Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 162017
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
317 PM CDT Sat Mar 16 2024

...New SHORT TERM, LONG TERM, MARINE...

.SHORT TERM...
(This evening through Sunday Night)
Issued at 317 PM CDT Sat Mar 16 2024

Though our CWA has not been void of thunderstorms today, the
presence of a thick LL/ML cloud deck has resulted in sufficient
stabilization to mitigate the thunderstorm coverage and intensity so
far. A weak boundary has been situated across our southern counties
today, separating the warmer / more humid coastal air mass (some
spots near 80 with dew points in the low 70s) with the less warm /
juicy air mass inland (generally mid 60s to low 70s temps with 60s
dew points). A weakening MCS is moving eastward along this frontal
boundary. Though it was producing some heavy thunderstorms earlier
today across our southwestern counties, it has since been downgraded
to a blob of showers as it enters the Houston metro area.

The atmosphere becomes more synoptically interesting tonight into
tomorrow morning. Southwesterly UL flow will become increasingly
diffulent overnight while a 50-60 kt 500MB southwesterly jet ejects
from northern Mexico into southern/coastal Texas. Peak synoptic
ML/UL ascent is expected to occur roughtly between the 3AM and 10AM
time frame. Meanwhile, PWATs are likely to surge overnight as well.
Ensemble means depict a high chance of 1.6" to 1.8" values while
deterministic guidance suggest the potential for our southern/coastal
counties to exceed 2.0 inches. LL instability is expected to be
lacking. HREF means and forecast soundings indicating very low LL
CAPE. However, MU CAPE and ML lapse rates should be more than
sufficient for deep convection. So synoptically speaking,
conditions are expected to be favorable for widespread showers and
thunderstorms. Confidence is lower regarding how small scale
features such as LL boundaries and `small` vort maxes embedded in
the flow aloft will enhance, or not enhance, convection.
Regardless, a few strong to severe thunderstorms will be possible
late tonight into tomorrow morning. The primary concerns will once
again be large hail and damaging wind gusts. Though strong
thunderstorms are possible across the entire CWA, the overall set
up does seem to favor the southern half of the CWA a little more
than the northern half. Given the high PWATs and recent heavy
thunderstorms, localized flash flooding will be possible as well.

By Sunday, a ~1030-1032MB SFC high will drift southward across the
northern and central plains, pushing a drier / cooler air mass
towards SE Texas. However, this air mass is not expected to reach
our neck of the woods until Sunday night. Therefore, we opted to
keep clouds, lingering showers, and 70s temps / 60s dew points in
the forecast through Sunday afternoon. Overnight lows are expected
to drop into the 50s with lowering humidity. Northernmost counties
could drop into the 40s.

Self

&&

.LONG TERM...
(Monday through next Friday)
Issued at 317 PM CDT Sat Mar 16 2024

Expect clouds to begin scattering out from ne-sw during the day
Monday as some drier filters in behind the front. We`ll see clouds
return by late Tuesday into Wednesday as some mid-upper impulses
move into the region from Mexico (in combination with llvl winds
gradually veering to the east & southeast). Doubt there will be
enough column moisture for these disturbance(s) to produce rain
that survives the fall to the surface prior to early afternoon
Wed...but also wouldn`t be too surprised to see some radar returns
from virga.

Heading into late Wed and Thurs, the cutoff low/trof that has been
hanging out across the Desert Southwest will be opening up and
making its way toward Texas and the Southern Plains. The airmass
will probably be modified enough to re-insert POPs back into the
forecast as this occurs by Wed evening. Best shower/thunderstorm
chances will probably occur on Thursday with the combination of
increased large scale lift, some coastal troffiness and the
dryline to our west all being players. Deterministic model
solutions are a bit more bullish than the blends in regards to
overall precip coverage than what the blends and current fcst
reflects...so rain chances may need to be bumped up going forward.

The upper trof passes to our east Thurs night & early Friday. A
drier northwest flow aloft will take shape into next weekend.
Overall, temperatures should be around seasonable norms for the
vast majority of the week.  47

&&

.AVIATION...
(18Z TAF Issuance)
Issued at 1242 PM CDT Sat Mar 16 2024

SHRA/TSRA likely in the region this afternoon. Best chance of TS
will be along and south of I-10. However, lightning has been
observed well north of the primary thunderstorms. Winds will
generally be east but are likely to vary at times due to the
impact thunderstorms will have on the pressure gradient. Tonight,
conditions are expected to become increasingly favorable for
SHRA/TSRA. Confidence is very low regarding timing of possible
thunderstorms. We have shifted the VCTS time frame earlier, with
most areas starting around 08Z or 09Z, continuing until about 13Z
to 15Z. A few strong to severe thunderstorms capable of damaging
wind gusts and hail remain possible. Overall winds are expected to
become more NE tomorrow. Worth mentioning that cigs and vis are
likely to jump around through the forecast period. However, conditions
are expected to average around low-end MVFR this afternoon followed
by predominantly IFR conditions overnight.  Self

&&

.MARINE...
Issued at 317 PM CDT Sat Mar 16 2024

The next upper level disturbance will be moving toward the region
late tonight and Sunday. Mariners should be prepared for some
potentially strong to severe cells, with best chances in the
5am-3pm timeframe for the coastal waters. Strong winds, hail and
isolated waterspouts will be on the table. As this disturbance
passes later in the day, look for winds to swing around to the
northeast as a front moves into the waters. Winds and seas will
increase Sunday night into Monday with sustained 20-25kt winds
likely with higher gusts in the Gulf waters. Small Craft Advisories
will be required. Improving marine conditions are anticipated
Tuesday as speeds diminish and veer to the east. Onshore winds
resume and slowly increase Wed and Wed night. 47

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  63  70  53  64 /  90  50  10   0
Houston (IAH)  65  74  56  69 /  90  70  10   0
Galveston (GLS)  65  71  58  67 /  80  80  10   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...High Rip Current Risk until 9 PM CDT this evening for TXZ436>439.

GM...None.

&&

$$


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