Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 130957
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
457 AM CDT Fri Oct 13 2017

.UPDATE...
Quick forecast update to expand the ongoing Dense Fog Advisory to
Brazos, Burleson, and Grimes Counties this morning. The GOES 16
fog product continues to show fog spreading northward across these
counties and visibilities at Caldwell have already dropped to one
quarter mile. No other changes made to ongoing forecast.

Huffman

&&

.PREV DISCUSSION... /ISSUED 356 AM CDT Fri Oct 13 2017/

DISCUSSION...
Dense fog has developed in areas west and southwest of the
Houston metro early this morning, with the GOES 16 fog product
showing the fog slowly spreading northward into Washington and
northern Waller counties. Cannot rule out having to add a few
more counties to the advisory as the morning wears on, especially
if the low stratus that has developed across the Brazos Valley is
able to build down.

Expect the fog to begin lifting after sunrise with a very warm
day on tap for Southeast Texas as a mid/upper level ridge remains
anchored over the Gulf coast states. Not only will this ridge
promote high temperatures in the upper 80s to low 90s across the
region, but it will keep dry weather in place across the region.
While a few flat cumulus may be able to develop during the peak of
daytime heating, expect clear skies to become established
overnight and promote another round of radiation fog development
Saturday morning. Favored areas for fog development are again
expected to be areas west and southwest of the Houston metro, but
continued moisture recovery today may result in more areas seeing
fog development tomorrow morning. Fog dissipation should occur
shortly after sunrise Saturday. Morning lows in the upper 60s to
upper 70s should warm into the upper 80s to low 90s again as
ridging aloft shifts slightly towards the east but maintains most
of its influence over the region. Slightly less subsidence as a
result of this shift may result in a few showers develop near the
coast on Saturday with heating.

An approaching shortwave trough now located near the Pacific
Northwest coast will swing across the Northern Plains Saturday,
sending a cold front southward across Texas on Sunday.
Deterministic guidance is fairly consistent with this cold front
reaching the Houston metro around midday on Sunday but appears to
differ with the amount of warming that will occur ahead of the
cold front as MOS guidance has a 5-10 degree high temperature
difference at inland sites. Cloud cover ahead of the front
appears to be an important factor in these temperature
differences and with forecast soundings showing scattering of
clouds ahead of frontal passage, have trended towards the warmer
side of guidance for Sunday with highs ranging from the upper 70s
to mid 80s. Otherwise, moisture returning ahead of the front`s
arrival should result in isolated to scattered showers developing
along the front as it sweeps across the region, with breezy and
drier conditions expected behind the front by Sunday evening and
continuing through Sunday night.

Dry northwest flow aloft becomes established across the region
Monday and Tuesday with temperatures near seasonal normals to
start the work week (highs in the mid 70s to near 80, lows in the
upper 40s/mid 50s inland to mid 60s along the coast). Poor
agreement in medium range guidance Wednesday and beyond provides
low confidence on when rain chances will return to the forecast,
but return flow resuming offers an opportunity for low rain
chances to return to the forecast mid to late next week.

Huffman

MARINE...
A light onshore flow will continue for the next 24 hours before
winds shift to the northeast at 10 to 15 knots during the day
Sunday in advance of a cold front that should move off the coast
early Sunday evening. Winds behind the front will be northerly at
15 to 20 knots...possibly increasing to 20 to 25 knots on Monday
morning. SCEC flags will likely be needed from Sunday night
through Tuesday morning except for Monday morning when a SCA may
be needed.

A band of showers and thunderstorms is likely around frontal
passage on Sunday evening. Otherwise...the chance of rain is below
30%. Tides are running about a foot above normal and should drop
to near normal values behind the front. 44

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      91  71  91  70  81 /   0   0   0  10  30
Houston (IAH)              91  71  90  71  87 /  10  10  10  10  30
Galveston (GLS)            87  79  87  78  85 /  10  10  10  10  30

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Dense Fog Advisory until 9 AM CDT this morning for the following
     zones: Austin...Brazoria...Brazos...Burleson...Colorado...
     Fort Bend...Grimes...Jackson...Matagorda...Waller...
     Washington...Wharton.

GM...NONE.
&&

$$

Discussion...14



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