Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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097
FXUS64 KHGX 212134
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
334 PM CST Sun Jan 21 2018

.DISCUSSION...
Light showers are streaming north across areas along and west of
Interstate 45 this afternoon in a corridor of Gulf moisture being
drawn into the Southern Plains by a potent surface low over
Kansas. Afternoon aircraft soundings out of Houston show fairly
persistent capping around 7000 feet (775 MB) that should limit
most convective development across Southeast Texas this afternoon.
Height falls associated with an upper low now churning over the
High Plains and the arrival of a Pacific front/dryline later this
evening may provide enough forcing to overcome this cap across the
Brazos Valley and Piney Woods this evening (likely sometime after
6-9 PM), but weak convergence along this boundary and the
majority of the forcing remaining over the Ark-La-Tex continues to
raise questions on how far south thunderstorm potential will
extend into Southeast Texas tonight. However, a low potential for
at least an isolated strong or severe thunderstorm still exists
north of a College Station to Livingston line tonight. The main
threat in this area still appears to be gusty winds as mid-level
lapse rates steepen with the upper low`s passage, but SPC
mesoanalysis does show low level (surface to 2 km) winds having
backed over the past few hours and cannot rule an isolated tornado
this evening should the line move east this evening faster than
anticipated.

High resolution guidance seems to be in fairly good agreement that
a thin line of showers and a few thunderstorms will fill in along
the Pacific front/dryline as it sweeps across the region this
evening and tonight, reaching the Brazos Valley mid-evening, the
Houston metro after midnight, and moving off the coast after
sunrise. Breezy northwest winds 10-15 MPH will settle in across
the region behind the front with morning lows in the upper 40s to
upper 50s warming efficiently into the mid 60s to lower 70s under
sunny skies. Elevated fire weather conditions will be possible on
Monday as a result of these dry and breezy conditions and are
detailed further in the Fire Weather Discussion below.

Surface ridging behind the front maintains influence over the
region through mid to late week, leaving the region dry with
temperatures near seasonal normals (highs in upper 50s to mid
60s, lows in the upper 30s to 40s). Onshore flow and a gradual
warming trend begins Friday as the surface ridge slides off to
the east ahead of the next storm system, with isolated showers
returning to the forecast as Gulf moisture is pulled back into the
region. Rain chances will continue into the weekend before the
next front clears the region Saturday.

Huffman

&&

.MARINE...
Periods of fog (some dense) will continue across the bays and
nearshore waters until the front pushes off the coast early Monday
morning. Moderate onshore flow ahead of this front is also
producing 15 to 20 knot winds and 6 foot seas in the offshore
waters, and caution flags are currently in effect. Expect some
shower development out ahead of the front this evening and
tonight, with the front itself dragging a thin line of showers and
thunderstorms through the waters Monday morning. This will be
accompanied by a gradual wind shift to the northwest. Caution
flags will likely be required Monday into Monday night.

Winds gradually become NE to E by midweek before returning to SE
by the weekend. Sea fog could become an issue again by the end of
the week as deeper moisture moves back over the waters. Another
much stronger front should push off the coast next weekend. 11

&&

.FIRE WEATHER...
A cold front will pass through the region overnight tonight,
bringing drier and breezy conditions in its wake. RHs on Monday
afternoon could fall into the mid to upper 20s with winds near 15
mph. This will create elevated fire conditions across the area for
Monday. Tuesday will be just as dry but with much lighter winds.
Moisture will begin filtering back over the area Wednesday. 11

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      48  68  37  67  37 /  60   0   0   0   0
Houston (IAH)              57  70  41  67  40 /  60   0   0   0   0
Galveston (GLS)            58  70  47  64  45 /  60  10   0   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...Dense Fog Advisory until 3 AM CST Monday 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.

     SMALL CRAFT SHOULD EXERCISE CAUTION through late tonight 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...14
Aviation/Marine...08



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