Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 171220
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
617 AM CST Sat Feb 17 2018

.AVIATION...
Stationary boundary draped over the city this morning may move
north a touch as a warm front in response to a reinforcing cool
front moving into our northern-most counties latter this morning.
A challenging forecast as cats in and around this boundary will
vary from as low as VLIFR to as high as MVFR. If this front creeps
a bit more north...then cats will typically stay under IFR south
of it/MVFR to north. But...`Typical` doesn`t seem to want to play
this morning as there are current (V)LIFR cats north of this
boundary (UTS). Showers have been streaming up within the mid-level
southwesterly flow pattern. Thus...will maintain VCSH through a
good part of the day as sites may see enough cloud breaks/sun to
aid in (re)generating pesky PM showers. Any improvement in ceilings
to MVFR/VFR will be short-lived as expecting that above mentioned
cool front will wash out and many south of the city boundary will
quickly fall back to under MVFR within lowering clouds and fog.
Maritime areas will be slow to improve through the early afternoon
...once again falling to at least IFR around sunset or similar to
what has been experienced these past few days. 31

&&

.PREV DISCUSSION... /ISSUED 411 AM CST Sat Feb 17 2018/

DISCUSSION...
Surface observations and area webcams currently indicate areas of
dense fog confined to locations mainly right along the coast and
in parts of our nearshore waters. A little further inland across
the coastal counties, visibilities are around 1/2 mile or greater.
Will continue to monitor for a possible Dense Fog Advisory. Frontal
boundary remains nearly stationary across the area, roughly around
the Highway 59 corridor with dew points at or below 60 to the north
and in the mid to upper 60s to the south. This boundary should meander
across the area today and could play havoc with our high temperature
forecast that currently has this afternoon`s peak around 60 degrees
across our northern counties to the mid 70s across the coastal counties.
Areas of fog will persist to the south of the front especially across
our coastal waters where some could be dense. Much of the area should
be cooler tonight, but temperatures will again be tricky as some models
indicate the frontal boundary possibly edging off the coast in/around
the Galveston Bay area. Have 30%-40% rain chances today decreasing
to 20%-30% tonight and tomorrow. For tomorrow, an onshore flow returns
to the area and strengthens, and this flow will persist through Tuesday
resulting in warming temperatures areawide. Still looking at significantly
increasing rain chances beginning as early as Tuesday afternoon and
possibly persisting into Wednesday night or Thursday morning as a
deep southwest flow aloft brings upper disturbances across the area
and combines with a slow moving front that interacts with deep Gulf
moisture and lift. 42

MARINE...
Periods of sea fog will persist through the weekend under persistent
warm onshore winds. A Dense Fog Advisory is currently in effect this
morning and will likely be re-issued or extended through Sunday.
Friday`s cold front has stalled just inland of the coast and will
remain near stationary before washing out or moving further inland
as a warm front Sunday. Due to little to no change of this warm and
moist air mass over cooler shelf waters...periods of returning fog
will impact our local waters through at least mid next week. Lowering
western Plains pressure ahead of the next developing cold front will
tighten the early week onshore pressure gradient. Sunday night through
early Wednesday southerlies will strengthen to Caution levels over the
bays/nearshore Gulf waters and (near) Advisory levels over the offshore
Gulf waters. Sunday`s 2 to 3 foot seas that will build to 4 to 6 foot
seas by Monday night. 31

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      62  54  72  63  78 /  40  30  30  20  20
Houston (IAH)              71  57  74  64  78 /  40  30  30  20  20
Galveston (GLS)            71  60  71  65  73 /  30  20  20  20  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...Dense Fog Advisory until noon CST today 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.

&&

$$

Discussion...42
Aviation/Marine...31


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