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

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FXUS64 KEWX 151149 AAA
AFDEWX

Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
649 AM CDT Sun Oct 15 2017

.AVIATION...
/12Z TAFS/
MVFR to high end IFR cigs are expected across the I-35 sites within
the next 2 to 3 hours as a cold front approaches and moves over
terminals. VFR conditions are expected behind the front with strong
northerly winds and gusts of 30 to 40 mph. Breezy conditions continue
through late tonight.

KDRT should have VFR conditions through the forecast period with
northerly winds picking up behind the cold front around 14Z.
Northerly gusts 25 to 30 mph are expected through mid afternoon.

&&

.PREV DISCUSSION... /ISSUED 321 AM CDT Sun Oct 15 2017/

SHORT TERM (Today through Monday)...
The cold front continues to quickly surge southward overnight and is
currently near a line from Midland to Abilene to Gainesville. Latest
analysis from area radars has the front moving at about 30 mph. Ahead
of the front, areas of low clouds continue to develop as well as
patchy fog. As of now, the fog is not as widespread as previous
nights and am not anticipating the need of a Dense Fog Advisory, but
will continue to monitor trends for any possible updates.
Temperatures are currently mild, in the lower 70s across much of the
area.

The upper trough associated with the cold front is passing through
the central and northern plains and upper dynamics with the FROPA
will be NIL to help support deep convection. However, isentropic lift
associated with mesoscale frontal dynamics will be in place just
behind the boundary and we should see a broken line of showers and
perhaps a thunderstorm as the front moves into South Central Texas.
This is already occurring with the front to the north at the present
time, but am not expecting as high of a coverage this far south with
the loss of any upper dynamics as the front travels south. Will show
40 PoPs in the northern CWA with values dropping to 20 and 10
percent to the south where the lift is expected to be less. PoPs will
generally end from north to south this morning. However, high-res
models are showing some lingering isentropic lift for areas just
northwest of our CWA through the early afternoon hours behind the
front. Will leave 20 PoPs for the NW CWA in the 18z-21z time frame to
account for any showers or storms sneaking into the CWA. All precip
should be over by 21z.

The main hazard behind the front should be strong northerly flow.
Wind speeds currently along the front in Midland and Abilene have
sustained speeds near 30 MPH with gusts over 50 MPH. Am not
anticipating a Wind Advisory for our CWA as these speeds should not
be that high for a prolonged period, but 15 to 25 mph winds with
higher gusts are expected today. We may need a short-term SPS for
mainly the higher terrain of the western counties this morning to
cover the threat for brief gusty winds. Will monitor this closely as
the front nears the CWA in the 6-7 AM window.

Temperatures behind the front will drop into the 60s in the Hill
Country with 70s likely holding steady for the the rest of the CWA
today. With clearing skies tonight and dewpoints in the 40s, night
time lows will reach the 40s and 50s but will not be a low as
theoretically possible due to lingering breezy northerly winds
prevent optimal radiational cooling. Another cool Fall day is
expected Monday with clear skies, weakening winds, and highs in the
70s.

LONG TERM (Monday Night through Saturday)...
With the clear skies and calmer winds Monday night, low temperatures
will be the coldest of the season for Tuesday morning. Lower 40s are
expected for the Hill Country with mid to upper 40s for much of the
rest of the CWA. Lows near 50 are expected for the southern counties
and locations closer to the Rio Grande. Weak flow will remain in
place through the week which will keep the dewpoints low and
temperatures cool through Wednesday. By Thursday, southeast flow
returns with a slow warm up expected, but highs are only expected to
get back into the lower to middle 80s with lows in the 60s through
the end of the forecast period. With the southeast flow on Saturday
and Sunday, there will be a return of low Pops for the eastern CWA
for mainly diurnal activity. The GFS is a bit more bullish than the
ECMWF, but there remain differences in their solutions in the
extended and will just keep 20 PoPs in the official forecast for now.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              74  54  74  49  78 /  30   0   0   0   0
Austin Bergstrom Intl Airport  75  54  74  49  78 /  30   0   0   0   0
New Braunfels Muni Airport     76  55  74  49  78 /  30   0   0   0   0
Burnet Muni Airport            72  49  72  45  75 /  40   0   0   0   0
Del Rio Intl Airport           76  56  76  50  78 /  30   0   0   0   0
Georgetown Muni Airport        73  51  74  47  77 /  40   0   0   0   0
Hondo Muni Airport             79  55  77  48  78 /  40   0   0   0   0
San Marcos Muni Airport        76  54  75  48  78 /  30   0   0   0   0
La Grange - Fayette Regional   78  56  75  49  78 /  20   0   0   0   0
San Antonio Intl Airport       77  56  75  49  78 /  40   0   0   0   0
Stinson Muni Airport           79  57  75  50  78 /  30   0   0   0   0

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 9 AM CDT this morning for the following
counties: Bastrop...De Witt...Fayette...Gonzales...Lavaca...Lee.

&&

$$

Mesoscale/Aviation...17
Synoptic/Grids...Hampshire



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