Tags

, , , ,

The January 3rd WeatherBrains podcast included a spirited discussion of the lack of coordination between local NWS offices and the Storm Prediction Center when it comes to convective outlooks. Mention was made of the seemingly antiquated SPC schedule of pushing out a single Day 3 outlook and only two Day 2 outlooks. Given the rise of instant communications and improved forecasting technology why doesn’t SPC update these outlooks more often?

While listening to the banter I harkened back to my early days of chasing when I relied heavily on SPC outlooks to guide me to target areas both in the Plains and here in Virginia. Given recent social media buzz apparently a lot of chasers still depend on the SPC for the same reason (“I just KNOW they’re going to put out a High Risk for xxx area today!!”). This personal reflection made me realize how little attention I’ve actually paid to SPC convective outlooks in recent years.

Now don’t get me wrong…I still look at the SPC web page for many things including the convective outlooks. (After all, they are the experts!) But with the availability of multiple short range high resolution models plus years of experience in looking at surface observations and satellite images I’ve found that these outlooks are definitely NOT the final word on whether a chaseable storm will fire.

One example of this occurred on July 16th 2009. The SPC waffled between a 5% severe risk and no risk at all during the Day 2 and Day 1 outlooks for northern Virginia. The best it got was a 5% risk area for damaging winds along and east of the I-95 corridor. To be fair the forecast discussion by NWS Sterling wasn’t very optimistic about severe weather that day either. I hadn’t planned to chase but noticed an updraft west of Fredericksburg as I rolled home from work that afternoon.

That updraft exploded into a supercell that looked like this when I finally caught up to it and found this vantage point near Thornburg off U.S. Route 1:caroline-county-supercellI had already watched the wall cloud cycle once before this and it cycled again (right side of photo) while I was on this hilltop almost underneath the updraft base.

I have numerous such examples of good chases under not-so-promising SPC convective outlooks in my chase library. The most recent example was September 29 2016. The second SPC Day 2 outlook showed a Marginal Risk for southern parts of Virginia as did all the Day 1 outlooks, although the latter also included an area of 2% tornado risk. Even with such a ho-hum SPC outlook I headed out that day after reviewing surface observations and short range model solutions, fully confident that I would see something worthwhile. As it turned out I chased not one but two supercells across Southside Virginia that afternoon. Both storms had obvious hook echoes on radar.

Storm #2 wound up dropping a couple of funnels that I witnessed, one of which occurred while I was located in the inflow notch (the 6:43 pm radar view above):funnel-w-of-museville

Given a number of successful chase experiences without a notable SPC convective outlook in place I no longer rely on these outlooks to determine where or whether to chase. (They do still serve as a general heads up.) And I don’t get wrapped around the axle when a given SPC outlook doesn’t match my take on the convective setup (“WHYYYYY didn’t they issue a High/Moderate/Enhanced Risk?”). I simply go out and look for something worth chasing. It’s what I do for enjoyment.

Advertisements