textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Issued at 1200 PM CST Sat Nov 7 2026

- Increasing potential for some localized flooding, favoring the northern ranchlands especially Sunday night. A Flood Watch is in effect for Zapata, Jim Hogg, and Brooks County for multiple rounds mainly late tonight and early Sunday and again Sunday night through Monday morning.

- Elsewhere, beneficial rains for most of the Rio Grande Valley, but potential for isolated flash floods continues from late tonight through Sunday night

- Surf becoming more dangerous through Monday, with high intensity rip currents arriving later tonight and continuing through Monday

- Increasing potential for water run-up to the dunes at narrow beaches by Sunday and Monday afternoon's high tides

DISCUSSION

Issued at 1200 PM CST Sat Nov 7 2026

Complicated forecast for rainfall location, intensity, and timing is coming into better focus today. In the big picture, we'll see rain across the entire area between tonight and Sunday night, gradually tapering off during the day Monday...all courtesy of the well- advertised and fairly vigorous closed 500 mb short wave diving into Sinaloa (Mexico) on Sunday before opening up into a broader wave from west Texas into northern Mexico Sunday night and early Monday.

Leftover shear energy from that wave and another weaker system hanging back into Chihuahua state (Mexico) Tuesday through Wednesday will maintain unsettled weather through then, though rainfall totals will be from scattered showers/few thunderstorms vs. more widespread coverage. Thursday and Friday...cross fingers...may bring in pleasantly dry air and cooler mornings with some of the lowest temperatures since the season's first true front in mid October.

For the sensible weather, here are the details:

Rest of today through early Monday: Instability and decent moisture (precipitable water at 1.81 here at Brownsville) should be enough to keep isolated to scattered shower this afternoon across the populated RGV. Not expecting the persistent heavier rain east of Tamaulipas to make much headway...but with low convective temperature (around 80), it won't take much to generate some locally heavier showers and perhaps a thunderstorm to drop a quick inch.

Tonight through mid-morning Sunday, the first round of heavy rain arrives into the Rio Grande Plains/Brush Country (Zapata/Jim Hogg/Brooks, potentially extending into northern Starr and Hidalgo) as the triple combination of an increasing low-level jet (LLJ) and the first spoke of leading 500 mb vorticity and 250 mb divergence in a building right-rear quad help focus rain along the surface front over the area. Incoming GFS 12Z run, along with the 12Z CAMs feeding the NBM suggest the prime period to be midnight through 9 AM from west to east. During this time, 1-2" area-wide is likely, with potential for 3+" in persistent bands. Elsewhere, including the populated lower/mid Valley, forcing at all levels is less impressive even though the region is more unstable. So...while it should rain everywhere before daybreak, the potential for urban flooding rainfall is muted.

Mid-morning Sunday through mid evening Sunday should see a relative lull...though scattered to numerous showers and perhaps a thunderstorm can be expected. Blended models hint at some continuation of more persistent locally heavy rainfall across the Brush Country into mid afternoon - so this is a potential (20-30%) to consider, even as the incoming models are less emphatic. Continued convective instability along the Lower Rio Grande could be sufficient to produce quick 1-1.5" situations for ponding or nuisance poor drainage minor flooding.

Sunday night-mid morning Monday: The potentially more impactful event may occur here, as the core of the upper level forcing arrives into the Rio Grande Plains by mid evening and marches east through early Monday. A surface boundary may form which would sharpen convective forcing along it...and there is a reasonable worst-case scenario for 2 to 4", locally 6", of rainfall in these areas through the night. Once again, forcing is less emphatic across the lower/mid RGV as the LLJ is less stout and mid/upper level forcing similar. All that said...it's never too smart to get too detailed when we're talking about a 50-100 mile shift that could change outcomes...though model focus/consistency places the populated/urban areas into more beneficial rains/nuisance ponding vs. more significant flash flooding.

For all of these reasons, will be expanding the flood watch into the the entire south Texas Brush Country/Rio Grande Plains, now to include Zapata, Jim Hogg, and Brooks. Kenedy's sandy soil and lesser forecast/probabilstic QPF suggest holding off for now. There's still time to expand this Watch farther south/east (Starr/northern Hidalgo) but will defer to later shifts for their evaluation.

Monday: While Monday sees a gradual tapering of rainfall from west to east, there remains potential for coastal convergence during the late morning and afternoon that could bring the first heavier rainfall into the lower Valley and coast, as the weakening but still notable mid/upper level forcing arrives. We should see these details sort out by Sunday, but Monday commuters/school bus rides could be a bit more difficult.

