Brownsville, Texas 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

133
FXUS64 KBRO 180938
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
338 AM CST Sat Jan 18 2025

...New SHORT TERM, LONG TERM, MARINE...

.SHORT TERM...
(Today through Sunday)
Issued at 328 AM CST Sat Jan 18 2025

Key Messages:

- Temperatures will turn about 20 degrees colder tonight and Sunday
as an arctic surge arrives.

Today will be warm (70s and 80s) and dry with partly sunny skies and
light northwest winds. Relative humidity values west of the I-69C
corridor will drop into the teens and 20s, contributing to a
slightly more enhanced fire weather threat.

Winds will become moderate to breezy north after midnight tonight
with the arrival of a much anticipated arctic blast/surge. Temps
will decrease overnight, landing in the mid 30s across the northern
tier counties, but will be more in the lower to mid 50s for the
remainder of the CWA. Rip risk will increase to high. Wind chill
values right after dawn on Sunday will bottom out in the mid 20s
across the northern tier to 30s elsewhere. Since the values barely
touch cold weather advisory criteria, we won`t issue a hazard
message for now. Conditions will remain rain-free as well. Sunday
will be raw, with increasing cloud cover and moderate north winds.
High temps will reach the 50s (lower 50s northern tier).

&&

.LONG TERM...
(Sunday night through Friday)
Issued at 328 AM CST Sat Jan 18 2025

Key Messages:

- Arctic blasts likely to lead to subfreezing temperatures as well
  as Cold Weather Advisories and Freeze Warnings Sunday night,
  Monday night and Tuesday night

- Rain chances build on Monday into Tuesday from potential coastal
  low

- General Nonzero to low chance of freezing rain late Monday
  night into Tuesday across western portions of the Northern
  Ranchlands

- Breezy conditions on Tuesday across coastal counties and windy
  at the beaches

- Widespread 20s and lower 30s possible Tuesday night into
  Wednesday morning

The long term starts off Sunday evening with Deep South Texas in the
wake of the first surge of Arctic air with mostly clear skies.
Overnight, clouds begin to build as upper level forcing becomes
conducive to troughing near the coast ahead of the next upstream
trough. By Monday morning, there is a low to medium (20-40%) chance
of showers closer to the coast and east of I-69C. Throughout the day
and night Monday, POPs increase northward and westward across all of
the CWA to possibly a 60-90% chance with the highest chances east of
I-69C from Monday night into Tuesday morning as a potential coastal
low pressure system develops. Meanwhile, an upstream mid/upper
trough is pushed eastward across the Desert Southwest by a ridge,
advancing closer to the region and tightening a pressure gradient by
Tuesday morning. A breezy day is expected near, and east of, I-69C
on Tuesday with windy conditions closer to the immediate coast as
the upstream ridge sends a secondary surge of of Arctic air through
the CWA via northerly winds. There is the potential for a Wind
Advisory on Tuesday across the coastal counties, most especially
along the immediate coastline (SPI). Precipitation chances are
expected to decrease Tuesday afternoon into the evening as the
northerly winds pushes the coastal low and associated moisture
southward and the trough passes to the northeast Tuesday night.

As the secondary surge of Arctic air meets the humid airmass in
place late Monday night into Tuesday, there continues to exist a
nonzero to low  of mixed wintry precipitation, possibly
in the form of freezing rain. The latest DESI NBM data supports a
less than 10% chance of freezing rain across the western portions of
the Northern Ranchlands (Zapata, Jim Hogg and Brooks counties) by
midnight Monday night, increasing to a low to medium (20-30%) by
Tuesday morning, lingering till midday Tuesday. Meanwhile, the LREF
indicates a similar scenario, but spreading and increasing chances
to a low (20%) chance to the the mid and upper RGV, a nonzero chance
to the lower RGV (less than 10%) and as much as a medium (30-40%)
chance across the northern portions of Zapata and Jim Hogg. Yet,
uncertainty remains high and confidence low as there continues to be
considerable disagreement between models in regards to moisture
amount, duration of precipitation and temperatures during this event.

Behind the trough, ridging takes over, leading to drier conditions
late Tuesday night through Wednesday night with winds possibly
shifting out of the east and southeast as the surface high moves
over the mid-Atlantic. Then, another, though much weaker, surge of
high pressure is possible on Thursday, shifting winds back out of
the north and potentially resulting in drizzle Thursday into Friday
as an overrunning pattern sets up. Drier conditions are possible into
Saturday as the larger scale trough may finally shift off to the
northeast.

