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Area forecast discussion
National Weather Service Houston/Galveston Texas
521 am CST Mon Jan 16 2017

Aviation...
an area of showers and thunderstorms will affect most of the
Houston Metro and points northward through mid morning. There is a
potential for isolated stronger storms. The strongest were west of
ksgr at 1115z and could affect ksgr, kiah, and the temporary
forecast site at kdwh between 14z and 17z (give or take an hour).
Not confident that the area of showers and storms will work its
way much further to the south. Models still showed a break from
the MVFR/IFR conditions this afternoon before ceilings and/or
visibility lowers again after 00z. Sea fog may become a threat
again for kgls, klbx, and khou after 06z tonight.

40

&&

Previous discussion... /issued 402 am CST Mon Jan 16 2017/

Discussion...
at 3 am, an area of weak of low pressure was located over central
Oklahoma with a weak warm front extending southeast from the low
across southern Arkansas. A cold front extended south-southwest of the
surface low and lies across central Texas. A line of showers and
thunderstorms extends north-S across southeast Texas and this will persist
for much of the morning. There is sufficient shear to support some
marginal wind gusts or isolated tornadoes this morning, especially
over the northwest zones. The line will progress slowly east today while
individual storms within the line move north-northeast. This will allow storms
to train today especially over the western zones and could produce
some locally heavy rain. Upper level winds are diffluent with precipitable water
values near 1.40 inches. There are enough parameters in place to
spark some interest in hoisting a Flash Flood Watch but it's been
dry and most areas should be able to handle 1 to 2 inches of rain
(isolated 3 inch totals) so will forego a Flash Flood Watch today.

A deep upper level trough over Baja California will remain nearly
stationary through Wednesday night. The upper low will slowly fill
as it meanders to the east toward the Central Plains through
Thursday. Precipitable water values remain between 1.30 and 1.50 inches through
Tuesday with a series of weak upper level disturbances embedded in
the SW flow aloft. Most of southeast Texas will experience intermittent
showers and thunderstorms. A cold weak front will cross or try to
cross southeast Texas Mon night through Wed night. Initially thought the
best chance for precip would be along the boundary but it's
looking more likely to focus behind the front with isentropic
upglide. Have gone with likely pops everywhere but have tapered
higher pops to the northwest and lower at the coast.

Rain chances will continue Tuesday night into Wednesday as a
weak disturbance approaches and fcst soundings show a nearly
saturated profile. Showers and thunderstorms are expected to
increase Wednesday night into Thursday as the upper low shifts
east and jet dynamics becoming increasingly favorable. Fcst
soundings over the southeast half of the region look super saturated with
precipitable water values peaking at 1.60 inches. Could get more heavy rain late
Wed night into early Thursday. Some drying is expected Thursday
afternoon with drier conditions expected Friday. Another fast
moving short wave will cross the Southern Plains on Saturday. Not
sure how much moisture will make it back into southeast Texas but will
maintain 20/30 pops late Fri night into Saturday. A dry northwest
flow aloft will develop sun/Mon with conditions turning drier and
cooler. 43

Marine...
after starting out with advisory conditions between 20 and 60 nm of
the coast, the winds will gradually diminish later this morning and
through Tuesday. The potential for fog develop increases late
Tuesday and early Wednesday as easterly winds are expected near the
coast. A frontal boundary is also expected to drift toward the coast
but remain inland both Tuesday and Wednesday which may further aid
in fog development. Otherwise, chances for thunderstorms will
increase later today through Thursday. Southwesterly winds are
expected to develop by Friday and end the thunderstorm and fog
threat.

40

&&

Preliminary point temps/pops...
College Station (cll) 73 57 61 52 65 / 80 70 60 70 70
Houston (iah) 77 64 69 59 72 / 40 70 60 70 70
Galveston (gls) 70 64 69 63 69 / 30 60 50 60 60

&&

Hgx watches/warnings/advisories...
Texas...none.
GM...Small Craft Advisory until 8 am CST this morning for the
following zones: waters from Freeport to the Matagorda Ship
Channel from 20 to 60 nm...waters from High Island to
Freeport from 20 to 60 nm.

&&

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