May 7, 2005

Storm Chase

Texas Panhandle

Editor:  Putnam E. Reiter

Forecast/Setup -

Risk Area:  Slight
Initial Target Area:  Shamrock, Texas

2005 is certainly going down as a bad year for storm geeks. Today is the prime example of what all can go wrong.

The past few months have been characterized by a very active southern jet stream and a Rex Block in the northern Jet over Alaska. While I'm sure Alaskans have been really enjoying the nice weather, chasers in this part of the world aren't too happy. The active southern stream has produced several closed lows that have moved across the southern U.S. These lows pushed moisture to the Yucatan, this prevented decent moisture return when the next system moved into the region. The parade of systems did slow in late April but a longwave trof developed in the eastern U.S. the early part of May. This sent a Canadian High into the central U.S. and right into the Gulf. To make matters worse the high setup residence in the Gulf, preventing recovery and moisture return.

Despite the Gulf surface high, moisture was progged to return during the day Saturday with low 60s expected in the Texas panhandle. Daytime temperatures were progged in the low 80s resulting in CAPE values of 2500 J/Kg and LIs to -8. Moisture was progged to be deep but not high quality. However, moisture was deep layer and should not mix out during the day. Aloft a closed low was progged to move from the western U.S. into the northern plains as it is deflected by the southeast U.S. ridge. The base of the trof was progged to move near the southern plains, assisting in convective initiation. Speed and directional shear were quite favorable during the afternoon and especially into the evening hours.

Early morning lots of clouds developed across the region. Some shower activity moved through parts of Oklahoma, per the models. As the sun angle increased, so did the clouds. Surface heating was seriously limited by the clouds. Clearing was noted in the Texas panhandle and it moved into western Oklahoma late in the day. However, as this occurred, rather thick cirrus moved over the threat region. Storms attempted to develop around 17:30 west of Childress and north of McLean. The storm north of McLean died rather quickly.  The storm near Turkey survived for several hours, but never got enough strength to do much.  In fact it barely rained under the thing.  Little else occurred until early morning Sunday when a severe MCS developed in central Texas.  Said MCS disrupted deep moisture return to Oklahoma on Sunday, limiting a potential chase day.  Two decent days, gone.

SPC Products:  SWO Day 1 Graphics:  Risk Area - Tornado Prob - Damaging Wind Prob - Hail Prob
Surface Maps:  Temperature - Dewpoint - Wind Speed - CAPE - LI - Moisture Convergence
Soundings:  Hobart (GFS 00z) and Norman (ARPS 22z)
Mesoeta 00z Initialization:  Surface Plot - 850mb Temperatures - 850mb Dewpoints - 850mb Windspeed - 850mb Vertical Velocity - 850mb Relative Humidity - 700mb Wind - 700mb Temperatures - 700mb Relative Humidity - 700mb Vertical Velocity - 500mb Vertical Velocity - 500mb Temperature - 500mb Vorticity - 500mb Wind - 500mb Relative Humidity - 250mb Wind - 250mb Relative Humidity

The Chase -

Team 1 - David Underwood, Ray Hardy, Rob Ferguson, and Putnam Reiter
Team 2 - Wayne Robinson, Kathy, and Heather
Miles Driven -  405
Departure Time -  14:15
Return Time -  00:00 - 05/08/2005

We left Oklahoma City and headed west on I-40.  The thick low clouds were a concern, but looking at visible satellite made us feel better as the Texas panhandle was clearing out.  As we got to the TX/OK border we got into the clear area but also started to note thick cirrus moving into the panhandle.  Temperatures had warmed nicely during the afternoon into the low 70s.  This was encouraging and probably would have been enough had the cirrus not got involved.  We reached Shamrock around 17:00 and sat there for a while.  We noted a storm near Turkey and seeing that was the only game in town, decided to go after it.  We took off south on Highway 83 towards Childress.  We got data along the way and didn't see much that impressed us.  We got a few miles south of Wellington and stopped for a little bit.  Seeing about the same unimpressive activity.  We headed back north of Wellington and then stopped for a little bit longer.  By this time it was about 18:40 and we figured there was little chance of additional development.  The dryline was retreating and there was no more heating.  We headed back to I-40 and drove home.

Lessons Learned -

The only thing to complain about here is forecasting.  Should have noted the 700mb RH.  I saw the expected 250mb RH but was surprised how thick the cirrus ultimately was.

Multimedia -

None

Encounters -

Engaged Storm:  None
Tornado:
Funnel:
Hail (larger than 0.75 inches):
Wall Cloud:
Wind (above 57.4 mph):