Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 171526

Area Forecast Discussion
National Weather Service Houston/Galveston TX
926 AM CST Sun Dec 17 2017

Quick morning update to extend the Dense Fog Advisory through 11
AM CST and add Montgomery, Polk, and San Jacinto based on latest
observations. Low clouds between 500-1500 feet AGL will result in
slower heating in these areas this morning and expect fog to
persist through the late morning hours as a result. Localized
areas of dense fog will be possible outside of the Dense Fog
Advisory, but TranStar webcams show most roadways clear of fog
around the Houston metro and have not included Harris County at
this time. Also updated temperature trends as a result of
clouds/fog and lowered high temperatures for the day a degree or
two. Remainder of forecast is on track with highs in the low to
mid 60s today.



.PREV DISCUSSION... /ISSUED 456 AM CST Sun Dec 17 2017/

Areas of fog continue to develop in the wake of the departing
system that brought rain and some tstms to the region overnight.
Look for this to scatter out along w/ some breaks in the low
cloudiness toward late morning. Get out and enjoy the
Monday thru Tue night are looking wet.

A warm front is expected to push northward toward the coast
Monday morning...slowly inland thru the day...and eventually
slow/stall just north of the region on Tue. Expect the typical
dreary wx associated with these fronts: rain, fog, drizzle, some
embedded tstms, etc to accompany the warm front. (PW`s actually
rebound fairly close to climo maximums, so can`t rule out some
fairly healthy downpours as well.

By Tuesday, the upper low seen on water vapor imagery near
southern Arizona will be approaching west Texas. Large scale lift
will be enhanced as the trof makes continued eastward progress
across north Texas. Guidance is suggesting a sfc wave/low may
develop along the previously described frontal zone just to our
nw. Forecast soundings indicate an increasing llvl jet, moderate
shear, CAPES between 1000-1500 j/kg and little capping Tuesday
afternoon and evening so we`ll need to keep an eye on the
potential for some strong/severe cells. The upper trof will move
over the Arklatex area Tuesday night and drag a surface front
through the area...with precipitation & the sea fog threat ending
with the wind shift.

Wednesday looks dry in the wake of that departing system. Thursday
is currently looking that way too, but onshore winds will be
resuming so a gradual increase in clouds/moisture levels will be
in store.

The much talked about late week strong cold front is still
expected to move through southeast Texas. The latest model
guesses are a touch later with the fropa (during the day Friday
now). And other than an initial bout of precip along the leading
edge, post fropa wx is being shown as mainly dry by most of the
current data. I`m not going to  every detail of the extended
model forecast as it will certainly change, several times, in the
coming days. Like tropical wx, trends are always fun to watch, but
until we get a bit closer to the time period in question, there`s
just too much uncertainty to accurately predict winter wx impacts
(if any) this far out. 47

While winds have decreased across the coastal waters this morning,
seas are lagging a bit behind. Have kept the SCA for the offshore
waters in place through mid morning and an SCEC for the nearshore
waters during this same time. The light/moderate NW winds will be
veering back to the E/SE today and tonight. The increasingly fav-
orable pattern for sea fog development (with warm/moist air flow-
ing across the cooler shelf waters) is expected to be in place by
tonight and persist into the start of the new week/until the next
cold front moves into the Gulf waters. This next front is progged
expected to push off the coast late Tues night/early Weds morning.
Light to mostly moderate offshore winds in the wake of this front
should be brief as onshore winds return/strengthen Thur and early
Fri out ahead of a second stronger cold front...which should push
into the marine waters Fri afternoon. Moderate/strong north winds
will develop in the wake of this boundary and an SCA is likely. 41

Will be dealing with a mix of IFR/MVFR VIS and CIGS for much of the
rest of this morning in the wake of the system last night. With the
winds veering back to the E/SE this afternoon...we should be on the
lookout for increasing low-level moisture tonight through early Mon
morning. IFR/MVFR conditions will likely prevail once again for the
overnight hours. We should see improvements to this afternoon (with
mainly high clouds). The exception to this may be GLS where sea fog
could make an appearance late this afternoon/early evening. 41


College Station (CLL)      63  52  66  60  70 /  10  10  60  70  70
Houston (IAH)              66  56  68  64  75 /  10  30  60  60  60
Galveston (GLS)            63  60  69  65  73 /  30  40  60  40  30


TX...Dense Fog Advisory until 11 AM CST this morning for the
     following zones: Brazos...Burleson...Grimes...Houston...
     Madison...Montgomery...Polk...San Jacinto...Trinity...



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