363
FXUS64 KBRO 300347
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
1047 PM CDT Fri Aug 29 2025

...New DISCUSSION, MARINE...

.KEY MESSAGES...
Updated at 1037 PM CDT Fri Aug 29 2025

 - Moderate to Major (Levels 2 to 3 of 4) Risk of excessive heat
   through Saturday with heat indices of 105-111. Visit
   weather.gov/heatsafety for more resources.

 - Mostly rain-free conditions expected today; rain chances
   increase Sunday to low (20%) and moderate (40-60%) Monday and
   Tuesday.

 - The Weather Prediction Center maintains the northern portions
   of Zapata, Jim Hogg, Brooks, and Kenedy counties in a Marginal
   Risk (level 1 of 4) of excessive rainfall on Monday.

&&

.DISCUSSION...
Issued at 1037 PM CDT Fri Aug 29 2025

The main concern this holiday weekend continues to be heat, as
subsidence under a mid-level high pressure over West Texas with low-
level moisture brought by south-southeasterly winds brings heat
indices into the triple digits each day through Labor Day. Near to
slightly above average high temperatures persist, but a moderate to
major (level 2 to 3 of 4) risk of heat-related impacts are expected
through the weekend. Heat indices from 105-111 are possible across
the region, with the highest values expected in the mid-upper RGV
and along US-77. Special Weather Statements (SPS) highlighting
this heat are not out of the question today and Sunday. For resources
on staying safe in the heat, visit weather.gov/heatsafety.

Mid-level ridging will maintain low rain chances today. As this
ridge shifts west, deeper layer moisture builds, bringing PWAT
values around 2". Shortwaves on the eastern periphery of this ridge
will allow for a low chance (<20%) showers along the sea breeze
Sunday afternoon. A stationary front located over north/central TX
will slowly work its way south, providing forcing for an increase in
rain chances to moderate (40-60%) along the boundary Monday and
Tuesday. WPC maintains a Marginal Risk (level 1 of 4) of excessive
rainfall for northern portions of Zapata, Jim Hogg, Brooks, and
Kenedy counties Monday, which brings the possibility of isolated
flash floods to low lying and poor drainage areas. These showers and
thunderstorms through Tuesday also carry the risk of gusty winds,
heavy rainfall, and lightning to the CWA. As the frontal boundary
washes out by midweek, expect seasonal to a touch below average
temperatures and a daily low chance (<30%) of showers and
thunderstorms along the sea breeze.

Late next week, guidance suggests surface high pressure over central
US surging southward behind a digging trough into next weekend. This
pattern is expected to bring well below-average temperatures to the
midwest. This is a week or more away, so confidence is lower at this
range, but deep South Texas is not expected to see as significant of
a departure from normal in temperatures. However, present guidance
suggests a low chance (<20%) that afternoon highs fail to reach 90
degF next weekend following the passage of the secondary cold front
tied to this strengthening high. This front can also provide
increased chances for showers and thunderstorms. Further updates to
come as we head into next week.

&&

.AVIATION...
(00Z TAFS)
Issued at 622 PM CDT Fri Aug 29 2025

VFR conditions will prevail over the period. Moderate south-
southeasterly winds will lessen overnight at all sites becoming
light to gentle. Late morning, moderate flow returns (gusts to
around 20 kts) at all sites through Saturday afternoon.

&&

.MARINE...
Issued at 1037 PM CDT Fri Aug 29 2025

Mid-level high pressure over west TX will allow for subsidence and
generally favorable marine conditions through the weekend. Expect
light (occasionally moderate in afternoon) south-southeasterly flow
and slight seas to prevail, before low rain chances (20%) return
Sunday. Moderate rain chances (40-50%) Monday and Tuesday as a
frontal boundary sinks southward across TX. Passage of this boundary
will shift winds out of the north, before returning to generally
southeasterly by late next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             97  79  96  79 /   0   0   0   0
HARLINGEN               99  76  98  76 /   0   0   0   0
MCALLEN                103  79 102  79 /   0   0   0   0
RIO GRANDE CITY        104  77 103  77 /   0   0   0   0
SOUTH PADRE ISLAND      90  83  90  82 /   0   0   0   0
BAYVIEW/PORT ISABEL     95  79  93  79 /   0   0   0   0

&&

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

$$

SHORT TERM...69-HK
LONG TERM....69-HK
AVIATION...69-HK