Austin / Travis County and South Central Texas Weather Update #2
Prepared by UT University/Incident Meteorologist Troy Kimmel
320pm CT – Saturday / 13 January 2018

.. Little Change in My Forecast Thought ..
.. Potential Winter Weather Event Late Monday Night into Tuesday ..
.. Ice/Sleet/Snow Accumulations Possible in Some Areas ..

On this Saturday afternoon, we continue to watch an arctic air mass that is forecast to move
southward into our area by late Monday into Tuesday. After a brief warm up on Monday
(highs now forecast into the lower 60s), we’ll see northerly winds increase and temperatures fall
rapidly following the surface cold frontal passage which I am expecting in the 9pm to 12 midnight
time period Monday night. In the hours before and around the forecast time of the surface cold frontal
passage, an upper air low pressure disturbance is forecast to track eastward over our area with
clouds picking up late in the afternoon Monday with light rain and drizzle starting sometime
around the dinner hour with the precipitation persisting as the front passes and continuing as
much as 12 to 18 hours after the frontal passage as moisture overruns the much colder surface air
moving into the area.

Surface temperatures, following the cold frontal passage, will fall into the 30s pretty quickly with freezing
temperatures likely by 4am Tuesday morning then into the upper 20s to near 30 by daybreak with
daytime highs on Tuesday (with the associated cloud cover) struggling to get back up to freezing.

As temperatures fall following the frontal passage, any precipitation that is occurring locally
would transition over to freezing rain, freezing drizzle and sleet (ice pellets) as we make our way into
post midnight hours Monday night/Tuesday morning. As the atmospheric column aloft continues to cool,
although we could continue to see some freezing drizzle/freezing rain, I still think that precipitation would
transition over to a little more sleet (ice pellets) and light snow after 9am Tuesday and continuing into the
afternoon. Given this temperature forecast, I think it is possible that some areas of south central Texas
could see at least some ice/sleet/snow accumulations with this event. Hazardous road conditions could
result throughout the IH35 corridor.

As it appears now, any precipitation associated with the passing disturbance will end, with the departure of
the disturbance, by late Tuesday with clouds decreasing by Tuesday night into Wednesday. If skies do partially
clear Tuesday night, we will see some temperatures in the teens in outlying areas to near 20 in the urban areas
of the IH35 corridor. Any left over standing water would likely refreeze quickly. Highs in Wednesday will be,
with the return of some sunshine, climbing back to the mid to upper 30s.

As I mentioned yesterday, I continue to be concerned that the models may be a little too warm with this air
mass – something we tend to see when you get this type of air mass this far south – so it is possible that we
will see temperatures trend a little colder with time especially if we see any ice/sleet/snow accumulations. The
exact time of the frontal passage could be a little earlier than we’re currently thinking – another possibility
when you see these arctic fronts pressing southward through Texas. At this point locally, my confidence in the
much colder air arriving continues to be quite high with medium to high confidence that precipitation will occur.
Being able to forecast exact precipitation type, at any given time in the forecast, is a lower confidence. Please
understand that timing of the individual ingredients (of colder air arrival, atmospheric column temperatures aloft
and the upper air disturbance) is indeed everything when you consider the forecast given this potential winter
weather event for south central Texas. In other words, if one thing changes, the forecast can and will change.

I’ll continue to keep you advised on this potential winter weather event.

tk

CALL TO ACTION:

Please remain “weather aware” and listen for the latest weather statements,
advisories, watches and warnings from the National Weather Service.

Make sure that your NOAA All Hazards Weather Radio is operational and are
set to alarm in case of severe and inclement weather watches and/or warnings.

FOLLOWUP STATEMENTS:

I will continue to keep you informed regarding this severe/inclement weather
event. Any questions or if you have a storm report that I can forward on your behalf
to the National Weather Service, please let me know at tkimmel@troykimmelweather.com