Special Briefings

Special Briefings….

by troyk | on May 30, 2017 | Comments Off

This is where, in periods of severe and inclement weather, I place special updates.

At this time, there is not a severe weather threat for south central Texas.

by troyk | on May 28, 2017 | Comments Off

Austin / Travis County and South Central Texas Weather Update #3
Prepared by UT University/Incident Meteorologist Troy Kimmel
310pm CT – Sunday / 28 May 2017

.. Authority NWS/Storm Prediction Center ..

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 293
NWS Storm Prediction Center Norman OK
310 PM CDT Sun May 28 2017

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Central and Southeast Texas

* Effective this Sunday afternoon and evening from 310 PM until
  1000 PM CDT.

* Primary threats include...
  Scattered large hail and isolated very large hail events to 2
    inches in diameter possible
  Scattered damaging wind gusts to 70 mph possible

SUMMARY...Thunderstorms are expected to rapidly develop over the
watch area this afternoon, spreading slowly eastward this evening. 
Damaging winds and hail will be possible in the strongest cells.

The severe thunderstorm watch area is approximately along and 60
statute miles either side of a line from 35 miles south southeast of
Del Rio TX to 65 miles north of Huntsville TX. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU3).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for severe thunderstorms in and close to the watch area.
Persons in these areas should be on the lookout for threatening
weather conditions and listen for later statements and possible
warnings. Severe thunderstorms can and occasionally do produce
tornadoes.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 292...

AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 550. Mean storm motion vector
25025.

...Hart

WATCH COUNTY NOTIFICATION FOR WATCH 293
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
310 PM CDT SUN MAY 28 2017

TXC013-019-021-029-031-053-055-091-123-127-137-149-163-171-177-
187-209-255-259-265-271-285-287-299-323-325-385-453-463-465-491-
493-507-290300-
/O.NEW.KEWX.SV.A.0293.170528T2010Z-170529T0300Z/

THE NATIONAL WEATHER SERVICE HAS ISSUED SEVERE THUNDERSTORM WATCH
293 IN EFFECT UNTIL 10 PM CDT THIS EVENING FOR THE FOLLOWING
AREAS

IN TEXAS THIS WATCH INCLUDES 33 COUNTIES

IN SOUTH CENTRAL TEXAS

ATASCOSA              BANDERA               BASTROP              
BEXAR                 BLANCO                BURNET               
CALDWELL              COMAL                 DEWITT               
DIMMIT                EDWARDS               FAYETTE              
FRIO                  GILLESPIE             GONZALES             
GUADALUPE             HAYS                  KARNES               
KENDALL               KERR                  KINNEY               
LAVACA                LEE                   LLANO                
MAVERICK              MEDINA                REAL                 
TRAVIS                UVALDE                VAL VERDE            
WILLIAMSON            WILSON                ZAVALA               

THIS INCLUDES THE CITIES OF AUSTIN, BANDERA, BASTROP, BLANCO, 
BOERNE, BRACKETVILLE, BURNET, CARRIZO SPRINGS, CRYSTAL CITY, 
CUERO, DEL RIO, EAGLE PASS, FLORESVILLE, FREDERICKSBURG, 
GEORGETOWN, GIDDINGS, GONZALES, HALLETSVILLE, HONDO, KARNES CITY,
KERRVILLE, LA GRANGE, LEAKEY, LLANO, LOCKHART, NEW BRAUNFELS, 
PEARSALL, PLEASANTON, ROCKSPRINGS, SAN ANTONIO, SAN MARCOS, 
SEGUIN, AND UVALDE.

$$

—–

Austin / Travis County and South Central Texas Weather Update #2
Prepared by UT University/Incident Meteorologist Troy Kimmel
205pm CT – Sunday / 28 May 2017

.. Authority NWS/Storm Prediction Center ..

Mesoscale Discussion 0901
   NWS Storm Prediction Center Norman OK
   0134 PM CDT Sun May 28 2017

   Areas affected...Central Texas

   Concerning...Severe potential...Watch likely 

   Valid 281834Z - 281930Z

   Probability of Watch Issuance...80 percent

   SUMMARY...A severe weather watch seems probable at some point late
   this afternoon and evening, perhaps as early as 20-21Z.

