Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Austin/San Antonio Texas
609 am CDT Tuesday Oct 13 2015
Aviation discussion...for 12z taf period...
beginning to see ceilings clear out at kaus with nearly 3kft ceilings
still present over ksat/kssf. This should clear out in the first
hour of the taf as the dry front is beginning to push southward
through the San Antonio area. Should be VFR ceilings for the rest of
Winds will be breezy and out of the north in the morning hours
before subsiding at or above 21z this afternoon. Should be the only
impact over the next 24 hours.
Previous discussion... /issued 408 am CDT Tuesday Oct 13 2015/
Short term (today through wednesday)...
The main highlight during the short term period will be this late
morning to early afternoon as near-critical and elevated fire
weather danger will likely occur. Minimum relative humidity values
will fall into the teen to 20 percentiles with winds near 10-15 miles per hour
at times. This could exacerbate any wildfire and hinder typical fire
control measures. These hazards have been mentioned in the hazardous
weather outlook as well as a Special Weather Statement.
A frontal boundary is currently moving through the region with the
north wind shift noted across the southern Edwards Plateau to near
Camp Mabry as of 3am. Winds are sustained near 10 knots with some gusts
to near 15 knots behind the boundary where a tighter pressure gradient
exists. The evolution of the pressure gradient and the subsequent
dry air behind the front will be critical for near red flag
conditions to occur 10am-2pm across the northern Hill Country to
portions of the northern I-35 corridor. Please see fire weather
discussion below for more details.
As the boundary moves south through the early to late morning hours
it will interact with some deeper moisture /pwats of 1.5"/ that
could help aid a few showers and thunderstorms towards the far
southeast prairie counties. Kvct modeled sounding suggest some surface
cin but 1500-2000 j/kg of ml/mu cape that would support some
shower/tstorm activity. By early afternoon...the boundary and any
showers that did develop will push south...leaving US with plenty of
sun and another above normal temperature day.
Wednesday will be another above normal temperature day as there is
no cooler air behind this boundary with sunny skies. Yet...with the
drier air in place...the humidity will be noticeably lower and
slightly more comfortable. Still...readings will remain about 10f
degrees above normal for maximum highs to near normal for lows. Elevated
fire weather concerns will remain on Wednesday.
Long term (thursday through next monday)...
No major highlights for the long term outside of the next
possible stronger frontal passage Tuesday-Thursday of next week.
Multi-suite global models indicate Texas will be under a middle level
ridge that will continue to promote above normal temperatures
through the end of the week. Temperatures will slowly decrease going
into the weekend as a backdoor front from the NE slides into the
eastern half of the region thanks to a stronger surface high
pressure system over the Ohio River valley. This will allow for
temperatures to fall back slightly towards normal but still may be 1-
By early next week...the middle-level ridge will break down as deeper
longwave troughing occurs across the western Continental U.S. Into the desert SW.
Global models are at odds on how to phase the southern and north
streams but are both hinting that a front of higher caliber could
approrach the region sometime next week. The ec is pointing towards
a wetter solution for much of region in the Wednesday/Thursday time frame and
the GFS is somewhat on board with this possibility. Will need to
monitor next week for frontal strength and rain/thunderstorm
Fire weather...near critical and elevated fire weather criteria
will likely be met late morning into the early afternoon across
northern Hill Country and northern I-35 corridor locations as low
relative humidity values coincide with 10-15 knots winds/gusts. The
main time window for critical relative humidity and wind thresholds will be near
the 10am-2pm time-frame as relative humidity drops to near 20
percent while 10 knots winds and 15 knots gusts occur. Surface and 20 feet
transport winds are expected to subside after 2pm while relative
humidity values continue to drop into the teens and 20s across
much of the region through the middle to late afternoon. We will
continue to monitor for reg flag conditions but it appears the
surface and 20-feet winds will be too low at this time.
Elevated fire weather conditions will likely occur again on Wednesday
but surface and 20-feet winds will be much lower than today.
Most counties are under burn bans and the fuel dryness map indicates
fuels continue to be ranked in the dry category across the impacted
area. Fire growth...should one occur...will hastened by the
conditions in place today and tomorrow.
Preliminary point temps/pops...
Austin Camp Mabry 93 61 94 61 92 / 0 0 0 0 0
Austin Bergstrom international Airport 91 55 93 56 91 / 0 0 0 0 0
New Braunfels Muni Airport 94 58 94 58 92 / 0 0 0 0 0
Burnet Muni Airport 90 59 92 61 91 / 0 0 0 0 0
del Rio International Airport 92 63 92 65 89 / 0 0 0 0 0
Georgetown Muni Airport 92 58 93 58 92 / 0 0 0 0 0
Hondo Muni Airport 95 57 93 58 91 / 0 0 0 0 0
San Marcos Muni Airport 93 57 94 57 91 / 0 0 0 0 0
La Grange - Fayette regional 93 57 93 59 91 / - 0 0 0 0
San Antonio International Airport 93 61 93 61 90 / 0 0 0 0 0
Stinson Muni Airport 95 62 94 61 92 / - 0 0 0 0