114
FXUS64 KBRO 211728
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
1228 PM CDT Fri Jun 21 2024

...New AVIATION...

.SHORT TERM...
(Today through Saturday)
Issued at 402 AM CDT Fri Jun 21 2024

Key Messages:

- Slow but steady recovery in the wake of Tropical Storm Alberto
- Monitoring a disturbance in the Southwest Gulf

.Short term...

Though TS Alberto is in the books, unsettled weather will remain in
the short term. Mid-level ridging and surface high pressure are
anchored over the Southeast United States, extending west into East
Texas. This seems to want to counter the remaining deep moisture
over the area. However, the NBM maintains solid rain chances through
the short-term. QPF amounts through the period are not extreme,
however, at only hundredths to tenths of an inch in any given six
hour period, suggesting that actual precipitation episodes may be
isolated to scattered and intermittent, as if the models are trying
to capture what looks like repeated pulses of moisture moving north
from the unsettled Southwest Gulf. Although the NBM may be over-
playing the percentages, don`t feel as if that is a huge problem,
since most locations could see additional precip in transitioning
away from the TS Alberto influence. SPC keeps the CWA in a general
thunderstorm outlook through the short term. WPC indicates slightly
higher rain amounts on Saturday than today, and a marginal risk of
excessive (above flash flood guidance) rainfall.

Light to moderate northeast to east winds will prevail under partly
to mostly cloudy skies. High temps will be near normal for this time
of year, mostly in the lower 90s. Elevated relative humidity values
may make conditions feel "muggy." Low temps will be mainly in the
mid 70s.

A disturbance in the Southwest Gulf has a chance, 40 or 60 percent,
to develop into a tropical system the next two to seven days,
respectively. This disturbance over southern Yucatan is producing a
large area of showers and isolated thunderstorms affecting SE
Mexico, Central America, northwestern and central Caribbean Sea. A
broad area of low pressure is forecast to form over southeastern
Mexico and northern Central America later today. Environmental
conditions appear conducive for gradual development after this
system moves over the Bay of Campeche on Saturday, and a tropical
depression could form over the southwestern Gulf of Mexico this
weekend while it moves slowly west-northwestward or northwestward.

Hazards: A high rip risk will continue through the short term while
wave heights slowly decrease. High surf will decrease this evening.
Coastal flooding is ongoing through the morning high tide, slowly
improving, allowing for replacement of the warning by an advisory by
this afternoon.

&&

.LONG TERM...
(Saturday night through Thursday)
Issued at 402 AM CDT Fri Jun 21 2024

The long term begins with increased chances of showers and
thunderstorms as Deep South Texas may once again be positioned on
the northern periphery of another tropical system. Guidance from The
National Hurricane Center (NHC) is indicating that an of low
pressure is expected to develop in southeastern Mexico and northern
Central America and track northwestward into the Bay of Campeche by
Saturday. Once over water, NHC suggests there is a 40% chance that
the low pressure center will develop into a tropical cyclone within
48 hours as well as a 60% chance of development over the next 7 days
as the system tracks northwestward into the southwestern Gulf of
Mexico. Although uncertainty exists within their forecast, tropical
moisture is expected to increase over the weekend for Deep South
Texas and the Storm Prediction Center (SPC) outlines a general
outlook for thunderstorms on Sunday.

Meanwhile, a mid to upper level high pressure over the Southern
Plains will retreat westward over Texas, northern central Mexico,
northwestern Mexico and the Desert Southwest U.S. throughout the
weekend and into the beginning of next week. As the tropical
moisture associated with the tropical system moves southwest and
away from Deep South Texas, subsidence underneath the ridge will
gradually limit chances of rainfall throughout the week. As such,
temperatures will rise and Special Weather Statements and, or Heat
Advisories may be needed towards the middle of next week as maximum
temperatures are expected to range from upper 80s near the coast to
mid-to-upper 90s further inland by midweek. At the surface,
southeasterly onshore flow will heighten humidity and send heat
indices to near, and above, 111 F. Minimum temperatures will also
slowly warm from mid 70s to upper 70s for inland portions as well as
expand low 80s near the coast further inland across Rio Grande
Valley throughout the period.

&&

.AVIATION...
(18Z TAFS)
Issued at 1228 PM CDT Fri Jun 21 2024

The latest radar and satellite observations reveal mostly VFR
conditions and widely scattered SHRA/isolated TSRA across the
region this afternoon. Expect these trends to continue through the
evening hours as low level easterly to southeasterly flow
transports tropical moisture across the region. Precipitation
chances increase late tonight into tomorrow as the broad area of
pressure over the Bay of Campeche translates west northwestward
toward Southeastern Mexico. Scattered showers and isolated
thunderstorms will likely persist by mid morning Saturday through
the afternoon/evening hours. Locally heavy rain may result in
reduced visibility at the terminals. Otherwise, MVFR ceilings will
return around 14-16Z.

&&

.MARINE...
Issued at 402 AM CDT Fri Jun 21 2024

Today through Saturday...Moderate to fresh, slowly decreasing,
northeast to east winds and elevated seas will prevail. The small
craft advisory on the Laguna Madre will expire at 7 AM. The small
craft advisory for the Gulf will likely need to be extended beyond
today as high seas will be slow in lowering. Marine weather will
remain unsettled, with showers and thunderstorms possible. Ridging
and high pressure over the Southeast United States, extending south
into the Gulf, will support a northeast to east wind and temporarily
larger waves through the short term.

Saturday night through Thursday...The marine forecast has
potentially multiple outcomes depending on the strength of the
potential upcoming tropical system and its associated wind field.
In either circumstance, Small Craft Exercise Caution (SCEC)
conditions are likely for the offshore (20-60 nm) Gulf Waters on
Sunday as remnant long period wind-driven swell originated from
Alberto continues to generate higher wave heights. If tropical
development is more substantial and winds expand into the coastal
waters, then Small Craft Advisories, may be needed. Otherwise,
gentle to moderate southeasterly winds will ensue and seas will
continue to improve throughout the forecast period.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             92  78  88  78 /  80  80  80  90
HARLINGEN               91  75  88  76 /  60  60  80  80
MCALLEN                 91  76  87  77 /  70  60  80  70
RIO GRANDE CITY         90  76  87  76 /  60  50  80  60
SOUTH PADRE ISLAND      88  81  85  81 /  70  80  80  90
BAYVIEW/PORT ISABEL     90  78  88  79 /  60  80  80  80

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...Coastal Flood Warning until 1 PM CDT this afternoon for TXZ351-
     354-355-451-454-455.

     Coastal Flood Advisory until 7 PM CDT this evening for TXZ351-
     354-355-451-454-455.

     High Rip Current Risk through Sunday morning for TXZ451-454-455.

     High Surf Advisory until 7 PM CDT this evening for TXZ451-454-
     455.

GM...Small Craft Advisory until 7 PM CDT this evening for GMZ150-155-
     170-175.

&&

$$

SHORT TERM...54
LONG TERM....60
AVIATION...22-Garcia