Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 02/24/20
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
938 PM CST Sun Feb 23 2020
.UPDATE...
Evening AMDAR Aircraft soundings out of SAT and AUS continue to show
a stout capping inversion around 800mb. This cap is the likely reason
that the evening high resolution model suite from SPC and multiple
runs of the HRRR have backed way off on precipitation along the front
late tonight and into tomorrow morning. Forecast soundings do show
that cap eroding gradually later tonight so have only pulled back
PoPs by 10 to 20 percent across parts of South Central Texas. In
addition, with the cap in place the likelihood of a thunderstorm
being produced continues to decrease, but can`t completely rule out
an isolated rumble of thunder, especially across areas east of I-35.
For the most part the forecast is on track though with the front
arriving overnight and most of the precipitation clearing the area
by sunrise. Skies will clear tomorrow with a northwest wind behind
the Pacific front, but temperatures won`t turn cooler until the next
front arrives Tuesday.
&&
.PREV DISCUSSION... /ISSUED 534 PM CST Sun Feb 23 2020/
AVIATION...
VFR conditions have broken out across all of South Central Texas this
afternoon. While DRT will be VFR through the period with the Pacific
front arriving by 06z, the I-35 terminals will see deteriorating
ceilings through the evening. The front is currently along a KPEQ
(Pecos) to KLBB (Lubbock) to KAMA (Amarillo) line and should be to
the I-35 corridor by 15z Monday morning. Ahead of the front MVFR
cigs will begin around 04z with IFR and possibly a few pockets of
LIFR between 08z and 12z. Light right is already showing up on area
radars across the Hill Country with showers expected overnight along
the I-35 corridor as the front approaches. An isolated thunderstorm
is possible, especially around AUS, but should the capping inversion
hold the majority of the precipitation should be rain showers so have
taken out the mention of thunder from the AUS TAF for now due to the
low confidence forecast. Winds along the I-35 corridor will go from
south easterly this evening to west and northwest by 14z Monday
morning.
PREV DISCUSSION... /ISSUED 228 PM CST Sun Feb 23 2020/
SHORT TERM (Tonight through Monday Night)...
Aircraft soundings this afternoon from AUS and SAT indicate a strong
capping inversion around 850mb. Abundant stratocu is ongoing beneath
the cap, with the exception of the southwest CWA. The cap will be
key to convective chances later tonight ahead of a Pacific cold
front. While the core of the main forcing aloft will pass north of
the region, the tail end of the forcing will assist with weakening
of the cap just ahead of the cold front across portions of the Hill
Country and I-35 corridor. 12Z GFS as well as latest runs of the
HRRR and NMM WRF soundings indicate a complete erosion of the cap
between 9PM and 3AM, allowing deeper convection to develop along and
ahead of the front across portions of the Hill Country and I-35
corridor, north of San Antonio. 12Z 3KM NAM, ARW WRF, and Texas Tech
WRF soundings do weaken the cap during the same time, but not as
fast, leading to mainly weak showers ahead of the front. The
majority of SREF members are indicating precip ahead of the front,
along and north of U.S. 90, so we have raised PoPs slightly for
showers in this forecast package. However, due to the uncertainty
with the cap and deeper convection being able to be realized we will
keep thunder chances at 20%.
Drier northwest flow and clearing skies will develop behind the cold
front Monday morning. The Pacific nature of the front and
downsloping flow will actually allow for warmer afternoon high
temperatures tomorrow compared to today. Many areas will reach the
mid 70s to near 80. Closer to the Rio Grande, elevated fire weather
conditions are forecast where low RH values in the teens combined
with occasional wind gusts near 20mph occur. Clear and cool
conditions are forecast Monday night.
LONG TERM (Tuesday through Sunday)...
An upper level low will move across the Central Plains Tuesday and
send a cold front through South Central Texas. Winds will become
northerly bringing cooler, drier air. Cold advection will continue
through Wednesday when the pressure gradient will intensify and winds
will be breezy. High temperatures Wednesday will be mostly in the
50s. Thursday morning low temperatures will drop below freezing
everywhere except the Rio Grande Plains and the Winter Garden region.
Lows in the Hill Country and Edwards Plateau will be in the middle
20s. The dry air and breezy winds will make for elevated to near
critical fire weather conditions Wednesday afternoon. Surface high
pressure will meander around the eastern half of Texas during the
second half of the week with no dominant flow regime. This will mean
dry weather and gradual warming through the end of the week.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 59 74 47 65 38 / 40 10 0 0 0
Austin Bergstrom Intl Airport 58 75 41 67 38 / 50 10 0 0 -
New Braunfels Muni Airport 58 76 45 69 38 / 50 10 0 0 -
Burnet Muni Airport 53 71 42 62 34 / 30 0 0 0 0
Del Rio Intl Airport 54 79 46 71 39 / 10 0 0 0 0
Georgetown Muni Airport 57 73 41 63 36 / 40 - 0 0 -
Hondo Muni Airport 56 78 43 72 38 / 30 0 0 0 0
San Marcos Muni Airport 59 75 43 68 38 / 50 10 0 0 -
La Grange - Fayette Regional 61 75 47 69 40 / 60 30 0 0 -
San Antonio Intl Airport 59 77 46 69 40 / 40 10 0 0 -
Stinson Muni Airport 60 78 47 72 41 / 40 10 0 0 -
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...Treadway
Long-Term...Hampshire