Area Forecast Discussion Issued by NWS Austin/San Antonio, TX
000
FXUS64 KEWX 151407
AFDEWX
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
907 AM CDT Fri Mar 15 2024
...New UPDATE...
.UPDATE...
Issued at 857 AM CDT Fri Mar 15 2024
This morning`s convection has mostly moved out of our CWA. There is
one supercell thunderstorm north of Edwards/Kerr Counties that is
moving toward the east-northeast and could move into Llano County
later this morning, but is at least a couple of hours away. Keep an
eye on it if you`re in that area. We have adjusted our POPs for this
afternoon, they looked a bit out of whack with something of a donut
hole over the northeast. I suppose that could happen, but I don`t
have the confidence to be that specific. Otherwise, still expecting
convection this afternoon with severe storms likely. SPC has upgraded
the risk to Enhanced for most of most of the area from San Antonio to
the Rio Grande. Large hail still the number one threat.
&&
.UPDATE...
Issued at 648 AM CDT Fri Mar 15 2024
Strong to severe thunderstorms have developed along the portion of
the cold front over the Edwards Plateau. It is possible that the
front sags into Edwards and Val Verde counties during the next few
hours allowing strong to severe storms to develop over those
counties. As a result, have issued Severe Thunderstorm Watch 52 for
those counties through Noon CDT.
&&
.SHORT TERM...
(Today through Saturday)
Issued at 211 AM CDT Fri Mar 15 2024
Key Messages...
* Isolated to scattered strong to severe storms mainly this
afternoon through Saturday
* Primary threat is large, possibly very large (>2 inch) hail
* Secondary threat is damaging wind gusts.
* Locally heavy rainfall is also possible this afternoon through
Saturday and may cause isolated flash flooding.
A mid level shortwave moving over our area and a cold front
approaching from the north will generate isolated showers and
thunderstorms early this morning. Small hail and locally heavy
downpours are the main threats.
There will be a lull in activity mid morning into early afternoon.
The cold front drifts to the south across our area today into this
evening. Convergence along the front and strong differential heating
across the frontal zone allow for the development of showers and
thunderstorms mid to late afternoon. The front stalls over southern
parts of our area or just south of our area and along with the low
level jet showers and thunderstorms continue tonight. On Saturday,
the front will drift back northwest, possibly as far as the I-35
corridor and along with the approach of a mid level shortwave, the
showers and thunderstorms continue. Hi-Res models show varying
locations on the showers and thunderstorms and have higher POPs most
areas.
CAPEs around 2,500 J/Kg and bulk shear of 40 to 50 KTs indicates a
potential of isolated to scattered strong to severe storms. SPC has
a 1 to 2 out of 5 risk for severe storms today and 1 out of 5 risk
on Saturday. The main threat is large hail, possibly very large hail
with stones greater than 2 inches. Cannot rule out some damaging
wind gusts in the warm sector south of the front. In addition, PWs
rise to 150 to 200 percent of normal and with the possibility of
training of cells, there is a potential of heavy rains and flash
flooding. WPC has a 1 to 2 out of 4 risk for excessive rainfall for
today and Saturday.
&&
.LONG TERM...
(Saturday night through Thursday)
Issued at 211 AM CDT Fri Mar 15 2024
A closed low will still be near the Four Corners Saturday evening
into Sunday, gradually weakening. It will remain in place to some
degree through the middle of next week before eventually opening up
and traversing across the southern Plains in the Thursday-Friday
time frame. This will keep chances for wet weather in our forecast
off and on next week. The most impactful weather in the long term is
likely to come Saturday night into Sunday morning, but the
Thursday/Friday time period may be worth watching as well.
Saturday evening, the cold front is expected to be draped near or
just south of our southern tier of counties, with the tail end of
most CAMS indicating one area of storms exiting to our east.
Although things can change before then, there`s decent agreement in
a good chance for another round to develop out west near the Rio
Grande overnight and move ENE through the region. Some elevated
instability will remain and there`s a low chance that a storm or two
could produce large hail or strong winds. However, there may be a
higher concern for localized flooding Saturday night through Sunday
morning, especially if any areas see significant rainfall amounts
between now and then. A Marginal (level 1 of 5) risk of Severe
storms will be in place, with a Slight (level 2 of 4) risk of
excessive rainfall for much of our region, with far northern
counties seeing lower risks.
Most guidance indicates a decline in shower/storm coverage through
the afternoon. A reinforcing cold front pushed in by strong surface
high pressure moving into the central Plains will arrive likely in
the overnight, and Monday and Tuesday will be the coolest of the
week with highs mainly in the 60s. Any additional shower and
thunderstorm activity is likely to be confined to near the Rio
Grande Sunday night through Monday. A subtropical ridge axis may
attempt to build overhead Monday night into Tuesday, but some weak
shortwaves could bring additional low shower/storm chances Tuesday
and Wednesday. Southerly flow will become re-established. As the
closed low finally moves across TX Thursday into Friday, there will
likely be one final round of showers and storms in the region, and
the amount of return flow may determine whether there would be any
additional severe weather or flooding concerns.
&&
.AVIATION...
(12Z TAFS)
Issued at 648 AM CDT Fri Mar 15 2024
Showers and thunderstorms continued to move to the east across our
area and are mainly along and east of I-35. Have maintained -RA
mention at KAUS and VCSH mention at KSAT/KSSF through 15Z. Expect
redevelopment of SHRA/TSRA this afternoon after 21Z, then they will
continue tonight into Saturday. Due to lack of consensus where they
will track, have maintained VCTS mention. A mix of IFR/low end MVFR
exists at the sites. They will slowly rise to low end VFR later this
morning into afternoon, then fall back to MVFR later this evening and
IFR overnight. Light SE winds will shift to NE 10 to 15 KTs and gusts
with passage of the front late morning into afternoon.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 78 62 69 61 / 50 30 80 60
Austin Bergstrom Intl Airport 77 61 70 60 / 60 30 80 60
New Braunfels Muni Airport 80 63 72 61 / 60 40 90 70
Burnet Muni Airport 72 59 66 57 / 60 30 90 50
Del Rio Intl Airport 88 64 76 62 / 40 70 90 70
Georgetown Muni Airport 75 60 69 59 / 50 30 90 60
Hondo Muni Airport 82 61 72 59 / 70 70 80 80
San Marcos Muni Airport 79 61 71 60 / 60 40 90 70
La Grange - Fayette Regional 80 65 72 63 / 60 40 80 70
San Antonio Intl Airport 80 63 72 61 / 70 50 90 80
Stinson Muni Airport 82 64 74 62 / 80 60 80 80
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term...04
Long-Term...KCW
Aviation...04