Area Forecast Discussion
Issued by NWS San Angelo, TX

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FXUS64 KSJT 271732

1232 PM CDT Wed May 27 2015

Showers and thunderstorms continue across the northwest Hill
Country this morning near Fredericksburg, developing west toward
Rock Springs. According the SPC mesoanalysis, MLCAPE values are
approaching 3500 J/kg, but effective shear remains generally
around 35 kts or less. This suggests that multicellular convection
would be the most likely mode, although a few supercells will be
possible as well. Mid-level lapse rates will be quite steep today,
supporting strong updrafts and the potential for severe weather
this afternoon and evening. The primary threats will be large hail
and damaging winds, in addition to locally heavy rainfall.


/18Z TAFS/

Scattered showers and thunderstorms have developed across the Hill
Country this morning and are expected to increase in coverage
across portions of West Central TX through this afternoon.
Ceilings have improved to VFR at the forecast terminals, but may
temporarily be reduced if thunderstorms impact the terminals. A
VCTS remark was included at all sites through around 02z. MVFR
ceilings are anticipated again tonight, mainly after 07z, and will
likely persist through at least mid-morning.


.PREV DISCUSSION... /ISSUED 638 AM CDT Wed May 27 2015/

/12Z TAFS/

A few areas of MVFR are expected through 14Z or so at most TAF
sites but the CIGs are quite variable changing from SCT to BKN
hour by hour, becoming VFR. Scattered thunderstorms should
develop this afternoon and evening. Some of these may become
severe and produce large hail, damaging winds, very heavy rainfall
with low visibilities, and a possible tornado.

Low MVFR to IFR Cigs will return after 08Z tonight.

PREV DISCUSSION... /ISSUED 443 AM CDT Wed May 27 2015/

(Today and Tonight)

A few elevated showers and thunderstorms continue to form near an
outflow boundary that stretches between Robert Lee and San Saba.
The cells were moving northeast.  And these showers may continue for
a few more hours.

Another risk for severe storms this afternoon with main threats
being large hail, damaging winds, very heavy rainfall and an
isolated tornado.  The combination of high mean layer CAPE values
from 4000-5000 j/kg from the NAM model, daytime heating, plenty of
moisture and old outflow boundaries from yesterday`s convection will
set the stage for another round of scattered strong to severe
thunderstorms this afternoon and tonight.  Yesterday afternoon we
had a baseball size hail report in Miles.  Also, the upper flow is
progged to become southwesterly a weak upper level disturbance will
provide additional forcing in the mid and upper levels.  High
temperatures will be similar to yesterday.


(Thursday through Tuesday)

An unsettled pattern will continue through the weekend, with
additional locally heavy rainfall possible and some possibility
for severe weather.

The chance of showers and thunderstorms continues on Thursday, when
an upper trough will approach from the southwestern states. We have
likely PoPs for Thursday night, when the 00Z GFS and ECMWF indicate
a potential for organized convection to move east across our area.

The next increased chance for showers and thunderstorms will begin
late Friday night across our northern counties, when a cold front is
expected to sag south toward that area overnight. Convection late
Friday night may also be enhanced by a weak upper level disturbance
entering northwest Texas. The cold front is progged to move south
across west central Texas on Saturday and Saturday evening, possibly
reaching the I-10 corridor by 7 PM. Decent amount of convection
should help to drive this front south, along with the flow aloft
becoming northwesterly.

The chance of showers and thunderstorms should linger into Sunday,
with northwest to north flow aloft and the possibility of a weak
disturbance entering our area. Temperatures over the weekend will
be a little cooler behind the front, especially during the day with
increased cloud cover.

Rain chances should drop off after Monday, as an upper ridge shifts
east into Texas.



Abilene  88  67  83  66  84 /  30  40  40  60  40
San Angelo  90  69  83  68  87 /  30  40  40  60  30
Junction  89  69  84  69  84 /  30  20  40  60  40





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