Scientific Forecaster Discussion
fxus64 khgx 171716
Area forecast discussion
National Weather Service Houston/Galveston Texas
1216 PM CDT Sat Aug 17 2019
Aviation [18z taf issuance]...
Radar is currently showing the development of scattered rain showers/thunderstorms and rain
across areas south of I-10. This activity is expected to continue
to track to the northeast, impacting Metro area terminals through
approximately 23z this afternoon.
Expecting some low cloud development to produce brief MVFR cigs at
cll, uts, and cxo tomorrow morning between 11 to 14z. Conditions
otherwise remain mainly VFR through the duration of the taf
period. Winds inland remain out of the south at around 8-10kts,
dropping off to around 5kts overnight. Along the coast, winds
remain slightly above 10kts with some gusts possible in the
18-20kt range through the rest of the afternoon and into the
Previous discussion... /issued 1021 am CDT Sat Aug 17 2019/
surface high pressure remains over the eastern/central Gulf with
lower pressures over eastern New Mexico. 12z crp/lch soundings
show 850 temps between 19-20 c which supports high temperatures in
the middle 90's this afternoon but considering the warm start to
to today, will add a few degrees to that which matches values
already in the forecast. Drier air is trying to work into the
western portion of the County Warning Area and the crp and forward soundings show
quite a bit of dry air above 900 mb. Think there will be some
mixing this afternoon and lowered dew points out west and
subsequently lowered heat index values. Heat advisory looks
marginal out west but still looks valid toward the coast. Will
maintain current advisory as previously configured. Radar is
showing scattered showers and thunderstorms along and east of I-69
this morning. Precipitable water values remain near or just above 2.00 inches over
the eastern third of the region. Convective temperatures are in
the upper 80's so shra/tsra should continue to develop with
additional heating and this is supported by hires guidance. Had
some reports yesterday of funnel clouds and waterspouts and
conditions look favorable for this to occur again today. Stay
alert if on the water today. Lastly, bumped wind speeds up a bit
for tonight over the Gulf waters and a scec will probably be need
over the western Gulf waters tonight. 43
Previous discussion /issued 420 am CDT Sat Aug 17 2019/...
Short term (today through sunday)...
isolated showers are popping up over coastal waters again early
this morning, but we will head into a lull in activity towards the
late morning. Satellite derived precipitable water has a surge of pwats of
around 2.1 inches across the region, which is slightly lower than
yesterday. However there is enough moisture that showers and
thunderstorms will pick back up in the afternoon hours. Cam
guidance mostly shows these showers staying on the eastern half of
the cwa, which is where I left the higher pops. Activity settles
down after sunset, but isolated to scattered showers make a return
Yesterday, heat indices at Sugarland got to 110, at Galveston to
109, and both Houston and Huntsville got to 107, with today
looking very similar if not a couple of degrees higher. That,
plus it being the weekend, have decided to put out a heat advisory
beginning at noon and lasting until 7pm. Increased cloud cover
and the increased chances of showers over the eastern counties may
prevent them from hitting criteria (which is 108 or greater), but
with the isolated nature of these showers have decided to just
put the advisory out for the entire area. Heat indicies will again
climb to similar levels on Sunday, but will wait to see how today
GOES before we re-issue any future advisories. Fowler
Long term (sunday night through saturday)...
no change in next week's weather pattern, at least from late
Sunday through Friday. A typical summertime pattern as the
region remains under the influence of desert SW to Southern Plains
593-ish dam upper ridging. The general mid layer steering flow
will out of the east with periodic lobes of higher moist northwest Gulf
air (1.9 to 2.1 inch pwat range) traversing southeastern Texas. As
these air masses pass through they will increase the occurrence
and areal coverage of showers and thunderstorms, especially if
their arrival is during the afternoon. A near 95 f noon convective
temperature should be achieved each mainly clear to partially
cloudy week day. Due to suppression brought on by the ridge,
background weak southerlies should prevail and allow for the local
mesoscale breezes to become more of a player as it relates to
afternoon convective focus. Low to moderate early day (southern
cwa) streamer showers transitioning to afternoon shower and
isolated storm cluster activity will all be dependent upon sea/Bay
breeze and outflow interaction behavior.
A general height weakness channel across the western Gulf will
support the northern advancement of weak Bay of Campeche-based
tropical waves that will skirt the coastline from Friday into
Sunday. Model ensembles are all pointing to a general inverted
trough feature but the member consensus is not wanting to close
off anything. So, as of this morning, expect higher coastal and
maritime rain/storm chances a week from now...the impetus from a
large scale tropical trough with weak embedded waves within greater
than 2 inch pw air introducing periods of marine and coastal zone
moderate precipitation. Southern third forecast area thicker
overcast and periodic precipitation will regulate weekend warmth
to the 80s. 31
very similar conditions compared to yesterday for today with
mainly light to occasionally moderate onshore flow with slightly
higher wind speeds during the overnight and early morning hours.
Isolated to scattered showers and thunderstorms are expected in
early morning hours today and tomorrow. Winds may become gusty
and erratic near any thunderstorms that do form. Seas will
generally be 2 feet or less today, but will be gradually
increasing to around 4 feet by tomorrow. There will be marginal
scec conditions due to both wind speeds and seas tonight into
Sunday morning. High pressure building into the region through
next week will bring more relatively quiet weather. Fowler
Preliminary point temps/pops...
College Station (cll) 78 100 78 99 76 / 10 0 10 20 10
Houston (iah) 81 96 81 97 80 / 10 20 10 60 10
Galveston (gls) 85 92 85 93 84 / 20 20 20 50 30
Texas...heat advisory until 7 PM CDT this evening for the following
zones: Austin...Brazoria islands...Brazos...Burleson...
Chambers...coastal Brazoria...coastal Galveston...coastal
Harris...coastal Jackson...coastal Matagorda...Colorado...
Fort Bend...Galveston Island and Bolivar Peninsula...
Grimes...Houston...inland Brazoria...inland Galveston...
inland Harris...inland Jackson...inland Matagorda...
Liberty...Polk...San Jacinto...southern Liberty...Trinity...