Now for the temperatures and additional hazards. Lows in the 30s
across inland Deep South Texas are likely Monday and Tuesday
mornings with subfreezing temperatures possible across the Northern
Ranchlands, especially Monday morning. NBM and LREF hold similar
probabilities of subfreezing temperatures across the Northern
Ranchlands for Monday and Tuesday morning, with a medium to high (30-
60%) chance of subfreezing temperatures across the Northern
Ranchlands as well as a low to medium (10-30%) chance for portions
of the mid and upper RGV on Monday morning and only a low to medium
(10-40%) chance of subfreezing temperatures on Tuesday morning.
Nonetheless, in addition to the potential Freeze Warnings for these
timeframe, Cold Weather Advisories are likely as wind chills bring
the apparent temperature down to the 20s and 30s. Highs in the 40s
and 50s are anticipated for Monday, but mostly in the low to mid 40s
on Tuesday. Tuesday night still looks to be the coldest night of
the season, so far, with lows in the lower 20s across the Northern
Ranchlands and upper 20s to near 30 degrees across the RGV and
Freeze Warnings and Cold Weather Advisories are likely.
Temperatures gradually increase Wednesday and into the rest of the
period with highs mostly in the 50s and lows mainly in the mid to
upper 30s and low 40s into Saturday, though lower 30s are still
possible for the western portions of the Northern Ranchlands
Wednesday morning. 60s and low 70s could return by Saturday.

&&

.AVIATION...
(06Z TAFS)
Issued at 1037 PM CST Fri Jan 17 2025

VFR conditions are expected to give way to MVFR and IFR conditions
late tonight as fog develops, with the best chance of any dense
fog at HRL. VFR ceilings return by mid morning Saturday. Southerly
winds continue to diminish into tonight with a cold front turning
winds northerly Saturday afternoon.

&&

.MARINE...
Issued at 328 AM CST Sat Jan 18 2025

Today through Sunday...With the arrival of a cold front tonight,
strong northeast winds and elevated (high) seas will develop,
meaning hazards will go into effect. Small craft advisories will go
up for the Laguna and Gulf starting at midnight tonight. Winds on
the Laguna may drop below criteria around 4 PM Sunday, but winds and
seas on the Gulf will stay above criteria through midnight Sunday
night, or beyond.

Sunday night through next Saturday...Conditions are expected to
briefly improve through Sunday night into Monday as northerly winds
diminish closer to shore, but as troughing sets up on Monday,
moderate nearshore (0-20 nm) and strong offshore (20-60 nm) east-
northeasterly build back throughout the day as a coastal low
pressure system develops into Monday evening, bringing medium to
high (40-90%+) chances of rain Monday into Tuesday night. Small
Craft Advisories and/or Small Craft Exercise Caution headlines are
likely for this timeframe. Overnight Tuesday, a surge of high
pressure brings in another blast of Arctic air with strong to near
gale-force northerly winds and gale-force gusts early Tuesday
morning into Tuesday Tuesday night, resulting in rough to very rough
seas. Gale Warnings are possible into Tuesday evening. Conditions
are expected to gradually improve late Tuesday night into Wednesday
and More favorable conditions resume into the rest of the period.

&&

.PRELIMINARY POINT TEMPS/POPS...
BROWNSVILLE             79  47  56  42 /   0   0   0   0
HARLINGEN               78  40  54  36 /   0   0   0   0
MCALLEN                 82  43  57  37 /   0   0   0   0
RIO GRANDE CITY         80  41  55  34 /   0   0   0   0
SOUTH PADRE ISLAND      71  49  57  48 /   0   0   0  10
BAYVIEW/PORT ISABEL     75  45  55  43 /   0   0   0   0

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...High Rip Current Risk from late tonight through late Sunday
     night for TXZ451-454-455.

GM...Small Craft Advisory from midnight tonight to 3 PM CST Sunday
     for GMZ130-132-135.

     Small Craft Advisory from midnight tonight to midnight CST
     Sunday night for GMZ150-155-170-175.

&&

$$

SHORT TERM...54-BHM
LONG TERM....65-Irish
AVIATION...56-Hallman