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FXUS64 KEWX 170118 AFDEWX

Area Forecast Discussion National Weather Service Austin/San Antonio TX 818 PM CDT Thu May 16 2024

New UPDATE

UPDATE
Issued at 807 PM CDT Thu May 16 2024

With the strong cool outflows from the late afternoon squall line, we were due for a foreast update. Low temps with a early start to cooling will get a nudge downward. A severe hailstorm over Menard County is barreling toward Llano County and could present a severe risk for the next hour. We think the storm should weaken some as the cool outflow winds should reduce some of the lower level instability.
By the looks of it, there's probably enough mid level instability to hold it together long enough to bring at least some small hail into the CWA SPC Mesoanalysis depict another county worth of steep mid level lapse rates downstream from the storm, but a significant drop off in lapse rates once it reaches Llano County. Thus we are still carrying low chance PoPs for the Austin metro area, but do not think the threat for severe weather is anywhere near the levels it was earlier. Nevertheless, there remains a Marginal Risk over most of the area with a Slight Risk over West Central Texas extending south into parts of our Edwards Plateau/Western Hill Country counties.

SHORT TERM
(Tonight through Friday night)
Issued at 129 PM CDT Thu May 16 2024

Showers and even a few thunderstorms are beginning to increase in coverage across the eastern half of the CWA, especially across the northern Hill Country in advance of a developing MCS. With this MCS, damaging wind gusts and heavy rainfall will be the primary threats, though isolated instances of large hail will be possible with any discrete storms that develop. This activity will continue to increase in coverage and move east across the Severe Thunderstorm Watch area into the evening hours. The current watch is in effect through 22Z, though a local extension in time may be needed if storms look to linger beyond then. South of the watch area, more isolated convection is possible through the evening. While this activity could be severe as well, coverage will likely be limited due to the widespread cloud cover that has been in place all day.

Confidence in the placement of convection, if any, decreases substantially overnight, though isolated storms will remain possible across generally the same areas as this afternoon. Chances for storms look to increase again around and after sunrise tomorrow morning as a second subtle upper level disturbance moves out of northern Mexico, but CAMs keep the majority of this activity south of our CWA border. Any activity that sneaks north of this border could be strong to severe, and therefore a level 1/5 risk is in place across the southern half of our area. As we move into Friday afternoon, a secondary area to watch will be near Val Verde County as isolated storms may develop across west Texas/northern Mexico and push east into the evening. A weak front will have moved south of this area by tomorrow afternoon, which leads to lower confidence in convection developing at all, but if it does it will be high based in nature and carry an isolated hail/wind threat. In the absence of these storms, conditions will be dry and mostly clear for Friday evening/night.

LONG TERM
(Saturday through Thursday)
Issued at 129 PM CDT Thu May 16 2024

Hot, above average, temperatures prevail over South-Central Texas through this weekend into next week as mid-level ridging across Mexico strengthens. Additionally, majority of the period will include light to moderate south-southeasterly winds off the Gulf with surface high pressure displaced to the east. This yields to higher humidity levels, especially across our southern and eastern most zones. The heat indices, especially into early to middle of next week, will climb into the 103 to 108 degree range for many areas. A drier heat is expected out west along the Rio Grande but afternoon high temperatures will easily climb above 100 degrees across those areas. Rain chances remain minimal through at least early next week. An approaching shortwave out of the west could allow for slight rain/storm chances to re-enter the forecast into the Hill Country next Wednesday and Thursday afternoon.

AVIATION
(00Z TAFS)
Issued at 722 PM CDT Thu May 16 2024

Convective trends are down to being negligible for the night at all four TAF sites. Some gusty outflows should settle down over the I-35 corridor in the next hour. New instability could show up after the modified air mixes out late in the TAF period but only isolated coverage is suggested. A large area of MVFR cigs has built over the I-35 corridor, but it could mix out to VFR for a few hours before dropping back to MVFR late this evening and possibly IFR after midnight. CIG forecasts could be a bit too pessimistic, but will wait and take a look at the 00Z forecasts before adjusting the latter periods if necessary.

PRELIMINARY POINT TEMPS/POPS
Austin Camp Mabry 64 87 67 92 / 30 10 10 0 Austin Bergstrom Intl Airport 65 86 66 92 / 40 10 10 0 New Braunfels Muni Airport 65 88 67 94 / 30 10 10 0 Burnet Muni Airport 62 85 64 91 / 40 0 10 0 Del Rio Intl Airport 70 99 71 105 / 10 20 20 0 Georgetown Muni Airport 62 85 66 90 / 30 10 10 0 Hondo Muni Airport 65 94 66 97 / 20 10 20 0 San Marcos Muni Airport 64 87 65 93 / 30 10 10 0 La Grange - Fayette Regional 66 84 68 90 / 60 20 10 0 San Antonio Intl Airport 66 90 68 94 / 20 10 10 0 Stinson Muni Airport 67 91 69 95 / 20 10 10 0

EWX WATCHES/WARNINGS/ADVISORIES
None.

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