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

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FXUS64 KEWX 261751
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1151 AM CST Sun Jan 26 2020

.AVIATION /18Z TAFs/...
VFR/SKC is expected to prevail through 06Z for the South Central
Texas terminals with north to northwest winds 10 knots or less. Made
some dramatic changes to the extended TAFs for the San Antonio
terminals where drier near surface air is expected to affect fog
development Monday morning. Shallow fog is still possible for
SAT/SSF, but terminal impacts appear to be better handled with TEMPOs
closer to fog onset. Drier air does not appear to completely make it
to AUS and fog potential will be higher there with IFR to LIFR
visibilities during the morning push. DRT is expected to remain VFR
through the period. VFR expected for all terminals again after 16Z
Monday.

&&

.PREV DISCUSSION... /ISSUED 535 AM CST Sun Jan 26 2020/

AVIATION...
Visibilities are improving for all sites this morning as drier air
moves in from the northwest. Continued improvement through the
morning with VFR expected by 15Z. Fair conditions this afternoon
through the evening. Winds start shifting to become northeasterly by
the end of TAF period. Overnight, confidence is increasing that
conditions return to LIFR for I-35 sites as fog spreads up from the
southeast to I-35.

PREV DISCUSSION... /ISSUED 321 AM CST Sun Jan 26 2020/

SHORT TERM (Today through Monday)...
Widespread fog across South Central Texas with Dense Fog Advisory in
effect until 9AM. Dry air begins to filter in this morning and
clouds will clear from northwest to southeast behind a weak cold
front. Temperatures still above normal today with highs in the mid
70s with mostly clear skies. Overnight lows will be in the mid to
upper 40s with the drier air in place. Northwest winds switch back
to southeasterly by Monday morning and moisture recovers. Mondays
highs will again be in the 70s for most of the area with fair skies
and light winds.

LONG TERM (Monday Night through Saturday)...
An upper level shortwave trough will move quickly through South
Central Texas late Monday night through Tuesday morning. Dynamical
forcing appears good with this system, with time height progs showing
strong mid-level vertical ascent atop a relatively shallow stable
layer. We are anticipating a complex of elevated showers and embedded
thunderstorms to develop across the southwestern Edwards Plateau and
Rio Grande after midnight and move east into the I-35 corridor
shortly before sunrise on Tuesday morning. This is indicated by most
global models as well as the 3KM NAM12 and 3KM Texas Tech WRF that
now go out through this time frame. While instability parameters
aren`t great, the amount of forcing, combined with sufficient deep
layer shear, could result in a stronger storm or two capable of
producing small hail.

The system is forecast to quickly move east of the I-35 corridor by
midday Tuesday with drier air filtering into the area from west to
east behind a cold front. Windy conditions behind the front are
forecast to develop down the Rio Grande, and combined with the drier
air could result in a period of elevated fire weather conditions
Tuesday afternoon across this region.

Cooler and dry conditions are forecast for Wednesday. Another upper
level system is currently indicated by global models to dig further
south than the previous system. Wednesday night an upper level low is
indicated the be digging into northwest Mexico, west of the Big Bend.
There are some differences between the ECMWF and GFS on how and
where the energy ejects northeast into Texas and how it phases into
a digging northern stream trough Thursday and Friday. Therefore PoPs
are capped at less than 50% during this time. Next weekend appears
dry and warm.

Climate...
A freeze is not forecast through the remainder of January at San
Antonio, Austin Camp Mabry, or Del Rio. Assuming a freeze does not
occur through the end of the month this will be the first time since
1939 that San Antonio has not had a freeze in the month of January,
since 1950 at Del Rio, and since 2006 at Austin Camp Mabry.

Here are the years where it did not freeze in the month of January
for our climate sites:

San Antonio.........1921 / 1923 / 1932 / 1939
Austin Camp Mabry...1923 / 1986 / 1990 / 1998 / 2006
Austin Bergstrom....1945 / 1952 / 1983
Del Rio.............1939 / 1941 / 1950

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              75  50  72  53  68 /   0   0   0  30  60
Austin Bergstrom Intl Airport  75  43  73  51  70 /   0   0   0  30  60
New Braunfels Muni Airport     75  46  74  52  70 /   0   0   0  30  60
Burnet Muni Airport            71  45  71  51  65 /   0   0   0  30  40
Del Rio Intl Airport           79  48  79  51  70 /   0   0   0  20  -
Georgetown Muni Airport        74  44  71  52  67 /   0   0   0  30  60
Hondo Muni Airport             79  46  77  52  72 /   0   0   0  30  30
San Marcos Muni Airport        74  46  74  52  70 /   0   0   0  30  60
La Grange - Fayette Regional   75  47  73  55  70 /   0   0   0  20  60
San Antonio Intl Airport       76  49  74  54  70 /   0   0   0  30  50
Stinson Muni Airport           77  48  76  54  71 /   0   0   0  30  50

&&

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

$$

Short-Term/Aviation...Huffman
Long-Term...17
Decision Support...KCW



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