March 17, 2003
Storm Chase
Western Oklahoma
Editor:
Putnam E. Reiter
Forecast/Setup -
Risk Area: Slight
Initial Target Area: Southwest Oklahoma
Forecast:
Forecasting for this event was decent up until the actual day. For some reason
forecasters got stupid. SPC had a moderate risk up for the early morning
issuance of the Day 1. Then at 13:00z Imy downgraded the risk area to a slight
risk, this was kept at the 16:30z issuance by McCarthy. To make matters
worse when it came time for watch issuance, a severe thunderstorm watch was
issued. Suffice it to say that said watch verified as a tornado watch several
times over. Additionally there were several reports of tennis ball sized hail.
This group had been watching this day for eight days. Models did a decent job,
albeit the GFS was a little fast much of the time. However, one cannot blame the
models. This group forecasted for several days and had picked southwest Oklahoma
as our primary spot. We decided to go but were in no hurry after the SPC
outlooks and other information from surrounding NWS offices indicating this was
a marginal day.
The complicating matters were moisture and cloud cover. Even though surface dewpoints were initially in the mid 50s, the GFS consistently forecasted
dewpoints in the low 60s. Early morning convection didn't get that strong and
ended up more as Virga than anything. This did keep the atmosphere somewhat cool
but many areas in Oklahoma warmed to near 70F by early afternoon.
General environment was for a shortwave trof to lift out as a negative tilt in
Oklahoma and wrap up into a large closed low. At the surface a surface low was
to form in SW Kansas. A dryline was progged to move into western Oklahoma during
the day. Complicating matters was the system that moved through this area on
Wednesday 03/12/2003. Additionally, periodic shortwave trofs moved through the
Gulf of Mexico turning winds at the critical 850mb
and surface levels to northerly and retarding moisture return. Models predicted
a few hours of moisture return that should allow decent low level moisture for
storms. Additionally, precipitable water values were progged above 2.0 over the
threat area. Mesoeta forecasted instability turned out to be pretty accurate.
CAPE values got up to about 2000 J/Kg and LIs to -8 before convective
initiation. All three models this morning forecasted that convective initiation
would take place by 3:00pm and it did. Mesoeta helicity values were way
off and will not use that as a forecasting tool in the future.
SPC Products:
SWO Day 1 Graphics:
Risk Area
-
Tornado Prob -
Damaging Wind Prob -
Hail Prob -
Watches
Surface Maps:
Temperature
-
Dewpoint -
Wind Speed -
CAPE -
Lifted Index
Upper Air Sounding at 00z:
Norman -
Forth Worth
GFS Model:
12z +12 hour - 00z Initialization
Dewpoint -
Dewpoint
Surface Pressure -
Surface Pressure
Precipitation
- None
Precipitable Water -
Precipitable Water
850mb Wind -
850mb Wind
700mb Wind -
700mb Wind
500mb Wind -
500mb Wind
500mb Vorticity -
500mb Vorticity
The Chase -
Team 1 - David Underwood, Rob
Ferguson, and Putnam Reiter
Miles Driven - @270
Departure Time - 13:15 CST
Return Time - 19:05 CST
We left Oklahoma City and
headed south on I-44. We noted some clearing, but lots of clouds around
the area. A severe thunderstorm watch had been issued for much of southern
into central Oklahoma. Upon hearing that storms had gone severe near
Hobart we turned off of I-44 at Chickasha onto Highway 62, heading west.
At Anadarko we turned north on Highway 281, which was my mistake. The
storm was still near Hobart at this time. After a 20 minute tour through
Binger and back down Highway 146 to Fort Cobb. As we finally got back to
Highway 62 to go west a tornado was reported. We were still 20 minutes
away from the storm. As we got close to Mountain View, we noticed several
lowerings. We turned south on Highway 115 for a few miles. We south
there for a little bit and then drove back into Mountain View and then north on
Highway 115. We sat north of Mountain View and continued to follow the
storm. Noting that the storm was losing its features, we dropped off of it
around Carneige. We figured that everything was over and started to head
back via Highway 58.
We got to I-40 and started east
towards Oklahoma City. We heard another storm go tornadic, to our
southeast. We drove to Highway 281 and south through Hinton. There
we noted several wall clouds and the storm cycling RFDs. After sitting
around for a few minutes, we drove back into Hinton and then took Highway 37
east. The storm continued to produce periodic wall clouds, but they would
quickly get cutoff by the RFD. This seems a function of a cold RFD
relative to the environmental temperature and the air the storm was ingesting.
The best storms shifted south during the day. Realizing that we were about
to play tag with the Canadian River, we drove north to I-40. We followed
the storm, but it did little more than cycle.
Getting to Highway 81, we
decided to take it to avoid Oklahoma City traffic. As we got south we
heard another storm near Lawton go tornadic. For a brief moment we thought
about going after this storm. However, the hour was late and the sun angle
low. For an event that wasn't progged to happen; we had a heck of a time.
Lessons Learned -
- Navigation and storm
location identification are essential to a good chase. I sent us the wrong way
and delayed us about 20 minutes. Once again we lost a tornado due to a 20 minute
delay. This sure brought back bad memories of the Throckmorton, Texas day April
2002.
- We learned a lot about our preparedness on this chase and several things
to work on for our next event.
- SPC and NWS information is guidance only. It is up to individual
forecasters to make their own decisions and live with it. This is a hard lesson
to learn and especially application. Many of the people forecasting this event are
some of the best around and it still got the better of us.
Multimedia -
This
video is of a wall cloud located about 5 miles east of Hinton near
Highway 37. We are traveling north during much of the video. About
15 minutes early this storm produced a brief tornado in southern Caddo County.
Encounters -
Storm 1
Near: Mountain View
Tornado: Yes, but we got delayed and got the tail end of it.
Wall Cloud: Numerous
Severe Hail: No
Severe Wind: No
Storm 2
Near: Hinton
Tornado: Yes, but not visible to us.
Wall Cloud: 2-3
Severe Hail: Yes, measured 1.15 inches, 20 minutes after the storm passed.
Severe Wind: No
