Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 190552

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1152 PM CST Thu Jan 18 2018

Ceilings will drive the forecast through the TAF period, and
trends in guidance and model soundings have began to lower
ceilings faster in their most recent runs. Expecting MVFR ceilings
to prevail by sunrise, and IFR ceilings to settle in early Friday

Additionally, short term guidance has backed off on shower
coverage associated with the area of low pressure pushing towards
the upper Texas coast Friday, keeping most of the precipitation
over the coast and Gulf waters. Have decided to remove VCSH from
IAH based on these trends, and also limited the time frame for
possible VCSH at SGR and HOU. Went ahead and slowed the timing for
shower development beginning to impact the coastal terminals in
the morning to early afternoon hours, and anticipating showers and
isolated thunderstorms to dissipate or move offshore by sunset.

Beginning late Friday into early Saturday, visibilities will begin
to lower. The most recent run of the SREF has lowered visibilities
significantly, allowing radiational fog to develop early Friday
evening into Saturday morning, impacting mainly SGR and CLL. Have
gone ahead and lowered visibilities to MVFR criteria for these
two sites. The threat of sea fog will also be a factor along the
coast, with the potential to lower visibilities and ceilings at
GLS and LBX early Friday evening.



.PREV DISCUSSION... /ISSUED 913 PM CST Thu Jan 18 2018/

At 800 PM, a weak area of low pressure was trying to develop over
the western Gulf east of KBO. At 850 mb, high pressure was noted
over the western Gulf and moisture on the backside of the high was
increasing from BRO to CRP to LCH. At 700 mb, a well defined short
wave extended from SE OK into the Big Bend region and moisture
had begun to deepen along the middle and lower coast. At 300 mb, a
cyclonic shear axis extended across Central Texas. Warm air
advection coupled with lift from the short wave and shear axis
will generate some light showers and have expanded the area with
20 PoPs to include the Brazos valley and a bit further east along
the upper coast. It`s very dry in the sub-cloud region and much
of the rain will evaporate but some sprinkles still possible.
Surface high pressure over the southern US was moving east and
surface winds were slowly veering to the southeast. Cloud cover is
helping to insulate and temperatures have been very steady this
evening, remaining in the mid/upper 30s. The clouds and weak
onshore flow will likely limit the temperature drop tonight and
bumped temps up a few degrees. Temps will likely remain
steady/slowly fall through 08z and then slowly warm between
09-12z. 43

PREV DISCUSSION... /ISSUED 340 PM CST Thu Jan 18 2018/


Winds will gradually veer to the southeast tomorrow as high pressure
moves to the east of the region. As an area of low pressure develops
offshore on Friday, winds will continue to veer to southerly as
seas build. Chances of rain will increase heading into the weekend.
In between periods of precipitation, expect patchy sea fog to
develop late Friday as warmer air moves over the colder shelf water.
The fog threat will persist into Sunday evening when the next cold
front is forecast to push off the coast. 22


College Station (CLL)      42  33  50  47  67 /  10  20  20  40  30
Houston (IAH)              40  35  54  51  69 /  10  10  30  40  40
Galveston (GLS)            42  38  55  54  65 /  10  10  50  50  30




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