textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 611 AM CDT Fri May 1 2026

Key Messages:

* One more day of hot temperatures on Friday, with a Minor to Moderate Heat Risk (Levels 1 and 2 out of 4) as afternoon heat indices reach into the lower 100s across most of the RGV.

* Showers and thunderstorms bring a low to medium (20-50%) chance of rain to the Northern Ranchlands Friday morning and afternoon, followed by a low to medium (30-60%) chance for the rest of the region Friday evening into the nighttime hours.

* Forecast confidence remains low at this time for the likelihood of isolated strong to severe thunderstorms late tonight through Friday night.

* High Surf Advisory and Small Craft Advisory go into effect Friday night as breezy to strong northerly winds along/behind the front result in large breaking waves, life threatening rip currents and adverse marine conditions into Saturday night.

* Temperatures drop at least 15-20 degrees behind the front Friday night into Saturday before steadily rising on Sunday back to above average by next Tuesday.

DISCUSSION

Issued at 1012 PM CDT Thu Apr 30 2026

Surface observations and radar imagery this evening reveal a stationary boundary draped across the Rio Grande Plains and the Northern Ranchlands as well as convection firing off the Sierra Madre to the northwest and southern-central Texas, where forcing from upper level divergence and ascent aloft are enhancing ahead of a mid/upper level trough moving into northern Mexico. As the trough draws further east and associated forcing expands southeastward tonight, showers and thunderstorms are anticipated to develop progressively further south and into southern Texas by Friday morning. At this time, the Convection Allowing Models (CAMs) best initializing the latest conditions are indicating strong to severe thunderstorms remaining well north of Deep South Texas tonight into Friday morning. Yet, the NAM 3 km and HRRR bring the convection further south and initiating off the frontal boundary, where the HRRR clips the extreme northern portions of Zapata, Jim Hogg, Brooks and Kenedy counties with showers and isolated, but short- lived, strong to potentially severe thunderstorms at some point from late tonight through the mid-morning hours on Friday. As such, SPC does include those areas within a Marginal (Level 1/5) risk of severe thunderstorms, with the primary threat of isolated large (1"+) hail and strong wind gusts transitioning to a hail risk in the morning due to deep layer shear in place along with relatively steep lower/mid-level lapse rates and marginally sufficient MUCAPE. However, it should be noted that the HRRR is an outlier at this point and the more likely scenario is that the strong to severe threat remains well to the north while light to moderate showers, and potentially a rumble of thunder or two, bring a low to medium (20-50%) chance of rain to the Rio Grande Plains and the Northern Ranchlands Friday morning into the afternoon. Temperatures minimize in the 70s tonight along with muggy conditions.

The trough ejects eastward and north of our region during the day Friday and surface high pressure and northerly winds on the backside of the associated surface low pressure system send a cold front southward through Deep South Texas late Friday afternoon into Friday night, increasing chances of rain to as much as a low to medium (30-60%) chance Friday night for areas south of the Northern Ranchlands. This will be another period to watch for any stronger storm potential; the RAP and GFS pose a small window of atmospheric instability and steep lapse rates coinciding with convection developing with the front to develop isolated strong to severe thunderstorms. Yet, again, CAM solutions still remain very incohesive and confidence is too low to say one way or the other beyond the current expectation of passing isolated to scattered showers and thunderstorms bringing generally around 0.3-0.7 of an inch of rain to the Lower and Middle RGV.

Temperature-wise, another hot day is anticipated ahead of the front on Friday, reaching into the low/mid 90s for most, though cloud coverage over the Rio Grande Plains and western portions of the Brush Country could keep temperatures in the 80s. Afternoon heat indices in the lower 100s are likely across most of the RGV, bringing mainly a Minor Heat Risk to the CWA as well as a Moderate Heat Risk roughly between US-281 and I-69 E. Behind the front, breezy northerly winds, gusting to 20-30+ mph, advect much cooler, drier and refreshing air, dropping temperatures down to the upper 50s/lower 60s by Saturday morning and only rising into the mid/upper 70s Saturday afternoon, which is a good 15-20 degrees cooler than Friday. Ridging aloft and the return of southeasterly winds by Monday moderate and warm temperatures back to above normal by next Tuesday. The next potential cold front and unsettled weather could be by the later part of next week.

Due to gusty northerly winds along the coast and strong winds over the Gulf behind the front, a High Surf Advisory goes into effect 1 AM Saturday morning until 1 AM Sunday morning for large breaking waves of 6-10 feet. Additionally, a High Risk of Rip Currents is likely to be issued overnight tonight or on Friday as winds and large waves lead to life-threatening rip currents, lasting possibly into the beginning of next week.

AVIATION

(12Z TAFS) Issued at 611 AM CDT Fri May 1 2026

MVFR ceilings at BRO are forecast to lift to VFR levels after sunrise, with all three TAF sites remaining VFR into the afternoon. A cold front is forecast to move through the area this evening, bringing gusty northerly winds and a return of MVFR ceilings. Showers and thunderstorms will be possible along the front.

MARINE

Issued at 1012 PM CDT Thu Apr 30 2026

Gentle to moderate southeasterly winds and slight to moderate (2-4 ft) seas continue tonight through Friday afternoon ahead of a cold front arriving in the evening into Friday night. A Small Craft Advisory goes into effect for all Lower Texas coastal waters (0-60 nm out) from 7 PM Friday evening until 1 AM Sunday morning as strong northerly winds and near gale force gusts along and behind the front result in moderate to rough (6-10 ft, or greater) seas and rough conditions on the bay into late Saturday night. Developing showers and thunderstorms ahead of and along the front increase chances of rain north to south from late Friday afternoon to as much as a low to medium (30-60%) chance late Friday night. Although confidence and chances are low at this time, there is a slight potential for isolated strong to severe thunderstorms as the unsettled weather arrives. Otherwise, chances of rain decrease throughout the day Saturday and winds and seas improve throughout the remainder of Saturday night and into the rest of the weekend. Gentle to moderate winds and moderate seas resume on Sunday, becoming southeasterly on Monday, with moderate to fresh winds and periods of Small Craft Exercise Caution conditions developing by midweek.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 91 61 73 63 / 10 60 30 0 HARLINGEN 94 59 76 58 / 10 50 20 0 MCALLEN 95 62 78 60 / 10 50 10 0 RIO GRANDE CITY 91 58 78 56 / 20 40 10 0 SOUTH PADRE ISLAND 83 66 73 69 / 10 60 40 0 BAYVIEW/PORT ISABEL 90 61 74 64 / 10 60 30 0

BRO WATCHES/WARNINGS/ADVISORIES

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

High Surf Advisory from 1 AM Saturday to 1 AM CDT Sunday for TXZ451-454-455.

GM...Small Craft Advisory from 7 PM this evening to 1 AM CDT Sunday for GMZ130-132-135-150-155-170-175.