   DISCUSSION...Objective analysis indicates that insolation within a
   boundary layer characterized by high moisture content (lower/mid 70s
   F surface dew points) is contributing to strong/extreme CAPE on the
   order of 4000+ J/kg across much of the region, including the
   Interstate 35 corridor between San Antonio and Waco.  Mid-level
   inhibition beneath warm elevated mixed layer air does still appear
   considerable, particularly given weak, or at least unclear,
   mid/upper forcing for ascent.  An area of enhanced ascent
   contributing to deepening mid-level based convection near the
   Interstate 20 corridor, west of the Dallas/Fort Worth metroplex, may
   remain displaced to the north of an area of sustained enhanced
   low-level convergence near the Waco area.  This is near the
   intersection of a surface front that extends southwestward into the
   Rio Grande Valley, to the west of Del Rio, and the western flank of
   composite outflow from extensive overnight convection, now advancing
   into the north central Gulf Coast.

   However, the latest Rapid Refresh suggests that additional surface
   heating, coupled with subtle mid-level height falls on the southern
   fringe of the westerlies, may be sufficient to support the
   initiation of thunderstorms as early as 20-21Z.  Once this does
   occur, intensification likely will be very rapid, and deep layer
   shear appears sufficient for the evolution of supercell structures
   with large hail  and perhaps an isolated tornado, in addition to
   strong downbursts accompanied by potentially damaging surface gusts.

   ..Kerr/Hart.. 05/28/2017

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...HGX...FWD...EWX...SJT...

   LAT...LON   30359938 31149852 31689787 31949702 31599588 30929570
               30419690 29639779 29409830 29329912 30359938

by troyk | on May 28, 2017 | Comments Off

Austin / Travis County and South Central Texas Weather Statement #1
Prepared by UT University/Incident Meteorologist Troy Kimmel
1245pm CT – Sunday / 28 May 2017

.. A Weak Cold Front Progressing Southward Across Texas ..
.. A Few Strong Thunderstorms Likely this Afternoon into Tonight ..
.. Rain and Thunderstorm Chances, Along with Lightning Risk, Continues into the New Week ..

http://www.spc.noaa.gov/public/fema/images/fema06_swody1.png

Hazards Expected and Time Periods (My Confidence) …

…. Larger hail threat – between 2pm and 10pm today and tonight (medium confidence)
…. Strong straight line thunderstorm wind threat –
between 2pm and 10pm today (low to medium confidence)
…. Tornado threat – between 2pm and 10pm today (low confidence)
…. Lightning threat – after 2pm today and continuing tonight into Memorial Day (very high confidence)
…. Flood threat – after 5pm through the nighttime hours tonight – mainly urban/small stream (low to medium confidence)

Current NWS Watches / Advisories / Warnings ….
There are no current NWS watches, advisories and/or warnings in effect for our IH35 corridor counties..
Given the “slight” risk outlook area currently over our area, if conditions materialize as
expected, I would anticipate a watch from the NWS/Storm Prediction Center being eventually
issued for parts of our south central Texas area sometime in the 2pm to 10pm time period today.

Weather Discussion ….
At midday on this Sunday.. a cold front is pressing southeastward and is located along a line
from west of Texarkana to just southeast of the DFW metroplex to near Lampasas to Llano
and then to south of Junction.
Ahead of the front, plenty of gulf moisture is combining with strong atmospheric instability
to set the stage for scattered rain showers and thunderstorms as the frontal lift increases with
the surface front and an associated upper level low pressure disturbance moving through the area.
The cold front should pass the local area by late this afternoon into early evening tonight with the
threat of stronger thunderstorms decreasing thereafter.
Clouds and rain shower and thunderstorm activity will continue in the post frontal environment
tonight through tomorrow (Memorial Day) as the front weakens and starts to shift back northward
as a warm front. Bottom line, lightning will continue to be a daily hazard for much of the coming week
as a typical late spring weather pattern prevails as weak upper level disturbances move west-to-east
overhead.

Aviation Weather Information for the
Austin Bergstrom International Airport (KAUS) Aerodrome and Associated Hubs ….
Given the weak cold frontal boundary expected in our area later this afternoon into tonight, scattered
rain showers and thunderstorms, with an associated lightning risk, are expected over or
in the vicinity of the KAUS aerodrome this afternoon into tonight with stronger
thunderstorms possible.
The front is expected to pass southeastward to the Texas coastal plains by late tonight into
tomorrow; even so, post frontal rain showers and thunderstorms are expected to continue
locally, with an associated lightning risk, through tomorrow (Memorial Day) through much
of the upcoming week.

