Chasers, 4/5/11 UPDATE: Wow, so 00z model runs from last night have complicated things a bit more with the GFS being a bit more progressive than the ECMWF. Even more difficult, is the fact that the ECMWF has the 300mb trough getting cutoff from the main flow for a 18-36hr period (Icky). Both models show timing issues with upper level support for earlier in the weekend and have lost the negatively tiled feature to the upper level trough, :( . However, Sunday is still looking very favorable across the lower Midwest/Mississippi river valley. Madison will not be a bad place to be starting from if these solutions hold. This setup is looking strangely similar to yesterdays system with multiple modes of severe convective activity but shifted to the West a few hundred miles. Given model discrepancies to the evlolution of the upper level system, I'll be hanging out along the dryline until further notice and holding off making a "Go Zone" (want to see SREF, 1st), lol. Come on ECMWF solution!!!! Anyone else care to take an early crack on Saturday and Sunday?
4-4-11: I've been watching the models very closely for the last 3-5 days for this upcoming weekend and it appears there could be several rounds of severe weather days with Sunday being the prime day (very good shot of a tornado outbreak) across the Mid Mississippi Valley. This evening I will post my thoughts on this coming weekend and speculate on how it could shake out complete with model output. Details to follow in a couple of hours. Dan aka Squall Line
Yes, I'll take a stab at it later today!
ReplyDeleteAtta Boy, feel free to throw it up on this thread if you like!
ReplyDeleteHere's a quick email that my dad sent me (he's still learning how to comment and blog, :) Figured I'd throw it up here.
ReplyDeleteRead your HHHR summary and could not agree more: the coming weekend can't come fast enough.
GLOBAL VIEW
Remember my concerns over the existing storm track back in February - well part 1 of a five part story played out over the past 48 hours. When was the last time we had 1356 severe weather events in 36 hours? Its been quite awhile and except for the minimal veering angle (< 30 degrees) between the 925mb to 500mb layer we would have had a record tornado outbreak over the weekend. The tornadic sweet spot for veering angles is 30-90 degrees, winds +/-30 degrees and hail ~150-210 degrees. Simplistic but provn. Okay that's a global view but the unusally strong and active jet stream with multiple jet streaks is lined up to give us two more very active (>1,000 severe events /48hrs) severe weather weekends in a row.
WEEKEND VIEW
The big difference between this past weekend and last weekend are two: one the jet stream will not be as progressive, i.e., a more digging negative trough ( read that more southerly component to jet stream) and a slower moving system. Last weekend and yesterday mid-level wind directions were predominantly 230-270 degrees with surface/sub-cloud layer winds within 10-20 degrees of cloud layer wind directions. The coming weekend's cloud layer winds should be 190-220 degrees meaning an opportunity to increase the amount of sub-cloud layer cyclonic baroclinicity will be equal to or more than the last system's more linear form. The negative tilt and more southerly compoennt could swing the severe weather number from extensive wind events (897 at last count) with low veering angles to more tornadic events with larger veering angles. So I agree with you that we'll see more tornadic events with the next system. Odds favor another 48 hour period with ~1,000 severe weather events with 3-5 % tornadic.
My two-cents - no nickles worth,
John F. Henz, C.C.M.
12 Z gfs shows a more chaseable situation in the Upper Midwest on Saturday rather than Sunday...what does the ECMWF show? I don't have access to that :(
ReplyDeleteI love having an AWIPS workstation at my desk...I get them all and early too ;)
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