NHC issued a TS Warning for the area previously under the watch that was dropped earlier this morning around Galveston. Guess it is for gusty winds in passing squalls.
Little surprised the SPC doesn't have the marginal risk to further include more of SETX. Helicity is on the increase and environment looks rather favorable for quick spin-ups through late this afternoon. I do see the mesoscale discussion does have Harris, Liberty and Chambers county included in that which makes sense.
Convection on the uptick with the feeder bands rolling in and some areas could pick up 4+ inches today where a feeder band sets up as Hanna slows down. While we aren't expecting widespread flooding and should be able to handle a few inches due to recently dry conditions, rainfall rates will be high and could result to quick flooding where training sets up.
Area Forecast Discussion
National Weather Service Houston/Galveston TX
625 AM CDT Sat Jul 25 2020
.AVIATION...
Tropical Storm Hanna strengthened during the overnight hours and
will continue to track west towards the Lower and Central Texas
Coast today. Rainbands generated by Hanna will continue move
across the local Gulf waters and into portions of the CWA through
this evening/night and will result in sporadic periods of
SHRA/TSRA and VFR-MVFR cigs. VCSH/VCTS remain in this forecast
due to the difficulty of knowing exactly when and where the
activity will occur for each TAF site and will utilize TEMPOs as
needed. The areas to receive the largest amounts of rain remains
across the southern portions of the CWA (includes LBX, GLS, HOU),
however, the environment will remain primed for rain chances
across all of SE Texas today. Conditions are expected to improve
gradually late this evening and tonight as Hanna continues its way
further inland. Forecast soundings show MVFR cigs again overnight
into early Sunday morning. 24
&&
.PREV DISCUSSION... /ISSUED 412 AM CDT Sat Jul 25 2020/
SHORT TERM [Today through Sunday]...
Tropical Storm Hanna is expected to continue to strengthen into
a hurricane and make landfall later this afternoon or early this
evening in/around the lower to middle Texas coast. Showers in
association with Hanna`s outer rain bands have been racing inland,
so far mainly across parts of the coastal counties. Expecting this
outer band of shower and thunderstorm activity to increase and
move further inland as the day progresses. Will keep generally
elevated rain chances in the forecast for both tonight and Sunday
as the moist flow off the Gulf persists. Per SPC`s Day 1 Outlook,
isolated tornadoes could develop today the closer you get to the
Matagorda Bay area due to elevated instability. Locally heavy
rainfall could occur where and significant training sets up, and
will not touch the Flash Flood Watch that was issued on Friday. If
training does materialize, rainfall totals of 2 to 4 inches with
isolated higher amounts possibly getting into a 6 to 8 inch range
could occur in/near the Watch area through Sunday morning. Further
inland and northward, rainfall totals generally in a 1 to 3 inch
range could occur in that same time period. 42
LONG TERM [Sunday Night through Saturday]...
Rain chances persist through the first half of the upcoming week as
deep tropical moisture continues across the area. Lowering rain
chances and warmer temperatures come back to the area beginning in
the Thursday-Friday time period as precipitable water values finally
decrease, and warmer temperatures can be expected too. 42
MARINE...
..TROPICAL STORM CONDITIONS OCCURING...
Tropical storm Hanna continues to move west and has certainly gotten
more organized in the last 3 hours. Multiple rain bands have
developed and were rotating through the Upper Texas Coastal waters.
Winds of 41g56kts at 42019 with seas of 21 feet at 08z! Winds do
slacken near the coast and most coastal observations coming in 18-
30kts and buoy 42035 southeast of Galveston reporting 21g27kt and
seas of 8 feet. Not expecting much to change across the area for the
next 6-8 hours then should finally begin to see winds and seas start
to come down. Tropical storm warnings for Galveston bay may come
down with the 10 am issuance though will still be dealing with the
squally weather and rain bands. Stout southeasterly winds will
remain this afternoon/early evening in the 20-25 knot range over the
eastern waters stronger in the west. As Hanna moves inland this
afternoon and eventually southwest the winds will swing back from
the southeast tonight to the east Sunday afternoon. Seas will still
support SCA conditions as seas a fairly long easterly fetch develops
through Sunday then veers back to the southeast Sunday night.
The threat of showers and thunderstorms will continue over the
coastal waters well into Monday as a boundary with very rich
tropical moisture pools along it from the waters off of LA into the
TX waters...and just hangs out. Southerly flow finally returns late
Wednesday and the weather returns to more typical summer-like
conditions.
Tide levels from Matagorda Bay entrance to Galveston all showing
about 2-2.7ft above normal and up into Galveston Bay right around 3
feet above normal. This will warrant maintaining the Storm Surge
Warning and the Coastal flood warning. Could still see some further
increases along the Sargent to Matagorda entrance as these large
swells push up into the coast. Tide levels will be slow to recover
and tidal overwash/beach flooding/very strong rip currents/enhanced
currents in general should continue throughout the day at these
levels and likely persist above normal through Tuesday. Though the
storm surge warning will come down later today it will likely be
replaced by a coastal flood warning/advisory.
45
CLIMATE...
Again Hobby tied the record high minimum temperature of 80 degrees
yesterday matching the 2018 record.
45
PREV DISCUSSION... /ISSUED 1240 AM CDT Sat Jul 25 2020/
AVIATION...
Tropical Storm Hanna has strengthened some in the last couple of
hours and will continue to track west towards the Central and
Lower Texas Coast through Saturday. Rainbands generated by Hanna
will continue move across the local Gulf waters and into portions
of the CWA through Saturday late evening/night. This will
result in periods of SHRA/TSRA and VFR-MVFR cigs starting from the
coastal sectors moving northward into the rest of the CWA as the
day progresses. Will keep VCSH/VCTS in this forecast due to the
difficulty of pin pointing exactly when and where the activity
will occur for each TAF site and will implement TEMPOs as needed.
The most likely areas to receive rain remains across the southern
parts of the CWA (includes LBX, GLS, HOU), however, the
environment will be primed for rain chances for all of SE Texas
for much of the day. Because Hanna has strengthen some, winds in
this TAF package were slightly increased. Conditions are expected
to improve gradually Saturday evening/night as Hanna continues its
way further inland. 24
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Flash Flood Watch through Sunday morning for the following
zones: Brazoria Islands...Coastal Brazoria...Coastal
Galveston...Coastal Jackson...Coastal Matagorda...Fort
Bend...Galveston Island and Bolivar Peninsula...Inland
Brazoria...Inland Galveston...Inland Jackson...Inland
Matagorda...Matagorda Islands...Wharton.
Tropical Storm Warning for the following zones: Brazoria
Islands...Coastal Brazoria...Coastal Jackson...Coastal
Matagorda...Galveston Island and Bolivar Peninsula...Inland
Jackson...Inland Matagorda...Matagorda Islands.
Coastal Flood Warning until 10 AM CDT Sunday for the following
zones: Brazoria Islands...Coastal Galveston...Coastal
Harris...Galveston Island and Bolivar Peninsula.
GM...Tropical Storm Warning for the following zones: Coastal waters
from Freeport to Matagorda Ship Channel TX out 20 NM...
Coastal waters from High Island to Freeport TX out 20 NM...
Galveston Bay...Matagorda Bay...Waters from Freeport to
Matagorda Ship Channel TX from 20 to 60 NM...Waters from
High Island to Freeport TX from 20 to 60 NM.