Likelihood of Hub Diversions..
DAL/DFW Aerodromes and ZFW Airspace..
Scattered rain showers and thunderstorms (50% rain) today decreasing to widely scattered
(20% rain) tonight. Some diversions and ZFW reroutes are possible mainly this afternoon into
the mid evening hours tonight.

HOU/IAH Aerodromes and ZHU Airspace..
Scattered rain showers and thunderstorms (30% rain) today increasing to scattered to
numerous (60%-80% rain) late tonight into the early morning hours tomorrow. Although
there will be lull in air traffic by the time the rain shower and thunderstorm chances peak
after midnight tonight, it is likely we’ll see some diversions and ZHU reroutes especially in
the morning hours tomorrow.


Current KAUS Terminal Aerodrome Forecast (TAF) – Issued 281735z ..

FTUS44 KEWX 281735
TAFAUS
TAF
KAUS 281735Z 2818/2924 18007KT P6SM BKN035 BKN250
     FM282000 13008KT P6SM VCTS BKN035CB BKN100
     FM282300 03010KT 4SM -TSRA BR OVC025CB
      TEMPO 2900/2902 VRB15G25KT 2SM TSRA OVC015CB
     FM290400 02010KT 5SM -SHRA BR OVC010
     FM291000 35008KT P6SM OVC008
     FM291700 07007KT P6SM BKN015 BKN120=

Current FAA National Airspace Status

CALL TO ACTION:

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

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

GENERAL WEATHER INFORMATION LINKS:

NWS/Austin-San Antonio Current Statements/Advisory/Watches/Warnings
NWS/Austin-San Antonio Web Page
NWS/Storm Prediction Center (Outlooks)
NWS/Storm Prediction Center (Mesoscale Discussions – Severe Weather & Snow)
NWS/Storm Prediction Center (Severe Thunderstorm/Tornado Watches)
NWS/Weather Prediction Center (Mesoscale Discussions – Heavy Rain & Flooding)
NWS/National Hurricane Center

tk

Troy’s Special Briefings….

by troyk | on May 11, 2017 | Comments Off

Austin / Travis County and South Central Texas Weather Update #2
Prepared by UT University/Incident Meteorologist Troy Kimmel
205pm CT – Sunday / 28 May 2017

.. Authority NWS/Storm Prediction Center ..

Mesoscale Discussion 0901
   NWS Storm Prediction Center Norman OK
   0134 PM CDT Sun May 28 2017

   Areas affected...Central Texas

   Concerning...Severe potential...Watch likely 

   Valid 281834Z - 281930Z

   Probability of Watch Issuance...80 percent

   SUMMARY...A severe weather watch seems probable at some point late
   this afternoon and evening, perhaps as early as 20-21Z.

   DISCUSSION...Objective analysis indicates that insolation within a
   boundary layer characterized by high moisture content (lower/mid 70s
   F surface dew points) is contributing to strong/extreme CAPE on the
   order of 4000+ J/kg across much of the region, including the
   Interstate 35 corridor between San Antonio and Waco.  Mid-level
   inhibition beneath warm elevated mixed layer air does still appear
   considerable, particularly given weak, or at least unclear,
   mid/upper forcing for ascent.  An area of enhanced ascent
   contributing to deepening mid-level based convection near the
   Interstate 20 corridor, west of the Dallas/Fort Worth metroplex, may
   remain displaced to the north of an area of sustained enhanced
   low-level convergence near the Waco area.  This is near the
   intersection of a surface front that extends southwestward into the
   Rio Grande Valley, to the west of Del Rio, and the western flank of
   composite outflow from extensive overnight convection, now advancing
   into the north central Gulf Coast.

   However, the latest Rapid Refresh suggests that additional surface
   heating, coupled with subtle mid-level height falls on the southern
   fringe of the westerlies, may be sufficient to support the
   initiation of thunderstorms as early as 20-21Z.  Once this does
   occur, intensification likely will be very rapid, and deep layer
   shear appears sufficient for the evolution of supercell structures
   with large hail  and perhaps an isolated tornado, in addition to
   strong downbursts accompanied by potentially damaging surface gusts.

   ..Kerr/Hart.. 05/28/2017

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...HGX...FWD...EWX...SJT...

   LAT...LON   30359938 31149852 31689787 31949702 31599588 30929570
               30419690 29639779 29409830 29329912 30359938


--

by troyk | on May 04, 2017 | Comments Off

Forecast not available today…

Please consult the NWS Austin Area Weather Forecast here.