Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 191129
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
629 AM CDT SUN JUN 19 2016

.AVIATION...
Surface boundary along the coastal areas should move inland later
today per the short range and high resolution models. A sea and
bay breeze may also help initiate showers and thunderstorms during
the afternoon. Confidence level in the models is moderate at best.
10Z HRRR initialized fairly okay and keeps the surface boundary
active through mid morning, and then develops scattered convection
around 21Z.

MVFR conditions at KCLL and KUTS should lift by 15Z. Otherwise,
the main impacts will be scattered showers and thunderstorms.
There is the potential for very isolated strong storms during the
afternoon and early evening.

40

&&

.PREV DISCUSSION... /ISSUED /

DISCUSSION...
At 3 AM, a cluster of storms was pushing west out of Austin, Wharton
and Jackson counties and will likely exit SE TX. Isolated showers
continue to develop over the gulf and near the coast and some of
these will showers will move inland prior to sunrise. 00z models
came in considerably drier today with PW values progged at 1.65 to
1.95 inches with significant dry near 700 mb. The lack of consistency
between models is troubling and have leaned toward the more
consistent Hi-Res NMM and the ECMWF.

A strong upper level ridge over SE CO is elongated from NE to SW
and this has allowed a brief weakness in the ridge over SE TX. A
weak inverted 500 mb trough is undercutting the ridge and will
slide westward into S TX later today. Fcst soundings start out
very dry but both the GFS and NAM12 increase PW values to 1.95 to
2.20 inches by 00z. Convective temperatures are in the upper 80s
closer to the coast and near 90 inland. Fcst soundings show very
little capping in place so would expect shra/tsra to increase in
coverage with heating. Jet dynamics look weak today. Moisture
levels stay high tonight so will continue to mention a slight
chance of showers. The NAM12 is more aggressive with moisture on
Monday and once again shows PW values peaking near 2.20 inches on
Monday afternoon. Convective temperatures remain in the upper 80s
so once again daytime heating should initiate convection. Jet
dynamics look a bit stronger on Monday so rain chances on Monday
might need to be nudged higher.

The upper level ridge begins to expand E-SE on Tuesday and heights
rebuild to 595 dm. Fcst soundings show a weak cap building in the
700-500 mb layer. PW values remain high, near 1.95 inches but
convective temps warm into the lower 90s. Can`t rule out some
isolated shra but chances look to be dwindling. By Wednesday, the
center of the ridge is over N TX with 500 mb heights back up to
596 dm. The ridge remains centered over N TX through Friday before
shifting toward LA through next weekend. The position and strength
of the ridge should preclude rain chances but both the GFS and
ECMWF show some light QPF each day. On Thursday, another weak
tropical wave will undercut the ridge. This trough will be
displaced well south of the region but the feature should still be
capable of eroding the southern edge of the ridge and allow a few
showers to develop. On Saturday PW values increase to 1.75 inches
so felt that also warranted a mention of showers.

MARINE...
Tropical wave evident in the 700-300 mb mean winds and the water
vapor satellite was moving into the western Gulf of Mexico at 330
AM. The models develop moderate onshore winds later today and
tonight as this system moves westward. Conditions could reach
caution criteria tonight or Monday. Winds and seas should then
diminish during the mid week period with light winds during the day
and slightly stronger wind speeds at night.

40

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      92  75  91  74  92 /  30  20  20  10  20
Houston (IAH)              91  75  91  75  92 /  50  20  40  20  30
Galveston (GLS)            89  82  88  81  89 /  50  20  40  20  30

&&

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

$$

Discussion...43
Aviation/Marine...40



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