textproduct: Brownsville/Rio Grande Valley

SHORT TERM

(Tonight through Thursday night) Issued at 254 PM CDT Wed Apr 2 2025

Key Messages:

- Windy with another Wind Advisory Thursday.

- Above Normal Temperatures

- High Risk of Rip Currents and Small Craft Advisories

The active spring synoptic pattern continue to support breezy to outright windy conditions for all of Deep South Texas, especially the coastal counties. A broad and strong cold low pressure trough continues to deepening over the Rockies and Inter-Mountain west and combine with subtropical ridge building over Florida and the Gulf. The pressure gradient remains strong over the Western Gulf with models suggesting the redevelopment of the 925-850mb low level jet tonight and again Thursday night/Friday morning. Models are suggesting the LLJ to peak around 50 knots late tonight/Thursday AM and 45-50kts Friday AM. Mechanical mixing starting around sunrise Thursday and continuing as daytime heating accelerates should allow for these winds to mix to the surface setting the stage for another wind Advisory favoring the coastal counties including the Lower RGV and SPI.

Other sensible weather, strong southerly winds maintain above normal temperatures for the short term with lows in the 70s both Tonight and Thursday night. High climb well into 90 away from the immediate coast. Combine these afternoon temperatures with dew points in the low to mid 70s heat indices will be bumping up in the 98-104 degree range maintain at least a moderate heat risk for most of Deep South Texas. Look for a thin layer of stratus overspread the CWA tonight and quickly burning off Thursday mid-morning. Similar to this morning, increasing clouds tonight with a mostly sunny day tomorrow.

Finally, the high risk of rip currents at our local beaches persist through at least Friday morning as the strong southerly winds continue to roughen up the surf.

LONG TERM

(Friday through next Wednesday) Issued at 254 PM CDT Wed Apr 2 2025

*Key Messages:

- Windy conditions on Friday, with a Wind Advisory possible

- Well-above average temperatures Friday and Saturday with the warmest day expected to be Friday

-Cold front passes through Saturday with below average temperatures Sunday and Monday before warming with more average temperatures Tuesday and Wednesday.

Breezy to windy conditions continue Friday into Saturday morning, with winds out of the south-southeast, as a tight pressure gradient develops between a strengthening surface low pressure near the AR/TX/OH borders and a high pressure offshore the southeast US coast. A Wind Advisory is possible on Friday as the NBM is already hinting at a 10-15% of sustained winds exceeding 30 mph across the barrier islands, coastal counties and the middle RGV. Additionally, the GFS is indicating a 35-50 knot low-level (925 mb) jet along and east of I-69 C. As the low pressure strengthens, an associated pre- frontal trough is expected to approach Deep South Texas from the north, with winds weakening and turning northerly as the trough passes through from Saturday morning into the afternoon. Meanwhile, a mid-to-upper level trough and cut-off low will advance east- southeastward from the Desert Southwest/northern Mexico on Friday to West Texas by Saturday morning. As it continues eastward and mid-to- upper southwesterly flow divergence increases over the County Warning Area (CWA), along with the lift provided by the approaching front, a gradual uptick in showers and thunderstorms over the lower Texas Gulf waters is expected to result in a low-to-medium (20-40%) chance over the western Gulf throughout the day Saturday. As the front arrives on the leading edge of a surge of high pressure later Saturday night, a low-to-medium (20-30%) chance of showers and thunderstorms is possible over the coastal counties and Middle RGV from Saturday night into Sunday morning. Behind the front, breezy conditions return late Saturday night and into Sunday as north- northwesterly low-level (925 mb) winds increase on the backside of the departing low pressure system.

Quiet weather is expected by Monday, and into the rest of the long term, as ridging aloft gives way to west-northwesterly flow. Northerly surface winds continue into Monday and become southeasterly by Wednesday as a high pressure moves into the Deep South.

Friday is anticipated to be the hottest day of the period with highs soaring into 90s across inland portions of Deep South Texas, nearing 100 degrees F over the Rio Grande Plains, with Friday night lows falling to the upper 60s to low-to-mid 70s. On Saturday, the wind shift out of the north is likely to limit highs to the upper 80s-to- low 90s. As the front passes through Saturday night, temperatures will cool off substantially and into the 50s. Highs in the 70s are expected for Sunday and Monday with 80s returning Tuesday and Wednesday as winds veer back to easterly and southeasterly. Lows in the 40s/50s Sunday and Monday night will slightly warm into mid-to- upper 50s Tuesday and Wednesday night.

