045
FXUS64 KEWX 241118
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
618 AM CDT Fri May 24 2024

...New AVIATION...

.SHORT TERM...
(Today through Saturday)
Issued at 219 AM CDT Fri May 24 2024

Nocturnal stratus continues to increase in coverage across the area
overnight. Breezy southeasterly flow also continues with
temperatures in the upper 70s to lower 80s. With the cloud cover and
wind conditions, lows tonight will not drop much more than current
values. 850 temps are slated to warm today much more than yesterday
as some weak southwest flow develops in the low-levels. This will
allow highs today to warm into the middle 90s in the northeast to
the 103-106 degree range out west. Dewpoints will range in the lower
to middle 70s for most of the area with lower dewpoints in the Rio
Grande and Edwards Plateau as the dryline moves into this region.
Where dewpoints remain elevated, afternoon heat index values will
range in the 105-110 range and a Heat Advisory is in effect for the
central portions of the area between 1 pm and 7 pm.

There is a chance of an isolated thunderstorm in the northern CWA
late this afternoon and evening as activity moves east off the
dryline. Much will be dependent on the strength of the CAP and
whether or not we can break it. High-res model guidance is in decent
agreement with about a half of the available models showing some
convection near the area. Will introduce a 20 PoP late this
afternoon and evening for areas north of a Fredericksburg to Austin
to Giddings line. If any activity does develop, the atmosphere will
easily support severe convection with large hail and damaging winds
being the main threats. Significant hail would also be possible
given the high CAPE values expected.

Low temperatures tonight will be warm once again with lows in the
middle to upper 70s once again. High temps will warm again
especially in the west as 850 temps increase further. The main
question tomorrow will be how much dewpoints can mix out. The NBM
keeps dewpoints relatively high over the region but some high res
models show some mixing. Regardless, another Heat Advisory will
almost certainly be needed for portions of the area tomorrow, but
some adjustments the area vs today`s advisory will likely be needed
and therefore will handle the Heat Advisories through the weekend
one day at a time.

&&

.LONG TERM...
(Saturday night through Thursday)
Issued at 219 AM CDT Fri May 24 2024

A more stable evening has been in the model consensus for Saturday
night, and the same can be said for late Sunday. Time-height sections
depict a gradual day-to-day decrease in low level moisture over the
weekend with better mixing of dry west winds into the mixing layer
and no surface focusing mechanisms to corral what low level moisture
still exists. Overnight cooling will again be limited which will
punish those spending the holiday weekend in the great outdoors.
Sunday and Monday are looking to become the hottest of the days in
regards to both ambient temperatures and heat index values. The low
to mid level thermal ridge advances farthest east on Sunday, so
there`s a chance for DRT to set the all-time record for May on Sunday
or Monday. Highest heat index values for the central and eastern
counties may come Sunday and the values will potentially warrant an
excessive heat warning for parts of the area.

The fairly tight mid level zonal pattern over TX relaxes a bit Sunday
night as the Central Plains upper troughing pattern pulls away to the
NE. This leaves a less stable zonal flow pattern over TX, allowing
for possible mid level shortwaves to capitalize on what little Gulf
moisture is available. So while the low level thermal ridge is in
place over South TX, the ingredients for instability begin to come
back together for Monday afternoon. Adding to the destabilization is
a weak front moving through North Central TX. It`s not certain what
the triggering mechanism is most dominant, but most deterministic
model runs depict a return of afternoon storms with the extra hot
temperatures likely to help some reach severe levels. Location is not
well agreed upon, so a general slight chance is placed over most
areas, which favors the GFS in location but not the amount of PoP.
The forecast trend collective of MOS guidance does show the 00Z GFS
as an outlier, but hopefully that trend will continue in later runs,
giving the area some more much needed rain. Nevertheless, will
continue running with near record highs assuming not enough areas
will be impacted by storm outflows.

Slightly better confidence goes into the Tuesday forecast as most
models assume the convective outflow influenced push of the front
modifies the air enough to weaken the thermal ridge and sent the
hotter air back westward. The GFS/ECM seem to 56think there will be
a round or two of more formidable shortwaves moving through low
latitudes which might suggest some of the better chances for rain
seen in several days, at least for the parched southern parts of the
forecast area. If nothing else, chances appear low that the heatwave
of this weekend will get an extension.

&&

.AVIATION...
(12Z TAFS)
Issued at 616 AM CDT Fri May 24 2024

MVFR stratus is in place at the I35 sites and inching closer to DRT
at the present time. VFR will return by 17-18z for all sites. There
is a low chance of a thunderstorm for AUS late in the afternoon or
evening. Will leave the forecast dry for now as confidence is only
around 20 percent. Another round of MVFR ceilings can be expected
tonight.

&&

.CLIMATE...
Issued at 219 AM CDT Fri May 24 2024

         FRI        SAT        SUN       MON
        05/24      05/25      05/26     05/27
------------------------------------------------
AUS    99/1955   100/2011    97/2018  100/2011
ATT   104/1925   100/2011    99/2018  100/2011
SAT   101/1989*  103/1989   100/1989  100/2011
DRT   109/2000   104/2011   106/2018  106/2018

* TIED RECORD WITH MOST RECENT OCCURRENCE SHOWN

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              96  75  97  77 /  20  20   0   0
Austin Bergstrom Intl Airport  96  74  97  76 /  20  20   0   0
New Braunfels Muni Airport     98  75  98  77 /  10  10   0   0
Burnet Muni Airport            93  73  94  75 /  20  10   0  10
Del Rio Intl Airport          107  77 108  82 /   0   0   0   0
Georgetown Muni Airport        94  73  95  76 /  20  20   0   0
Hondo Muni Airport            102  75 104  75 /   0   0   0  10
San Marcos Muni Airport        97  74  97  74 /  10  10   0   0
La Grange - Fayette Regional   94  77  95  77 /   0  20   0   0
San Antonio Intl Airport       98  76  99  76 /   0  10   0   0
Stinson Muni Airport          100  77 100  77 /   0  10   0   0

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 1 PM this afternoon to 7 PM CDT this evening for
Atascosa-Bastrop-Bexar-Caldwell-Comal-Dimmit-Frio-Gonzales-
Guadalupe-Hays-Karnes-Medina-Travis-Wilson-Zavala.

&&

$$

Short-Term...29
Long-Term...18
Aviation...29