Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX

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FXUS64 KEWX 150005
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
605 PM CST Wed Feb 14 2018

.UPDATE...
Please see the 00Z aviation forecast discussion below.

&&

.AVIATION...
Low clouds have managed to push east of all TAF sites this afternoon,
leaving VFR skies for now. The last few scans of the visible
satellite imagery does show the low cloud edge across the coastal
plains is beginning to move back to the west. We anticipate low
clouds to first move into the I-35 corridor around 01Z, with cigs either
low end MVFR or upper end IFR. Conditions will continue to
deteriorate this evening and overnight with LIFR expected for all TAF
sites along the I-35 corridor well into tomorrow morning. Slow
improvement is then expected, and will mention low end MVFR returning
between 18-19Z. At DRT, VFR will persist through most of this
evening. Low clouds will make it to DRT around 05Z and should
initially be in the IFR range. We will keep IFR intact overnight,
with conditions improving to MVFR around 18Z, with VFR after 20Z.

&&

.PREV DISCUSSION... /ISSUED 304 PM CST Wed Feb 14 2018/

SHORT TERM (Tonight through Thursday Night)...
As of 230PM, latest satellite trends actually show the sun peaking
out of the clouds for the first time in the last couple days across
the eastern half of the CWA. This welcome sunshine this afternoon
will only be brief unfortunately as low clouds, fog, and
drizzle/light rain develop again overnight tonight with the continued
southerly and southeasterly moisture flux into the region that we
have been seeing over the last several days.

While overnight lows will be allowed to warm into the upper 50s and
60s tonight and highs warm as high as the low 70s Thursday, this
should be the last day of this warming before our next cold front on
Friday. However, until then, the large high pressure system over the
Gulf will maintain our current southwesterly H5 wind direction and
subsequent southerly and southeasterly surface flow.

LONG TERM (Friday through Wednesday)...
There appears to be good agreement between the NAM/GFS/ECMWF and even
tail end of the TTU-WRF 12Z run on frontal timing Friday, reaching
the northern CWA border just before noon. Due to the moisture content
being confined to the lowest 50 mb, the prospect of much rain
associated with fropa will be minimal, and have left only slight
chance PoPs in the grids for Friday for much of the CWA and slightly
higher in the eastern zones as a bit deeper moisture is available.

The front is progged to stall just to the south of the CWA overnight
Friday night and with a 30 kt 850 mb LLJ setting up a textbook
overrunning pattern towards Saturday morning, expect more light rain
and drizzle to develop moving into the weekend. A broad disturbance
will shift across the northern half of the state Saturday as well,
resulting in decent PoPs and QPF north of our area, but we will
likely miss out on the higher rainfall totals being a bit displaced
too far south from the associated upper level support beyond our
low level isentropic forcing and stalled front to the south.

A series of subtle disturbances will keep slight chance PoPs or low
end chance PoPs in the forecast through the weekend, but the most
significant feature in the long term is likely going to be Monday as
a much deeper trough sets up over the Rockies and sends various
shortwave energy across the state from the southwest. The ECMWF/GFS
differ in specifics, but in general, the region will be influenced by
the broad right entrance region of an upper jet with a strong (~40-50
kt) LLJ. In addition, we may even have CAPE over 1000 j/kg during
the afternoon and evening hours Monday and again Tuesday afternoon.
Thus our best thunderstorm chances in a while look to be this time
frame, with the more ideal set up being Tuesday vs Monday currently.
More to come on this potential with later forecast packages.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              62  72  59  66  45 /  10  10  10  20  40
Austin Bergstrom Intl Airport  61  72  58  66  45 /  10  10  10  20  40
New Braunfels Muni Airport     60  73  58  70  47 /  10  10  10  20  40
Burnet Muni Airport            58  74  55  63  41 /  10  10  -   20  40
Del Rio Intl Airport           57  75  59  75  51 /  -   10  -   20  40
Georgetown Muni Airport        60  72  57  64  42 /  10  10  10  20  40
Hondo Muni Airport             59  73  59  73  50 /  10  10  -   20  40
San Marcos Muni Airport        60  72  58  69  46 /  10  10  10  20  40
La Grange - Fayette Regional   62  73  61  70  49 /  10  10  10  30  40
San Antonio Intl Airport       61  74  61  71  49 /  10  10  10  20  40
Stinson Muni Airport           62  74  60  72  50 /  10  10  10  20  40

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

Mesoscale/Aviation...24
Synoptic/Grids...LH



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