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000
FXUS64 KEWX 190258 AAA
AFDEWX

Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
958 PM CDT Thu Apr 18 2024

...New UPDATE...

.UPDATE...
Issued at 947 PM CDT Thu Apr 18 2024

We canceled the Severe Thunderstorm Watch for Burnet and Williamson
counties. The Severe Thunderstorm Watch continues for the rest of the
counties included in the first issuance. We may cancel other
counties earlier based on latest radar trend. As of 950 PM, there is
one storm just to the north of our CWA in Mason county ahead of the
cold front. We continue to monitor things closely.

&&

.SHORT TERM...
(Tonight through Friday night)
Issued at 207 PM CDT Thu Apr 18 2024

Clouds continue to scatter this afternoon ahead of a surface front
to the north and a dryline to the west. This dryline will move into
western Val Verde County this afternoon with the surface front
reaching the northernmost portion of the CWA later tonight where it
overtakes the dryline. Late this afternoon and evening, isolated
thunderstorms may develop along both of these boundaries. Models
indicate potential development over the higher terrain of Mexico
late this afternoon and evening which could move into areas along
the Rio Grande, although the better potential for storms in South
Central Texas will be along the cold front. Storms will likely first
initiate north of the area this afternoon in Central Texas. As the
front continues south, thunderstorms may move into or initiate over
the Hill Country and southern Edwards Plateau this evening.

Steep mid-level lapse rates, upwards of 3000 J/kg of CAPE, and 30-40
knots of bulk shear will lead to a threat for severe storms this
evening. Storm coverage should remain isolated to scattered with
large to very large hail and damaging wind gusts the main threats.
An isolated tornado also cannot be ruled out over the Hill Country.
Storms may continue to move south into the Rio Grande Plains or
portions of the I-35 corridor as the front sags across the CWA
around midnight, although the majority of guidance does fizzle out
any activity before reaching these areas.

Expect a lull in activity overnight into Friday morning. The exact
position of the front will play a big role in temperatures and
precipitation chances tomorrow. Latest guidance indicates the front
will be draped somewhere over the middle or southern half of the CWA
during the afternoon. Went a bit cooler with temperatures tomorrow
given the forecast position of this feature. The afternoon should be
relatively dry with precipitation chances returning Friday night
into Saturday, mainly for the western and northern portion of the
area. Isolated to scattered storms may develop near this stalled
front with the best chances in the west.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 207 PM CDT Thu Apr 18 2024

The long term period will start out active, with a heavy rain event
looking increasingly likely Saturday night, followed by several days
of temperatures below normal, with Sunday being the coolest day of
all.

We start off with the meat and potatoes of the forecast: Saturday`s
heavy rain threat. The latest WPC Excessive Rainfall Outlook for
Saturday night puts areas from the Edwards Plateau, through the Hill
Country, the I-35 Corridor from Bexar County northward, along with
the Coastal Plains mainly north of I-10 in a level 2 of 4 (slight)
risk for flash flooding. Model guidance remains in fairly good
agreement with the NAM12 being a bit of an outlier. For now, we will
not put too much stock in the drier solution depicted by the NAM,
but it is worth noting that the NAM does well with cold frontal
passages. The NAM has the front moving through a bit faster than
global models, hence undercutting storms as they develop along and
out ahead of the boundary and push east. A shortwave in northern
Mexico will team up with the cold front to initiate numerous showers
and storms, and with surface dewpoints in the 60s and 70s ahead of
the front, we won`t have much of any trouble developing widespread
showers and storms over the region Saturday evening. Rainfall
amounts in excess of 1" are at 60-70% odds per the latest 13Z NBM
over the majority of the slight risk area. Once the front shifts
south of the CWA, we should see rain and storms come to an end
before lunchtime Sunday.

Beyond Sunday, the upper level pattern flattens out considerably,
with zonal flow expected through the bulk of the upcoming week.
Temperatures should slowly but surely moderate back into the 80s by
Tuesday afternoon. There is an outside shot at some showers or
storms Wednesday, but the threat remains quite low at this time.

&&

.AVIATION...
(00Z TAFS)
Issued at 558 PM CDT Thu Apr 18 2024

All area terminals are forecast to remain VFR through at least 06Z
Friday. The exception to this is KAUS as some showers and storms roll
over the site between the 03Z-06Z time frame and cigs could lower to
MVFR for that period. However, MVFR/IFR cigs are forecast for all of
the sites along the I-35 corridor overnight into late Friday morning
or as late as 19Z/20Z time frame. Northeast to east winds at 5 to 10
knots are forecast for the I-35 airports through the period while
KDRT remains from the southeast and east around 5 to 10 knots with
higher gusts mainly on Friday afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              63  78  66  78 /  10  10  20  70
Austin Bergstrom Intl Airport  63  79  65  78 /  10  10  20  60
New Braunfels Muni Airport     64  79  66  80 /  10  10  10  60
Burnet Muni Airport            61  74  64  72 /  30   0  30  80
Del Rio Intl Airport           72  87  69  83 /  20  10  50  70
Georgetown Muni Airport        61  76  65  75 /  20   0  30  70
Hondo Muni Airport             66  84  65  81 /  20  10  20  70
San Marcos Muni Airport        63  79  65  79 /  10  10  10  60
La Grange - Fayette Regional   66  80  67  80 /  10  10  10  60
San Antonio Intl Airport       66  80  67  80 /  10  10  20  70
Stinson Muni Airport           68  82  68  82 /  10  10  10  60

&&

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

$$

Short-Term...17
Long-Term...Platt
Aviation...17