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Area forecast discussion
National Weather Service Houston/Galveston Texas
603 PM CDT Wednesday Apr 16 2014
see aviation for 0z taf issuance.
winds have been gusty at times today thanks to low pressure
forming in West Texas. This low will begin to weaken tonight which
should help winds to calm down a bit. An extensive cirrus shield
can be seen on visible satellite this evening just to the south
and west of the area. These high clouds are in association with
the subtropical jet and will likely move into the area tonight.
NAM soundings showing IFR to LIFR ceilings forming tonight while
GFS... rap... and sref showing MVFR ceilings. High clouds will likely
inhibit some of the radiational cooling which will also help winds
from fully decoupling (especially in urban areas). This would
favor MVFR ceilings instead of LIFR/ IFR. 23
Previous discussion... /issued 313 PM CDT Wednesday Apr 16 2014/
a progressive upper air pattern will bring a series of upper
level shortwave troughs across southeast Texas during the next
7-day period. The first affects the Gulf waters on Thursday...with
a weak system over the inland areas Thursday night. Another weak
system moves overhead on Saturday. A strong upper trough then
moves out of The Rockies on Saturday and into the Southern Plains
on Sunday...however this system shears out as it moves across the
area on Monday. The surface ridge overhead southeast Texas this afternoon
will generally stay in place...although it does recede somewhat
through Sunday and rebuilds the ridge over the la and Upper Texas
coastal areas on Monday and Tuesday.
The main item of concern the next few days will be temperatures
and cloud cover. A fairly strong cap will keep rain chances under
20 percent through Saturday. The shortwave moving over the Gulf
will lead to mostly cloudy skies and at least sprinkles or
drizzle under the cap on Thursday. Even though there will be warm
air advection...temperatures are expected to only be a few
degrees warmer on Thursday as compared to today mainly because of
the cloud cover. Warmer temperatures will arrive on Saturday with
decreasing cloudiness. On Sunday the best vorticity advection
will be well north of the forecast area although the jet dynamics
aloft will be somewhat favorable for at least weak convection
over southeast Texas. The GFS bufr is still capped while 12z GFS and European model (ecmwf)
are both dry on Saturday and actually keep the bulk of the quantitative precipitation forecast to
the west on Sunday. For now will lower rain chances both days...10
percent on Saturday and 20 percent on Sunday. Even though the
upper trough moves overhead...went with 20 percent Sunday night
and Monday as well since both models keep the best rain chances to
the north and west both periods.
light to moderate east to southeast winds along with slightly
elevated seas will persist through Thursday night. A brief wind
shift to the NE will be possible on Friday before onshore winds
become reestablished Friday night...persisting through the end of
next week. 43
Previous discussion... /issued 1206 PM CDT Wednesday Apr 16 2014/
see 18z aviation discussion.
VFR conds expected through this evening. NAM and GFS differ with
regard to the moisture profile after 03z with the NAM more
aggressive with moisture and consequently lower ceilings. Nam12
verified well from yesterday but feel it might be a bit too
aggressive so leaned a bit toward the GFS. The GFS suggests MVFR
ceilings overnight with conds becoming VFR by middle Thursday morning.
Preliminary point temps/pops...
College Station (cll) 52 72 57 78 58 / 10 10 10 10 10
Houston (iah) 55 73 58 80 59 / 10 10 10 10 10
Galveston (gls) 61 72 63 75 66 / 10 10 10 10 10
GM...small craft should exercise caution from 10 PM this evening to 4
am CDT Thursday for the following zones: waters from
Freeport to the Matagorda Ship Channel 20 nm to 60 nm...
waters from Freeport to the Matagorda Ship Channel out 20
nm...waters from High Island to Freeport 20 to 60 nm...
waters from High Island to Freeport out 20 nm.