6/20/04 FCST: Central high plains

[Kevin Scharfenberg]

The latest runs of the eta and GFS suggest unseasonably strong upper winds will be in place over the central high plains (particularly western Kansas) Sunday afternoon, with sufficient shear for supercells. CAPE values are progged to be fairly large, potentially 3500+ in some areas, presuming some recovery from overnight convection. LCLs should be unseasonably low given temperatures progged in the mid 80s and dewpoints near 70. There is a capping inversion there but it doesn't appear to be too strong. Forcing doesn't look too terribly strong either.

I would expect scattered supercells to develop in the upslope regime from northeastern Colorado down to the low position in the northern Panhandles, and possibly even down the warm front into northwestern Oklahoma. A few of these storms are likely to produce tornadoes. Later, a forward-propagating MCS should emerge from western Kansas as the cold pools from the storms eventually combine, and that MCS should move southeast down the instability axis into southern KS and Oklahoma overnight.

This is probably the last system many of us will be able to chase this spring. Post your forecasts here...

 

[Gabe Garfield]

Although absolute wind speeds are fairly weak, I'm impressed by the directional shear, especially in the lowest kilometer across SC/SW KS and NW Ok. The 12z ETA indicates that 0-3 km helicities will range from 200-450 m2/s2 across the warm sector. For this time of year, that is fantastic. CAPE is also forecast to be quite high, although that is fairly seasonable.

The most important factor here is storm mode, IMO. We may have tons of CAPE and shear tomorrow, but if the storms quickly transition into an MCS, it'll be game over...unless, of course, we can get a storm or two to form ahead of the line.

Right now, my target is Pratt, KS. Of course, that will likely shift to Medicine Lodge/Attica by tomorrow!


Gabe

 

[Bryan Burkholder]

Pratt doesn't look too bad. No doubt there will be intense convection tomorrow (and probably supercells), I am not certain the shear will be as high as progged by the 00z ETA. The pretty meager values of 0-1km helicity worry me a bit when considering the tornado threat tomorrow at 00z. 0-3km helicity is decent in the area where convection looks likely, but it may be a bit overdone, and is mostly at upper values (cosidering low 01-km values). If a storm can initiate late and maintain itself until the low level jet kicks in, then it will have a load of shear to play with.

Still undecided whether it will be worth going or not. Right now, with the ETA showing a dryline bulge in SW KS/ OK panhandle with dewpoints probably being slighty under-forecasted, with moderate CAPE values, I would have to go with from Buffalo, OK to Coldwater, KS as a target. I don't expect a convective outlook higher than Slight .

 

[Jeff Snyder]

I agree that tomorrow has a decent tornado risk... Of main concern to me is the ETA-progged relatively weak CAPEs courtesy of sfc Tds only ~65 across much of KS... Latest 0z ETA has CAPEs generally in the 2000-2500 range, except for a small bullseye in NW KS, where CAPEs are progged to be near 3000. Now, the 0z GFS, on the other hand, is considerably more gracious with sfc dewpoints (AOA 70), which yields a nice wedge of 3000-4000 CAPE from nw OK into southwestern KS by 0z. ETA projects strong low-level shear along and north of a Wichita to Pratt line by 0z. IF the GFS dewpoint field can verify, which would yield much stronger instability than ETA is forecasting, than I'd love to be anywhere along that ICT to Pratt line. Given that this area is also on the nose of the 850mb low-level jet (ala May 12th, etc), I think things could get interesting IF the surface dewpoints can make it up there...

Either way, I'm up in MN, leaving to come back to OK tomorrow morning, so it's a no-chase day for me... Maybe I can get lucky and catch a storm to my west as I get on the KS Turnpike...

 

[Tony Laubach]

Happy Father's Day to all you chasing fathers out there..

I'm thinking the reign of crazy weather may be coming to an end (at least the day-after-day athon).. I'm not all too impressed with things today, although I think if the cap can be broken in areas northeast; combined with the shear and moisture, I think SPC's 5% is justified.. closer to home, I'm not all that optomistic. Its a cool, grey day on the west sides of town, but I am hearing thunder, so I know the instability still remains..

My excitment for today actually comes after dark.. I'm hoping to break in my first lightning chance in two years and score some good lightning shots.. forecasts indicate storms well passed midnight. Fortunately with nighttime stuff, all I want is lightning; nothing severe.

If storms get heavy over the area, I may track them eastward, but I am not going to make a huge day out of things. For those wondering why I am passing up these local days, I just signed the leased on a new apartment and have a few work-related things going on, so I've been restricted in mostly money in recent times.

Again, Happy Dad's Day everyone and maybe MOTHER nature will treat ya a bit! 8)

 

[Larry J. Kosch]

Possible WW for SE WY and E CO

The NWS is having a MSC discussion about putting up a WW for WY and CO:

MESOSCALE DISCUSSION 1353
NWS STORM PREDICTION CENTER NORMAN OK
0148 PM CDT SUN JUN 20 2004

AREAS AFFECTED...ERN CO...SE WY CONCERNING SEVERE THUNDERSTORM POTENTIAL VALID 201848Z - 202045Z

LARGE HAIL AND ISOLATED DAMAGING WINDS WILL BE LIKELY AS THE STORMS GRADUALLY STRENGTHEN THIS AFTERNOON. A WW MAY BECOME NECESSARY THIS AFTERNOON BY 20Z ACROSS ERN CO AND SE WY.