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

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000
FXUS64 KEWX 190440
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1040 PM CST Mon Feb 18 2019

.AVIATION...
As isentropic lift strengthens, CIGs will gradually lower to MVFR
overnight while areas of -RADZ develop. The strongest lift will be
Tuesday morning into early afternoon when IFR/LIFR conditions are
expected. ISOLD TSRA are possible with the best chances at KAUS,
however still too low to mention even there. The lift wanes with the
areas of -RADZ moving off to the northeast, although CIGs remain IFR
in the afternoon. Except out west, little or no lift keeps KDRT MVFR.
Weak isentropic lift redevelops -RADZ Tuesday evening. Then, the lift
ends and subsidence ensues with skies becoming VFR Tuesday night,
however, there is a possibility of BR. Northerly winds at 7 to 14 KTs
will prevail through Tuesday night, except southeast at KDRT through
Tuesday.

&&

.PREV DISCUSSION... /ISSUED 243 PM CST Mon Feb 18 2019/

SHORT TERM (Tonight through Tuesday Night)...
High cirrus will continue to stream into the region from the
southwest this afternoon and tonight. Overnight, a developing
coastal low off the Mid Texas Coast will re-enforce northeast flow
over the eastern half of the CWA and a relatively shallow, cool
airmass. At the same time an upper level trough digging through AZ/NM
and northern Mexico will induce a return of moist, south to southeast
low level flow over the shallow airmass. Descent isentropic ascent
and low condensation pressure deficits are indicated on the 290-300K
surfaces, and should see light rain developing during the morning
hours Tuesday across the eastern 2/3rds of the CWA. A weak mid level
impulse and steeper mid level lapse rates could contribute to an
isolated thunderstorm or two across northeast areas of the CWA. The
low level flow over the shallow airmass will turn more southwest in
the afternoon with rain chances decreasing across western and central
areas. Clouds and rain will contribute to cold temperatures
tomorrow, with highs along and north of I-10 locked into the mid
40s, low to mid 50s across southern and western areas.

LONG TERM (Wednesday through Monday)...
The upper level trough will lift northeast into the Central Plains
Tuesday night. A low level trough will move through the CWA early
Wednesday morning with drier conditions as downglide develops. There
is some uncertainty on the cloud cover Wednesday, as southwest upper
level flow has the potential to carry cirrus plume into the region.
Low levels moisten back up on Thursday, with a weaker and slightly
further east isentropic set-up leading to a chance of light rain
across eastern areas.

The next upper level trough will dig through the Southwest U.S. and
northwest Mexico Friday. Lead shortwave in the southwesterly
subtropical flow aloft is indicated by models to move across the
area Friday and Friday night. Increasing low level warm air advection
and forcing from the shortwave could contribute to scattered showers
across the CWA, and potentially a few isolated thunderstorms Friday
and Friday night.

The base of the trough ejects northeast through West Texas and the
Panhandle Saturday and into the Southern Plains Saturday Night. This
sends a Pacific cold front through the area Saturday, with drier
westerly flow, clearing, and warmer temps in its wake. There is the
potential for elevated to critical fire weather conditions across the
northwest CWA Saturday afternoon, where RH values are indicated to
dip into the teens and westerly winds gust to 20-30 mph. We will add
mention of this into the Hazardous Weather Outlook.

The progressive pattern will continue with the potential for another
coastal trough developing Sunday night into Monday and isentropic
pattern developing across the eastern CWA leading to another chance
for rain on Monday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              42  45  39  65  42 /  30  90  30   0  10
Austin Bergstrom Intl Airport  42  45  39  65  41 /  30  90  30   0  10
New Braunfels Muni Airport     43  47  39  66  42 /  30  80  30   0  10
Burnet Muni Airport            38  43  36  62  40 /  20  90  20   0  -
Del Rio Intl Airport           47  57  41  67  44 /   0  -    0   0   0
Georgetown Muni Airport        40  43  37  64  40 /  30  90  30   0  10
Hondo Muni Airport             45  51  39  69  43 /  20  50  20   0   0
San Marcos Muni Airport        42  46  39  66  42 /  30  90  30   0  20
La Grange - Fayette Regional   45  47  42  64  43 /  30  90  30  10  20
San Antonio Intl Airport       44  49  41  68  44 /  30  70  20   0  10
Stinson Muni Airport           45  50  42  68  44 /  30  60  20   0  10

&&

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

$$

Aviation...04
Short-Term/Long-Term...05


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