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

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FXUS64 KEWX 181130

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
630 AM CDT Sun Mar 18 2018

For KAUS, KSAT, KSSF, IFR/MVFR CIGs/VSBYs slowly lift and erode as a
dryline shifts east around midday or shortly thereafter, leaving VFR
skies for afternoon into evening. As dryline shifts back west, IFR
CIGs redevelop late evening. A Pacific front moves across the sites
eroding the CIGs again, with VFR returning late tonight through
Monday. S/SE winds less than 10 KTs turn SW late morning to midday,
then back to S/SE in the evening, before finally W/NW late tonight
and increasing to 10 to 20 KTs and gusty Monday. There is a potential
for SHRA/TSRA today and late tonight, however, chances are currently
too low to mention.

For KDRT, VFR skies will prevail. Although there is a potential for
brief IFR CIGs early this morning, chances are low and have only
mentioned FEW clouds. NE winds 5 KTs turn to W and increase to 12 to
25 KTs in the wake of the dryline today, then decrease to less than
10 KTs in the evening, and finally become NW 10 to 20 KTs and gusty
late tonight into Monday.


.PREV DISCUSSION... /ISSUED 506 AM CDT Sun Mar 18 2018/

SHORT TERM (Today through Monday)...
Current observations show the dryline has retreated westward into the
Rio Grande plains and southern Edwards Plateau early this morning.
The dryline is expected to advance eastward to the I-35 corridor by
late afternoon. Most of the hi-res models show some potential for
convection to develop along and east of the dryline today and we will
mention a fairly low chance (20-30%) for showers and storms today.
While we can`t completely rule out the possibility of a strong storm
or two, it looks like most of the stronger storms will remain to the
north of our region. Otherwise, expect another warm day with highs
ranging from the mid 80s in the Hill Country to lower 90s Rio Grande.
For this evening, the dryline will briefly retreat westward to near
the Balcones Escarpment before a Pacific cold front overtakes the
dryline early Monday morning. Several of the hi-res models show a
brief window of opportunity for convection to develop along the cold
front during the very early morning hours Monday. Confidence is
fairly low in this scenario, but given agreement among several of the
hi-res models, we will keep a low chance in the forecast for the
early morning hours Monday. The bigger concern will be the very dry
conditions expected behind the front on Monday. Please see the fire
weather section below for more information. We will see some cooling
behind the front on Monday, but northwesterly downslope will likely
offset any significant cooling. We still expect highs to be above
normal, with mid 70s in the Hill Country to mid 80s in the coastal

LONG TERM (Monday Night through Saturday)...
A fairly uneventful weather pattern is in store for south central
Texas during the early and middle portion of this week. A northern
stream cold front will move through Monday night into early Tuesday
morning, resulting in temperatures near normal on Tuesday. On
Wednesday, southerly flow in the low-levels will return as a
subtropical ridge axis builds in the mid and upper levels. This will
result in dry weather along with a warming trend through Friday. We
could see an increasingly active flow aloft develop late in the
forecast period on Saturday. Fro now, we will only mention a 20%
chance for showers and thunderstorms generally along and east of

Fire weather concerns for today will be centered across portions of
the Rio Grande plains and southern Edwards Plateau. With the onset of
daytime heating and mixing, the dryline will move eastward today,
with dry and breezy conditions in store following the passage of the
dryline. Afternoon humidities are expected to drop below 20% across
the Rio Grande plains into portions of the southern Edwards Plateau.
While we do expect an increase in winds behind the dryline, it
appears winds may remain just below critical levels. Current thinking
is we could see enough mid and high level clouds through mid-
afternoon to help limit the mixing of higher momentum air to the
surface. With this in mind, we will hold off on a Red Flag Warning
for Val Verde county and continue to highlight our concerns in a
Special Weather Statement. Should mixing be better than expected, a
Red Flag Warning may be needed for Val Verde county today.

The greater period of concern for fire weather will be on Monday,
following the passage of a Pacific cold front. Minimum humidities for
Monday afternoon will drop into the teens and single digits for most
of south central Texas. In addition, we expect an increase in
northwesterly winds from mid-morning through late afternoon. The
current Fire Weather Watch across portions of the Hill Country,
Edwards Plateau, Rio Grande Plains, and Winter Garden regions will
remain intact. We will hold off on pushing the Fire Weather Watch any
farther east at this time as winds may be the limiting factor in
reaching critical levels.

Dry weather is expected again on Tuesday, with minimum humidities
from near 20% along the Rio Grande to near 30% in the coastal plains.
Northwesterly winds of 10-15 mph are also expected generally along
and east of Highway 281.


Austin Camp Mabry              87  58  83  49  72 /  20  20   0   0   0
Austin Bergstrom Intl Airport  86  57  80  47  72 /  20  20   0   0   0
New Braunfels Muni Airport     88  57  81  46  73 /  20  20   0   0   0
Burnet Muni Airport            86  50  76  45  69 /  20  10   0   0   0
Del Rio Intl Airport           90  55  82  49  77 /  10   0   0   0   0
Georgetown Muni Airport        87  54  81  47  69 /  20  20   0   0   0
Hondo Muni Airport             90  55  85  46  78 /  20  10   0   0   0
San Marcos Muni Airport        88  56  83  46  73 /  20  20   0   0   0
La Grange - Fayette Regional   85  59  83  49  71 /  30  30  -    0   0
San Antonio Intl Airport       90  59  84  49  75 /  20  20   0   0   0
Stinson Muni Airport           88  59  85  50  76 /  20  20   0   0   0




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