Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS64 KHGX 070026

Area Forecast Discussion
National Weather Service Houston/Galveston TX
626 PM CST Tue Dec 6 2016

Saturation under a low level (post) frontal inversion will
develop areawide MVFR ceilings this evening...falling to IFR
around midnight and through the early Wednesday morning hours.
Moisture trapped under this post-frontal inversion may saturate
the lower 1 km enough to allow LIFR decks to form during the pre-
dawn hours. Damp ground and weak north winds may also create an
environment favorable for MVFR visibility-restricting fog. Due to
the thick overcast inhibiting radiative cooling...there is some
uncertainty concerning the development and extent of early Wednesday
morning fog. Due to light winds leading to weak mixing...there
will be slow improvement from (L)IFR ceilings to MVFR Wednesday
morning. Many terminals may be dealing with MVFR decks through
the latter 6 hours of the period...or Wednesday afternoon. 31


.PREV DISCUSSION... /ISSUED 310 PM CST Tue Dec 6 2016/

Weak frontal boundary inching its way into the region. Cloudiness
along/behind the boundary is making for a wide spread of temps
this afternoon (50s-70s). Look for it to move off the coast this
evening. Shallow layer of trapped moisture under the inversion
will lead to some patchy drizzle/fog. This boundary will washout
off the coast on Wed.

More model differences regarding potential for sct precip late
Wed & Wed night ahead of the approaching strong cold front. GFS &
Texas Tech WRF have backed off chances, but other guidance still
suggesting decent overall coverage. Suspect the lesser QPF may be
the way to go as time for quality moisture to return will be
limited. Will leave POPS about as/is for now to see if there`s
some more consistency. May just see some dz/-ra ahead of & behind

Strong CAA and cloudiness in place on Thurs will produce dropping
temps thru the day. Wind advsy will likely be necessary as
well...esp at the coast where gusts aoa 40 mph are expected. Much
of the area will see freezing temps Fri morning and Freeze
Warnings will be needed for locations that haven`t seen one yet.
Guidance, which is usually a bit underdone in these airmasses, is
pointing to a freeze line to near I-10. Uncertainties regarding
overnight lows Thurs night/Fri morning include: whether cloudiness
exits in sufficient amount of time, if winds diminish, and the
affect of wet grounds across the area.

Cold conditions on Fri will gradually modify Sat and this weekend
as high pres moves off to the east and onshore flow resumes/increases.
Looking like there will be enough return moisture for a band of
precip to develop along the next front that pushes thru the area
Sunday night(ish). 47


A weak front will approach the coast tonight but will likely not
make its way off the coastline. A stronger front will move off the
coast Wednesday night. Strong offshore winds will develop behind
this front with at least gale force wind gusts possible most of the
day on Thursday. A Gale Watch will likely be issued later tonight. The
winds will slowly diminish Thursday night as the pressure gradient
relaxes and cold air advection diminishes.

There may be some impact on Thursday in the more north-to-south ship
channels as water is pushed out of the bays. The wind direction is
currently forecast to be north or even north-northeast and am not
expecting any low water advisories. However, will need to keep an
eye out for any adverse impacts if the wind direction changes more
to more northwesterly.

Moderate onshore winds are expected to develop on Saturday and near
advisory conditions will be possible on Saturday night. The winds
will diminish on Sunday ahead of another front Sunday night.  40


College Station (CLL)      46  64  41  41  28 /  10  10  30  20   0
Houston (IAH)              48  67  47  47  32 /   0  10  40  20   0
Galveston (GLS)            56  67  53  53  41 /   0  10  40  30   0




Aviation/Marine...31 is the U.S. government's official web portal to all federal, state and local government web resources and services.