Special Briefings

TK’s Special Briefings…

by troyk | on Feb 12, 2014 | Comments Off

This is where I will issued special/unscheduled updates during periods of inclement/severe weather.. tk

TK’s Special Briefing….

by troyk | on Feb 11, 2014 | Comments Off

Austin / Travis County and South Central Texas Weather Update #5
Prepared by Incident Meteorologist Troy Kimmel (www.troykimmelweather.com)
420pm CT – Tuesday / 11 February 2014

…. Precipitation Currently Tapering Off West to East Across the IH35 Corridor ….

…. NWS/Winter Weather Advisory continues for Travis (Metro Austin).. Williamson and
Hays County and all counties to the west until 6pm this evening
….
The NWS Office says that, as of this moment, they will allow the advisory expire at 6pm.

LCRA Hydromet gauge network (including current temperatures) – a good tool to use to monitor
real time temperatures:

http://hydromet.lcra.org/full.aspx

At 4pm.. the temp at Austin/City (Camp Mabry) is holding at 35 F.. ABIA has dropped to 33 F.
Lago Vista, Georgetown and Austin Executive Airport in Pflugerville are all at 32 F. San Marcos
Airport is 34 F.

As precipitation ends along the IH35 corridor by 6pm, temperatures are close to or even a degree
or two below the freezing mark. As a result, as this winter weather event wraps up, we need to
closely monitor roads and, particularly, elevated roadways, bridges and flyovers over western
parts of Williamson.. Travis and Hays Counties and adjacent hill country counties to the west
even after the precipitation ends with the possibility of  some icy patches developing into the
nighttime and overnight hours.

Overnight lows.. following decreasing clouds after midnight.. will likely fall into the upper 20s to
near 30 degrees areawide.

tk

TK’s Special Briefing….

by troyk | on Feb 11, 2014 | Comments Off

Austin / Travis County and South Central Texas Weather Update #3
Prepared by Incident Meteorologist Troy Kimmel (www.troykimmelweather.com)
717am CT – Tuesday / 11 February 2014

…. Threat of Icing Limited to Areas Outside of Immediate Urban Areas ….

…. NWS/Winter Weather Advisory continues for Travis (Metro Austin) and all surrounding
counties to the west until 6pm this evening
….

LCRA Hydromet gauge network (including current temperatures) – a good tool to use this morning:
http://hydromet.lcra.org/full.aspx

At 7am.. the temp at Austin/City (Camp Mabry) has risen to 35 F.. ABIA holds at 34 F. I do not think
these temperatures will fall much more even as precipitation becomes more widespread.

On the other hand, in outlying west/northwest areas of Travis as well as Williamson and Hays Counties..
where temperatures are currently right at 32 F or  just below..  we could see some icing on exposed objects,
including bridges, overpasses and flyovers, as the precipitation becomes more widespread in the next hour or
two.

Based on the latest trends areawide, we should temperatures climb to above freezing by 10am
to 11am this morning.

tk

TK’s Special Briefing….

by troyk | on Feb 11, 2014 | Comments Off

Austin / Travis County and South Central Texas Weather Update #2
Prepared by Incident Meteorologist Troy Kimmel (www.troykimmelweather.com)
525am CT – Tuesday / 11 February 2014

…. Not Much Change in My Forecast Thought ….
…. Low Probability Winter Weather Event Possible This Morning into Midday ….
…. Extremely Low Probability Winter Weather Event Possible Tonight ….

…. NWS/Winter Weather Advisory continues for Travis (Metro Austin).. Williamson.. and
Hays Counties and hill country counties to the west until 6pm this evening
….

LCRA Hydromet gauge network (including current temperatures) – a good tool to use this morning:
http://hydromet.lcra.org/full.aspx

A shallow wedge of colder arctic air continues to settle southward into Texas.

A low pressure disturbance is approaching the area and then trek overhead west-to-east.. on top
of the cold arctic surface air.. by later today into tonight.  It will depart the area by 9pm to 12
midnight tonight.

As the disturbance moves slowly over our area, it is resulting 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 good rain chances today. Rain chances decrease rapidly by this evening and ending by
9pm to midnight tonight as the system departs the area.

The two possible nighttime freezing rain/drizzle episodes are addressed separately below…

This morning into midday:
Clouds and, although a little slow to start, chance of light overrunning rain will be increasing over the
next few hours and continuing through the daytime hours before rapidly decreasing by the evening
rush hour as the upper air disturbance departs to the east northeast.
According to the LCRA Hydromet and NWS/FAA surface observation sites, temperatures at 5am, as
predicted, are right at or just a degree or so above above the freezing mark. in Travis County.
As precipitation becomes more widespread over the next few hours, temperatures are expected to be
very close or just below the freezing mark. While overall precipitation amounts will remain below
1/10th of an inch, any precipitation that does fall in this environment could cause icing especially to
elevated bridges, overpasses and flyovers as well as exposed objects in areas where the temperatures
are at or below freezing.
Temperatures should climb above freezing my late morning across the area.
My forecast has a 60% probability of rain today with highs around 36F.. the NWS/Austin-San Antonio
is currently calling for a 70% probability with highs in the mid 30s. Most of the atmospheric
model computer guidance.. along with all local broadcast meteorologists and private forecast firms..
shows highs between 35 and 39 F today with all showing at least a 50% chance of precipitation.
I continue to think that the greatest threat of freezing precipitation over the next six hours or so be from
the western and northern parts of the Austin metro area north and westward over Williamson and Burnet
counties as well as to the southwest over northwestern Hays County.
Location will be extremely critical as far as any potential problems over the next few hours…
Potential precipitation types: Mainly light rain.. possible freezing rain/freezing drizzle/sleet
My thought locally: A low probability event with potential moderate to high impacts if it materializes

Tonight night/Wednesday morning:
The clouds and the chance overrunning light precipitation will end quickly with the passage of the upper
air low pressure disturbance by 5pm this evening. Precipitation, as I see it now, will over in the area by
6 pm. Clouds will break overnight with a partly cloudy sky expected after midnight.
Temperatures should cool to near freezing by 9pm this evening, but with precipitation tapering off
before then, the only issue may be patchy pooling of water from precipitation today that might freeze
overnight.
My forecast is showing precipitation probabilities falling through 20% by 5pm this evening and then dropping
completely by 6pm.. so does the NWS/Austin-San Antonio and other forecast entities.
Potential precipitation types: No additional precipitation after 6pm
My thought locally: An extremely low probability event with low impacts (freezing of pooled water) with
freezing temps in the overnight hours

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

TK’s Special Briefing….

by troyk | on Feb 10, 2014 | Comments Off

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