505
FXUS64 KEWX 121740
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1240 PM CDT Sun May 12 2024

...New AVIATION...

.UPDATE...
Issued at 739 AM CDT Sun May 12 2024

Adjusted PoPs through today into this evening according to latest
radar trends and forecast guidance. Greatest rainfall and strongest
convection that is currently situated along our northern boundary
with FWD/SJT CWAs should mainly pivot north and northeastward away
from our area. However, we`ll need to watch for any straggler cells
still across our northern counties. This afternoon, attention then
may turn more towards areas east of I-35 into the coastal plains
where new convection could try to develop with daytime heating. A
few hi-res models, like the RRFS, pick up on this potential. If
storms do fire within this area, this could be the best opportunity
for a strong to severe cell within our CWA. San Antonio and west
looks to be mainly dry on this Mother`s Day with temperatures into
the upper 80s and 90s.

&&

.SHORT TERM...
(Today through Monday)
Issued at 207 AM CDT Sun May 12 2024

The latest GOES 16 IR imagery shows a 500mb closed low over
southwestern Colorado. At the surface, easterly flow has resumed
after a cooler and comfortable day by early to mid-May standards.
Moisture should start to work back in, but dewpoints should start to
rise once again overnight and get back into the 70s by midday
Sunday. Mother`s Day will be a muggy day, but on the cooler side
over the eastern half of the region as cloud cover will be hard to
break. Further west, highs should climb back into the mid to upper
80s and lower 90s once again along the Rio Grande as low clouds
break towards the afternoon hours.

The short term forecast is a messy one, as precip chances look
difficult to predict through Sunday night. Confidence remains low on
timing of any thunderstorms and where they ultimately develop. Light
showers and occasional drizzle should continue through the morning
hours as isentropic ascent is realized with east to southeasterly
flow on the 300k surface. By the afternoon, as instability
increases, some strong to severe storms will be possible. The latest
day 1 outlook from the Storm Prediction Center places the Hill
Country, I-35 Corridor, and Coastal Plains within a Level 1 of 5
Risk, while a small portion of the CWA from east of Austin to La
Grange and northward is in a Level 2 of 5 Risk. All modes of severe
weather are possible, but at this time, the greatest threat appears
to be large hail. Any discrete storm that can tap into rich boundary
layer moisture could also start rotating, with a tornado or two also
possible. Ultimately, the greater severe threat for Sunday lies just
to our east, but conditions should be monitored closely nonetheless.

Monday brings a greater threat for widespread strong to severe
storms as the associated 500mb trough starts to move eastward. On
it`s southern periphery, a potent shortwave will round its base and
move through south Central Texas. A cold front will approach from
the northwest and work through the entire CWA by sunset Monday. SPC
places the eastern Hill Country, I-35/I-37 Corridor, and Coastal
Plains within a Level 2 of 5 Risk on Monday. The primary concern
looks to be large to very large hail along with damaging winds, but
a tornado or two cannot be ruled out along the boundary early in the
afternoon. The RRFS, HRRR, FV3, and NSSL WRF are all on board with
afternoon convection. The real item up in the air is what happens
before the lunch hour. Some members of the HREF develop early
morning convection over the Hill Country and spread it eastward
while others show little to no activity at this time. For now, focus
will be on the afternoon storm chances as instability, shear, lift,
and lapse rates will be highest within this time frame, but morning
storm chances will have to be monitored as well.

&&

.LONG TERM...
(Monday night through Saturday)
Issued at 207 AM CDT Sun May 12 2024

A cold front will be moving out of the area with possibly some
showers or thunderstorms Monday night over the Coastal Plains before
pushing east overnight. Dry conditions are then expected for Tuesday
through Wednesday morning as upper ridging moves overhead. Above
normal temperatures are expected Tuesday afternoon from the mid 80s
in the northeastern portion of the area to the upper 90s and 100
degree mark in the west along the Rio Grande. A trough located just
off the southern coast of California on Tuesday will move east
towards the Plains Wednesday and Thursday. This will bring the next
chances for precipitation to the area late Wednesday afternoon
through Thursday night. There remains the potential for some severe
thunderstorms and heavy rainfall with this activity. The current
forecast places the heaviest rain potential over the northeastern
portion of the CWA which is also where WPC has placed a level 2 of 4
risk for excessive rainfall.

For now, the forecast remains on the dry side Friday through the
weekend although there is decent spread in model guidance after the
mid-week system. Some low precipitation chances may be introduced
for next weekend in the coming forecasts. A warming trend is
possible late week into next weekend.

&&

.AVIATION...
(18Z TAFS)
Issued at 1229 PM CDT Sun May 12 2024

The San Antonio terminals (KSAT and KSSF) and KDRT improves to VFR
levels later this afternoon into this evening. KAUS remains MVFR to
IFR through this afternoon into this evening. Shower activity may
still remain closer to the vicinity of KAUS, mainly east and
northeast, through this afternoon while the other sites should stay
rain free into this evening. MVFR to IFR ceilings return overnight
through Monday morning across the I-35 terminals (KAUS, KSAT, and
KSSF). Very low confidence on timing and placement but an isolated
thunderstorm may try to develop overnight into early Monday from
southwest to northeast across the CWA. Did not have enough of
confidence for impacts to put into the TAF package at this time. A
greater concern for scattered thunderstorms, which could become
strong to severe, develops into and through Monday afternoon across
and east of the I-35 corridor. Have inserted PROB30s at the 30 hr
sites (KAUS and KSAT) for this potential. Timing, location, and
flight impacts of these storms will be fine tuned through the next
several TAF cycles. Otherwise, sites should improve towards VFR
levels at all sites into MOnday afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              72  86  64  90 /  10  40  10   0
Austin Bergstrom Intl Airport  72  87  63  89 /  20  40  10   0
New Braunfels Muni Airport     73  88  64  92 /  20  40  10   0
Burnet Muni Airport            69  84  62  88 /  10  30  10   0
Del Rio Intl Airport           73 100  69 101 /  10  10   0   0
Georgetown Muni Airport        69  85  63  87 /  20  30  10   0
Hondo Muni Airport             73  93  63  94 /  20  30  10   0
San Marcos Muni Airport        72  87  62  90 /  10  40  10   0
La Grange - Fayette Regional   74  85  65  88 /  30  60  20   0
San Antonio Intl Airport       74  90  65  92 /  20  30  10   0
Stinson Muni Airport           74  90  66  93 /  20  40  10   0

&&

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

$$

Short-Term...Brady
Long-Term...27
Aviation...Brady