240
FXUS64 KEWX 220833
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
333 AM CDT Wed May 22 2024

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(Today through Thursday)
Issued at 155 AM CDT Wed May 22 2024

* Level 2 to 3 out of 5 risk for isolated to scattered severe storms
  this evening across portions of the northern Hill Country
  and central Texas.
* Dangerous heat indices this afternoon - those spending extended
  time outdoors and not acclimated to the early season heat could be
  susceptible to heat related illness if not taking proper heat
  precautions.

Nocturnal stratus has developed across south-central Texas and will
scatter out midday. In addition, hazy conditions, associated with
seasonal smoke from agricultural burning to the south, persists
across our region and will continue east of the dryline through the
short-term.

The upper level ridge axis has shifted into the southeast U.S. and
western Gulf of Mexico. This will open the door for convective
initiation along a weak cold front over north-central Texas and
along the dryline just to the west in the higher terrain of Mexico
this afternoon. There is a low chance (20%) that an isolated storm
or two could cross the Rio Grande into Val Verde, Kinney, or
Maverick Counties between 4PM and 7PM today. However, the bigger
chance (30-40%) of storms will be across the northern forecast area
this evening. CAMs indicate the aforementioned storms that develop
along the front to the north moving east-southeast into Llano and
Burnet Counties 7PM to 10PM, and potential as far south as the
Austin metro area after 10PM. There is a Level 2 to 3 out of 5 risk
for severe storms across these areas this evening, with large to
very large hail and damaging wind gusts the primary threats. An
isolated tornado can`t be ruled out, mainly in the Level 3 risk area
across Llano and Burnet Counties.
this afternoon
Farther south, convective inhibition will be increasing out of the
Coastal Plains and into portions of the I-35 corridor late evening,
and we anticipate a weakening trend of the storms at that time,
eventually dissipating. We do not currently expect the storms to
reach the San Antonio metro area or Coastal Plains.

On Thursday the dryline makes a slightly farther east progression.
With the surface cold front washed out to the north, forcing will be
weaker and convective coverage less. There is a very low (10-20%)
chance of an isolated storm or two late Thursday afternoon across
Llano and Burnet Counties.

Otherwise, continued well above normal temperatures today and
Thursday. Heat indices today to the south and southwest of the San
Antonio metro area are forecast to reach advisory criteria, and a
Heat Advisory will be issued. The elevated dew points east of the
dryline, influences from evapotranspiration where better spring
rainfall has occurred, and early nature of the summer heat will
result in an increased risk for heat impacts. Those spending
extended time outdoors and not acclimated to the early season heat
could be susceptible to heat related illness if not taking proper
heat precautions.

&&

.LONG TERM...
(Thursday night through Tuesday)
Issued at 155 AM CDT Wed May 22 2024

* Dangerous heat indices and hot temperatures will continue to
  worsen into the Memorial Day Weekend - those spending extended time
  outdoors and not acclimated to the early season heat could be
  susceptible to heat related illness if not taking proper heat
  precautions.

A compact upper low moving into the Northern Plains states helps to
shape the Central and Southern Plains surface pattern with a more
stable flat zonal pattern over TX by 00Z Friday. This has us pulling
back on the already low chances for convection for the period
Thursday night through Friday night. There is still a deterministic
signal for some isolated Central TX convection to crop up again for
the PM hours Friday, but this pattern looks closer to the one we saw
Tuesday evening: 1 severe storm and well to the north of our CWA. By
comparison to the SPC Day2 Outlook, the small area of general
thunder over our northern counties for the Day3 Outlook shows an
appropriate level of concern for what was previously another
possible round of rain, still much needed over the Hill Country. Fast
forward to the other side of the heat wave and a weakness in the
flat ridging over TX and a possible weak cold front could bring our
next possible chance for isolated to scattered storms. Cold fronts in
late May over South Central Texas are somewhat a rarity, so the
confidence is going to remain low that we`ll see anything but another
escalation of our drought conditions in what looks to be another
projected drier than normal summer.

Temperatures and heat indices are thus the primary hazard concern for
the Memorial Day weekend. Heat products will likely be needed for
each day through Monday, and the potential will exist for some areas
to need an Excessive Heat Warning Friday through Monday. this
afternoon
this afternoon
Thanks to a generous rainfall pattern over Central TX, the Austin
metro area will possibly stay out of the triple digits during this
period, but a drier heat on Sunday could get the first triple digit
day for that area.

The San Antonio and New Braunfels areas have already flirted with
triple digit heat and the drier soil and vegetation there could bring
that into the picture as early as Friday.

In general, the eastern half of the forecast area will be reaching
the advisory (or worse) conditions based on the Heat Index. Farther
west, a more dry heat is projected. While RH values overachieved to
hold down the max over much of the western counties Tuesday, the
progressively hot and dry days under this zonal pattern will bring
the thermal ridge a little farther east each day and mixing out the
morning clouds with more efficiency as we approach the weekend.
The metro cities could see near record temperatures over the weekend,
but with the drier heat over the western counties the chance for high
temperature records for DRT will be much higher. On May 10th, the
Monthly max for May at DRT was already tied, so we should expect to
see a new monthly record to be set in this pattern.

Finally on Memorial Day, a cold front is expected to push into North
and Central TX. This could pull back on some of the heating
potential around AUS, but compressional heating could bring the
climate sites near Highway 90 close the values seen Saturday and
Sunday. Cooler maxes are projected for Tuesday and next Wednesday,
and hopefully some rain and moisture will thwart the return of more
heat waves until we get deeper into the summer season.

&&

.AVIATION...
(06Z TAFS)
Issued at 1235 AM CDT Wed May 22 2024

Stratus is quickly developing across the Coastal Plains, I-35
corridor, and Hill Country, and is forecast to expand west into the
Rio Grande early Wednesday morning. Mainly MVFR ceilings are
expected, although some isolated pockets of IFR ceilings can`t be
ruled out over the Hill Country. In addition, visibility will be
reduced to MVFR in some spots overnight and Wednesday morning in a
mixture of BR and HZ. Ceilings are forecast to scatter out 15Z-17Z,
with VFR conditions through the afternoon, but 6SM visibility in HZ
for some locations. Finally, isolated TSRA are forecast to develop
in Mexico after 21Z, and there is a low probability (20%) of storms
moving across the Rio Grande 21Z-03Z. The better chances for storms
will develop after 21Z across north-central and may enter northern
areas of south-central Texas after 00Z Thu. There is a 30% chance of
TSRAs reaching AUS Wednesday evening.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              94  76  94  76 /  10  30  10   0
Austin Bergstrom Intl Airport  94  75  93  76 /  10  30  10   0
New Braunfels Muni Airport     97  76  97  76 /  10  10  10   0
Burnet Muni Airport            91  73  91  74 /  30  40  20   0
Del Rio Intl Airport          104  81 106  80 /  10  20   0   0
Georgetown Muni Airport        93  73  92  75 /  20  40  10   0
Hondo Muni Airport             99  75 100  74 /  10  10   0   0
San Marcos Muni Airport        95  75  96  75 /  10  20  10   0
La Grange - Fayette Regional   92  77  92  77 /  10  10   0   0
San Antonio Intl Airport       96  77  97  76 /  10  10  10   0
Stinson Muni Airport           97  77  98  77 /  10  10   0   0

&&

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

$$

Short-Term...76
Long-Term...18
Aviation...76