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

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FXUS64 KEWX 190924
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
424 AM CDT Fri Oct 19 2018

.SHORT TERM (Today through Saturday)...
Light to moderate showers continued across South Central Texas with
some heavy showers lurking to our southeast across the middle Texas
coastal areas. There are upper level troughs over the western states
and over the Canadian plains with an upper level ridge centered just
east of Florida extending west across the Gulf of Mexico. The right
entrance region of an upper level jet is over our area. An inverted
surface trough is off the middle to lower Texas coast. Well above
normal moisture levels persist with PWs ranging from 1.7 inches over
Val Verde county to 2 inches along the I-35 corridor to 2.2 inches
near the coastal plains.

The upper level jet region, weak mid level impulses moving over the
area, and the surface trough will provide lifting to maintain the
showers today into tonight. Areas of 1 to 2 inch rainfall amounts
can be expected with localized amounts up to 5 inches possible if
showers can train over the same areas. These amounts will lead to
renewed flash flooding as soils remain quite saturated from rains
since early September. This could also generate new and aggravate
ongoing river flooding. Will maintain the Flash Flood Watch for areas
along and west of I-35 as these areas are the most sensitive to
flooding. The favored areas for heaviest rains will extend from the
surface trough across the I-35 corridor into the Hill Country. One or
two thunderstorms are possible due to weak elevated instability.

Tonight into Saturday, half of the western trough phases with the
Canadian trough and moves across the plains states to the eastern
states while the other half forms a closed low along the California
coast with upper level ridging over Texas. The phased trough forces a
reinforcing surge of surface high pressure to move across our area.
Isentropic lifting continues while moisture levels only slowly
decrease as ridging at the surface and aloft builds in. As a result,
areas of showers continue tonight into Saturday. It`s possible that
some locally heavy rains occur leading to portions of the Flash Flood
Watch being extended.

&&

.LONG TERM (Saturday Night through Thursday)...
Sufficiently drier air filters south to end rain chances for eastern
areas on Sunday. However, this will be short lived. By Monday, the
ridging moves off to the east allowing a southwesterly flow aloft to
return while deeper moisture moves back into area. Showers again
increase in areal coverage and intensity as mid level impulses move
across in the flow aloft. There is a potential for moderate to heavy
rains which may result in a renewed flood threat due to above normal
moisture returning. Isolated thunderstorms are possible due to weak
elevated instability. Models have backed off on the potential of the
remnants of an eastern Pacific tropical system moving over our area.
Should this feature pan out, then rainfall would be enhanced from
that currently expected for next week. Later next week, the
California low opens up and moves across the plains states. In its
wake, subsidence and a drier airmass should finally end the showers.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              64  59  67  56  67 /  90  90  60  20  10
Austin Bergstrom Intl Airport  65  60  67  58  66 /  90  90  50  20  10
New Braunfels Muni Airport     67  60  68  59  67 /  90  90  60  20  10
Burnet Muni Airport            61  57  66  53  64 /  90  80  60  20  10
Del Rio Intl Airport           65  61  68  58  64 /  50  50  60  60  40
Georgetown Muni Airport        62  59  67  55  66 /  90  90  60  10  10
Hondo Muni Airport             67  62  69  59  67 /  60  50  60  40  20
San Marcos Muni Airport        66  60  67  58  67 /  90  90  60  20  10
La Grange - Fayette Regional   70  61  69  59  68 /  80  70  50  10  10
San Antonio Intl Airport       67  61  69  59  68 /  80  80  60  30  20
Stinson Muni Airport           69  62  69  61  68 /  80  70  60  30  20

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through this evening for Bandera-Bexar-Blanco-
Burnet-Comal-Edwards-Gillespie-Hays-Kendall-Kerr-Kinney-Llano-
Maverick-Medina-Real-Travis-Uvalde-Val Verde-Williamson-Zavala.

&&

$$

Aviation...Treadway
Short-Term/Long-Term...04


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