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

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FXUS64 KEWX 222329
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
629 PM CDT Mon Apr 22 2019

.AVIATION...
VFR conditions with breezy southerly flow continue late this
afternoon. However, ceilings will lower into MVFR then perhaps IFR
categories overnight and into tomorrow morning. Forecast soundings
also show the possibility of drizzle and some visibility restrictions
as well. Conditions will slowly lift into high MVFR, but these should
continue through the period. Another round of IFR ceilings is
expected tomorrow night, just beyond this valid TAF period.

&&

.PREV DISCUSSION... /ISSUED 314 PM CDT Mon Apr 22 2019/

SHORT TERM (Tonight through Tuesday Night)...
Breaks in a dense cirrus canopy streaming ahead of a closed low over
Arizona/California have allowed for a broad, flat cumulus field to
develop this afternoon. The development of these cumulus clouds is
heralding the return of lower level moisture into the region. Expect
enough moisture to return overnight to allow for fog and patchy
drizzle or light rain to spread across much of the Interstate 35
corridor by the start of the morning commute with lows only falling
into the mid to upper 60s. Patchy drizzle or rain will linger into
the morning hours with a few showers or possibly a thunderstorm
developing across Central Texas or the Hill Country as a weak
disturbance ahead of the approaching upper low translates across the
region.

Forecast soundings show at least some weak capping lingering across
the region during the day Tuesday, helping to limit overall
thunderstorm potential, but height falls ahead of the approaching
upper low will help erode at least some of the cap across the Rio
Grande during the late afternoon and evening hours. High resolution
guidance shows that a few discrete thunderstorms should be able to
develop along the Rio Grande into Val Verde County during this time
and with mid-level lapse rates approaching 8 C/km, 0-6 km bulk shear
exceeding 50 knots, and over 1500 J/kg CAPE some of these storms may
become strong or severe. Continued height falls are also expected to
induce a surface low or wave in southwest or west central Texas
along a slow-moving cold front, which may overtake the initial round
of activity that develops along the Rio Grande Tuesday night.

As the surface low nudges towards the east Tuesday night, pulling
the attendant frontal boundary farther south into the Hill
Country/Central Texas. Increasing forcing for ascent and a 40-50 knot
low level jet feeding into the low will result in showers and
thunderstorms developing along and north of the frontal boundary
Tuesday night into Wednesday morning. This, combined with
precipitable water values surging over 1.4 inches, will allow for a
threat for at least locally heavy rain to enter the forecast for the
Hill Country and Central Texas.

LONG TERM (Wednesday through Monday)...
Showers and thunderstorms will linger along the frontal boundary
Wednesday and Wednesday night as the main upper level system
translates across the region. Slightly different placements for the
frontal boundary will ultimately affect who sees the heaviest rain
during this time. Confidence continues to remain low with the
boundary location as the GFS/NAM have continued their trend of
shifting the heaviest rainfall more north of the region coincident
with where the best 850 MB convergence is... while the European
continues its more southerly solution in South Central Texas. Will
have to watch where this 850 MB axis is located for future
adjustments to rain amounts as there are some signals for this system
to overperform with the amount of rain it produces, but for now
continuing with the 1-2 inch forecast amounts for areas along and
north of a Del Rio to Bastrop to San Antonio line with isolated 2-4
inch amounts possible.

Rain will end from west to east by Thursday morning as the main
system exits the region with temperatures in the mid 70s to low 80s
at the end of the work week warming into the mid 80s to lower 90s
over the weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              66  78  65  74  60 /  20  30  40  80  70
Austin Bergstrom Intl Airport  67  78  64  75  60 /  20  30  40  80  70
New Braunfels Muni Airport     67  79  65  76  60 /  20  30  50  80  70
Burnet Muni Airport            65  76  63  72  58 /  20  30  40  90  70
Del Rio Intl Airport           69  83  66  83  59 /  10  20  70  70  10
Georgetown Muni Airport        66  77  64  73  60 /  20  30  30  90  80
Hondo Muni Airport             67  82  67  79  58 /  20  20  50  80  40
San Marcos Muni Airport        67  78  65  76  61 /  20  30  40  80  70
La Grange - Fayette Regional   67  79  67  78  64 /  10  20  20  60  70
San Antonio Intl Airport       68  79  66  76  60 /  20  30  50  80  60
Stinson Muni Airport           68  80  68  77  61 /  20  20  50  80  60

&&

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

$$

Aviation...Hampshire
Short-Term/Long-Term...Oaks
Public Service/Data Collection...33



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