Update AFD Area Forecast Discussion — Fri Apr 3, 2026 7:36 PM

AFDBRO

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
627 PM CDT Fri Apr 3 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 624 PM CDT Fri Apr 3 2026

Key Messages:

* Significant weather pattern change (cooler and wetter) is
  expected to take place this weekend through early next week.

* Much needed rainfall in the form showers and thunderstorms are
  expected to bring some drought relief to the region this weekend
  through early next week.

* Heavy rainfall and slow moving thunderstorms could result in
  instances of flooding/flash flooding over parts of the area.

* WPC has all of Deep South Texas and the Rio Grande valley under a
  Marginal Risk (Level 1 of 4) of Excessive Rainfall on Saturday and
  Sunday.

* Preliminary rainfall amounts by Monday morning will range
  between 1-2 inches with locally higher amounts; additional
  rainfall amounts are possible Monday-Tuesday.

* Outside of the risk for showers and thunderstorms Saturday night
  through early next week, adverse to hazardous marine conditions
  are expected through next week.

&&

.DISCUSSION...
Issued at 246 PM CDT Fri Apr 3 2026

A significant weather pattern change (cooler and wetter) is in the
offing this weekend into the early parts of next week. After 6
months of long-term drought (since last October) that has much of
the region currently under a D3 (Extreme Drought) to D4 (Exceptional
Drought), much-needed rainfall is on the way across Deep South Texas
and the Rio Grande Valley. A cool frontal boundary ejecting out of
the southern Rockies and sweeping through Texas will be the focus of
waves of scattered to numerous showers and thunderstorms this
weekend into the early parts of next week. Showers and thunderstorms
will develop over Deep South Texas ahead, along, and behind this
frontal boundary.

During the day on Saturday, ahead of the cool front, strong warm air
advection (WAA) on breezy southerly winds, will allow for high
temperatures to rise into the upper 80s to lower 90s near the coast
to the mid 90s further inland (all above normal levels).
Additionally, southerly winds 10-20 mph with gusts up to 30 mph will
allow for deep/rich tropical moisture to continue to advect into the
region. Dewpoint (Td) values are expected to rise into the lower 70s
across the region with precipitable water (PWAT) values rising to
between 1.75-2 inches, some +1 to +3 STDEVs above normal.

During the day on Saturday, most of any showers and thunderstorms
that form will be confined to the western sections of the area (i.e.
along and west of IH-69C). That`s where we currently have PoPs
ranging between 30-60%. Saturday evening and especially Saturday
night, the coverage and probabilities for showers and thunderstorms
will spread eastward to include the rest of Deep South Texas and Rio
Grande Valley. Categorical PoPs will begin Saturday night (ahead of
the front) and prevail through Sunday night (behind the front) as
the aforementioned cool front pushes through the region. Overall,
appreciable rainfall amounts are expected from this event.
Preliminary rainfall estimates by Monday morning is still in the 1-2
inch range with locally higher amounts.

While, a strong to severe thunderstorm or two is possible during
this event, the main concern will be on the hydrology side. Given
the high atmospheric moisture content (i.e. PWAT values between
1.75-2 inches, some 2-3 STDEVs above normal) and the fact that
these storms will likely be slow movers due to the lack of air
flow aloft (i.e. LCL-EL winds being weak), heavy rainfall could
result in instances of flooding/flash flooding across parts of the
area. (flooding/flash flooding is possible in this supersaturated
environment).

The Weather Prediction Center (WPC) has maintained the entire
area under a Marginal Risk for excessive rainfall for both
Saturday and Sunday. Oil slick roads are possible at the onset of
any rainfall. That said, we urge motorist to review flood safety
tips at weather.gov/safety/flood. Additionally, motorists should
save extra time to get to their destinations if you must go out,
leave extra distance space between vehicles, drive slowly, and
never attempt to drive over flooded roadways.

Some lingering post-frontal showers are possible Monday and Tuesday.
On Monday, PoPs will begin to decrease with values ranging medium-
high between 40-70% (highest southeast). Categorical PoPs on Monday
will be confined across Mid-Lower Valley. The drying out process
could begin as early as Tuesday. On Tuesday, PoPs are ranging
low- medium between 20-40% (highest mid to lower valley). Overall,
grand total rainfall amounts from Saturday through Tuesday will
range between 1-3 inches with locally higher amounts. These
amounts will certainly help to address the D3 (Extreme Drought) to
D4 (Exceptional Drought) over the region. If not Tuesday,
Wednesday, will begin the drying out process across Deep South
Texas as high pressure builds into the region. Dry and tranquil
weather conditions will persist through the remainder of the week.

Temperatures will be that of a roller coaster pattern. We start off
up or above normal on Saturday with highs mainly in the 90s across
the region. As mentioned earlier, the cool frontal passage along
with the presence of showers, thunderstorms, and clouds will
result in cooler than normal temperatures across Deep South Texas
and the Rio Grande Valley Sunday through Tuesday/Wednesday of next
week. Warmer than normal temperatures return to the region next
Thursday and Friday. Daytime highs Sunday through Tuesday are
progged to be in the 60s/70s. By Wednesday, daytime highs are
expected to be in the low to mid 80s and by Thursday/Friday the
mid to upper 80s. Outside of tonight, overnight lows will mainly
be in the 50s/60s.

&&

.AVIATION...
(00Z TAFS)
Issued at 624 PM CDT Fri Apr 3 2026

VFR to MVFR conditions are expected with gusty southeasterly
winds persisting into late tonight. A southeasterly breeze is
anticipated on Saturday, but not as gusty as today. The chance of
showers and isolated strong to severe thunderstorms increases just
beyond this TAF period from the northwest into Saturday night.

&&

.MARINE...
Issued at 246 PM CDT Fri Apr 3 2026

Outside of the threat for showers and thunderstorms Saturday night
through early next week, adverse to hazardous marine conditions can
be expected through the forecast period or through next week.
Mainly Small Craft Exercise Caution (SCEC) conditions can be
expected. There could an instance of Small Craft Advisory
conditions on Sunday.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             73  88  71  78 /  20  10  80  90
HARLINGEN               69  90  66  78 /  20  10  90  90
MCALLEN                 75  94  69  77 /  20  20  90  90
RIO GRANDE CITY         73  93  63  71 /  20  40  90  90
SOUTH PADRE ISLAND      74  80  72  75 /  20  10  80  90
BAYVIEW/PORT ISABEL     71  87  69  78 /  20  10  80  90

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Advisory until midnight CDT tonight for GMZ130-132-
     135-150-155-170-175.

&&

$$