Severe Weather Discussion for January 26 – February 1, 2009.
– Freezing rain is likely across much of the I-44 corridor and into
east-central Oklahoma Monday afternoon through Wednesday morning.
– Temperatures will be cold Monday and Tuesday as reinforcing high
pressure and clouds keep us near 30F. Wednesday will start a slight
warm-up to the upper 30s, with this continuing into the weekend.
Thursday will be mid 40s, Friday upper 40s, Saturday low 60s and
Sunday upper 50s.
– Severe Thunderstorms in Oklahoma: < 5%
– Storm Chase: < 5%
– Winter Precip: 60%
Main forecast effort today has been on the impending ice storm. I
have set the probability at 60% to coverage a moderate-end event for
much of the state with a small area that may receive a high-end event
in the far northeast. I won't spend much time talking about the ice
storm as a special discussion will be issued later.
12z GFS/00z ECMWF are in decent agreement through much of the week.
All models agree that a southern stream shortwave trof will eject out
of the southwest U.S. on Monday. As the trof approaches it will get
sheared apart and take on a strongly positive tilt. Shallow cold air
at the surface overlaid by warm and moist air will provide a favorable
environment for freezing rain.
GFS generates small area of light snow in northeast Oklahoma late
Thursday as a northern stream shortwave trof starts to carve out an
eastern U.S. longwave trof. This shows up in the BUFKIT data and QPF
plots, so will go with a slight chance of snow for northeast Oklahoma.
Little to no impacts are expected. All POPs zero Sat/Sun.
In the dailies, I have used the NAM/GFS surface temps through
Wednesday. The Arctic air should hang around for a while and the
development of northwesterly flow aloft may start the cold front train
again. However, the midlevel flow will not be near as amplified as
last week, so the intensity of the cold fronts appears reduced. The
GFS numbers are reasonable beyond Thursday and my numbers are also a
nod to Andy and Greg's from this morning. I was expecting cooler
number for Saturday but as noted above the longwave trof will not be
near as amplified as last week and the high is of Pacific origin. The
surface pattern is progressive, so time for CAA is limited.
Monday 30F. Tuesday upper 20s. Wednesday in the upper 30s. Thursday
mid 40s. Friday upper 40s, Saturday low 60s, Sunday upper 50s.
BTW – I will say I'm happy I did a cold bias for today from last week,
I'll hit the high from 7 days out. Of course it is all luck!
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