Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 191003
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
503 AM CDT Fri May 19 2017

.DISCUSSION...
Like yday, can`t rule out some brief isolated & insignificant
shra under the cap. Otherwise, continued warm and breezy today.
May see another record or two in jeopardy at Galveston (record
high 87/2008 & record high min 78/2015).

Beyond that...forecast confidence between Sat afternoon and
Tuesday is quite low.

The upper trof currently stretching across the Rockies will make
its way into the cntl and nrn plains this weekend. Its associated
surface cool front will make its way into se Tx Saturday aftn but
gradually loose it`s support and southward momentum. It`ll eventually
stall somewhere near the coast Sunday. This boundary, or remnants
of such, will meander about the region into Tuesday and provide a
focus for precip as a series of upper disturbances embedded in
the sw flow aloft move overhead.

As to exactly where the boundary will be, timing/placement of the
disturbances, and how much rain will occur -- unfortunately
there`s a high degree of uncertainty. Much of this will be likely
be determined on a smaller scale than models can resolve this far
out.

Expect some scattered showers and tstms to develop along the
front late in the day Saturday as it pushes in. Late Saturday
night & Sunday morning, several models indicate a fairly healthy
vort moving ene from the Big Bend area and parallel to the slow
moving boundary. There is some concern for some localized heavy
rain as PW`s pool to 1.7-1.9" along the front, cap has eroded,
mean steering flow diminishes to <8kt, along with some notable
upper diffluence aloft. Most solutions, including SREF plumes show
total QPF`s into Monday morning less than 1.25" which would be
highly welcome rainfall. But, we`ve also noticed some much higher
bullseye`s pop up for several days now. They`re highly inconsistent
from model-to-model and run-to-run, but can`t completely ignore
such signals that keep showing up with a surface boundary
lingering about in May. (Also of note, is the Tx Tech WRF which
has been excellent as of late, isn`t all that impressed). Think
the main threat area for heavy rain Saturday night and Sunday, if
there ends up being one, will mainly be n/nw of HWY 59.

As mentioned above, chances of precip should continue thru the
day Tuesday until a stronger front moves into the region and off
the coast late in the day. This front should have enough upper
support to do so. 47

&&

.MARINE...
Onshore winds are continuing to decrease this morning but will keep
the SCEC/SCA up for the coastal waters through 18Z/1 PM at the very
latest. However, that being said, we could see the gradient tighten
up briefly once again late this afternoon as models try to bring a-
nother shortwave into the area from the west. These moderate/strong
wind speeds should finally start to decrease Sat/Sun as a weak cold
front moves into northern portions of SE TX. Scattered showers with
possibly strong thunderstorms will be possible Sun through Tues for
our marine locations. This activity is expected to shove out of the
area will late Tues with the passage of a cold front. Moderate off-
shore winds will develop across the bays/coastal waters in the wake
of this front by early Weds morning. Onshore winds are then progged
to return Thurs afternoon. 41

&&

.AVIATION...
Not planning on a lot of changes with the 12Z TAFS...keeping with a
mix of MVFR/overcast VFR CIGS this morning. The strong WAA in place
could help to produce an isolated SHRA through mid morning but, the
best chances for precipitation should be for our northern sites for
this afternoon/early evening with the approach of the dry line from
the west. The cap will likely hold so not going with any mention at
this time. Hazy conditions are expected down at GLS once again this
afternoon. MVFR CIGS should return tonight/early Sat morning. 41

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      90  75  87  68  83 /  20  20  50  70  30
Houston (IAH)              90  75  89  72  86 /  20  10  40  50  60
Galveston (GLS)            87  79  87  77  85 /  20  10  20  30  50

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 5 AM CDT early this
     morning for the following zones: Galveston Bay...Matagorda
     Bay.

     Small Craft Advisory until 5 AM CDT early this morning for the
     following zones: Coastal waters from Freeport to the
     Matagorda Ship Channel out 20 NM...Coastal waters from High
     Island to Freeport out 20 NM.

     SMALL CRAFT SHOULD EXERCISE CAUTION until 1 PM CDT this
     afternoon for the following zones: Coastal waters from
     Freeport to the Matagorda Ship Channel out 20 NM...Coastal
     waters from High Island to Freeport out 20 NM.

     Small Craft Advisory until 1 PM CDT this afternoon for the
     following zones: Waters from Freeport to the Matagorda Ship
     Channel from 20 to 60 NM...Waters from High Island to
     Freeport from 20 to 60 NM.

&&

$$



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