Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
FXUS64 KEWX 211754
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1254 PM CDT Fri Apr 21 2017
VFR conditions with southerly winds gusting to 20-25 knots are
expected this afternoon ahead of a cold front expected by sunrise
between 9-12Z at all sites. Light showers will be possible with the
front, but significant capping aloft should prevent thunderstorms
from developing. Ceilings will lower to MVFR by 7Z at the I-35 sites
with IFR ceilings possible for a few hours with the frontal passage.
Ceilings will be slower to lower at DRT, so currently only have MVFR
ceilings at 11Z with the frontal passage there. Although ceilings
should improve to MVFR at the I-35 sites by mid morning, they should
stick around through at least the early afternoon due to weak
isentropic ascent allowing moisture to overrun the front. Northerly
winds behind the front will gust to 20-25 knots tomorrow afternoon.
.PREV DISCUSSION... /ISSUED 541 AM CDT Fri Apr 21 2017/
MVFR ceilings remain in place for the I-35 TAF sites with IFR being
reported at KDRT. Think the probabilities for IFR for the I-35 sites
are less than what they were during the previous TAF issuance and
have removed it from the 12z package. VFR will return to all sites
around the noon hour with southerly winds around 12-18 knots
prevailing this afternoon. Another round of MVFR ceilings and perhaps
visibility is expected tonight as a cold front approaches the area.
There will be a chance of a shower or perhaps a thunderstorm with the
frontal passage, but the probabilities were too low to mention in
the TAFs at this time.
PREV DISCUSSION... /ISSUED 355 AM CDT Fri Apr 21 2017/
SHORT TERM (Today through Saturday)...
Surface pressure gradient to tighten for today with some daytime and
early wind gusts to around 25 mph in advance of the next storm system
and associated cold front. Models are pretty good agreement on
timing with a consensus fropa expect by 09Z through Austin metro and
around 15z over the final 2-3 counties of the Rio Grande Plains. The
overnight showers and a few thunderstorms remains in poor confidence
on location, with low 20-30 PoPs over most of the area. A small area
of predawn 40-50 PoPs are saved for parts of Central TX overnight,
but expect the surface convergence pattern to be weakened by daybreak
with weak dynamics aloft at best.
With the winds shifted well ahead of the late morning timing for
accelerated daytime heating and a lingering patch of cloud cover
trailing the front, will lean on the slightly cooler side of
guidances for max temps.
LONG TERM (Saturday Night through Thursday)...
Low level moisture should be scoured away by late Saturday afternoon
with well mixed low level winds continuing through much of the night.
The morning lows over the next couple days will be the coolest seen
in a couple weeks but do not look to threaten any records. Midday
winds could combine with falling humidities over areas west of Hwy
281 to bring a potential elevated fire day, but given above normal
fuel dryness tracked by the Texas Forest Service and good recent
rainfall amounts received over much of the area, the breezy and dry
conditions should not be a significant concern. By 21z Sunday winds
should begin to flatten off as the driest humidities develop. Temps
under decoupled winds Sunday night could fall several degrees below
normals with the dry air and especially in protected valleys. Dry air
leads to a high diurnal temperature range on Monday with over 30
degree spread expected in the Hill Country. Another mostly clear
night is expected Monday night but increasing sly winds could
possibly bring a chance of fog for a few spots at daybreak Tuesday.
Moisture continues to stream in through Wednesday with some scattered
low clouds expected Wednesday morning and more widespread for
Thursday morning. Broad zonal flow transitioning to shallow troughing
over the Central Plains in the middle of next week could lead to a
few showers, but the amplification of the trough late in the week
could suggest better chances for next Friday into next weekend.
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 86 61 71 51 74 / - 30 20 - 0
Austin Bergstrom Intl Airport 86 60 72 50 74 / - 20 20 - 0
New Braunfels Muni Airport 87 62 74 49 74 / - 20 20 - 0
Burnet Muni Airport 84 56 69 47 71 / - 30 10 - 0
Del Rio Intl Airport 92 64 78 54 77 / 0 - 10 - 0
Georgetown Muni Airport 85 57 69 49 72 / - 30 10 - 0
Hondo Muni Airport 90 64 77 50 76 / 0 10 20 - 0
San Marcos Muni Airport 86 61 72 49 74 / - 20 20 - 0
La Grange - Fayette Regional 86 64 76 51 73 / - 30 20 - 0
San Antonio Intl Airport 87 64 74 52 74 / 0 10 20 - 0
Stinson Muni Airport 89 65 76 53 74 / 0 10 20 - 0
Public Service/Data Collection...YB