AVIATION

(06Z TAFS) Issued at 1232 AM CDT Thu Apr 3 2025

MVFR conditions will quickly give way to windy VFR conditions near daybreak, like yesterday. Expect AWWs needed for wind gusts over 35 kts through the afternoon hours. The low level jet increases towards 50 kts this morning along the coast and gradually works offshore, have kept wind shear into this package until mid-morning when better mixing increases surface winds.

MARINE

Issued at 254 PM CDT Wed Apr 2 2025

Tonight through Thursday night...Western Gulf pressure gradient persist through Friday morning as high pressure combines with a strengthen low pressure trough settling over the Southern Rocky Mountains. A diurnal wind pattern with strong offshore winds developing overnight and lowering during the day. While winds on the Laguna Madre are likely to be stronger during the afternoon hours with limited diminishing during the evening and overnight hours. Seas have responded today due to earlier strong winds at buoy 42020 and are in the range of 6 to 9 feet offshore. The high sea state persist through Friday morning and may even builds overnight. Small Craft Advisory are already in effect until 1 AM Friday for all coastal waters.

Friday through next Wednesday...Small Craft Advisories are likely to persist through Monday. Fresh to strong south-southeasterly winds and moderate to rough (6-10 ft) seas are likely Friday and Friday night due to a tight pressure gradient between a strengthening low pressure system over the Central Plains and high pressure to the east. Winds temporarily weaken on Saturday as a pre-frontal trough shifts winds out of the north. Seas are anticipated to subside to moderate (6-8 feet) during this time. As the front draws closer throughout the day Saturday, chances of showers and thunderstorms are expected to gradually increase from a low-to- moderate (20-30%) to a moderate (30-40%) chance by late Saturday evening. Following the passage of the cold front late Saturday night, northerly winds will increase to strong into Sunday morning, building seas back to rough, possibly very rough, into Sunday afternoon. Fresh to strong northerly winds maintain into Monday with much more ideal conditions returning throughout the beginning of next week with gentle to moderate winds and slight seas returning by Tuesday, gradually shifting out of the southeast by Wednesday.

HYDROLOGY

Issued at 246 AM CDT Wed Apr 2 2025

Due to historical rainfall last week across the mid to lower Rio Grande Valley, water levels across both the Arroyo Colorado and Rio Grande remain elevated and both the main floodway and north floodway are flowing.

The Arroyo Colorado at the HAGT2 gauge in Harlingen is reporting 18.03 ft and falling. The gauge in Rio Hondo, ACHT2, is reporting 12.62 ft and falling.

The Rio Grande near San Benito, SBNT2, reached action stage of 44.0 ft around 12 PM Friday and crested at 54.04 ft early Sunday morning, just shy of minor flood stage at 55.0 ft. Water levels at San Benito have fallen to 49.10 ft and are expected to fall back below action stage of 44.0 ft this afternoon.

The Rio Grande at Lower Brownsville, LOBT2, reached action stage of 24.0 ft around 5 PM Monday afternoon, and crested at 24.71 ft Tuesday afternoon. Water levels at Lower Brownsville have fallen to 24.56 ft and are expected to fall back below action stage of 24.0 ft late this afternoon or early this evening.

The main floodway through Weslaco at WSLT2 is at 18.40 ft and falling, with the north floodway near Sebastian at SBST2 at 12.03 ft and falling.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 76 89 76 90 / 0 0 0 10 HARLINGEN 74 92 74 91 / 0 0 0 10 MCALLEN 77 96 77 94 / 0 0 0 0 RIO GRANDE CITY 73 97 71 89 / 0 0 0 0 SOUTH PADRE ISLAND 74 81 74 82 / 0 0 0 10 BAYVIEW/PORT ISABEL 74 88 74 88 / 0 0 0 10

BRO WATCHES/WARNINGS/ADVISORIES

TX...High Rip Current Risk through this evening for TXZ451-454-455.

GM...Small Craft Advisory until 1 AM CDT Friday for GMZ130-132-135- 150-155-170-175.