Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 261457
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
957 AM CDT Wed Jul 26 2017

.UPDATE...
Minor changes to the forecast package this morning to account
for cloud cover and PoPs. Mostly clear skies this morning across SE
TX, with some lingering clouds over the coast. By afternoon expect
cloud cover to thicken with the development of showers and
thunderstorms starting as early as 19Z. Both the HRRR and RAP short
term guidance is indicating widespread isolated showers and
thunderstorms between 21 to 00Z today. ECMWF is in agreement with
this coverage, while the GFS is remaining on the drier side.
Considering initialization and performance over the last few
days, leaning towards the ECMWF and HRRR solutions for today. The
moisture is also on tap this morning, with PWs up to 1.9 to 2.0
inches across the coastal counties, lowering to 1.5 to 1.7 inches
in our northern counties. With the center of the surface high
pressure scooting westward and strengthening, low level
southeasterly winds will continue to help advect in these higher
PW values currently located over the northwestern Gulf of Mexico
throughout the day today. Based off current radar trend, lowered
PoPs for this morning to keep the 20% contained over the coastal
counties and 10% over the remainder of the CWA. Kept the afternoon
coverage the same, increasing to 30% PoP at 18Z through 00Z
across most of the western zones where we see these higher PW
values. Expecting convection to diminish by 01Z this evening, once
removing daytime heating. High temperatures today should reach
into the mid to upper 90s inland and upper 80s to lower 90s along
the coast.

Hathaway

&&

.PREV DISCUSSION... /ISSUED 442 AM CDT Wed Jul 26 2017/

DISCUSSION...
Southeast Texas looks to remain on the southern edge of mid/upper
level ridging today, and this position in combination with
daytime heating and precipitable water values rising back above 2
inches as deeper tropical moisture levels surge into the area from
the Gulf should allow for some shower/thunderstorm development.
Some models are indicating this increasing rain
probability/coverage while others are keeping a majority of the
area dry. For now, 20%-30% POPs look good, and will adjust upward
during the day if needed. Lowering pw values and slightly stronger
ridging should keep most of the area dry Thursday and Friday.
Heat and increasing heat index values are still the main weather
concern over the next several days. As noted for a while now, heat
index values in parts of our forecast area will be approaching
our heat advisory criteria of 108 degrees, and heat advisories
might be needed. The weather pattern changes over the weekend and
into next week as ridging moves westward and an eastern U.S.
trough sets up. This should allow a frontal boundary and
associated increasing rain chances to enter our area over the
weekend and possibly persist on and off into next week, but
initially the western ridge might stay strong enough to keep a
majority of the rainfall off to our east as depicted by the latest
WPC QPF forecasts. Better rain chances might end up coming toward
the middle to end of next week when ridging influence moves
westward and Southern Plains troughing sets up. This pattern
change is supported by CPC`s 6 to 10 day and 8 to 14 day outlooks
that indicate increasing probabilities of below normal
temperatures and above normal rainfall. 42

MARINE...
High pressure situated over the north central Gulf will maintain
light onshore winds and low seas going into the weekend. A weak
frontal boundary will sag into east Texas late in the weekend and
could meander close to the coast into early next week. Other than
any associated storms...no significant concerns thru the period.  47

AVIATION...
There`s some patchy 4-6nm fog across portions of the region this
morning and satellite pix look like some brief 1000-2000ft cigs may
be a possibility mainly w/nw of the metro area until shortly after
sunrise. We`ll have slightly higher moisture levels to work with
today compared to Tue. As temperatures climb 90-94 degrees, look for
some scattered storms to develop inland. Forecast soundings show
some CAPEs of 3000-4000, LI`s around -9 and and inverted V profile
later this afternoon...so cannot rule out a couple of strong storms
capable of producing some elevated wind gusts.  47

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      99  77 100  78 101 /  20  10  10  10  10
Houston (IAH)              95  77  97  78  98 /  30  10  10  10  10
Galveston (GLS)            90  82  93  82  92 /  20  10  20  10  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

Update...08


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