Areal Flood Warning 24, NWS Houston/Galveston, TX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
651 AM CDT Sat May 29 2021

.AVIATION [12Z TAF Issuance]...

Convection remains situated well to the west of all terminals,
and this should continue to be the case over the next several
hours. Furthermore, last night's gusty winds have become light and
variable with the offshore departure of showers and storms along
with the associated localized area of low pressure. VFR decks are
likely to persist through the day, though another round of showers
and storms should begin to develop by late morning/early
afternoon and expand in coverage through late afternoon. While any
prolonged category restrictions aren't expected until the
evening/overnight hours (where MVFR cigs are expected), temporary
visibility reductions due to precipitation are possible. Expect
increasing east/southeasterly winds to develop tomorrow.

Cady

&&

.PREV DISCUSSION... /ISSUED 405 AM CDT Sat May 29 2021/

SHORT TERM [Tonight Through Sunday Night]...

With the line of showers and storms that impacted SE TX this
evening now having advanced offshore, lighter winds and broken
clouds have developed across the area. We're continuing to monitor
the progression of an MCS with embedded strong thunderstorms to
the northwest of the San Antonio metro. While HiRes models and
radar trends continue to point to this feature largely tracking
west of our region, it's possible that some locations within the
western/southwestern zones will see another brief round of
showers and storms this morning.

The main weather focus for today will be the slow approach of a
weak surface cold frontal boundary, which should allow for some
additional showers and storms to develop this afternoon. While
moisture availability should be fairly plentiful (total PWs of
1.5-1.75in) and surface instability/mid-level lapse rates should
be favorable for convective development, a lack of strong forcing
should inhibit strong to severe storms.

Easterly winds and the in the wake of the advancing boundary
should result in a drier and slightly cooler Sunday. High
temperatures should max out in the low to mid 80s, with winds
remaining relatively light. As the aforementioned surface high
drifts to the east later on Sunday, we'll start to see a
redevelopment of south to southeasterly winds by the evening. This
should bring about increasing moisture and set the stage for a
wetter week ahead.

Cady

LONG TERM [Monday Through Saturday]...

If you're planning on being outdoors on Memorial Day, the weather
will be in your favor! Afternoon temperatures will reach the mid 80s
underneath mostly cloudy skies with a southeasterly breeze. For our
northern counties (mainly towards the Brazos Valley) there will be a
slight chance of afternoon showers/thunderstorms. The rest of the
region will get their fair share of PoPs going into rest of the
week. The weak upper-level ridge that builds in over the early half
of the weekend will gradually become replaced by a deep upper-level
trough that digs down towards the Baja Peninsula. The GFS and ECMWF
are in agreement on a cutoff low developing within this trough in
the mid-levels towards the middle of next week. This will keep the
subtropical jet active over the region and send numerous shortwaves
throughout the week.

With PW values remaining in the 1.5"-1.8" range due to persistent
onshore flow and CAPE values in the 1500-2000 J/kg range, PVA from
the shortwaves will have plenty of moisture and instability to lift.
As a result, showers and thunderstorms become a prominent feature in
the grids for southeast TX with PoPs remaining above 20-30%
throughout most of the period from Tuesday through Saturday. You'll
definitely want to keep an umbrella on hand throughout this week as
we head into yet another wet pattern. Enjoy the dry conditions on
Sunday and Monday while you can. The good news is those that receive
rainfall will get a temporary relief from the heat! Small victories?
Afternoon temperatures throughout the early half of next week will
top out in the mid 80s with upper 80s towards the end of the week.
Remember the persistent onshore flow? The steady southerly to
southeasterly winds throughout the week will keep the humid
conditions in place, so heat index values are expected to gradually
increase next week. While high temperatures in the 90s are not in
the forecast, it'll feel like the 90s (not the decade unfortunately)
in the afternoon hours.

Batiste

MARINE...

Scattered showers and storms continue to advance offshore, with
winds remaining gusty and variable. A Small Craft Advisory remains
in effect through 11 AM, with winds expected to quickly diminish
by early afternoon. The approach of a surface cold frontal
boundary will bring another chance of showers and storms to the
bays and waters today, though neither widespread coverage nor
severe weather is anticipated. In the wake of the boundary's
departure, a return to moderate onshore flow is expected. By
Tuesday, rain chances will be on the increase again as the first
of a series of upper-level disturbances traverses the region.

Cady

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      84  68  84  68  85 /  40  10  10   0  20
Houston (IAH)              85  69  84  69  85 /  50  10  10   0  10
Galveston (GLS)            82  74  81  76  82 /  40  10  10   0  10

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...Small Craft Advisory until 11 AM CDT this morning for the
     following zones: Coastal waters from Freeport to Matagorda
     Ship Channel TX out 20 NM...Coastal waters from High Island
     to Freeport TX out 20 NM...Galveston Bay...Matagorda Bay...
     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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