Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 242011

Area Forecast Discussion
National Weather Service Houston/Galveston TX
311 PM CDT Sun Jun 24 2018


This week can likely be summed up with a single word: summer.
The days are looking to back down slightly from the heat level of
the past several days, but still look to be near to above normal,
with humidity to bring peak heat index to the 100-105 degree range
most days. Conversely, rain chances will be higher than in recent
days, but no specific day stands out as having a particularly high
chance for showers and storms.

.NEAR TERM [Through Tonight]...

Temperatures have mostly risen into the low 90s across Southeast
Texas, with only the immediate coast lagging in the upper half of
the 80s. With dewpoints in the 70s, the heat index at all sites
are around or above the 100 degree mark. Meanwhile, we`ve been
more successful at seeing vertical growth in clouds near the
seabreeze and even a small handful of showers have popped up
today. To this point, most showers have been shallow enough that
satellite RGB imagery does not indicate much ice water content,
with the exception of one cell over Galveston County in the 2-3 pm

As the weak seabreeze pushes in through the remainder of the
afternoon, air will continue to stabilize near the coast, putting
the showers we`ve seen earlier today to an end. The potential for
showers will move inland with the boundary, but as the boundary
loses definition farther from the shore, we may not see quite as
robust activity as we saw around mid-day. Otherwise, look for lows
again near or a little above seasonal averages with clouds
scattering earlier in the evening - but with some low stratus
returning later in the night.

.SHORT TERM [Monday Through Tuesday Night]...

Look for a moisture surge overnight into tomorrow, as seen in a
pouch of higher precipitable water air approaching the area in
conjunction with a weak upper trough crossing the southern Gulf
into Northeast Mexico. This will help boost rain chances a little
more for tomorrow, though the trough will likely be too far south
for convection to get too out of control. Along with that, the day
may be a touch cooler, particularly in the west and southwest.

The subtropical ridge builds back then on Tuesday, along with a
patch of lower moisture air coming in the trough`s wake should
result in a drier, slightly warmer day. This is a relative
descriptor here as the differences from day to day still look
relatively small.

.LONG TERM [Wednesday Through Sunday]...

A subtle weakness in the subtropical ridge looks to roll overhead
on Wednesday. While the NAM, GFS, and Euro all show this feature
to some extent, it is not terribly apparent beyond a hint of
higher vorticity and a little dent in the 592 dm line in the 500
progs. The midlevel feature is perhaps strongest in the NAM, but
the GFS is the wettest. Because of this, choose this day to nudge
of rain chances higher, but not dramatically so. My initial model
blends were spitting out a band of 40+ PoPs along the seabreeze,
so the official PoPs may end up being a little low...but at this
time, I just don`t have the confidence in such a weak feature at a
range of 4 days to go that high just yet. If this feature
continues to be consistently forecast in the coming days, we can
ramp up the numbers.

Beyond that, we see not much change for the rest of the week. The
subtropical ridge strengthens again, with a relative maxima over
the Southeast US. This should keep rain chances pretty limited,
but is far enough away that with onshore flow and a coastal
boundary, we probably won`t be entirely dry, either. Similarly,
temperatures should hold near seasonal averages, with maximum heat
indices around or a little above the century mark.


.AVIATION [18Z TAF Issuance]...

Starting to see some SHRA development around the LBX and GLS
area. Might need to update and add some SHRA and/or TSRA at inland
TAF sites this afternoon as some models show activity spreading
into those areas. Otherwise, expect VFR with gusty winds this
afternoon. Winds will weaken this evening and some MVFR ceiling
development can be expected during the overnight hours. Gusty
south winds develop again tomorrow morning after sunrise and any
MVFR ceilings will eventually become VFR. Plan on keeping
tomorrow`s TAFs dry with the current thinking that risk for
SHRA/TSRA formation will be higher to the west of our sites. 42



Caution flags will remain up for elevated winds
through tomorrow morning, and we`ll keep an eye
on things and upgrade to an advisory if winds pick
up like they did last night. Strong rip currents
will persist. Winds/seas are still expected to come
down Monday night-Tuesday when the gradient relaxes
a bit. For the remainder of the week, both winds and
seas are expected to remain below caution level.  42



College Station (CLL)  76  93  75  95  75 /   0  20  10  10   0
Houston (IAH)          78  92  77  93  76 /  10  20  10  10  10
Galveston (GLS)        82  87  81  87  81 /  10  10  10  10  10



TX...High Rip Current Risk until 8 PM CDT this evening for the
     following zones: Brazoria Islands...Galveston Island and
     Bolivar Peninsula...Matagorda Islands.

     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.



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