Austin / Travis County and South Central Texas Weather Update #2
Prepared by Incident Meteorologist Troy Kimmel (www.troykimmelweather.com)
915am CT – Monday / 10 February 2014
…. Not Much Change in My Forecast Thought ….
…. Very Low Probability Winter Weather Event Possible Tonight into Early Tuesday ….
…. Very Low Probability Winter Weather Event Possible Tuesday Night into Early Wednesday ….
…. There Are No Current NWS Watches/Advisories/Warnings For Any of Our Area ….
A shallow wedge of colder arctic air has moved into our area and will continue to settle
southward through the area through midweek.
A low pressure disturbance will approach the area and then trek overhead west-to-east.. on top
of the cold arctic surface air.. by later today and tonight through Tuesday. It will depart the area
by late Tuesday night.
As the disturbance approaches and moves slowly over our area, it will result in an “overrunning”
pattern with an extensive cloud layer moving in and over the top of the surface based cold air with
enough atmospheric lift to give us rain chances. Rain chances decrease rapidly Tuesday evening
into Tuesday night as the system departs the area.
The two possible nighttime freezing rain/drizzle episodes are addressed separately below…
Tonight/Tuesday morning:
Clouds and the chance of light overrunning rain will be ongoing at sunset today. Temperatures
should be in the upper 30s after sunset and then fall to right around freezing.. with ongoing rain chances..
from about 2am to 7am Tuesday. The rainfall probabilities continue to look to be about 40% to 50%
during this period. The real question is whether temperatures will fall to below freezing across the area
which will obviously cause more significant problems.
My forecast has a 50% probability of rain tonight with lows around 32F.. the NWS/Austin-San Antonio
is currently calling for a 40% probability with lows in the low to mid 30s. Most of the atmospheric
model computer guidance.. along with all local broadcast meteorologists and private forecast firms..
shows lows tomorrow morning right at 32 F or just slightly above.
I think that freezing precipitation should remain to the north and west of the local area.. but it is going
to be close (perhaps into Williamson County). Where it occurs, we could see hazardous road conditions.
Potential precipitation types: Mainly light rain.. possible freezing rain/freezing drizzle
My thought locally: A very low probability event with potential moderate to high impacts if it materializes
During the day Tuesday:
Light rain will continue through the day with the very low possibility of freezing rain/freezing drizzle
through about 9am.. after which temperatures should rise in to the mid and upper 30s. It is possible
that some sleet could be mixed with the rain by late afternoon as the atmospheric column above
us cools a bit.
I’m carrying a 50% probability of precipitation for Tuesday.. the NWS/Austin-San Antonio has
increased their probabilities to 60%. I’m going for highs in the mid and upper 30s while
everyone else has others are going for highs closer to 40 F.
Tuesday night/Wednesday morning:
The clouds and the chance overrunning light rain and perhaps mixed sleet will be continuing.. with
quickly falling precipitation probabilities.. into the evening and nighttime hours Tuesday night before
shutting off completely sometime around 9 pm to 12 midnight Tuesday night with the passage of the
upper level disturbance. Temperatures should cool to near freezing before the precipitation shuts off
so there is a fairly slim risk of some patchy freezing rain/freezing drizzle and/or sleet from about 7pm
through the end of the precipitation by 10pm to midnight. As this occurs, we could see the very patchy
development of hazardous road conditions.. again mainly north of the Austin area proper. No
precipitation is expected after midnight through the morning rush hour Wednesday.. so if we see any
problems first thing on Wednesday, it’ll be the result of precipitation that fell Tuesday evening into
nighttime hours.
My forecast is showing precipitation probabilities falling to 20% by mid evening Tuesday.. so does the
NWS/Austin-San Antonio and other forecast entities.
Potential precipitation types: Patchy decreasing light rain.. possibly freezing rain/freezing drizzle/sleet
My thought locally: A very low probability event with moderate to high impacts if it materializes
—
A couple of reminders…
— With what we’ve seen over the past two months, it is painfully apparent that even a sprinkle or
several hundredths of an inch of rain in a subfreezing surface environment, in the Austin metro area
and the IH35 corridor with our extensive above ground road network (flyovers, upper level of IH35),
can produce a hazardous mess in a hurry. You should be prepared in case the forecast or the on going
weather conditions change expectantly at the last minute. I will do the best I can to keep you informed
during this potential weather event.
— Winter weather episodes are difficult to predict at 30 degrees north latitude.. the latitude
of the Austin metro area and the IH35 corridor. Precipitation types.. i.e., sleet, snow, freezing rain..
are difficult to predict.
tk