Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 170251
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
851 PM CST Tue Jan 16 2018

.DISCUSSION...

...Icy roads will produce dangerous driving conditions through
Wednesday morning...

The last bit of precipitation is exiting the coast near Matagorda
Bay. Additional precipitation is not expected overnight as upper
level winds become increasingly confluent and much drier air works
into the region from the surface up to 700 mb. Since the precip
has ended, can`t really justify the Winter Storm Warning so will
replace it with a Winter Weather Advisory. The Advisory is going
to be used to heighten awareness about how dangerous driving will
be tonight. Raods are wet and as temperatures drop, the roads and
bridges will become icy. Winds don`t decouple so the combination
of the moderate winds and cold temps will yield dangerous wind
chill values in the single digits. The Wind Chill Advisory and
Hard Freeze Warning will remain in effect through 10 AM Wednesday
morning.

Forecast soundings at FWD show significant drying and satellite
imagery shows clearing just on the doorstep of the HGX CWA. The
clouds have kept the temperatures stable over the last couple of
hours but feel once skies begin to clear, the temperatures will
begin to drop. Temperatures are in the teens upstream and
continued cold air advection should allow temperatures to fall
into the teens over the north and lower/mid 20s south.

&&

.PREV DISCUSSION... /ISSUED 527 PM CST Tue Jan 16 2018/

AVIATION...
The main band of wintry precipitation is continuing to shift
southward this evening, leaving behind VFR ceilings. This
precipitation which has been a mixture between ice pellets and
light snow, is continuing to impact SGR, HOU, LBX, and GLS.
Expecting the remnant precipitation to push offshore by 03Z.
Ceilings will continue to rise and VFR conditions will prevail
across all TAF sites.

North winds will decrease through the early evening across the
northern set of terminals. The metro and coastal terminals will
keep wind speeds between 10-20 kts overnight, with conditions
gusting to around 25 kts specifically at GLS. By sunrise, wind
speeds will have decreased to around 10 kts for all terminals
beside GLS which could still see wind gusts approach 20 kts.
Wind direction will gently veer from the north to northeast.

Hathaway

PREV DISCUSSION... /ISSUED 345 PM CST Tue Jan 16 2018/

DISCUSSION...
You know you have had a busy day when you completely forget to
write a morning update AFD. Sorry but on the bright side we did
get all the other products updated and put information in NWSChat
for EMs and media to know our plans for the forecast.

Today we saw a mix of precipitation but mainly sleet. There was
some freezing rain to start but the accumulations remained low.
However accumulations were not low enough to not cause problems
and then there was sleet/snow falling on top of that ice and
frozen structures to make for a mess on area highways, bridges and
overpasses. Radar still shows a batch of precipitation coming from
the west which should reach Houston over the next hour or two in
time for rush hour. Hopefully people stay home or left work early
because any precipitation that falls will be sleet/snow making
travel conditions worse than they are already. Temperatures are
solidly in the mid/upper 20s so we will continue the winter storm
warning for a portion of the area. This area is basically south of
Brenham to Huntsville. North of that line a winter weather
advisory is in effect mainly for hazardous travel conditions.

Tonight temperatures drop more into the teens and low 20s so a
hard freeze warning is in effect for the whole area through
Wednesday morning. Winds are still blowing quite strong which
lowers wind chill values below 13F so we have a wind chill
advisory in effect for the same time frame as the hard freeze
warning. It is just best not to be outside tonight or travel. If
stuck outside frost bite and hypothermia will be issues.

The plan for the winter weather advisory and winter storm warning
will be to cancel as needed this evening with precipitation ending
from north to south. Look for updates to these products through
the evening tonight.

Extended Forecast...cold continues Wednesday. The record low
maximum temperature for IAH is 36F. We have a high of 37F so we
will be flirting with that record. That should let you know how
cold it will be tomorrow. From there conditions do warm up with
warm air advection occurring Friday through Sunday. Low
temperatures will be back in the 50s for the weekend. Another
front and storm system moves across on Sunday so will keep some
solid rain chances going for Sunday. High pressure builds in early
next week but temperatures will be back near normal or slightly
above Monday and Tuesday next week.

Overpeck

MARINE...
Small craft advisory in effect now with winds gradually
diminishing tonight/early Wednesday. Seas though will still be big
problem offshore with 11-13 feet but these too will be coming
down after midnight.

Tide levels have dropped to -1.2 to -1.8 feet and so have
continued the low water advisory through the next full tide cycle
Wednesday afternoon. Some slight improvement possible but still
challenging marine conditions with the strong winds/currents and
low water levels.

High pressure settles in Wednesday and winds relax and eventually
turn to the east Thursday and southeast Thursday night/Friday
morning. By late Friday dewpoints will rebound and potential for
sea fog increases dramatically. SST getting a good chilling today
and at GLS was down to 44 this afternoon.
45

FIRE...
Very low dewpoints will filter into the area but with winds
relaxing do not anticipate any elevated fire conditions. Sunny
skies Wednesday with an increase in clouds Thursday as winds turn
around to the east.
45

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      17  37  21  43  32 /  10   0  10  10  10
Houston (IAH)              20  37  23  43  36 /  10   0  10  10  20
Galveston (GLS)            25  36  31  45  43 /  30   0  10  10  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Hard Freeze Warning until 10 AM CST Wednesday 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.

     Winter Weather Advisory until 5 AM CST Wednesday 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.

     Wind Chill Advisory until 10 AM CST Wednesday 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.

GM...Low Water Advisory from 4 AM to 6 PM CST Wednesday for the
     following zones: Galveston Bay...Matagorda Bay.

     Small Craft Advisory until 4 AM CST Wednesday for the following
     zones: Galveston Bay...Matagorda Bay.

     Small Craft Advisory until 6 AM CST Wednesday 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 noon CST Wednesday 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...43


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