Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 172339
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
639 PM CDT Fri Mar 17 2017

.AVIATION...
Still expecting a mainly MVFR ceiling to develop tonight through tomorrow
morning. Weakening winds could assist in possible IFR ceilings and/or
visibilities too. VFR conditions develop in the late morning through
afternoon hours tomorrow with lighter south to south southwest winds
generally 5 to 8 knots. Any mainly afternoon sea breeze associated
SHRA/TSRA development should be isolated, so not confident enough to
include in the TAFs.  42
&&

.PREV DISCUSSION... /ISSUED 302 PM CDT Fri Mar 17 2017/

DISCUSSION...
Clouds linger over SE TX and visible satellite imagery shows a
weak sea breeze trying to develop. Gusty onshore winds will
diminish overnight and should become light enough after 06z for
some fog to develop. Overnight temps should remain mild overnight
and will likely stay in the lower/mid 60s. Moisture levels deepen
on Saturday as PW values climb to between 1.00 and 1.20 inches.
Differential heating should allow another weak sea breeze to
develop. The convective temperature on Saturday is around 82-83
degrees. Fcst soundings show a capping inversion in the 850-700
mb layer eroding late in the day. Not sure this will actually
occur but can`t rule it out so will maintain 20 PoPs for possible
late day sea breeze activity. Fcst soundings show lapse rates near
7.1 degrees and an inverted V signature, so if storms can
develop, and that`s a big if, a few of the storms could put out
some gusty winds. Skies will begin to clear Saturday evening and
conditions look favorable for fog late Saturday and early Sunday.

Weak upper level riding remains anchored over South Texas Sunday
through Thursday. Moisture levels remain very low through the
period with PW values under an inch. Fcst soundings show a weak
cap in the 850-700 mb layer and the overall moisture profile just
looks too dry to support precipitation. Some change toward the end
of the week with the GFS bringing a strong upper level trough
toward Texas on Friday. The GFS brings PW values up to 1.60 inches
with some rather impressive jet dynamics, i.e., a splitting jet
structure and a departing 100 kt RRQ. The ECMWF has less mstr but
the jet dynamics look somewhat similar. The Canadian model looks
similar to the GFS at 500 mb, but looks closer to the EC at the
sfc. Will maintain the chance PoPs for next Friday but there is a
lot of inconsistency right now so will lean toward the blend and
wait for the models to come into better consensus.

Issued a Rip Current Statement earlier today based on reports from
the Galveston Beach Patrol. The strong rip currents should weaken
over the weekend as sfc winds decrease a bit. 43

MARINE...
Surface high pressure that is currently nestling into the
northeastern Gulf of Mexico will expand westward through tomorrow
and weaken the currently tight onshore pressure gradient.
Thus...southerlies will remain light this weekend with responding
lowering sea heights back to an average 2 to 3 feet by tomorrow
evening. Little change in the large scale as flattened ridging of
high pressure over the lower United States weakens ahead of an
approaching weather system Thursday. Much uncertainty on the timing
and strength of this passing upper level trough/surface cold front.
Boating interests will want to monitor weekly forecasts for a
possible late work week frontal passage leading to increased
rain/storm chances. 31

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      63  82  61  82  60 /  10  10  10  10   0
Houston (IAH)              64  82  61  84  60 /  10  20  10   0   0
Galveston (GLS)            66  76  66  77  66 /  10  10  10   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...High Rip Current Risk through Saturday morning for the following
     zones: Brazoria...Chambers...Galveston.

GM...NONE.
&&

$$

Discussion...11
Aviation/Marine...42



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