April 15, 2003
Storm Chase
Texas Panhandle
Editor:
Putnam E. Reiter
Forecast/Setup -
Risk Area: Moderate - Enhanced
at 8:00pm with a 10% hatched area on the tornado probability graphic.
Initial Target Area: Western Oklahoma - Erick
Per usual the models had picked up on this event several days ago. I can't
complain about the forecasting as a whole,
some specifics like moisture return really got on my nerves. It seems that
moisture is the escape goat for forecasters
this year. Several tornadoes later, I tend to think that we had adequate
moisture.
The mid-level environment provided the development of a longwave trof over the
western U.S. A lead shortwave trof was
progged to eject out as a negative tilt trof during the day. This trof developed
a surface low in Kansas with
associated dryline across the Texas panhandle. Southerly winds had presisted
across much of the area, bringing in
some moisture. Deep moisture did remain in south Texas, however across the
threat area dewpoints did make the upper
50s/low 60s. Additionally, PW values were near 2.5.
A thick cirrus shield with embedded mid-level showers moved into the threat
region early in the morning. The Mesoeta
did a great job showing that this would be east of the threat region by 14:00
CDT. We noted this as we got into far
western Oklahoma. Said cloud deck kept things rather cool, but as it cleared
temperatures quickly warmed into the
mid 70s. The dryline was about on queue remaining in the central Texas panhandle
through early afternoon. By 16:00 it was on the move into eastern sections of
the Texas panhandle.
Wind speeds in the atmosphere were progged to increase dramatically during the
day. The surface and 850mb winds would bring in additional moisture, which they
did. The atmospheric wind profile made conditions very favorable for storm
rotation. Thermodynamics were reduced, but easily compensated for by very
intense dynamics. This is noted through
strong diffulence and co-located UVV's across the threat area.
As the mid-level jet max approached elevated storms develop west of the dryline.
As these storms moved east they
became rooted in the boundary layer, then became supercells. Many of the
clusters that formed west of the dryline turned into discrete supercells, many
of them producing tornadoes. A squall line eventually developed, but was not a
big deal.
Our crew did a great job forecasting this event. Many thanks to Gusty and
Oklahomey for forecasting assistance. Yet
again we picked the correct spot to be. I just wish we could chase as well as we
tend to forecast. We're 3 for 3 this
season, much better than last year. Unfortunately we have no tornadoes to show
for it and all three have been tornado days.
SPC Products:
Day 1 -
Watches -
MDs Graphics:
Day 1 -
Tornado Prob -
Wind Prob -
Hail Prob
01:00z (8:00pm)
Tornado Prob
Norman WSFO:
Public Information Statement -
Local Storm Reports
Surface Plots:
Temperature
-
Dewpoint -
Pressure/Wind Speed -
CAPE -
LI
GFS 00z Initializatio
n
Surface Pressure
Surface Dewpoint
Precipitable Water
850mb Wind
700mb Wind
500mb Wind
500mb Vorticity
300mb Wind
The Chase -
Team: David Underwood, Rob
Ferguson, and Putnam Reiter
Miles Drive: 479
Depature Time: 13:12 CDT
Return Time: 23:51 CDT
Left Oklahoma City and headed west on I-40. Central Oklahoma had dense overcast
of cirrus and stratus clouds, there was
also some light rain as we headed west. The rain ended when we reached
Weatherford, but the overcast continued. As we
neared Sayre the overcast began to break with a very sharp edge to the cirrus
deck occurring around this time. We decided
to move our initial location to Shamrock, Texas, a little closer to the dryline.
We got to Shamrock around 16:00 and
fueled up. By this time the temperature was in the mid-70s with a very strong
south wind. There was some mid-level stuff
that had developed behind the dryline and was moving slowly east. We decided to
drift south to Wellington. SPC MD
indicated that SW OK/NW TX would be very favorable for supercells and tornadoes.
We traveled south on Texas Highway 83 to Wellington, reaching this town around
16:45. We went just west for a little bit
and watched the storms. Around this time we got word that the mid-level stuff
that we had watched near Shamrock
became rooted in the boundary layer and had actually developed a tornado. This
storm continued east-northeast
into Oklahoma, producing several tornadoes.
A lot of light activity continued near us at Wellington. Thinking that this
wouldn't do much, we headed south to Childress
to intercept the rather big storm moving towards that town. We continued south
on Highway 83 towards Childress. We got
close and started to receive moderate rain. Turning southeast on Highway 287 we
attempted to get south of the storm.
About that time we learned that it was moving more east than northeast. Fearing
a repeat of April 5th, we turned around
and went back into Childress. About this time we heard tornado reports from the
storms that had been near Wellington
about 30 minutes earlier. These storms were in Oklahoma at this time.
Additionally, a squall line had developed and was
moving east. Said squall line absorbed many of the storms in northern Oklahoma.
We ended up just north of Childress on
Highway 83 as the squall line approached. We received 61 mph (measured) winds as
it moved over us.
Thinking that there wasn't much to be had after this we started back and decided
to go near a damage area around
Texas FM 680. We drove north to it and never found the damage path. Turning back
to Highway 287 we headed to Quanah
and then Altus, then on to Oklahoma City. Stopping briefly in Altus for a late
dinner. Several storms in southwest Oklahoma
and northwest Texas continued to outrun the squall line and produce tornadoes
until about 21:30.
Of all the storms we managed to only get the squall line. It was a perfect game
of keep-away. Maybe some of it was gun
shy due to April 5th. However, there were several tornadic storms and we should
have been able to make one of them.
Thanks Marc for data support.
Lessons Learned -
- Stick with initial forecast unless
current conditions indicate a change is necessary. We should have stayed in
Shamrock.
Encounters -
Engaged Storm: No
Tornado: No
Funnel: No
Hail (larger than 0.75 inches): No
Wall Cloud: No
Wind (above 57.4 mph): Yes - Squall line north of Childress.
Measured 61 mph.
