Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 090430

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1030 PM CST Mon Mar 8 2021

.SHORT TERM [Tonight Through Tuesday]...
Moistening of the atmosphere continues with southeasterly flow
firmly in place. Expect a warmer night across the region with lows
in the 50s to around 60. Nudged up temperatures inland west a
degree or two based on current trends and the 00z NAM/RUC. Winds
although light continue throughout the night. Clouds a mix of
4000-6000 foot and cirrus overnight.

Dewpoints well offshore already in the upper 50s to lower 60s and
this along with the aforementioned NAM indicating a slight
increase in the chances for sea fog Wednesday morning near
Galveston Bay.

SE winds offshore creeping up and seas have slowly built with
longer periods as well. Fluctuating at 5-6 feet looks likely
through the night and much of Tuesday so have hoisted a SCEC for
the 20-60nm waters.



.AVIATION [06Z TAF Issuance]...
VFR most of the forecast. Some SCT/BKN ceilings on tap Tuesday
night across the west/northwest. Will also be looking for the
increased threat of fog near Galveston Tuesday night. 45


.PREV DISCUSSION /Issued 550 PM CST Mon Mar 8 2021/...

.LONG TERM (Wednesday through Monday)...

An upper level ridge will be located over the western Gulf with a
developing SW upper flow over East Texas. At the surface, high
pressure will be over the eastern US with low pressure over the
central plains. A moderate to strong onshore wind will continue to
draw low level moisture into SE TX under a strong and persistent
cap in the 850-700 mb layer. Pw values remain under an inch on
Wednesday but forecast soundings show a semi-saturated profile
from the sfc to 850 mb so it`s possible to generate some very
light showers beneath the cap, however, most of the area will
remain dry. 850 mb temps support MaxT values near 80 degrees but
with the level of mixing from the winds and expected cloud cover,
will trim a few degrees and keep MaxT values in the mid 70`s. Fcst
soundings show a saturated profile beneath 850 mb on Wednesday
night and PW values reach 1.20 inches so feel the potential for
additional streamer showers will persist. Capping will remain very
strong so only showers and expected. Cloud cover and winds will
keep MinT values on the warm side, probably remaining in the
middle 60`s.

Thursday through Saturday look about the same as Wednesday, albeit
a bit warmer. Fcst soundings show a semi-saturated profile below
850 mb with a significant dry layer between 850 and 500 mb with
strong capping in the 850-700 mb layer. PW values remain between
1.00 and 1.20 inches so can`t rule out an isolated shower but most
of the area will remain dry. Forecast soundings also show some
potential for more afternoon sun so went a bit warmer with MaxT
values warming into the lower 80`s. Overnight lows will remain
very warm with MinT values in the mid/upper 60`s.

Have added patchy fog near Galveston Bay/nearshore waters and the
adjacent coastal areas. Surface dew points are progged to increase
into the middle 60`s. The water temperature is currently 60
degrees so there is some potential for sea fog. However the long
and persistent S-SE fetch will bring warmer water toward the coast
and this should help negate the sea fog potential.

The real fun and games begin next weekend as a deep upper level
low becomes cut off from the main flow over Southern CA Thursday
night and the system slowly meanders across the southern Rockies
through Sunday. The upper ridge over will remain stout so the
upper level low is going to have go up and over the top of the
Gulf ridge. The upper low will pivot into the central plains on
Sunday and it will take on a negative tilt. There are still some
significant timing differences between the faster GFS and the
slower ECMWF, ICON and GEM solutions. Prefer the slower solutions
as cut off systems with no real kicker to get it moving, tend to
travel slower. At this time, feel the most active weather will
occur late Sunday afternoon into Sunday night. Speaking of active,
PW values reach 1.55 inches and coupled with some mid level
instability and a very favorable jet structure (splitting jet and
SE TX will lie in a 130 kt RRQ) should yield a good chance of
thunderstorms on Sunday night. SPC has already placed a part of SE
TX in an outlook area for Day 7. 43


High pressure over the eastern U.S. and low pressure in the lee of
the Rockies will maintain a moderate to occasionally strong
onshore flow this week. SCEC conditions will be possible over the
offshore waters Tuesday night through Friday. The warmer/more
moist air mass overriding the cooler shelf waters will create a
favorable environment for sea fog mid week. The persistent
onshore flow will also bring elevated seas to the coastal waters
and more importantly, warmer water temperatures. The water
temp/dew point spread will narrow and this will hinder fog
development over the second half of the week. Have added patchy
fog for the nearshore waters and Galveston Bay from late Tuesday
night through Friday for the potential for sea fog but confidence
on when, where and the duration of this sea fog event is low. 43



College Station (CLL)  55  75  58  78  64 /   0   0   0  10  20
Houston (IAH)          56  75  60  78  65 /   0   0   0  10  10
Galveston (GLS)        61  70  61  71  64 /   0   0   0  10  10



     for the following zones: 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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