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

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FXUS64 KEWX 211753
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1253 PM CDT Thu Mar 21 2024

...New AVIATION...

.UPDATE...
Issued at 1043 AM CDT Thu Mar 21 2024

Severe Thunderstorm Watch #57 has been cancelled for DeWitt and
Lavaca counties. No other significant changes have been made to the
forecast at this time.

&&

.SHORT TERM...
(Today through Friday)
Issued at 151 AM CDT Thu Mar 21 2024

Key Messages

* Isolated strong to marginally severe storms with the main threats
  of hail and locally strong gusts possible near day-break over
  parts of the Coastal Plains

* Isolated to scattered strong to severe storms with the main
  threats of large hail and locally strong gusts possible late this
  afternoon into the evening

An abundance of cloud cover prevails overnight across South-Central
Texas and with that temperatures remain in the upper 50s to lower
60s. An upper level trough axis is located across AZ/NM and
continues to slowly move east. Ahead of this system we are seeing
some light returns on radar overnight but much of this is not likely
reaching the ground at this time. Latest high-res model guidance
shows better updrafts developing south of our area by daybreak with
this scattered activity moving into our Coastal Plains counties by 8-
9 am. Mid-level lapse rates may support some small hail threat, but
widespread severe weather associated with this activity is not
expected. Rain chances will continue mainly for areas along and east
of the 135/37 corridor through the early afternoon hours ahead of
the trough axis in a warm-air advection regime. For points to the
west, westerly winds will move into the area bringing warmer
conditions to the region. Highs today will range from the upper 60s
in the northeast CWA to the lower 80s in the west.

The attention will then turn to the west late this afternoon and
evening as the base of the upper trough axis moves into the area.
Latest high-res guidance shows some threat for scattered to perhaps
a line of thunderstorms developing in the northern Hill Country near
7 pm then moving east into the I35 corridor by 9pm and through the
CWA by midnight. However, it should be noted that a couple of
members do not show too much.

Mid-level lapse should be steep enough to support some risk for
severe hail but instability amounts are somewhat limited. The new
Day 1 outlook shows a marginal risk for the eastern Hill Country and
I35 corridor with a slight risk in the Coastal Plains. This shows a
trim in the slight risk areas out of Austin and San Antonio for the
Day 1 compared to yesterday`s Day 2 outlook and this is due to the
slightly lower values of MUCAPE along and west of the I35 corridor.
All convection should be east of the area after midnight with the
remainder of the short-term dry.

High temperatures on Friday will be quite warm in the west,
approaching 90 degrees near the Rio Grande with middle 70s likely in
the east. Breezy northerly winds could create some elevated fire
weather conditions in the west during the afternoon hours.

&&

.LONG TERM...
(Friday night through Wednesday)
Issued at 151 AM CDT Thu Mar 21 2024

The weekend will start off rather comfortable with a cool, crisp
start to Saturday morning. Afternoon highs will climb into the 70s
and lower 80s under partly cloudy skies as shortwave ridging in the
mid-levels takes over for the first half of the weekend. The quiet
weather won`t last long as southwesterly flow aloft returns as early
as Sunday morning as an approaching longwave trough over the western
CONUS results in increased midlevel moisture. Cloud cover will be a
bit more prevalent on Sunday afternoon as a result of the
approaching trough, however temperatures will remain on the mild
side, generally in the 70s and lower 80s. A shortwave will round the
base of the trough Sunday night, sending a cold front through our
neck of the woods early Monday morning. Showers and thunderstorms
look to be a good bet with this frontal boundary, but the severe
threat appears to be minimized at this time due to a lack of
instability. Nevertheless, with ample deep layer shear, a few
stronger storms will be possible as the frontal boundary slides
through the region. Much drier air will move in behind the front,
resulting in some elevated fire weather conditions over the Rio
Grande Plains and Southern Edwards Plateau on Monday afternoon.

Beyond Monday, the overall pattern looks to remain dry for South
Central Texas as zonal flow aloft takes hold through mid to late
week. Temperatures will steadily warm from the 70s for most on
Monday to the lower to middle 80s by Thursday afternoon for all
locations. Minimum relative humidities will remain less than 25%
west of the I-35 corridor Tuesday-Thursday, so some elevated fire
weather risk may present itself.

&&

.AVIATION...
(18Z TAFS)
Issued at 1238 PM CDT Thu Mar 21 2024

Low clouds are likely to remain in place for the I-35 corridor
through this evening and into Friday morning. The latest visible
satellite does show some clearing just west of SAT/SSF and have put
in a TEMPO group for some brief clouds lifting above IFR between
22-02Z. Otherwise, will keep cigs LIFR to IFR until roughly sunrise
Friday. We will keep a PROB30 group for TSRA at AUS this evening as
activity moves out of the Hill Country into the I-35 corridor. Will
continue to leave out the mention of TSRA at SAT and SSF due to
expected lower coverage of storms. Low clouds should decrease fairly
quickly tomorrow as dry air moves in with a northwest to northerly
wind shift. For DRT, we will keep the forecast VFR through the period
as some drier air will remain over this region. We may need to
monitor for some patchy fog around sunrise, but confidence in this is
too low to mention at the present time.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              68  55  78  55 /  70  50   0   0
Austin Bergstrom Intl Airport  67  55  77  52 /  70  50   0   0
New Braunfels Muni Airport     71  55  81  53 /  60  30   0   0
Burnet Muni Airport            68  53  76  51 /  60  60   0   0
Del Rio Intl Airport           83  55  90  56 /  20  10   0   0
Georgetown Muni Airport        66  55  74  52 /  70  60   0   0
Hondo Muni Airport             78  53  85  51 /  30  20   0   0
San Marcos Muni Airport        69  55  79  52 /  70  40   0   0
La Grange - Fayette Regional   68  58  76  54 /  70  40   0   0
San Antonio Intl Airport       72  56  82  55 /  40  20   0   0
Stinson Muni Airport           74  57  84  55 /  40  10   0   0

&&

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

$$

Short-Term...Platt
Long-Term...Brady
Aviation...Platt


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