Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS64 KHGX 220224
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
924 PM CDT Wed Jun 21 2017

.UPDATE...
Changes: Will be issuing a Coastal Flood Advisory for Brazoria
County through 15z Thursday.

Tropical Storm Cindy getting closer to the Louisiana coast. This
feature will make landfall early Thursday. 00z sounding data shows
a very moist airmass at LCH with PW values near 2.50 inches
(probably a bit contaminated by a shower). PW values at CRP are
considerably drier with values under an inch. It appears that the
dry air on the western edge of Cindy is prevailing as
precipitation moving west continues to evaporate as it moves west.
Have lowered rain chances over the western half of the CWA due to
the dry air. Kept rain chances high over the east and added
locally heavy rain to the weather grids over the extreme east as a
cluster of strong storms over Western Louisiana pushes west.
Tweaked min temps a degree or so mainly to match obs.


PW values are progged to increase to over 2 inches on Thursday and
daytime heating coupled with the higher moisture should yield
scattered shra/tsra during the day. Very high sfc dew pts and warm
afternoon temps on Friday will yield some high heat index values.
Would not be surprised if a few locations reached or exceeded 105
degrees on Friday aftn. 43

&&

.PREV DISCUSSION... /ISSUED 634 PM CDT Wed Jun 21 2017/

AVIATION...
Tropical Storm Cindy`s impacts are the main concern for the first
12 hours and especially so for the first 6 hours. Rain bands were
evident on radar. Winds were gusting to 30 knots at KGLS and
expect winds to gust to between 20 and 30 knots over the inland
over the inland areas through 04Z. An exception is KCLL since the
site appears to be too far west for the rain bands to reach.
However, there is a slight chance the bands could reach KCLL. If
so, gusty winds of about 25 knots will be possible there as well.
MVFR conditions should develop later this evening over most of the
sites. As Cindy moves inland on Thursday, do expect conditions of
generally improve during the late morning to midday time period.
However, bands of showers and thunderstorms will be possible again
during the afternoon.

40

PREV DISCUSSION... /ISSUED 323 PM CDT Wed Jun 21 2017/

DISCUSSION...
Tropical Storm Cindy continues heading toward the TX/LA border area
with a landfall still anticipated to happen tonight. Showers and
thunderstorms have begun moving into the Chambers County-Galveston
Bay-Bolivar Peninsula area. Breezy/gusty north to northeast winds
this afternoon (generally running around 15 to 25 mph inland and
25 to 30 mph coast) will shift to the northwest and west overnight
as the circulation center works its way onshore. Look for periods
of showers and thunderstorms to move westward into the area overnight
with the best chances and highest amounts possibly setting up across
parts of our far eastern counties (Chambers/Liberty/San Jacinto/Polk).
Rainfall totals tonight through Thursday should range from around/under
1/4 inch out west to 1 to 3 inches out east, and higher amounts are
possible in/around those far eastern counties listed mentioned above
where WPC is currently carrying a slight risk of excessive rainfall.
Still looking for rain chances to persist for the end of the week,
on into the weekend, and into the start of next week as precipitable
water values remain very high under a persistent onshore flow while
a weak frontal boundary sags southward into our area.  42

MARINE...
Overview and winds:  Still looking at tropical storm force winds to
develop over the marine areas tonight. Around 2:50 PM, a platform
just outside our marine zones at the East Breaks at 393 feet
recorded a wind of 39 gust to 45 knots. Even though it is way above
the surface, it does show the potential for tropical storm force
wind gusts in showers and storms currently moving through the marine
areas. No change in the warning/advisory configurations.

Tides/seas:  Tides have gradually been piling up against the islands
and peninsulas on the lower sides of the bays. For example, Rollover
Pass on the bayside of the Bolivar Peninsula has tides over 3 feet,
while Pier 21 was between 3.9 and 4 feet since noon time. Even along
the coast with the downside of the earlier high tide, tide levels
at 2:48 PM were near 4 feet at the Galveston Bay Entrance and 3.4
feet at Freeport. Do expect some subsiding levels during the times
of low tide later this evening. However, tide levels will rise back
up to possibly reach levels seen earlier today as Cindy makes
landfall. Have received reports of tidal flooding on portions of the
Strand in Galveston -- on the bayside of the island.

Seas at buoy 42035 and 42019 were 7 to 12 feet with a period of 10
to 11 seconds early this afternoon. Wave runup combined with the
rough seas and high tides will continue to provide a flood potential
most certainty in the areas under the tropical storm warning and
could affect the Blue Water Highway further down the coast.
Currently have a coastal flood advisory in effect for Brazoria
County through 4:00 PM and will look to see if this needs to be
extended.

Have not had any indications of low water problems up in the Ship
Channel yet. Manchester actually had water levels about 1.5 feet
above the Mean Lower Water Levels. Will continue to monitor this
possibility later tonight. Still a complicated scenario.

As was discussed earlier, as Cindy moves inland, winds will
gradually back to the west on Thursday then to the south Thursday
night. Moderate onshore winds will then persist into the weekend.

40

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      74  91  76  93  77 /  20  30  20  30  30
Houston (IAH)              76  86  77  92  78 /  50  50  40  50  30
Galveston (GLS)            78  85  82  90  82 /  60  50  40  60  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Tropical Storm Warning for the following zones: Chambers...
     Galveston...Harris...Liberty.

GM...Small Craft Advisory until 7 AM CDT Friday for the following
     zones: Coastal waters from Freeport to the Matagorda Ship
     Channel out 20 NM...Matagorda Bay...Waters from Freeport to
     the Matagorda Ship Channel from 20 to 60 NM.

     Tropical Storm Warning for the following zones: Coastal waters
     from High Island to Freeport out 20 NM...Galveston Bay...
     Waters from High Island to Freeport from 20 to 60 NM.

&&

$$



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.