Tuesday, March 16, 2021

Mar. 16 21

 Area Forecast Discussion

Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 162356
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
656 PM CDT Tue Mar 16 2021

.AVIATION...
Weak warm air advection will persist tonight and VFR ceilings will
become MVFR by mid evening and then IFR to LIFR after 09z. A few
showers will be possible late tonight in the WAA pattern. Could
also get sea fog yet again at KGLS but winds are stronger tonight
and water temperature has increased another degree. A cold front
will cross the area between 15-18z and a line of showers with an
embedded thunderstorm will be possible along the fropa. Should get
some rapid clearing behind the front with VFR conds developing
between 189-22z. 43

&&

.PREV DISCUSSION... /ISSUED 348 PM CDT Tue Mar 16 2021/

SHORT TERM [Tonight Through Wednesday]...

Winds have finally started increasing across much of the area and
skies have gone scattered to broken across the region and
temperatures have jumped up into the upper 70s to around 80 at 2 pm
and have another hour of heating to work with before starting the
very slow downward slide. Overnight expect cloud skies to set in
again with some fog near the coast and expanding inland after
midnight. Visibility restrictions overnight should be offset by the
stronger winds tonight and a more likely stratus night versus a fog
night. A few showers will be possible this afternoon and into the
early evening as the area of lift over the central counties shifts
further north. Then expecting a lull in the precipitation overnight
until the cold front starts to near the region toward sunrise.

Wednesday should start off with a strong to very strong cap over the
area as the cold front pushes into the area some erosion of the cap
will take place but it looks like much of the area will remain
capped and a band of showers should develop ahead of the front and
then come to an end as the front passes. Timeline as of this package
brings the showers into College Station 9-10am...Conroe/Houston noon-
1pm...Galveston...1-2 pm. Again the main form of precip should be
showers though some of the northeast/eastern areas where the cap
should be a little weaker will have a greater chance of isolated
thunderstorms. These areas are in a marginal risk with a sliver of
Houston County in slight risk and this is probably close to a worst
case scenario there given the cap strength.  Rainfall accumulations
should come in averaging less than 0.25". WNW winds in the wake of
the front should get gusty Wednesday afternoon and temperatures
won`t fall much if any given the combination of warm start,
downsloping, mild 850 temperatures in the afternoon, and abundant
sunshine in the very dry column in the wake of the front.

45

LONG TERM [Wednesday Night Through Tuesday]...

Behind the departing cold front on Wednesday, SE TX will enter
into a period of cooler, drier, and generally pleasant weather
that should persist into the upcoming weekend. By Thursday the
synoptic picture will dominated by a building ridge aloft and
broad surface high pressure over the Central CONUS. Moderate
northerlies in the wake of the departing cold front will enhance
CAA, pushing temperatures down to more seasonable levels and
maintaining dew points in the 40s across most of the area. Highs
through Saturday will remain near seasonal norms...near 70 inland
and in the mid to upper 60s along the coast and barrier islands.
Clear skies will allow for efficient nocturnal radiative cooling
during this time, with lows ranging in the 40s to lower 50s.
Overall, it looks to be a great weekend ahead to enjoy any outdoor
activities that may be in your plans.

The aforementioned surface high will slide eastward by late
Saturday, allowing for a redevelopment of onshore winds by Sunday
morning. This pattern shift will result in a modest increase in
both temperatures and moisture into the early part of next week,
with highs reaching the mid-70s on Sunday and upper 70s by
Tuesday. Global models continue to show significant divergence in
the evolution of the next potential cold front, with the more
progressive GFS solution showing an amplified 500mb trough and
associated surface low dragging a stronger front through the area
on Monday night/Tuesday morning and the EC indicating a weaker
fropa late Tuesday/early Wednesday. Due to this, I have been
fairly broad in assigning PoPs for the beginning of next week but
have kept the values themselves low for the time being.

Cady

MARINE...

Moist onshore flow in place and should be strengthening this
evening. Will hoist an SCEC for the 20-60nm waters tonight as winds
and seas build.  Mixing over the Gulf this afternoon looks much more
robust than yesterday and visibilities have improved. Sea fog may
return after 8 pm with increasing chances through 2 am for the
nearshore/bay waters. The fog once it forms should persist through
around 6 or 7 am then start mixing out again with winds more south
and southwesterly beneath the cap. Will be looking for the cold
front to push off the coast near Matagorda around 10 am and through
Galveston Bay by around 1 pm. Winds become WNW around 10 knots in
the wake of the cold front and start increasing after 9 pm Wednesday
and will be needing an SCA for late Wednesday night/early Thursday
for sustained winds near 20 knots and gusty. Showers and an a
thunderstorm or two may be possible with the passage of the front
through the Upper Texas Coastal waters. Pacific high pressure builds
in Thursday with CAA waning Thursday evening. Saturday winds
becoming easterly and onshore flow develops.

45

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      65  77  46  67  43 /  60  40   0   0   0
Houston (IAH)              69  81  49  68  47 /  30  50   0   0   0
Galveston (GLS)            68  74  54  67  53 /  20  50   0   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

Discussion...99
Aviation/Marine...99

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