textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1027 PM CST Fri Mar 6 2026

Key Messages

- Breezy conditions and gusty southeasterly winds continue across Deep South Texas tonight through Saturday afternoon, especially east of US-281, where gusts up to 30 mph, or greater, are possible ahead of an advancing frontal boundary.

- The Storm Prediction Center (SPC) has placed the Northern Ranchlands, Upper Rio Grande Valley and most of Zapata County within a Marginal (Level 1 of 5) Risk as well as a Slight (Level 2 of 5) Risk for the northwestern tip of Zapata County for severe storms Saturday evening, with the primary threat of isolated severe wind gusts (of at least 60 mph) and large hail.

- While generally one to three quarters of inch of rain is anticipated Saturday into Sunday, heavy rain is likely within the deepest convection or areas in which convection redevelops and persists, with the possibility of several inches in a few locations.

- Breezy conditions and unsettled weather are possible by the middle of next week ahead of a cold front passing through, possibly next Wednesday.

- Temperatures finally drop to near average behind the front, but with an increased risk of fire weather conditions into the later parts of next week.

DISCUSSION

Issued at 1027 PM CST Fri Mar 6 2026

Tonight into Saturday, a 30-40 knot nocturnal low level jet and tightened pressure gradient, resulting from a mid/upper level trough and associated low pressure system departing the Central Plains, continue to lead to gusty southeasterly winds across Deep South Texas, especially along/east of US-281, where gusts up to 30 mph, or higher, remain possible. Additionally, a High Risk of Rip Currents continues overnight, becoming a medium risk Saturday morning through the afternoon hours. Temperatures on Saturday are expected to increase from the low/mid 70s in the morning to the low/mid 90s across most inland areas in the afternoon.

The arrival of ridging aloft and building surface high pressure over the Central and Southern Plains behind the low pressure system pushes the low's attendant cold front southeastward, arriving to southern Texas by Saturday evening. As the front moves closer to our region, deterministic guidance continues to portray it losing forward momentum, perhaps stalling near or over the Northern Ranchlands and areas along/west of US-281 Saturday night into Sunday morning. Enhanced moisture pooling, instability, synoptic forcing and lift ahead of the front increase chances of rain across Deep South Texas Saturday evening into Sunday morning to as much as a medium to likely (50-90%) chance, with the higher chances further north and west. Although CAM guidance varies with the southward extent of the cold front and areas of convection initiation, there is fair agreement amongst this evening's 00Z runs, portraying strong to severe thunderstorms developing over southern Texas, and possibly the Sierra Madre, Saturday afternoon or evening, moving into the Rio Grande Plains, Northern Ranchlands and the Upper Rio Grande Valley during the early evening or early nighttime hours. The primary threats are likely to be large hail and isolated severe and damaging wind gusts. Indeed, the RAP model soundings depict MUCAPE values greater than 2,000 J/Kg, mid-level lapse rates of around 6.5- 7.0+ C/Km, cloud layer mean winds in excess of 60 knots in addition to increasing DCAPE values of near, or greater, than 900 J/Kg persisting across these areas into the early nighttime hours Saturday night.

As such, the Storm Prediction Center (SPC)'s Day 2 Convective Outlook highlights a Marginal (level 1/5) Risk for severe thunderstorms across the Northern Ranchlands, the Upper Rio Grande Valley and central/southern Zapata County within a 5% chance of isolated severe wind gusts (at least 60 mph) and large hail. Meanwhile, the northwestern tip of Zapata County is included within a Slight (Level 2/5) Risk, where there is a 15% chance of large hail in addition to the 5% chance of severe wind gusts. SPC further mentions that a "...more intense supercell or two remains plausible in...(the) Brush Country vicinity, capable of very large hail..." which could potentially further increase the risk of severe storms for Saturday evening. By Monday afternoon, we currently expect generally one to three quarters of an inch of rain across these areas, highest over northwestern portions of Zapata County. The Weather Prediction Center keeps all risks of flash flooding from excessive rainfall just north of our CWA Saturday into Sunday, though this could change, depending on how models trend over the next 24 hours. There is the potential for several inches within the deepest convection and/or areas in which showers and thunderstorms redevelop and persist as evident by the HRRR and RAP.

Following, southwesterly flow aloft ahead of a cut-off low over the Baja Peninsula, builds a mid/upper level high pressure over eastern Mexico and subsidence northward, decreasing chances of rain throughout Sunday to less than 10% by Monday morning as breezy to windy conditions return from a tightened pressure gradient. Increased clouds and rain likely keeps Sunday's highs in the 80s, possibly 70s over the Rio Grande Plains, before warming back to the 90s on Monday into Wednesday, with overnight low falling to the 60s/70s through Tuesday night. Unsettled weather is anticipated again Tuesday into Wednesday as the cut-off low aloft and trough move into central Texas. Global and long-term models indicate a general weakening trend of the low, which would limit the severity of convection, though still bares monitoring. As the system moves north and east of our region, a cold front is expected to pass through Deep South Texas on Wednesday, bringing breezy northerly winds into the end of next week; fire conditions and concerns increase as much drier air is advected southward into the CWA. Temperatures could drop to near average for the first time in weeks by the end of next week.

AVIATION

(06Z TAFS) Issued at 1027 PM CST Fri Mar 6 2026

Southeasterly winds of around 10-15 knots, gusting to 20-25 knots, and MVFR ceilings continue tonight across all terminals. VFR conditions return by mid-morning as southeasterly winds increase back to 15-20 knots, gusting to 25-30 knots. The approach of a stalling frontal boundary has introduced PROB30s into the TAFs for KMFE beginning Saturday evening, where this is the possibility of strong to isolated severe thunderstorms, bringing damaging winds and large hail. Low ceilings (IFR or lower) are likely at all terminals Saturday night.

MARINE

Issued at 1027 PM CST Fri Mar 6 2026

Moderate to fresh southeasterly winds and moderate (3-4 feet) seas continue through Saturday afternoon. Winds become gentle to moderate and chances of rain increase Saturday evening into Sunday to as much as a medium to likely (40-70%) chance as showers and thunderstorms develop along and ahead of a frontal boundary stalling near inland Deep South Texas. A few storms may bring gusty winds and/or hail Saturday night before transitioning to mostly rain showers on Sunday. A pressure tightens again on Monday, leading to moderate to fresh southeasterly winds and moderate seas into Tuesday. Chances of rain increase again Tuesday into Wednesday to a low (15-30%) chance, followed by a cold front on Wednesday, with moderate northerly winds and moderate seas continuing into the end of next week.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 72 87 72 86 / 10 0 30 50 HARLINGEN 69 91 69 87 / 10 0 40 60 MCALLEN 74 94 73 89 / 10 10 50 80 RIO GRANDE CITY 71 97 67 82 / 10 10 70 90 SOUTH PADRE ISLAND 71 79 72 78 / 10 0 30 50 BAYVIEW/PORT ISABEL 69 86 69 84 / 10 0 30 50

BRO WATCHES/WARNINGS/ADVISORIES

TX...High Rip Current Risk until 6 AM CST Saturday for TXZ451-454-455.

GM...None.