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

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
000
FXUS64 KEWX 270851
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
351 AM CDT Sat May 27 2017

.SHORT TERM (Today through Sunday)...
Rich low level moisture and favorable isentropic lifting in the
lowest 100 mb early this morning will result in drizzle/mist for the
eastern half of the CWA. RAP moves this lifting area north around 12Z
and should reduce the drizzle but many areas will likely wake up to
wet ground this morning.

Moving through the rest of the day, a dry line will set up to the
west again this afternoon. While dewpoints in the 70s, a dry line in
the west, and a continued southerly fetch typically is an eyebrow
raiser this time of the year for storm development, a stout cap at
around 800mb doesn`t look to budge as evidenced in RAP forecast
soundings over Austin, San Antonio, and the Hill Country. Farther
west near Del Rio, much weaker capping is forecast but surface
moisture will be a bit less impressive which results in convective
temps of 101+ this afternoon. Looks like the best shot at any storms
for the CWA this afternoon will be if any Del Burro supercells can
get going. There are some indications this may occur due to an
easterly shift to the low level wind field this afternoon which may
be enough to get convection firing over Mexico. Chances of these
cells crossing the border look slim though. Left slight PoPs out
there for now. Also, forecast heat indices may reach into the upper
100s this afternoon, but opted against a heat advisory at the moment
as values looked to be just below criteria. Will need to watch this
closely this afternoon.

Later tonight, an approaching cold front will be the focus for
lifting and perhaps some showers and thunderstorms tomorrow morning
as it approaches the northern periphery of the CWA. However, a weak
shortwave disturbance is progged to move across the area Sunday
afternoon and amplify lift over our very moist atmosphere. TTU-WRF
aggressively convects tomorrow afternoon along a line from Sonora to
Lampasas and then shifts the activity southeast into South Central
Texas. With GFS PWAT 1.7+" tomorrow afternoon across the area and
3000+ J/KG for surface based parcels to tap into as the convection
produces outflow and shifts southeast, should see heavy rainfall
rates and likely a straight line wind and hail threat. We are
currently slight risked for Sunday for 2/3 of the area.

&&

.LONG TERM (Sunday Night through Friday)...
A stalled front will be positioned north of the CWA Monday which will
keep South Central Texas in the moist regime it`s been in. Weak low
level flow out of the east should limit potential for heavy rainfall
Monday beyond the previous night`s complex. But having said that,
both the GFS and ECMWF produce another 1/2 inch to inch of rainfall
over the southern half of the CWA, likely due to an uncapped unstable
atmosphere. If remnant outflow boundaries are present Monday, they
would be the focus for potential heavy rainfall, but for now, have
kept QPF values generally conservative due to the unfavorable wind
field being advertised.

The H5 pattern agreement begins to diverge beginning mid week as
either weak ridging (GFS) or weak troughing (ECMWF) sets up across
the region. The troughing solution would prove to the rainiest as
continued broad upper level lifting allow for rain chances through
the next weekend. GFS solutions keep the majority of the QPF
generation north and west of the CWA, closer to the main shortwave it
advertises set up over the Rockies. As a result, opted to broad brush
at least chance PoPs or better throughout the remainder of the
extended, hopeful that more clarity will come in the extended with
later runs.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              94  76  90  69  83 /  10  10  40  60  50
Austin Bergstrom Intl Airport  95  75  91  69  82 /  10  10  30  60  50
New Braunfels Muni Airport     94  76  91  70  81 /  10  10  30  60  50
Burnet Muni Airport            93  73  86  66  81 /  10  20  50  60  40
Del Rio Intl Airport           98  77  91  71  83 /  20  20  40  60  60
Georgetown Muni Airport        93  75  88  67  81 /  10  20  40  60  40
Hondo Muni Airport             96  76  91  70  83 /  10  10  30  60  60
San Marcos Muni Airport        94  76  91  69  81 /  10  10  30  60  50
La Grange - Fayette Regional   95  76  91  71  81 /  10  10  30  60  60
San Antonio Intl Airport       95  76  91  71  82 /  10  10  30  60  50
Stinson Muni Airport           97  76  91  72  82 /  10  10  20  60  60

&&

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

$$

Mesoscale/Aviation...Hampshire
Synoptic/Grids...TB3



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.