Saturday, February 27, 2021

Feb. 27 21

 Area Forecast Discussion

Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 280008
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
608 PM CST Sat Feb 27 2021

.AVIATION [00Z TAF Issuance]...

LIFR conditions persist through the night along the coastal flying
areas with MVFR elsewhere. Fog will effect most of the area as a
warm front continues to push north of the region and sea fog
persists along the coastal areas. This pattern looks to persist into
the week. 35

&&

.PREV DISCUSSION /Issued 439 PM CST Sat Feb 27 2021/...



.SHORT TERM [Tonight Through Sunday Afternoon]...

Warm and humid this afternoon with southerly flow and stronger band
of winds over the west in the entrance corridor of the LLJ. Low
clouds near the coast will be spreading north quickly this evening.
Fog over the coastal waters will continue to advect inland and
already getting close to needing a dense fog advisory for
Galveston Island and will let the evening shift issue as needed
which it should be.

Overnight fog expands well inland and even areas from Conroe
southward has a chance of dense fog. Very warm overnight but not
getting into record territory. Sunday dawns cloudy and foggy then
will be watching for development near the cold front that will be
sagging south. Corridor out ahead of the front will destabilize in
the afternoon and for areas generally north of a line from Brenham
to Livingston will have a least a slight chance of showers or
isolated thunderstorms and the later in the afternoon the greater
the chance.  Small threat for some training of storms though
probably north of the area.
45


.LONG TERM [Tomorrow/Sunday Night through Friday]...

Rain chances will be on the increase tomorrow night with the ar-
rival of the next cold front. This boundary is expected to move
into a fairly warm/moist air mass already in place across SE TX
during the evening/overnight hours tomorrow. While the best jet
dynamics are progged to be north of our FA, there may be enough
instability for isolated elevated thunderstorms along with some
locally heavy rainfall as this line moves slowly south. Hard to
say what locations are at most risk at this time, but did trend
with the higher POPs over our northern counties for this time.

As we head into Mon, rain chances should remain elevated as the
front lingers over the region...along with PWs near 1.5 to 1.8"
just ahead of it. However...we`ll have to keep an eye on things
Mon night/Tue morning with the development of a coastal surface
low around the middle TX coast. Models seem to be in decent ag-
reement with the development of this feature, but there`s still
some differences with speed and how far from the coast it could
track (GFS faster/further away than ECMWF and Canadian). As the
surface low and upper low/trof moves out to the ENE through Tue
afternoon, the associated cold front should finally move off in
to the Gulf. Cooler/drier/quiet weather expected for Weds...and
likely most of Thurs (even with the return of SE winds). Exten-
ded guidance indicating another strong upper low developing and
heading this way late Thurs/Fri. Temps next week should be near
seasonal norms. 41


.MARINE...

While there was a brief break earlier today, sea fog seems to be
moving back into Galveston Bay at this time. Have already issued
the Marine Dense Fog Advisory for GLS (and its nearshore waters)
for the rest of this afternoon...expanding the Advisory for the
rest of the upper TX coast tonight on through noon tomorrow. The
tightening gradient in response to lowering surface pressures to
our west could elevate winds/seas to SCEC criteria overnight. As
the next cold front approaches tomorrow, winds will begin to de-
crease. A coastal trof is expected to develop late Mon/early Tue
near the middle TX coast, and is forecast to track NE into SW LA
by Tue afternoon. This will allow the cold front to finally push
through SE TX as moderate/strong offshore winds develop over the
marine waters in its wake. SCEC/brief SCA flags may be needed at
this time. High pressure will settle over the state on Weds with
onshore winds returning late Weds night/Thur. Another cold front
will move across the coastal waters on Fri with an offshore flow
progged for next weekend. 41

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL)  68  78  55  58  45 /  10  40  70  80  60
Houston (IAH)          68  78  65  69  51 /  10  20  50  70  60
Galveston (GLS)        61  69  62  66  54 /  10  10  20  60  50

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...Dense Fog Advisory until 10 AM CST Sunday for the following
     zones: Brazoria Islands...Galveston Island and Bolivar
     Peninsula...Matagorda Islands.

GM...Dense Fog Advisory until noon CST Sunday for the following
     zones: Coastal waters from High Island to Freeport TX out
     20 NM...Galveston Bay.

     Dense Fog Advisory until noon CST Sunday for the following
     zones: Coastal waters from Freeport to Matagorda Ship
     Channel TX out 20 NM...Matagorda Bay.


&&

$$

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