Area forecast discussion
National Weather Service San Angelo Texas
1158 PM CDT Wednesday may 22 2013
Discussion...
see 06z aviation discussion below.
&&
Aviation...
MVFR stratus is expected to develop across the southern terminals
between 09z and 10z along with patchy MVFR visibilities. Kabi
should remain VFR but did include a two hour tempo group for
MVFR ceilings at ksjt this forecast cycle given latest model guidance.
VFR returns by middle to late morning as stratus scatters out.
Convection is expected to develop over northwest Texas Thursday
evening and some of this activity may approach the kabi and
possibly the ksjt terminals towards the end of the forecast
period. Timing and placement of convection is too uncertain to
mention at this time but will continue to monitor. Winds will
remain south to southeast through the period.
&&
Previous discussion... /issued 626 PM CDT Wednesday may 22 2013/
Discussion...
see 00z aviation discussion below.
Aviation...
VFR conditions will continue across the terminals this evening.
MVFR stratus is expected to develop across mainly the kbbd...kjct
and ksoa terminals after 09z. Confidence continues to remain low
for stratus to affect kabi and ksjt but will continue to monitor
for this potential. Expect stratus to scatter out to VFR around
14z with VFR thereafter. South to southeast winds will continue
through the forecast period.
Previous discussion... /issued 304 PM CDT Wednesday may 22 2013/
Short term...
upper level ridging is currently moving into west central
Texas...which has resulted in mainly sunny skies and quieter weather
today. At the surface...temperatures have responded by warming up
into the lower to middle 90s across the entire area...along with
moisture being increased or maintained as southeasterly flow has
already begun low level moisture return to west central Texas.
Warm temperatures will be expected overnight as moisture increases
and winds remain around 10 miles per hour out of the southeast. Expect lows to
only be able to fall into the upper 60s to lower 70s. Expecting
another very warm day Thursday with highs again climbing into the
middle 90s across much of the area.
On Thursday...a cold front will ease into The Caprock region of West
Texas. Surface convergence will be strong along this front as a
dryline mixes east to the frontal location during the afternoon.
Aloft...lapse rates will increase to greater than 7.5 c/km...with
low level cape values of near 3000 j/kg. As a result...while Texas
will remain under a ridge with relatively weak flow aloft...
thunderstorms are expected to develop northwest of our forecast area
during the afternoon hours. The activity is expected to
develop/propagate to the south along the frontal boundary during the
afternoon hours toward our County Warning Area. Initially...due to the instability
that will be available...thunderstorms will likely be quick to
intensify to severe strength with large hail and damaging winds
being the main hazards. With all that in mind...will include a
slight chance for thunderstorms along the western border of our area
tomorrow afternoon should these thunderstorms move into the area
during the late afternoon/early evening hours.
20
Long term...
the main highlight Thursday night through Saturday is the increasing
chance for showers and thunderstorms. Unable upper level ridge will be
located across the central part of the country Thursday...but will
slowly begin to shift east late Thursday. In addition...models
continue to indicate a weakness in the ridge over West Texas and the
Texas Panhandle...likely associated with a weak cold front that will
stall here. These factors should aid in shower and thunderstorm
development. Any convection that does develop during the late
afternoon/early evening...has the potential to slowly make its way
into at least the western counties of west central Texas during the
overnight hours. I increased probability of precipitation across the western half of the
area...with the best probability of precipitation across the western Big Country. Although
widespread severe weather is not expected...a few storms could
become strong to severe...with large hail and damaging winds being
the main hazards.
Rain chances look more promising for a good portion of the area on
Friday and Friday night as the upper level ridge continues to shift
east and a weakness in the ridge remains across west central Texas.
Precipitable water values from Thursday night into Saturday morning
remain in the 1 to 1.5 inch range...so locally heavy rainfall is a
possibility. The best chance of precipitation looks to be across the
western two thirds of the area...with only a slight chance across
our southeast counties. Rain chance should slowly come to an end
Saturday...although I did keep slight chance probability of precipitation through the day
Saturday. High temperatures on both Friday and Saturday will be
dependent on exactly where precipitation develops and the amount of
cloud cover. For now...I knocked high temperatures down
slightly...but these may need to be lowered if confidence is rain
chances increases. Beyond Saturday...expect slightly above normal
temperatures with highs generally in the lower 90s and low
temperatures in the upper 60s to near 70. Models diverge in the
synoptic pattern for the middle of next week. The 12z GFS is
indicating an upper level trough approaching our area...while the
European model (ecmwf) indicates a ridge building in. For now...I have kept the
forecast dry.
Daniels
&&
Preliminary point temps/pops...
Abilene 92 70 93 70 87 / 0 10 10 30 30
San Angelo 96 71 96 70 89 / 0 5 5 20 30
Junction 93 70 92 70 87 / 0 0 0 10 20
&&
Sjt watches/warnings/advisories...
none.
&&
$$
99/99/24
