Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX

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FXUS64 KEWX 241147

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
647 AM CDT Wed May 24 2017

Please see the 12Z aviation forecast discussion below.


VFR conditions are in store for area TAF sites through the current
forecast period. Light west-northwest winds and mostly clear skies
will continue this morning. For the afternoon, northwest winds
continue along I-35, with southeasterly winds developing at DRT.
Southerly winds will then develop across the remainder of south
central Texas this evening.


.PREV DISCUSSION... /ISSUED 419 AM CDT Wed May 24 2017/

SHORT TERM (Today through Thursday)...
Clear skies and cold air advection behind yesterday afternoon`s cold
front has allowed temperatures to rapidly fall into the 50s across
most of the region with some mid to upper 40s in the Hill Country
where winds are relatively calm. A record low temperature has already
been set at AUS, but it looks like our other major climate sites
should remain above record low values (SAT`s of 55 in 1913 being the
next closest possibility for a new record). Northwest flow and NVA on
the backside a strong trough digging from the mid-south into the
southeast U.S. will allow for an absolutely beautiful day for late
May with highs in the mid 80s and northwesterly 10 mph winds. Clear
skies with light and variable winds will allow for a very efficient
cool down tomorrow evening with lows in the upper 50s and lower 60s
(most likely just above record lows). Upper level ridging will settle
over the region for Thursday to allow for another sunny day with
highs warming up into the lower 90s across most of the region with
some mid to upper 90s in the Rio Grande Plains. Southerly flow will
return by Thursday morning to allow low-level moisture to begin its
return to the region, with wind gusts to 25 mph possible in the
afternoon due to a stronger pressure gradient and efficient mixing.

LONG TERM (Thursday Night through Tuesday)...
Morning low clouds should return to the region by Friday to quickly
bring above normal temperatures in the lower to mid 70s back with
gusty southerly winds early in the evening. This return of moisture
coupled with ridging aloft will cause the hottest day of the period
in the hot and muggy day with high temperatures in the mid to upper
90s with humidity values allowing heat indices to climb into the
100-105 degree range. Although this will be below Heat Advisory
criteria, Friday will certainly feel like summer and will be quite a
change from today`s pleasant temperatures so it will be important
for people to remember to stay hydrated during the heat of the day.
Low morning clouds should persist a bit longer into the day on
Saturday with the ridge sliding to the east as a trough digs down
from the northern Rockies. This will keep highs from climbing much
further on Saturday relative to Friday, but heat indices will likely
be closer to 105 across the entire region with slightly higher
humidity values. Model soundings suggest the environment will remain
capped, but we may see a rogue thunderstorm or two in the northern
Hill Country by late Saturday afternoon or evening as a weak cold
front approaches.

The trough in the northern Rockies will dig into Oklahoma to help
push a cold front into the region on Sunday morning or afternoon.
Although upper level forcing and polar jet will be northeast of the
region (as would be expected for late May), a weak subtropical jet
and some weak shortwaves moving on the southern fringe of this trough
with a weak southerly low-level jet perpendicular to the front
possibly stalling along the Escarpment may enhance convection. This
set-up coupled with relatively deep moisture aloft suggest locally
heavy rainfall may occur overnight Sunday into Monday morning. A few
GEFS ensemble members suggest there may be a lull in the action for
several hours on Monday before convection ramps back up again late
Monday afternoon and evening into Tuesday morning once again.
However, the operational GFS pushes the front off the Gulf Coast
during this time frame and a deep trough off to our west will not be
present. Thus, there is enough uncertainty at this time to avoid
mentioning any hazards, but the second half of the long Memorial Day
weekend will once again be a period worth watching over the next few
days as it certainly looks wet. Extended forecasts into the second
half of next week also look to be cool and wet as weak frontal
forcing and additional shortwaves help trigger more convection that
may lead to saturated soils and an increased flash flood threat.


Austin Camp Mabry              85  63  92  74  94 /   0   0   0   0  -
Austin Bergstrom Intl Airport  84  60  92  74  95 /   0   0   0   0  10
New Braunfels Muni Airport     84  58  92  74  95 /   0   0   0   0  10
Burnet Muni Airport            82  60  91  72  93 /   0   0   0   0  -
Del Rio Intl Airport           86  63  97  74  96 /   0   0   0   0  -
Georgetown Muni Airport        83  61  92  74  94 /   0   0   0   0  -
Hondo Muni Airport             85  58  94  74  95 /   0   0   0   0  10
San Marcos Muni Airport        84  58  92  74  94 /   0   0   0   0  10
La Grange - Fayette Regional   82  61  91  74  93 /   0   0   0   0  10
San Antonio Intl Airport       85  62  94  75  95 /   0   0   0   0  10
Stinson Muni Airport           87  60  94  75  96 /   0   0   0   0  10




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