Small Craft Advisory 21, NWS Brownsville, TX

251 
WHUS74 KBRO 132039 AAA
MWWBRO

URGENT - MARINE WEATHER MESSAGE...UPDATED
National Weather Service Brownsville TX
339 PM CDT Wed Mar 13 2024

GMZ132-135-155-132145-
/O.CAN.KBRO.SC.Y.0021.000000T0000Z-240314T0200Z/
Laguna Madre from the Arroyo Colorado To 5 NM north of Port
Mansfield TX-
Laguna Madre from 5 nm north of Port Mansfield to Baffin Bay TX-
Gulf waters from Baffin Bay to Port Mansfield out 20 nm-
339 PM CDT Wed Mar 13 2024

...SMALL CRAFT ADVISORY IS CANCELLED...

Surface observations along the Lower Texas Coast indicate 
that Small Craft Advisory conditions are not materializing 
as originally forecast. As a result, the Advisory has been 
canceled a few hours early. 

However, Small Craft Should Exercise Caution along the Lower 
Texas Coast tonight, mainly due to winds. 

$$

TOMASELLI

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
1150 PM CDT Tue Mar 12 2024

...New AVIATION...

.SHORT TERM...
(Tonight through Wednesday night)
Issued at 230 PM CDT Tue Mar 12 2024

Some model guidance continues to indicate some limited potential for
isolated convection across portions of the CWA tonight.  With steep
mid level lapse rates of greater than 7 C/km, sufficient moisture,
and another shortwave moving through the CWA, slight chance POPs are
in order for portions of Zapata and Starr counties this evening.
Consistent HRRR runs have shown isolated Sierra Madre convection
firing up in the next few hours and some of this possibly affecting
Starr and Zapata counties early this evening.  Further east...there
may be a weak shower or sprinkle or two from residual moisture as
the initial shortwave moves quickly through the area.  Otherwise,
dry conditions are expected through Wed night as the overall
moisture profile diminishes with some weak ridging aloft noted
albeit for a brief time before southwesterly flow aloft
reestablishes itself.  More sunshine and persistent increasing
southerly flow will warrant a warming trend through the period.  In
fact, high temperatures on Wed should average 6-10 degrees above
normal for mid March.  Each overnight and morning period will have
abundant low clouds but these will tend to burn off faster on Wed
with the drier tropospheric profile and better mixing.

&&

.LONG TERM...
(Thursday through next Tuesday)
Issued at 230 PM CDT Tue Mar 12 2024

The long term period begins with a 500mb closed low digging into
the Desert Southwest. This low looks to break from the main
circulation on Friday, and remain largely in place through the
weekend. This will support upper level southwesterly flow over
Deep South Texas through the period.

At the surface, a low pressure system looks to develop over the
Texas Panhandle on Thursday before traveling northeast towards the
Great Lakes. The cold front associated with this system looks to
move into Central Texas by Friday afternoon, and finally reaching
Deep South Texas Saturday night into Sunday morning.

A series of pressure perturbations will likely move through the
southwesterly flow aloft through the period. The first of these
looks to enhance a leeward low pressure off the Sierra Madre on
Thursday, tightening pressure gradients across Deep South Texas.
This will likely result in breezy southeasterly winds late
Thursday morning into Thursday afternoon, especially along the
coast and the Lower Rio Grande Valley. Winds are expected to die
down Thursday night as the low weakens. The southeasterly flow
will continue to bring warmer temperatures and low level moisture
Friday, leading to increased instability. Combined with some weak
forcing from another pressure perturbation, there is a slight
chance (~20-30%) for some isolated convection over western
portions of the CWA Friday night, and northern portions Saturday.
Additional showers and thunderstorms will be possible Saturday
night through Sunday with the passage of the cold front. Behind
the front Sunday night some elevated convection is possible, but
as instability continues to decrease, light stratiform rain
becomes more likely going into Monday as an overrunning pattern
sets up. There is some uncertainty in the timing of the front, and
the distribution of precipitation along and behind it. Models are
in better agreement this run on the timing of the front, but
still differ on the rain chances associated with it. For now, rain
chances will stay between 20-30% across most of Deep South Texas
Saturday night through Monday.

High temperatures are expected to reach the low 90s across most of
the CWA Thursday and Friday, with areas along the cost remaining
slightly cooler, in the mid 80s. Increased cloud cover Saturday
will likely keep highs in the mid to upper 80s. Behind the cold
front, High temperatures Sunday look to be in the mid to upper
70s, with continued cooling dropping high temperatures into the
upper 60s to low 70s Monday and Tuesday. Likewise, low
temperatures ahead of the front are expected to be in the upper
60s to low 70s, falling to the 50s to low 60s by Sunday night.

&&

.AVIATION...
(06Z TAFS)
Issued at 1139 PM CDT Tue Mar 12 2024

Some low clouds are in the area with KMFE reporting OVC020
(MVFR). Winds are light south southeast (but a little stronger
currently at KMFE). Still seeing upper moisture and clouds lifting
across East and South Texas ahead of a shallow short wave trough
just upstream. Guidance suggest MVFR ceilings will develop
overnight through mid Wednesday morning before increased south
southeast winds help scatter out the ceilings.

&&

.MARINE...
Issued at 230 PM CDT Tue Mar 12 2024

Tonight through Wednesday night...A slowly increasing southerly
gradient and slowly building seas will prevail through the period.
On Wed night, sufficiently higher dewpoints around 70 degrees
coupled with the SSTs in the upper 60s to around 70 degrees will
produce at least some patchy sea fog across portions of the Laguna
Madre and adjacent nearshore waters. The cooler nearshore waters
will likely translate into slightly lower winds given the added
stability.  No flags are expected through the short term as the
gradient will not be quite that strong during the short-term
forecast period.

Thursday through next Tuesday...Tightening pressure gradients
Thursday, as the result of low pressure developing along the
Sierra Madre Mountains, will support stronger southeasterly winds
Thursday afternoon. Small Craft Should Exercise Caution headlines
or Small Craft Advisories will likely be needed for the Laguna
Madre and nearshore Gulf waters Thursday. Conditions look to
improve Thursday night, with light to moderate winds and moderate
seas continuing through Sunday. The passage of a cold front Sunday
morning will bring a northeasterly wind shift, as well as the
potential for some isolated to scattered showers and thunderstorms
through the remainder of the period. Stronger winds and building
seas Monday may require Small Craft Advisories, but conditions
look to improve slightly Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             80  69  85  71 /  10   0   0   0
HARLINGEN               82  66  88  69 /  10   0   0   0
MCALLEN                 83  67  92  71 /  10   0   0   0
RIO GRANDE CITY         85  65  95  68 /  10  10   0   0
SOUTH PADRE ISLAND      73  68  76  69 /  10   0   0   0
BAYVIEW/PORT ISABEL     78  67  84  68 /  10   0   0   0

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&

SHORT TERM...54-BHM
LONG TERM....68-McGinnis
AVIATION...54-BHM