, and if it occurs it could likely be a nocturnal setup. That in itself is dicey with low-topped convection and a dearth of illumination from lightning. Still, it is fascinating to consider the possibility....

Friday, November 14, 2014

November chasing rare but not unheard of

I have had a longstanding empirical cutoff date of Veterans Day (Nov. 11th) for the stormchase season in northern Virginia. That date represents the two sigma limit - for those statisticians in the readership - of the chase data I have recorded starting in 2002. I didn't make it a 3 sigma limit due to a couple of chases past that date, one of which occurred on Nov. 15th 2008.

My son and I headed out to chase a setup created by the approach of a strong cold front that led to first a Mesoscale Discussion and then a Tornado Watch being issued for our chase area. We motored to rural Culpeper county where we watched a low-topped convective band head toward us. This line had a lowering underneath it that showed weak rotation:

As this line and the associated rain drew near we beat feet eastward to stay ahead of it, winding up in King George county east of Fredericksburg. Several convective lines had formed and we watched one of them approach from the west with a shelf cloud out ahead of it. This photo captures the essence of November chasing in Virginia:

We had to pull off the chase early since I had dinner guests coming into town but as we did so we were treated to one more rotating wallcloud under the low-topped convection:

Now that I chase in southern Virginia I am having to revise the end-of-season date but I haven't gathered enough data to determine it yet. Meanwhile it's time to set sights on chase season 2015!

Thursday, November 06, 2014

First Virginia SPC "Marginal Risk" issued today

Today marks the first issuance of the new "Marginal Risk" category for severe storms here in Virginia. The Storm Prediction Center instituted their new five risk level system last month. 

The low-topped convective line that blasted across northern Virginia late this afternoon seemed to verify this risk level forecast. That in turn helped verify my empirically derived end to the northern Virginia chase season as Veterans' Day (Nov 11th), especially given next week's pattern change. Unfortunately here in southern Virginia that bookend date hasn't held true the past 3 chase seasons so I may have to revise it accordingly.

Monday, October 27, 2014

Four year anniversary of a fruitful late October chase

Four years ago today a strong cold front triggered severe storms across the Mid-Atlantic that resulted in the SPC issuing this probabilistic outlook graphic:
This, in turn, led to the following storm reports from that day:

Having followed the progress of this system across the country with its accompanying eastward march of severe weather I was primed to chase. With my chase gear in the vehicle I attended a meeting in southern Maryland that day, departing (fortunately) just as severe weather warnings were first posted for the region. Following a quick stop at a WiFi spot to check radar - not having mobile WiFi at that time - I rolled westward along VA Route 3 toward Fredericksburg.

Spying this approaching storm I stopped to observe and photograph the obviously rotating cell:
Zooming in to the area circled in red I saw this funnel:

I stayed east of this storm for a while as it cycled down and then back up but never witnessed another funnel. It was a very productive chase as the season was reaching its conclusion that year!