Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 180916
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
416 AM CDT Fri Aug 18 2017

.DISCUSSION...
Yes summer time doldrums are here. But on the plus side
temperatures at 3AM are actually in the 70s instead of the low
80s like the last couple mornings. Yay. The heat index at
Galveston is only 96 not 101 like yesterday morning. Galveston may
not set another record high minimum temperature today which they
have done the last 3 or 4 days. Houston HOU is down to 81F so far
and could drop into the 70s with near calm winds. Their streak of
record high minimums could come to an end too. The heat will still
be the main weather story going into the weekend. Heat index
values especially along the coast will be in the mid 100s, but
there should be enough mixing with SW/S flow for inland areas to
see a drop in dewpoints and heat index values only in the low
100s. This heat can still be dangerous so take recommended
precautions to deal with the heat.

Aloft the weather pattern still features elongated ridging which
will limit convection again today and one of the reasons why it
will be hot outside with high temperature in the upper 90s. Upper
level troughing will stay over the northern U.S. mainly over the
Great Lakes region. We are still in that time of year where we
will need to look east or even southeast to see what will be the
next weather maker. In this case, there is a tropical upper
tropospheric trough (TUTT) over Cuba and the Bahamas. This TUTT
should move into the Gulf the next few days and the part of the
TUTT favoring upward vertical motion should be over SE Texas by
Monday. So rain chances will remain low through the weekend with
an increase in rain chances Monday and Tuesday. Precipitable water
values are expected to be around 1.6 to 1.8 inches on Monday so
not a lot of moisture for this time of year. PW increase closer to
2 inches on Tuesday but still only enough to support scattered
showers and thunderstorms. PoPs of 30-40 percent look on track for
this part of the forecast.

By the middle to end of the week, synoptic models either shear out
the TUTT or dissipate it over S Texas and Rio Grande through
Friday. This does leave a weakness in the ridge but the GFS is apt
to build the ridge over the northern Gulf. The ECMWF and CMC are
more willing to hold onto the weakness with troughing over the
Great Lakes into New England. The ECMWF and CMC both bring a cold
front to the northern Gulf on Thursday with the GFS having the
front stall along I-20. With there being some uncertainty with the
frontal push, the forecast will go with 20 PoPs to split the
difference until models come into better agreement.

Overpeck

&&

.MARINE...
With surface high pressure continuing to build in over NW Gulf of
Mexico, southerly winds between 10-15 kts can be expected through
the rest of tonight lowering to 5-10 kts during the day Friday. This
pattern of slightly higher wind speeds during the overnight hours
and weaker winds during the daytime hours will continue through the
weekend. Wave heights should also stay between 2-3 feet, eventually
lowering to 1-2 feet early next week. The chance for precip will
also be on the rise beginning Monday as a weak disturbance
propagates across SE TX.

Tides also appear to be running near normal to slightly above
normal, by a half foot at certain locations. Expecting the tide
levels to remain fairly consistent through the weekend with the area
of high pressure in control and little variation in wind speed and
direction.

Hathaway

&&

.TROPICS...
It`s the last half of August so getting closer to that
climatological peak of hurricane season on September 10. There is
TS Harvey over Barbados with two more tropical waves in the main
development region of the Atlantic. At this point, TS Harvey will
be the one to watch next week. Consensus of the tropical models
takes Harvey towards Belize next Wednesday. There are still lots
of question marks as to what happens after that with a wide
disparity in the model solutions between the GFS, ECMWF and
Canadian. Again, something to keep track of during the weekend and
early next week.

Overpeck

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)     100  78 100  77  99 /  10  10  10  10  10
Houston (IAH)              98  79  97  78  96 /  10  10  10  10  20
Galveston (GLS)            91  83  90  83  90 /  10  10  10  10  20

&&

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

$$

Discussion...39
Aviation/Marine...08


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