Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 03/10/21
Area Forecast Discussion
National Weather Service Houston/Galveston TX
624 PM CST Tue Mar 9 2021
.AVIATION [00Z TAF Issuance]...
Moderate SSE winds and gusty this afternoon should be gradually
relaxing and losing much of the gusts in the next 2 hours. Clouds
will be the primary issue with this package of TAFs. AMDAR
soundings clearly showing a very moist layer 1800-6000ft then dry
subsidence inversion atop that.
Pattern looks to change very little the next 30 hours so other
than a gradual lowering of ceiling heights tonight then rising
ceilings mid to late morning. MVFR conditions setting in between
02z and 07z and expanding into many of the TAF sites. Throughout
the afternoon can`t rule out --R with shallow convection but
insignificant for flight ops. Still some concerns with sea fog
but the afternoon model runs have swung back to drier air aloft
and not the surge of low level moisture. Dewpoints well offshore
still only 61 and with the rising SST nearshore sea fog threat
looks low.
45
&&
.PREV DISCUSSION /Issued 236 PM CST Tue Mar 9 2021/...
.SHORT TERM [Today Through Wednesday Night]...
High pressure off to the east has allowed for onshore flow to
persist. The southerly winds have developed a layer of clouds around
4,000-6,000ft across SE Texas. Even with the cloud cover, suitable
WAA will be enough to get afternoon temperatures into the mid 70s.
Speaking of advection, the southerly winds will be a bit gusty today
thanks to steep lapse rates past 1km. Moderate winds aloft will be
able to mix down to the surface, so gusts of 20-25 kts are likely
for today. For tonight, the SREF is hinting at fog along the coast,
especially near Galveston Bay. Otherwise, no significant weather is
expected over the next 24 hours. Cloud cover increases tonight, so
overnight lows will remain rather mild in the upper 50s/low 60s.
For tomorrow, expect more of the same except with slightly stronger
winds as the pressure gradient tightens between a developing area of
low pressure to our north and high pressure to the east. Winds will
transition to a bit more southerly as well, and afternoon
temperatures will be a touch higher with highs in the upper 70s/low
80s. There is a small chance (we`re talking around 10% at most) that
we could see some warm advection showers tomorrow afternoon, but
only a few models are hinting at this including the ECMWF. The ECMWF
also shows warm advection showers for today, but as of right now
there are only a couple of small, short-lived showers in the area so
this is why I have largely leaned against that scenario and kept low
PoPs in the grids through tomorrow night. With the increase in cloud
cover tomorrow night, leaned a bit higher for low temperatures with
lows in the mid 60s. Sea surface temperatures in the nearshore
waters are still in the low 60s and by tomorrow night, dew points
will be approaching the mid 60s. Included patchy sea fog in the
grids during this timeframe, but the risk is very marginal at least
for now.
Batiste
.LONG TERM (Thursday through Monday)...
A broad upper level ridge will be located over the western Gulf
on Thursday with a slow moving upper level over central CA. At the
surface, high pressure will remain anchored over the SE US with
low pressure developing in the TX panhandle. A tight pressure
gradient will foster a moderate to strong onshore flow bringing a
surge in low level moisture. The moisture will remain shallow,
staying below 850 mb with considerably drier air between 850 and
500 mb. Could get some streamer showers from time to time but most
of the area will remain dry. 850 mb temps support a MaxT values of
around 80 degrees. There`s really not a lot of change for Friday
as moisture and thermal profiles look similar. Some minor change
for Saturday as the upper low over CA moves toward the 4 corners
region. That said, the moisture profile actually looks a bit
drier on Saturday with PW values falling to less than an inch. But
the lowering of PW values doesn`t last long as moisture deepens
quickly Saturday night reaching 1.50 inches by Sunday morning.
Surface low pressure over the TX panhandle will begin to move east
on Sunday and this will aid in moving the dry line into SE TX.
This feature will serve as a focus for showers and thunderstorms
late Sunday into Sunday night. Jet dynamics which looked very
favorable yesterday looks much less so today. The upper level
support is a bit further north taking the best splitting jet
structure north. Even the RRQ is looking out of phase with the
surface feature. Low level instability is also looking rather
paltry but things could change by Sunday. As for temps, think the
GFS is trending too cool and have leaned toward the warmer side of
guidance as there doesn`t look like much of a cold air intrusion.
Another weak short wave will move into the area late Monday into
Tuesday and depending on the timing of the dry line and front,
thinks it`s best to keep slight rain chances in the forecast
Monday into Tuesday.
Lastly, some potential for some sea fog near the coast but it
looks like those chances will be small. Water temps is up to 62
degrees this afternoon and with a persistent S-SE wind, feel
water temperatures will only become warmer. It`ll become
increasingly difficult for dew pts to be much warmer than the
water thus reducing the fog threat. That said, the potential is
not zero and will carry patchy fog from 06-12z into Saturday. 43
.MARINE...
A moderate to occasionally strong onshore flow will persist
through the end of the week as high pressure remains over the
eastern US and low pressure develops in the lee of the Rockies.
Warm and moist air overriding the cooler shelf waters could
yield some patchy fog at times but widespread dense fog is
looking less likely as water temperatures slowly warm by the
weekend. Sustained winds will exceed 15 knots offshore and a SCEC
will be required probably into Saturday. Due to the persistent
onshore fetch, seas will also be building in excess of 7 feet so
an SCA may be needed before all is said and done. There may be a
brief offshore flow late Sunday into Monday associated with some
storms but onshore winds will return quickly for the first half of
next week as low pressure develops in North Texas. 43
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 58 79 64 80 64 / 0 0 0 20 10
Houston (IAH) 61 79 65 79 65 / 0 10 0 20 10
Galveston (GLS) 62 71 64 72 64 / 0 0 0 10 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION through Wednesday afternoon
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.
&&
$$
AVIATION...45