Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 231454
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
954 AM CDT Wed May 23 2018

.UPDATE...
Typical summer-like weather anticipated across SE TX today, with
temperatures as of 9 AM already in the low 80s and dewpoints in the
mid to upper 70s. Convective temperatures have already been met
along the coast and over the Gulf waters, and should quickly be met
further inland with convective temperatures ranging between 82-85
degrees. High temperatures today will warm into the upper 80s to
low 90s. Cloud cover will become more widespread by the afternoon
hours as precipitable waters approach 1.8-1.9 inches. Current
radar imagery shows a scattering of showers and thunderstorms
across the bays and Gulf waters, with most of the inland precipitation
south of I-10. Short term guidance indicates decent shower and
thunderstorm coverage continuing to fill in along the coast this
morning, with coverage increasing and spreading inland this
afternoon. Instability parameters show lapse rates becoming
unstable and rising to 7.5-8.0 deg C/km with CAPE values between
2,000-3,000 J/kg, but little in the way of wind shear. Stronger
storms could yield locally heavy downpours, and frequent
lightning can be anticipated. The HRRR, ARW, and Texas Tech WRF
solutions are all in agreement with convection pushing further
inland past I-10 around noon. Most of precipitation should begin
to dissipate shortly after sunset with the loss of daytime
heating. Low temperatures tonight will fall into the upper 60s to
low 70s, with skies should become partly cloudy.

Hathaway

&&

.PREV DISCUSSION... /ISSUED 653 AM CDT Wed May 23 2018/

AVIATION [12Z TAF Issuance]...

Patchy ground fog has been observed at a few of the terminals
this morning but overall should not be an issue. VFR ceilings are
expected today with convection beginning in the next 3-6 hours.
TAFs have convection starting around 15-17Z with VCTS for the
afternoon from 17Z to around 22Z. Timing based upon HRRR and WRF
model trends. Axis of higher moisture noted on GOES derived
precipitable water imagery was loated just off the coast SE of
Galveston. This moisture should begin to push inland and with
daytime heating allow for scattered showers and thunderstorms
starting along the coast and then pushing inland. TSRA affecting
each airport will be difficult to pinpoint given the scattered
coverage of the activity but may need to update for TSRA and gusty
thunderstorm winds as convection evolves. After 00-02Z Thursday
winds should become less than 5 knots with mainly VFR ceilings if
any. There may be some ground fog again for Thursday morning.

Overpeck

PREV DISCUSSION /Issued 413 AM CDT Wed May 23 2018/...

Patchy fog has begun to settle in across portions of the area
again this morning with some very isolated showers over the
waters and right along the coast. Much like the past several days,
any fog should dissipate quickly after sunrise. Another round of
showers and thunderstorms is expected today, although short term
guidance is suggesting higher coverage than yesterday. Model
soundings indicate PWs between 1.7 and 2 inches, which is up from
yesterday and likely the cause of the higher coverage. Soundings
also indicate an inverted V again this afternoon, so gusty winds
will remain a threat with the stronger storms. Showers and storms
should diminish after sunset with loss of heating.

Scattered showers and thunderstorms will still be possible each
day heading into the weekend, but the better potential will shift
off to the east as upper level ridging pushes into West Texas.
Conditions look much drier heading into the start of next week as
we are sandwiched between upper ridging over West Texas and an
upper low over the N Central Gulf. Models are also indicating the
possibility of some tropical development in the eastern or central
Gulf, taking the center of the surface low anywhere from E
Louisiana to Florida. This should keep the better rain potential
well off to our east. However, with dry conditions and upper
ridging sliding even closer, high temperatures will climb into the
mid to upper 90s by early next week with heat index values in the
low to mid 100s. If realized, this would give us another multi-
day run at record high temperatures across the area. Given the
onset of these hot temperatures this early in the year coupled
with the upcoming holiday weekend, heat safety and check the
backseat messaging will be paramount.

11

MARINE...
Surface analysis at 08Z shows a weak pressure gradient across much
of Texas. Onshore winds should continue around 10 knots for the next
several days with seas around 2-3 feet offshore and 1-2 feet near
shore.

We continue to monitor the possibility of tropical cyclone formation
over the eastern Gulf of Mexico for Friday into the weekend. At this
time, no impacts are expected other than maybe higher seas. That is
if something forms to begin with.

Overpeck

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      89  70  90  71  93 /  30  20  30  10  20
Houston (IAH)              89  72  90  73  93 /  50  20  30  20  30
Galveston (GLS)            87  77  86  77  87 /  50  20  30  20  30

&&

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

$$

Update...08


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