One final thing to keep an eye on: While beach weather will not be perfect, better rainfall (if any at all) may hold off until late Sunday night into Monday. At the same time, easterly swell and winds will continue to increase into Sunday, and higher surf, high intensity rip currents, and potential for tidal run-up to the dune line at narrow beaches both Sunday and Monday high tides (afternoon) are on the table. Look for rip current and coastal flood statements...potentially an advisory...Sunday and Monday.

Monday night through Wednesday: The main event exits stage right (western Gulf) Monday night, but residual moisture and the aforementioned residual upper level support does not leave a "clean" break to drier/clear weather. The coastal trough may hang near enough to shore to keep the beaches wet, with a few light showers elsewhere.

Thursday through Saturday: Deterministic model differences show up...not surprising in energetic flow this time of year, which makes confidence in the sensible weather lower than average. On the good news side, a potentially notable dry plume could bring sunshine by day and clear, cool overnights/early mornings especially Friday and Sataurday. On the more pessimistic side, a flatter flow aloft could allow clouds and perhaps light showers, with a slower drop in temperatures (still cooler than average, though) Thursday into Friday. For now, will continue with the optimistic forecast to close next week and begin next weekend.

AVIATION

(18Z TAFS) Issued at 1200 PM CST Sat Nov 7 2026

For the Valley terminals, a fairly quiet afternoon and evening with mainly VFR conditions (low to medium level ceilings) though can't rule out isolated to scattered convection (VCTS) just to be safe. Overnight, conditions may deteriorate a bit, especially after midnight and favoring McAllen/Miller which will be closer to the main shower/thunderstorm banding farther north.

Sunday shows a better opportunity for at least TEMPO conditions for MVFR visibility (showers) with PROB30 for lower ceilings and visibility just about anywhere, mainly between 15-18Z but potentially a bit earlier. While confidence is not high given the uncertainty, will include to cover the potential, which is about 30 percent now.

MARINE

Issued at 1200 PM CST Sat Nov 7 2026

Today through Monday: Today's decent conditions will deteriorate later tonight and especially Sunday/Sunday night into Monday. Pressure gradient increases substantially and easterly winds should pick up to 20 knots or higher, with gusts 25 to 30 knots, later tonight and especially Sunday and Sunday night. This will build seas to 6 to 7 feet. While rain will be less impressive over water than over land, gusty showers and a few thunderstorms can be expected, with more coverage north of Port Mansfield from pre-dawn Sunday through Monday morning before shifting farther south on Monday. Will likely need a Small Craft Advisory for this period, and will issue this afternoon or evening.

Monday Night through Wednesday Night: Gradient slackens Monday night, then becomes diffuse Tuesday through Wednesday night as surface ridge/trough pattern collapses. While isolated to scattered showers and thunderstorms will continue, winds/seas fall well below hazardous levels. The filtering of drier air on northerly flow may pick up Thursday and Thursday night as stronger surface high pressure builds in from the northwest. The stronger model solutions would be sufficient for Small Craft Advisories (mainly winds at first) but confidence is low at this time.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 72 81 72 80 / 40 70 70 60 HARLINGEN 70 80 69 78 / 50 70 60 Today through Monday: Today's decent conditions will deteriorate later tonight and especially Sunday/Sunday night into Monday. Pressure gradient increases substantially and easterly winds should pick up to 20 knots or higher, with gusts 25 to 30 knots, later tonight and especially Sunday and Sunday night. This will build seas to 6 to 7 feet. While rain will be less impressive over water than over land, gusty showers and a few thunderstorms can be expected, with more coverage north of Port Mansfield from pre-dawn Sunday through Monday morning before shifting farther south on Monday. Will likely need a Small Craft Advisory for this period, and will issue this afternoon or evening.

Monday Night through Wednesday Night: Gradient slackens Monday night, then becomes diffuse Tuesday through Wednesday night as surface ridge/trough pattern collapses. While isolated to scattered showers and thunderstorms will continue, winds/seas fall well below hazardous levels. The filtering of drier air on northerly flow may pick up Thursday and Thursday night as stronger surface high pressure builds in from the northwest. The stronger model solutions would be sufficient for Small Craft Advisories (mainly winds at first) but confidence is low at this time. 60 MCALLEN 72 82 70 79 / 80 80 90 70 RIO GRANDE CITY 67 78 66 75 / 90 80 100 80 SOUTH PADRE ISLAND 75 78 74 77 / 40 70 50 60 BAYVIEW/PORT ISABEL 71 80 70 78 / 40 70 60 60

BRO WATCHES/WARNINGS/ADVISORIES

TX...Flood Watch from 6 PM CST this evening through Monday morning for TXZ248>250.

GM...None.