Daily Archives
April 18, 2015

TK’s Special Briefing…. (652pm CT-Sat/18Apr2015)

by troyk | on Apr 18, 2015 | Comments Off

Austin / Travis County and South Central Texas Weather Update #19
Prepared by UT University/Incident Meteorologist Troy Kimmel
652pm CT – Saturday / 18 April 2015

…. NWS/Storm Prediction Center Issues Mesoscale Discussion ….
MD 366 graphic
Link: http://www.spc.noaa.gov/products/md/md0366.html

MESOSCALE DISCUSSION 0366
NWS STORM PREDICTION CENTER NORMAN OK
0640 PM CDT SAT APR 18 2015

AREAS AFFECTED…PORTIONS OF TEXAS

CONCERNING…SEVERE THUNDERSTORM WATCH 72…76…

VALID 182340Z – 190115Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
72…76…CONTINUES.

SUMMARY…AN EVOLVING MESOSCALE CONVECTIVE SYSTEM WILL CONTINUE
SPREADING EWD ACROSS PORTIONS OF CNTRL TX…WITH DMGG WIND GUSTS AND
SVR HAIL EXPECTED.

DISCUSSION…CONVECTION HAS CONGEALED INTO A FORWARD-PROPAGATING MCS
ACROSS PARTS OF CNTRL TX AND WILL CONTINUE SPREADING EWD TOWARD THE
INTERSTATE 35 CORRIDOR INCLUDING THE DFW METROPLEX AND WACO. STEEP
TROPOSPHERIC LAPSE RATES SUPPORTING 1500-2000 J/KG OF MLCAPE COUPLED
WITH 30-45 KT OF DEEP SHEAR ORIENTED LARGELY ORTHOGONAL TO THE
LEADING CONVECTIVE LINE WILL CONTINUE TO SUPPORT SVR WIND/HAIL. THE
LARGE HAIL POTENTIAL MAY BE SOMEWHAT GREATER WITH TRAILING SUPERCELL
STRUCTURES ON THE SRN FLANK OF THE EVOLVING COLD POOL AND FARTHER S
WITH MORE DISCRETE CONVECTION ACROSS PARTS OF THE EDWARDS PLATEAU
AND TX HILL COUNTRY. IN THE WAKE OF CONVECTIVELY STABILIZED AIR…
PROSPECTS FOR ADDITIONAL SFC-BASED CONVECTIVE DEVELOPMENT MAY
BE RELATIVELY LOW OWING TO INCREASED MLCINH — NOCTURNALLY ENHANCED.

Continuing to monitor… tk

TK’s Special Briefing…. (458pm CT-Sat/18Apr2015)

by troyk | on Apr 18, 2015 | Comments Off

Austin / Travis County and South Central Texas Weather Update #18
Prepared by UT University/Incident Meteorologist Troy Kimmel
458pm CT – Saturday / 18 April 2015

…. NWS/Austin-San Antonio Has in Association with the NWS/Storm
Prediction Center Locally Extended the Severe Thunderstorm Watch
for the Texas Hill Country Into IH35 Corridor Counties ….

…. A Severe Thunderstorm Watch Is Now In Effect Until 9pm for
Williamson.. Travis and Hays Counties… along with all of the Texas
Hill Country …
http://www.spc.noaa.gov/products/watch/ww0072_overview_big_wou.gif

The latest high resolution computer data suggests that rain showers
and thunderstorms..potentially severe with large 1″ or greater in diameter
hail and/or straight line thunderstorm winds of 58 mph or higher along with
the smaller risk a isolated tornadoes.. along with frequent deadly cloud to
ground lightning
will likely occur across the IH35 corridor counties in the
600pm to 12 midnight time frame tonight.

Monitoring.. tk

TK’s Special Briefing.. (225pm CT – Sat/18Apr2015)

by troyk | on Apr 18, 2015 | Comments Off

Austin / Travis County and South Central Texas Weather Update #17
Prepared by UT University/Incident Meteorologist Troy Kimmel
225pm CT – Saturday / 18 April 2015

…. “Enhanced” Risk of Severe Thunderstorms for Texas Hill Country….
….”Slight” Risk of Severe Thunderstorms IH35 Corridor and Eastward ….

