Monday, April 26, 2021

Apr. 26 21

 Area Forecast Discussion

Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 262350
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
650 PM CDT Mon Apr 26 2021

.AVIATION [00Z TAF Issuance]...

MVFR stratus are expected to develop along the coastal terminals
early this evening. Stratus will further expand inland late
tonight and will persist into late Tuesday morning. Areas of light
drizzle and/or patchy fog will also be possible at KLBX and KGLS
by daybreak. KCLL could see some showers and isolated thunder in
the afternoon, but confidence is low to mention in TAFs at this
time. Some high-end MVFR to VFR cigs will be possible Tuesday
afternoon before gradually dropping back to MVFR towards the end
of the TAF period. Gusty southeasterly winds are expected from
mid-late morning into the afternoon.

05

&&

.PREV DISCUSSION /Issued 234 PM CDT Mon Apr 26 2021/...



.SHORT TERM [Today Through Tuesday Night]...

Another day of slightly above normal temperatures with highs topping
out in the low-to-mid 80s this afternoon. Moderate southeasterly
flow will persist throughout the day as high pressure continues to
sit in place off to our east. Steep low-level lapse rates and
unidirectional flow aloft is allowing for some gusty winds to mix
down to the surface. After sunset, the boundary layer will
decouple and winds will decrease down to around 10-12 kts. This is
important to note because models are in agreement on low-level
moisture increasing underneath an inversion around 900 mb. The
winds should remain steady enough to make this more of a low cloud
ceiling event rather than fog. With the increasing cloud cover
and WAA continuing to persist, overnight temperatures will be a
bit above normal with lows in the upper 60s/low 70s.

PW values will reach the 1.6"-1.8" range by Tuesday afternoon along
with increased instability with CAPE ranging from 1000-2000 J/kg. A
shortwave swinging through the area in the afternoon/evening hours
will provide enough lift for scattered thunderstorms to develop
mainly north of Harris County. Increased CIN will be in place
further to the south, so expecting the cap around 850 mb to hold and
inhibit any convection that attempts to develop. Moderate
southeasterly flow will continue to provide steady WAA, so while
Tuesday will remain a mostly cloudy day, high temperatures will
still reach the low-to-mid 80s. PoPs drop off quickly going into
Tuesday night as the PVA comes to an end. Anticipating an even
warmer night for Tuesday. Overnight temperatures will be 8-10
degrees above normal with lows in the low 70s.  26


.LONG TERM [Wednesday Through Monday Night]...

Increasing rain chances remain in the forecast from northwest
to southeast beginning Wednesday afternoon and continuing
through Thursday as a mid/upper level low out west slowly drags
a front into and through our area. At this time, the best dynamics
for possible strong/severe storms and heavy rain with this system
look to remain off to our west and northwest, but we will just have
to see how everything evolves/unfolds as the low makes its way
slowly eastward (models continue to show differences in the timing/
strength). If we can get this system off to the east as expected,
expect a dry weekend with cool night and warm days (lows in the
50s/60s and highs in the 80s). If things slow down and the system
takes its time, some lingering or wrap around clouds will be
possible, and daytime highs might end up not being as high as
anticipated. Hope to see better model agreement/consistency over
the next couple of days.  42


.MARINE...

Increasing onshore winds and building seas can be expected through
midweek in response to lowering pressures to our west. Have raised
some caution flags already, and we will likely need more caution/
advisory flags on into Thursday or Thursday night after the next
storm system`s cold front has moved on through. Before the front,
still think we could be seeing periods of haze/fog development.
Offshore winds in the wake of the front will transition back to
the southeast this weekend as high pressure moves away from the
area. 42

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL)  68  83  71  89  68 /  10  30  10  20  60
Houston (IAH)          68  83  72  87  71 /  10  10  10  10  30
Galveston (GLS)        71  78  72  80  72 /  10  10   0   0  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...High Rip Current Risk until 9 PM CDT this evening for the
     following zones: Bolivar Peninsula...Brazoria
     Islands...Galveston Island...Matagorda Islands.

     Coastal Flood Advisory from 2 AM to 9 AM CDT Tuesday for the
     following zones: Bolivar Peninsula...Brazoria
     Islands...Galveston Island...Matagorda Islands.

GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 6 AM CDT Tuesday for
     the following zones: Coastal waters from Freeport to
     Matagorda Ship Channel TX out 20 NM...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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