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fxus64 khgx 180542 

Area forecast discussion
National Weather Service Houston/Galveston Texas
1142 PM CST Sat Feb 17 2018

ceilings vary across southeast Texas with LIFR at kgls and klbx and MVFR
further north. A weak cold front has moved off the extreme upper
coast but the tail end of the front has hung up. Dense fog
continues near klbx but drier air will work into that area and
some brief improvement in visibility is expected. Ceilings will
lower overnight and IFR/LIFR ceilings expected through mid Sunday
morning. Winds should begin to veer to the east-southeast and increase as
low pressure develops in the Lee of The Rockies. Additional mixing
should allow ceilings to rise into MVFR and eventually scatter
out by late afternoon. Areas near the coast will likely endure low
ceilings and periods of fog as warmer air continues to flow over
cooler waters. 43


Previous discussion... /issued 900 PM CST Sat Feb 17 2018/

the main update with the forecast tonight is to account for a
farther south progression of a cold front than previously
advertised. The khgx radar shows this boundary stretching from
Vanderbilt to Bonney to Texas City and with the khgx VAD wind
profiler showing very light winds above the surface doing little
to inhibit the southward movement, expect density differences to
drive this boundary off the coast within the next 2-3 hours. As
this front cleared the National Weather Service Houston office, the temperature dropped
7 degrees within 30 minutes. Given these short-term trends, have
lowered low temperatures a few degrees into the upper 40s to near
60. A brief northerly wind shift associated with this boundary
moving off the coast may result in a brief respite in sea fog
(detailed in the marine section below) before winds veer to the
east sometime in the 3-6 am timeframe.

Storm Prediction Center mesoanalysis shows the 925 mb front located farther north,
roughly north of Interstate 10, and convergence along this feature
may produce isolated to scattered showers through the overnight
hours north of a Columbus to Liberty line. Patchy radiation fog
may also be possible as dew point depressions decrease overnight
through mid morning, with best chances west of a Madisonville to
Katy to San Luis Pass line.


a weak boundary continues to move toward the coast. Models are
not in great agreement but the latest hrrr shows the boundary
making it into the coastal waters before becoming diffuse later
tonight. North winds will develop in the wake of the front and
slightly drier air will likely make it into the waters. The drier
air will help erode the fog and the north winds should push any
remaining fog away from the coast. There should be some brief
improvement in visibility between 04-08z. East winds will develop
after midnight and become southeast on Sunday. Fog is expected to
redevelop between 08-10z and persist intermittently through Sunday
morning. Onshore winds will strengthen Sunday afternoon as low
pressure over eastern Wyoming deepens. The low will push east on
Monday/Tuesday and drag a cold front into the state. The front
will probably stall and onshore winds will persist into Wednesday.
Periods of sea fog will likely hang around during the first half
of next as warm and moist air continues to flow over the cooler
shelf waters. The long S-southeast fetch will bring slightly warmer water
toward the Upper Texas coast and this may mitigate the threat for
dense sea fog early next week. 43



Preliminary point temps/pops...
College Station (cll) 52 71 64 79 66 / 30 20 20 20 20
Houston (iah) 57 74 65 78 67 / 30 20 20 20 10
Galveston (gls) 60 71 64 73 66 / 20 20 20 20 10


Hgx watches/warnings/advisories...
GM...dense fog advisory until noon 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...Galveston Bay...Matagorda Bay.


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