Sunday, April 04, 2010

Severe Weather/Chase Forecast: April 5th

I don't even remember what a 65ºF dewpoint feels like. If the operational GFS and NAM verify, then I will likely get a taste on Monday. What we have is massive return flow ahead of a nice upper level system on its way across the continent. The GFS is still slightly more progressive with this feature and as it has been *too* progressive with this type of feature all year, I'll lend my confidence in the NAM's solution.

On Monday evening, a quasi-stationary front will stretch from Wyoming along the Nebraska-Kansas border and become a warm front bulging northward into Iowa. The dryline looks to intersect the QSF in north central Kansas. With backing winds at the surface along the QSF, the dryline should be drawn westward immediately along the boundary. However, just south, the dry southwesterlies look to cause a nice bulge along the line. This is an area that will have to be monitored.

The wind shear is best in this area. However, the models are outputting QPF further south along the dryline into south central Kansas and possibly into northern Oklahoma. The wind shear is still good but less ideal than that of the northern stretches. However, the amount of instability is more than enough to get an atomic tower to blow up.

Inhibition could be an issue though both models are lessening inhibition along the dryline where enhanced moisture convergence will limit the inhibition. Unfortunately, any storm that forms along the dryline will not have a long lifespan. Though storm motion will be rather slow, movement into the heavily inhibited deeper warm sector will likely kill off the updrafts. Also, models suggest there may be some high clouds in the jet further north, possibly over the DL/QSF intercept which could lessen surface heating in this area, keeping it more inhibited.

In the upper levels, the main energy will still be back to the west. However, with its approach, a weak general lift will be in the cards. Weak vertical velocities will still aid in initiating convection.

Further east, along the warm front, there exists an area for significant severe. Due to increased distance to that target, I have not been focusing on it and will not in this forecast. I prefer the dryline play...

Isolated dryline supercells can be very photogenic and it is certainly where I would prefer to be. Multi-parameter analysis points me to two targets, one being Hays, Kansas and the second being Coldwater, Kansas. Perhaps some place in between would be ideal since these two points aren't too far apart. Since I'm not driving, I might not have a choice but if it were up to me, based on the parameters I have seen today, I would be in Kinsley, Kansas, waiting for initiation.

I don't believe by Monday evening we will have a full cut off surface cyclone yet. At the DL/QSF intercept there will be some cyclonic action, but until the left front quadrant of the jet rolls over and really amps up vorticity, we will still be looking at that boundary intersection. Later that night and into the morning, the surface low should begin to get rolling and eventually start dragging cooler air from the north down along the high plains. The Pacific front with this system never really looks to make it through the Rockies, so the eventual cold front, which should really materialize in early to mid Tuesday will be polar in origin. For a while, Tuesday looked like a decent day, but the cold front should sweep down and overrun the dryline Tuesday afternoon, so any convection would be squally, similarly to what we saw on Friday (April 2nd). So, Tuesday looks like a dud to me. So much for all the discussion about all of the other models painting Tuesday as "the day".

Anyway, I will try and update this tomorrow night but if an early wakeup call is in order, I might be heading to bed early after cooking up a ham for dinner tomorrow! ... in which case, this may be the last you hear from me until we're on the road on Monday. If that is the case, I will try and post periodic updates on Facebook. I won't be on Spotter Network, but Tony (Laubach) or Scott (Hammell) may be and we'll all be together. In fact, Scott may be streaming live over at So, if you'd like to chasestalk, there will be plenty of opportunity!

PS: Super glad SPC is only giving my target area a "see text". Hopefully the SPC chasers will all be in Missouri or Iowa! Keep that beautiful Kansas blacktop free of detritus!

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