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

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992
FXUS64 KEWX 260003
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
703 PM CDT MON JUL 25 2016

.EVENING UPDATE...
Isolated to scattered showers and storms have continued to slowly
progress farther southwest into the Austin area and surrounding
locations through 7 PM. So far, this convection has resulted in
some very localized rainfall totals of between 1 and 2 inches,
namely in the Jollyville area in Travis County. Some half inch to
inch amounts were seen with earlier cells in northern Bexar and
Comal counties.

Latest HRRR and TTU WRF show this activity continuing to push
southwest and persist until about midnight. Most concernable
factor is high PWATs this evening, namely 2"+ from the I-35
corridor and east, maxing out at 2.4" near College Station. Thus,
isolated heavy rainfall will continue to be a threat with this
activity through the evening hours. Should this activity congeal
into more organization...some spots could see a quick 2+ inches
of rainfall...wherever that occurs. Could result in some minor
urban flooding.

As a result, increased PoPs for the evening hours and accounted
for the decrease in coverage noted in the high res suite after
midnight.


&&

.PREV DISCUSSION... /ISSUED 647 PM CDT MON JUL 25 2016/

AVIATION.../00Z TAF CYCLE/

Scattered TSRA is ongoing just north and west of KAUS and is over
KATT as of 2345z. A wind shift to the east due a localized gust
front is moving through KAUS currently with gusts to near 15-20
knots. Winds will weaken to near 10 knots within the next hour
and return more southeasterly. Additional TSRA is located farther
north and east of KAUS and KSAT and this could impact both sites
periodically through the evening. Have placed TEMPO group in for
this activity as it slowly decreases after 05Z.

A strong outflow boundary is east of KAUS/KSAT as of 2345Z and
could help develop renewed TSRA activity farther south towards
KSAT/KSSF. For this reason, have also placed a TEMPO group there.
KDRT will be clear of most TSRA this evening as Hill Country
storms should diminish before reaching the Rio Grande Plains.

A lull in activity is expected late overnight and through morning
but scattered to numerous TSRA is expected to redevelop near and
after 18z for most TAF sites Tuesday. Have placed VCTS in for now
and will likely add direct TSRA wording on either the 06Z or 12Z
TAFs when timing and coverage confidence increases based on
latest trends.

PREV DISCUSSION... /ISSUED 314 PM CDT MON JUL 25 2016/

SHORT TERM (Tonight through Tuesday Night)...
The latest water vapor satellite loop shows a weak upper
disturbance over east Texas this afternoon. The water vapor loop
also shows a broad area of low pressure and convection over the
northern Gulf of Mexico. The satellite-derived total precipitable
water product shows moisture levels have increased today with
current values ranging from 1.75" along the Rio Grande to 2.0"
over the coastal plains.

The upper level disturbance over east Texas will drift
southwestward into south central Texas through tonight. Daytime
heating along with increased moisture will result in scattered
showers and thunderstorms this afternoon and evening. We have
already seen an increase in convective activity this afternoon and
with continued heating, this trend will continue. Most activity
will likely be tied to daytime heating. However any remnant
outflow boundaries and subtle lift should continue isolated to
possibly scattered convection tonight. The upper disturbance
currently over east Texas will drift west of the Rio Grande by
Tuesday afternoon as the broad low in the Gulf slowly moves
westward toward the region. With continued moisture advection and
daytime heating, our rain chances will increase into the 50-60% on
Tuesday. Given plenty of moisture (PWATs of 2.0-2.3") and slow
storm movement, can`t rule out some locally heavy rainfall. It
will be difficult to pinpoint where the heaviest rain will occur
as much will likely depend on any remnant outflow boundaries from
earlier convection.

LONG TERM (Wednesday through Monday)...
Broad, cyclonic flow aloft and deep layer moisture will persist
across south central Texas on Wednesday. This along with daytime
heating should be enough to generate another round of scattered
convection, mainly during the afternoon and evening hours. For
now, we will keep rain chances in the 30-50% range, but this may
need to be increased if subsequent model trends remain consistent.
The broad area of low pressure aloft continues to weaken on
Thursday, leaving a col over south central and eastern Tx. Rain
chances will decrease, but given plenty of moisture and daytime
heating we should see at least isolated diurnally-driven
convection across most of the region. Temperatures will also begin
to creep upward on Wednesday and Thursday, but are forecast to
remain near climatological normals. The upper pattern changes
little through the end of the week, but the atmosphere will begin
to slowly dry out. While we can`t rule some additional isolated
convection over most areas, suspect the coastal plains will be
favored given the afternoon sea breeze. Temperatures will also
rise back to above normal with lows in the 70s and highs in the
mid 90s to near 100.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              77  94  76  96  76 /  60  60  30  40  20
Austin Bergstrom Intl Airport  76  93  75  94  76 /  60  60  30  40  20
New Braunfels Muni Airport     77  94  75  95  75 /  60  60  30  40  20
Burnet Muni Airport            75  92  74  94  75 /  50  50  30  40  20
Del Rio Intl Airport           80  97  77  97  78 /  20  50  20  30  20
Georgetown Muni Airport        76  92  75  94  76 /  60  50  30  40  20
Hondo Muni Airport             76  94  75  95  75 /  40  60  20  40  20
San Marcos Muni Airport        76  93  75  94  75 /  60  60  30  40  20
La Grange - Fayette Regional   76  93  76  95  77 /  50  60  30  50  20
San Antonio Intl Airport       77  93  77  95  77 /  50  60  30  40  20
Stinson Muni Airport           78  95  77  96  77 /  50  50  30  40  20

&&

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

$$

Mesoscale/Aviation...Allen
Synoptic/Grids...TB3
Public Service/Data Collection...33



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