Winter Weather Discussion 2010-1-6

Winter Weather Discussion for January 28-29, 2010.
Valid: 2010-01-27

*Significant Winter Storm Heading to Oklahoma*
*Preparations for this storm should be rushed to completion*

Highlights:

– Winter Storm Warning continues from midnight tonight through 6am
Friday for the Oklahoma panhandle. 8-10 inches of snow is expected in
this area.

– Winter Storm Warning continues from 6am Thursday thru 6am Friday
north of a line from generally Lawton to Konawa (south of Seminole).
A mixed bag of precipitation is expected across the warning area.
Primarily snow in far northwest and west-central Oklahoma with 6-10
inches likely. Altus to Enid to Ponca city will likely see rain
change to freezing rain and then sleet by midday Thursday. Sleet will
continue during the day, changing to snow during the evening hours,
with 2-6 inches accumulations of sleet and snow. The I-44 corridor
continues to be the best spot for primarily freezing rain with at
least 0.25 inches accumulations and isolated amounts to one inch.
South of a line from Walters to Ada to Sallisaw will see mainly a cold
rain with a changeover to freezing rain Thursday night, up to 1/4
inches accumulations.

– Winter Storm Warning continues from 6am Thursday thru noon Friday
north of a line from Okemah to Sallisaw.

– Winter Storm Watch continues for south-central and southeast
Oklahoma. There may be changes to this product on Thursday to better
refine expected impacts in these areas.

– As stated many times, conditions in Oklahoma City will likely
deteriorate after the work day has started. This may lead to issues
with stranded motorists and wrecks. As of this writing there are 151
closings in/around Oklahoma City. These closings may offset some of
the travel impacts. Despite this, OEM will need to watch out for
stranded motorists and sheltering needs. I'll have the ODOT cameras
up and we'll be monitoring speed sensors in OKC and Tulsa. Widespread
travel problems are likely by late Thursday, continuing into the
overnight hours.

– Winds will be in the 20-30mph range with higher gusts as the system
impacts Oklahoma. This will aggravate any ice accumulations on
exposed objects. Widespread power outages continue to look likely.

Discussion:

00z models continue prior trends and there are no changes to the
forecast. Pre-frontal trof has reached I-44 and will continue
southeast during the overnight hours. Subfreezing air is analyzed in
central Kansas and much colder air in Nebraska. 00z NAM arrived
slightly cooler and believe the models have a good handle on the
temperature profile the next 48 hours. However, the standard caveat
applies regarding winter weather.

Temperature reached 65F today with plenty of sunlight, as such the
surface and exposed objects are quite warm. Rain drops will initially
be warm as they pass into the subfreezing air across the area on
Thursday and will likely require additional time for accumulations.
There is no way to accurately pinpoint when and where this will occur.
The first notice will be an interstate wreck and from there
conditions will likely go rapidly downhill.

00z GFS keeps the dryslot in Texas while the NAM has a much more
pronounced dryslot in Oklahoma. There appears to be no major
differences at the QPF level but that is probably due to the GFS being
6 hours faster. At this point I'm not going to split hairs among the
models.

Short term discussions will be started first thing in the morning and
will focus on details, I'll try to give a general overview as I have
time. At this point I do not expect any changes with regards to the
mesoscale setup. I do expect plenty of changes on the microscale
(county level).

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About Putnam Reiter

Putnam has been storm chasing since 1990 and is a co-founder of Hook-Echo.com. For his day job, Putnam works in emergency management for information technology.
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