2011-06-01 FCST: NE

[jshields]

I've been watching wednesday's severe wx potential and with fairly good model consistency the last couple of days, though I would start a thread. A warm front will be retreating back north across the state laying across central to possibly northern nebraska depending on which model you believe. CAPE forecasts show 2500-3500 j/kg with a weakening cap in the late afternoon. the biggest difference I see is the mid level wind fields and the strength of a mid level wave moving through at 0Z thursday. The NAM has much stronger winds at 500 mb and a stronger wave than the GFS. 0-6 km shear is near 40 kts on the GFS to over 50 kts on the NAM in central Nebraska, with a nicely curved long hodograph. thankfully with this setup we have westerly winds in the midlevels rather than those annoying backing winds and the S-shaped hodos. NAM also shows near 200 m/s2 of 0-1 helicity and over 300 m/s2 of 0-3 km. EHI values are over 3 on the 0-1, and over 8 for 0-3 EHI! the piece of energy along with a fairly decent LLJ kicking in should be enough to set off some storms late afternoon, early evening. i think the tornado potential could be pretty decent especially with anything that can form near the warm front.

 

[Doug Drace]

Probably should add KS/OK to this this morning. Very strange model output for today, when comparing SPC, RUC, NAM, GFS, HRRR along with VIS SAT. I dont know what the heck to think?!?!? First off, SPC has the Slight Risk much further west than yesterday, though I had originally been thinking about heading up to the Hays, KS area. This morning, HRRR/NSSL WRF Hi-Res Models indicate a cap breach east of the Slight Risk area in extreme NW OK/SW KS from Alva, OK-Greensburg, KS. Vis Sat also indicated less in the way of debris cloud cover through that area, when compared to the entire Slight Risk area, especially NE. RUC only goes out to 18z, so its not much use as of this moment, NAM shows a narrow strip of 2000 cape through the previously mentioned zone, with 0-3 EHI around 3, 0-1 around 1 by 21z, nothing to impressive, but just as good as Nebraska, along with a relatively weak cap. HRRR also pops a pretty decent cell right on the OK/KS Border by 23z, WRF pops a couple nice looking cells just on the KS side of the border....again...all of this east of the SPC Day 1 Outlook area. LCL's less than 750m/GFS, less than 1250m/NAM...my eyes are crossing and think im gonna do something I rarely if ever do....chase east of the Slight Risk area...or at least head up to the Alva, OK area and hope to chase something on one side of the border or the other today.

Edit:

Just after I posted, new RUC came out...more confusing than before....best area IMO looking like NW KS again...though it pops NO Convection through there or NW OK by 0z, and RUC is usually pretty reliable within 12 hours of an event, though not the be all end all. Richer Tds from 65-70+ in the NC OKLA/SC KS area, along with a consistantly localized area of backing surface winds by RUC/NAM...whats causing the models to back the winds through this zone, I have no idea, unless its some kind of remnant outflow boundry from early convection they are picking up on??? Either way, its beyond my meteorlogical knowledge. So I think im just gonna save the gas $$$ and let everyone else try and figure this one out...unless next HRRR keeps firing storms in extreme NW OK/SW KS on the next run. Good Luck to all who chase today!

 

[John Peters]

I'm sitting in North Platte right now trying to formulate a plan. RUC doesn't really initiate much in South NE, where recent runs are now bringing 0-1 EHIs into the 3-4 range; however, both NMM and ARW initiate discrete cells a little bit south and east of here by 0z. Not sure whether it's a better idea to drive further down the dryline into W KS, where there is more confidence w/r to storm initation, but the wind fields aren't quite as good. The failure of RUC to initiate activity by 0z makes me a little bit suspect, especially since (as mentioned earlier) the precip graphics have been pretty reliable as of recent.