Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 260447
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1147 PM CDT Thu May 25 2017

.DISCUSSION...

06Z Aviation...A stratus deck around 1500 ft is moving into the
area from the SW. Expecting MVFR ceilings to spread across all of
the taf sites between 7Z (CLL) and 11Z (GLS). It is possible that
CLL will see a brief period of IFR ceilings towards 12Z. Should
see clouds rise above 3 kft and become sct early to mid
afternoon. Will see 10 to 20 KT sustained south winds again
tomorrow by mid-morning. Expect the MVFR ceilings to return
Friday evening. 33

&&

.PREV DISCUSSION... /ISSUED 828 PM CDT Thu May 25 2017/

UPDATE...
Surface high pressure is continuing to shift east this evening,
placing SE TX in an area of weakness between systems tonight
through Saturday. Expect winds to pick up tonight across the
region as the surface pressure gradient tightens around 00Z. This
should help to prohibit any chances of fog for Friday morning.
Onshore winds will begin to weaken in speed by Friday afternoon.
Overnight low temperatures tonight should be slightly above
normal for this time of year, with mid to upper 70s along the
coast and low to mid 70s farther inland.

The largest concern in the forecast as we move into Friday and
this weekend will be the heat. Friday`s forecasted high
temperatures bring much of the western zones into the low 90s, and
eastern zones into the upper 80s. Along the coast, high
temperatures will reach into the mid 80s. With onshore flow
continuing through late Sunday, dewpoints will be on the rise
toping off in the mid 70s. The forecast overall seems to be in
good shape, therefore only tweaked the temperatures and dewpoints
a tad to account for current observations.

Hathaway

PREV DISCUSSION... /ISSUED 624 PM CDT Thu May 25 2017/

DISCUSSION...

00Z Aviation...The main concern is the development of MVFR
ceilings. Expect to see some low clouds begin to form after 6Z
across western portions of the area (CLL). Will likely see these
develop between 1-2 kft and eventually become BKN. Not sure how
far east these clouds will extend during the early morning hours,
but by 15Z expect most of the area to see MVFR ceilings. Will see
southerly winds continue overnight around 10 kts, becoming closer
to 15 kts with mixing again tomorrow. 33

PREV DISCUSSION... /ISSUED 409 PM CDT Thu May 25 2017/

DISCUSSION...
Regional temperatures reaching the 90 F mark today...with increasing
humidity...a signal of what to expect in the coming days. Very warm
and humid weather over the next several days. More overcast skies
will have mornings starting out warm with maximum temperatures still
forecast to reach the average upper 80s. This will equate to upper
90 to lower 100 heat indices for a couple of hours during the mid
to late afternoon hours.

The late week near-zonal mid to upper flow pattern will undergo
slightly change as a Gulf-centered upper ridge builds up to the
northwest in response to deepening upstream Great Basin upper
troughing. This will likely make Saturday the warmest day of the
week. A fairly tight onshore pressure gradient between Florida-
based high pressure and lowering western Plains pressures will
produce a few days of breezy onshore winds. Sunday will be the
transition day as the upper levels become more diffulent and lower
level moisture picks up to well above normal seasonable values.
An approaching weak cold frontal boundary stalling somewhere over
southeastern Texas early Monday could easily be the focus needed
to generate (frequent) periods of showers and storms. A series of
shortwave trough passages both on Monday and then again on Wednesday
will keep precipitation chances high early next week. Way too early
to determine QPF or the location of most the susceptible counties
(for strong to severe weather) but confidence is growing that there
will be a rain event on Memorial Day...this trend may easily continue
for a third year. As of now...the main threat will be from slow
moving storm clusters putting down high enough rainfall rates that
could induce localized flooding issues. Tuesday and Wednesday`s
convective behavior will be highly dependent upon Monday`s chain
of events. 31

MARINE...
Strong onshore winds will persist tonight in response to low pressure
over southwest Kansas and high pressure over the eastern Gulf. A Small
Craft Advisory is in effect for the Gulf waters for tonight. A moderate
onshore flow will prevail through the weekend with low pressure over
West Texas and high pressure over the eastern Gulf of Mexico. A SCEC will
likely be required at times through the weekend. A weak cold front will
approach SE TX Sunday night but is not forecast to make it off the coast.
Lighter onshore flow is forecast for the beginning of next week. Scattered
thunderstorms will also be possible on Memorial Day and mariners should
remain alert for lightning and possibly variable winds in and near storms.
43

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      72  91  76  93  76 /   0  10  10  10  20
Houston (IAH)              74  90  78  92  78 /   0  10  10  10  10
Galveston (GLS)            78  85  80  86  79 /   0  10  10  10  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 7 AM CDT Friday for
     the following zones: Galveston Bay...Matagorda Bay.

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

&&

$$

Discussion...33


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