As anticipated, clouds have broken  with surface heating acting to quickly
destabilize the atmosphere over the central and western parts of our area.
This is happening as the next upper level low pressure disturbance.. rotating
in a counterclockwise direction around the upper low over Colorado.. heads
eastward out of west Texas. As this occurs.. atmospheric lift and instability
will cause the development of rain showers and strong thunderstorms to our
distant west over the next few hours with severe weather a possibility..

The NWS/Storm Prediction Center has issued a SEVERE THUNDERSTORM
WATCH valid until 9pm tonight for the Texas Hill Country west of the IH35
corridor counties. The IH35 corridor counties.. Williamson.. Travis and Hays
are NOT in this watch.

WW0072 SAW
Continuing to monitor.. tk

TK’s Special Briefing… (1135am CT-Sat/18Apr2015)

by troyk | on Apr 18, 2015 | Comments Off

Austin / Travis County and South Central Texas Weather Update #16
Prepared by UT University/Incident Meteorologist Troy Kimmel
1135am CT – Saturday / 18 April 2015

…. Risk of Severe Thunderstorms Increased to “Enhanced”
Western Areas Including all of the Texas Hill Country….
….”Slight” Risk of Severe Thunderstorms IH35 Corridor and Eastward ….

An update in the outlook risk as prepared by meteorologists at the NWS/Storm
Prediction Center…


Other points in my earlier update still hold.

Point to make.. isolated tornadoes possible later this afternoon into
tonight.. especially in the “enhanced” risk area.

Continuing to monitor.. tk

TK’s Special Briefing…. (845am CT-Sat/18Apr2015)

by troyk | on Apr 18, 2015 | Comments Off

Austin / Travis County and South Central Texas Weather Update #15
Prepared by UT University/Incident Meteorologist Troy Kimmel
845am CT – Saturday / 18 April 2015

…. “Slight” Risk of Severe Thunderstorms Late This Afternoon into Tonight ….

Outlooks prepared by meteorologists at the NWS/Storm Prediction Center
continue to indicate the possibility of severe thunderstorms areawide later today
and tonight with a “SLIGHT” risk posted for our IH35 corridor counties of
Williamson.. Travis and Hays…

The latest short range high resolution computer models (HRRR and Texas Tech
WRF) suggests that we’ll see initial thunderstorm development, in response to next
strong upper level disturbance and associated surface trough/weak front, during the
afternoon into evening hours. While the Texas Tech models are more bullish and suggest
some pre-trough/pre-frontal scattered strong thunderstorms developing in areas immediately
to our west and southwest as early as 2pm, the main push is in the 3 to 4 pm hour this
afternoon in  a north south line from Wichita Falls  southward to Abilene and Del Rio
with the line of thunderstorms forecast to progress eastward to the Austin metro area
and the IH35 corridor by mid to late evening. Both models show all precipitation and
any threat of severe weather to the east of the IH35 corridor by 11pm to 12 midnight
tonight.

As we go into our Saturday morning, our atmosphere has become more stable
as a result of being “worked over” by the thunderstorms late yesterday afternoon
and nighttime hours. How efficiently we’re able to destabilize our environment today
into tonight in advance of the next strong upper air low pressure disturbance is going
to be an important key as it regards the extent of (severe) thunderstorm development
later today into tonight. If we can’t destabilize the atmosphere efficiently today, this
event will not be as significant. If we are able to create some breaks in the overcast
and get a bit more significant surface heating, the severe weather risk will increase.

Current NWS/Weather Prediction Center rainfall forecast guidance confirms the
fairly progressive movement of this system through the area with most areas expected
to receive 1/2 to 3/4 inch of rain or less with this passing system later today into
tonight. As a result, other than very localized low water crossing flooding as well as
some brief urban flooding effects, I do not expect flooding to be a big issue.

Remember.. with the risk of severe thunderstorms comes the threat of large hail,
up to an inch in diameter or larger, along with straight line thunderstorm winds
gusts to 58 mph or higher and even isolated tornadoes. Frequent deadly
cloud-to-ground lightning will occur around any thunderstorms as well.

Let’s remain weather aware today and listen for the latest information from the
National Weather Service..

I will continue to monitor… tk