An issue with nginx rewrite rules would not let my image uploads be great, but that’s all settled now. I’m looking to transition away from so much reliance on Twitter and switch to more of a live blog format during events (though weather Tweets won’t go away). The P2 theme lets me create a fully integrated environment to receive storm reports on a thread, which is awfully nice. Keep this page bookmarked as I’m going to try out a few cool things there. (Eventually, the whole chswx.us site will run on WordPress — stay tuned.)
Golf-ball hail was reported in Sun City earlier today; these reports weren’t far from where there are a lot of new car dealerships out along Highway 278. Ouch.
The Ravenel continues to be a rough ride this evening thanks to a tight pressure gradient between high pressure to the northeast and a stationary front (the front that’s cooled us off back to the upper 60s) to the south.
Gusts to 62 and 50 MPH recorded within the past hour on the Ravenel Bridge — still a really tough go of it up there.
— Charleston Weather (@chswx) April 22, 2013
Today marks five years since supercells packing tornadoes, strong straight-line winds, and large hail ravaged South Carolina and Georgia in an incredibly unusual atmospheric setup for mid-March known as the Ides of March Tornado Outbreak. (Typically, our most favored time for tornadoes is April and May, according to a National Weather Service research study.)
The March 15 outbreak introduced me to the concept of a Particularly Dangerous Situation Tornado Watch, an enhanced type of severe weather watch more common in the Plains and in Dixie Alley (MS/AL). (Indeed, it was this outbreak which triggered my most intense study into meteorology as well as watch and warning dissemination and spurned on the creation of @chswx a few weeks later.) Here is the archived watch, PDS Tornado Watch 120, at the Storm Prediction Center website.
Three supercells from this event stand out for me: one spawned a EF1 tornado in the Strawberry mobile home community, causing $250,000 in damage and injuring several people (source). It struck a little too close to home for comfort; my parents live just a few miles south of Strawberry in Goose Creek and were very fortunate to dodge that bullet. A second supercell over Hollywood brought very strong winds to where I was living in downtown Charleston at the time — believe it or not, it was the first classic supercell thunderstorm I had ever been in! I didn’t see any hail but the wind was fierce — reminiscent of Hugo videos — with driving heavy rain. On Hilton Head Island, the third supercell produced baseball-size hail at the Hilton Head Airport causing severe damage to aircraft.
In the end, tornado damage up to an EF3 rating was found in several parts of the state (particularly on NWS Columbia’s turf). The Charleston metro area dodged a big bullet as a seabreeze had moved through earlier in the day which helped cut off needed surface-based instability for tornado formation closer to the coast.
For more information, including a great technical discussion of the ingredients that led to such a rare outbreak, read NWS Charleston’s summary of the event; I also recommend their research paper (PDF) as it gets really deep into the meteorology. It also explores the challenges of issuing storm-based severe weather warnings in such a widespread severe weather situation (especially since storm-based, polygon warnings had just rolled out).
Fortunately, this March has been very calm and I’m pretty sure we all prefer it that way.
This video was shot Tuesday evening by Drew Cavanaugh in central Florida, where several tornado warnings were issued due to strong rotation on radar and reports of funnel clouds, including this video. Nothing like driving down the road to see a tornado kicking up ahead of you to perk you right up.
Hat tip to more people than I can name over on Google+.
Dual-polarization data isn’t flowing to most people yet — based on my experience with the upgrade at Sterling, VA earlier this year, a day or two of calibration is still needed before the products are turned on over the Level III data stream (which serves a majority of the radar apps out there, including GRLevel3 and RadarScope). Dual-pol moments are available over Level II, though I’ll wait to rely too heavily on them until NWS gives the data its public blessing.
It’s cool to be getting a few scans of live Level II dual-pol data from the Charleston radar site tonight, presumably as testing continues on the upgrade. This particular screenshot shows the Correlation Coefficient product, which essentially helps a radar operator identify what’s precipitation and what isn’t. One way meteorologists use the CC product (called RHO in GR2Analyst due to its roots in mathematics) is to help identify possible debris signatures associated with severe storms (including tornadoes) (warning: PDF).
Note to my fellow weather nerds and enthusiasts: While it’s fun to look at, this data needs calibration and won’t be reliable until NWS says it’s live. You also won’t see it in RadarScope or GRLevel3 (2.x) until that time. Stick with Columbia, Wilmington, and the other surrounding radars for now.
For more, take a look at NWS Charleston’s Facebook post earlier Sunday.
We’ll see more high pressure wedges as the winter rolls on. If you love this cooler weather, it won’t be around to see tomorrow; if you hate this cooler weather, it’ll be much nicer tomorrow (with a thinning cloud deck to boot).
Noteworthy: Several feet of snow have been dumped on northern Minnesota by an unnamed early-season winter storm.
I am still kind of on the fence about this. It makes me feel better that there is National Weather Service precedent for naming winter storms — Buffalo has been doing this for a while, so it seems — but I think I would prefer if this initiative originated with NWS. I’m not sure how I would approach it on @chswx in the event a powerful winter storm affected Charleston’s weather (we usually don’t get snow from them but the strongest ones can cause severe weather). I have always tended to take the lead from the NWS to avoid the potential for mixed messages, and I have a bad feeling that’s exactly what’s going to happen here.