Chasing Tomorrow

Just did a quick run through model data. Still planning on chasing tomorrow. Going forecast is still on track it seems. My map from last night needs adjusted slightly to account for a northward trend with the surface pattern. I’d shift the box up north a bit, maybe 50 miles or so. There’s still some discrepancies between the HRRR and the NAMnest at the surface with the HRRR being a little farther north. I’m leaning that way and as of tonight my initial starting point target looks to be Garden City, possibly Liberal. I’ll move a bit west from either of those targets when storms are getting ready to initiate, but those are the two towns I’m looking at initially going to before moving in close when storms are developing. Wherever you get the moisture wrap around I’m going to get just off the north edge where surface winds will back hard to easterly. I’m a little worried about whether or not we’ll have some dry pockets or less than pristine air to work with. I’ve only started glancing at that because it’s kind of a if it happens it happens and more at mitigating factor than a target adjusted or deal breaker type issue, so we’ll just see how it plays out. What I’m a little worried about is ongoing storms in Texas and how they may affect the airmass that advects into the target area tomorrow. Again I didn’t really look at it much since there’s no potential target adjustment really that will result from forecasting this aspect of the setup, but the current storms seem to be a little farther east and impacting the air more than the NAM accounted for. I tried to glance over low level winds between now and tomorrow afternoon to see where the source of the air over the target area would be and we’ll probably pull in air in that is over the TX/OK panhandles currently and air from ahead of the ongoing convection, but these storms could potentially compromise the moisture return and air mass over the target area. Assuming we get dewpoints in the low 60’s, deep layer shear CAPE combos should be fairly supportive of supercells where surface winds back north of the moisture wrap around. Looking at 40-45kts or so with CAPE well over 2000. How much supercells will fill in and get clustered is a bit of a question mark, but I think we’ll have some degree of separation with several supercells over the threat area. I think the key will be picking the ones in the backing surface winds that are leading other storms or have a good opening off their southeast sides. Any more discrete tail end type storms will initially have a low tornado threat, but may have some really solid structure with excellent directional shear. However the low level shear that will initially be weak is forecast to ramp up significantly in the 7-10pm timeframe. As that ramps up the tornado threat will go up proportionally with any discrete storms. If we have discrete storms at 7pm, I think we’ll have a pretty decent tornado threat. I see this as a Leoti type day. That was initially clustered up with numerous cells and struggling until later in the evening and it got a beautiful sculpted updraft with a couple weak tornadoes. This setup is very similar with the dramatic directional shear and I think deep layer shear and CAPE is about the same as well. The potential is there. Just need convective evolution to go our way with storms firing later or remaining discrete through the 7-8pm window for the tornado potential to come together. I’m planning on heading out around 10:30 probably headed to Garden City. I’ll fire up the stream and link it on facebook and twitter. I think this is a 5% tornado prob setup for SW Kansas with the initial day 1 outlooks and maybe bump it up to 10% in later outlooks if it looks like storms will remain discrete in the 7-8 window.

Friday also looks like a probably chase day. Maybe a boom or bust type setup with an outflow boundary playing an important roll in initiation and enhancing low level shear. Could end up crapping the bed completely or it may work out well. Figure that out after tomorrow’s chase is done. Then Saturday is showing good potential. Great parameters ahead of a dryline in Kansas minus the weak upper level winds. The question mark and potentially huge problem for Saturday’s setup is a cap along the dryline and high probability it won’t break. There’s other plays if that’s the case, but we’ll get into that later. Good luck if you’re chasing and I’ll update during the day tomorrow.

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