Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 040536
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1136 PM CST Sat Dec 3 2016

.AVIATION...
Areas of -RA with embedded SHRA/TSRA have begun to move into the area
from the west and southwest. Looking at periods of SHRA/TSRA and
associated IFR ceilings and visibilities overnight and on into tomorrow.
Hard to pinpoint the spots that will have the most impact, but current
thinking is that the locations closest to the coast (LBX and GLS) and
offshore might be at the greatest risk for periods of TSRA while the
rest of the area has mostly SHRA. In the stronger activity, LIFR conditions
will be possible. Do not anticipate significant improvement until Monday
and Monday night when this storm system finally moves off to the east.
42
&&

.PREV DISCUSSION... /ISSUED 707 PM CST Sat Dec 3 2016/

UPDATE...
Per radar and surface/marine observations, the frontal boundary
continues to sag farther offshore, and the heaviest rain is
currently over our Gulf waters, extending into Southwest
Louisiana. Over land, numerous light to moderate showers are still
falling across the entire area. These showers will continue
through the evening, but we should at least be looking at a brief
respite from the heavy rain this evening into at least the early
overnight hours.

That said, multiple convection allowing models fill back in with
more precip over the area after midnight and towards Sunday
morning. Like Saturday, both the boundary near the coast and
(to a lesser extent) farther inland near the 850mb front will be
the foci for precipitation. There is general consensus that the
surface front/coastal trough will be forced back towards shore
some overnight, and if it sets up in a similar spot, we could see
a repeat rain performance. On the plus side, recent runs of the
HRRR seem to be trending to the heaviest rain setting up more
offshore than right on the coast, which would be very welcome.
Regardless, the heavy rain in coastal communities Saturday create
a saturated situation in which lesser rains Sunday still look to
pose flooding problems. And even if the axis of heaviest rain just
misses, rain will fall.

Luchs

MARINE...
Areas of rain with embedded thunderstorms continued to occur over
most of the nearshore Gulf waters and Galveston Bay at mid
afternoon. The rain was occurring along a warm frontal boundary that
was nearly stationary just off the immediate coast. Isolated
stronger storms with wind gusts and waterspouts will continue to be
possible into this evening east of the warm frontal boundary.
Periods of rain and embedded thunderstorms will continue through
Sunday night into Monday and end late Monday as the storm system
moves east of the area.

Tidal flooding will continue to be a threat along low-lying areas
at the coast through tonight. Problems may persist into Sunday and
Monday.

Other impacts expected are advisory conditions due to winds and seas
over the Gulf waters. The pressure gradient weakens slightly tonight
and may lead to diminishing winds; however, seas will probably stay
up at least over the offshore waters tonight. Winds may pick back up
later Sunday into Monday.

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      49  54  48  56  45 /  80  90  90  80  10
Houston (IAH)              53  56  50  59  48 /  80  80  90  90  10
Galveston (GLS)            59  61  57  64  56 /  90  90 100  90  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Flash Flood Watch through Sunday evening for the following
     zones: Austin...Brazoria...Brazos...Burleson...Chambers...
     Colorado...Fort Bend...Galveston...Grimes...Harris...
     Houston...Jackson...Liberty...Madison...Matagorda...
     Montgomery...Polk...San Jacinto...Trinity...Walker...
     Waller...Washington...Wharton.

     Coastal Flood Advisory until 6 AM CST Sunday for the following
     zones: Brazoria...Chambers...Galveston...Harris.

GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 6 AM CST Sunday 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 6 AM CST Sunday 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.

&&

$$

Discussion...25
Aviation/Marine...42



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