Port Mansfield, TX to the Rio Grande River 20 - 60 NM Marine Forecast
|Tonight...Southeast Winds 10 To 15 Knots. Seas 3 To 5 Feet. Chance Of Showers And Thunderstorms.|
|Wednesday...Southeast Winds 10 To 15 Knots. Seas 3 To 5 Feet. Chance Of Showers And Thunderstorms In The Morning, Then Slight Chance Of Showers And Thunderstorms In The Afternoon.|
|Wednesday Night...Southeast Winds 10 To 15 Knots. Seas 3 To 5 Feet.|
|Thursday...Southeast Winds 10 To 15 Knots. Seas 4 To 6 Feet With Occasional Seas Up To 7 Feet.|
|Thursday Night...Southeast Winds 15 To 20 Knots. Seas 4 To 6 Feet With Occasional Seas Up To 7 Feet.|
|Friday...Southeast Winds 10 To 15 Knots. Seas 4 To 6 Feet With Occasional Seas Up To 7 Feet.|
|Friday Night...Southeast Winds 15 To 20 Knots. Seas 4 To 6 Feet With Occasional Seas Up To 7 Feet.|
|Saturday...Southeast Winds 10 To 15 Knots. Seas 3 To 5 Feet.|
|Saturday Night...Southeast Winds 10 To 15 Knots. Seas 3 To 5 Feet. Slight Chance Of Showers And Thunderstorms.|
|Sunday...Southeast Winds 5 To 10 Knots. Seas 3 To 5 Feet. Chance Of Showers And Thunderstorms.|
|Sunday Night...Southeast Winds 10 To 15 Knots. Seas 3 To 5 Feet. Chance Of Showers And Thunderstorms.|
| Synopsis for Baffin Bay to Rio Grande out 60 nm: GMZ100|
417 PM CDT Tue Jun 22 2021
Generally moderate winds and seas are expected along the Lower Texas Coast with high pressure in control over the western Gulf of Mexico. However, winds and seas may be adverse enough to warrant Small Craft Exercise Caution for portions of the waters late in the week, especially between 20 and 60 nautical miles offshore.
| Area Forecast Discussion|
National Weather Service Brownsville TX
248pm CDT Tuesday Jun 22 2021
Short Term - Now through Wednesday night
Scattered showers and thunderstorms continue to develop across Deep South Texas early this afternoon. Most locations in the area have received at least a few hundredths of an inch of rain. But the real winners of today's rainfall (so far) have occurred around the Harlingen/Rio Hondo/San Benito vicinity as well as just northeast of Rio Grande City, where doppler radar estimates between 3 and 5 inches of rain have fallen since this morning. As daytime heating persists, so will the chances of convection, though chances should gradually decrease into the evening. Slow storm movement and training may cause some very heavy downpours and produce rainfall amounts up to an inch or more at one time.
500mb riding should become re-established by Wednesday morning as troughing along the east coast lifts northeastward and the center of the ridge progresses east over the state of Texas. With ridging back in control, should see more sunshine tomorrow and high temperatures closer to seasonal averages -- mid to upper 90s. However, an abundance of residual low-level moisture will cause PWATs (Precipitable Waters) to remain generally around 2 inches tomorrow. And although coverage is not expected to be as widespread as today, isolated to scattered convection will be possible, including the possibility of an afternoon seabreeze. Best chances of precipitation will be near the coast or east of US-281/I-69C. Precipitation chances will quickly dissipate early Wednesday evening. Another warm and humid night is anticipated Wednesday night, with lows generally in the upper 70s and lower 80s.
Long Term - Thursday through Tuesday
A mid level ridge will build over Texas the latter half of the workweek, cutting off mentionable rain chances. Then, the combination of a mid level trough that will dive into the Plains this weekend and an inverted trough setting up over the northern Gulf of Mexico will weaken the ridge over deep South Texas and bring a chance of showers and thunderstorms to the area Sunday through Tuesday. With persistent southeasterly winds advecting Gulf moisture across the CWA and a lack of strong upper level forcing, any shower or thunderstorm activity will likely be diurnally or seabreeze driven with the best chances near the coast and offshore, though chances could expand to the mid Valley.
Temperatures will remain near normal through the workweek with a slight decrease Sunday through Tuesday due to increased cloud cover and PoPs. Heat index values continue to look manageable through the long term...but it will still feel hot with heat index values touching or breaking through the century mark across most of the CWA each day through Saturday, with 103 to 108 degree readings possible at times across western sections.
Now through Wednesday Night: A stationary front along the northwestern Gulf of Mexico will maintain a weak pressure gradient along the lower Texas coast tonight before it lifts northward as a warm front later tonight. A light to moderate onshore will prevail tonight and on Wednesday and a moderate swell will continue to subside through the rest of the short term period, resulting in mostly favorable marine conditions. Isolated to scattered showers and thunderstorms should continue tonight and into Wednesday before decreasing in probability and coverage by Wednesday evening. Some of the storms will produce gusty winds, heavy rainfall, lightning and locally higher seas. Not anticipating small craft advisories or exercise caution wording through Wednesday night.
High pressure will become reestablished over the Gulf the latter half of the week with brief increases in winds and seas. Moderate seas and light to moderate southeast winds will occur through the rest of the workweek and into the weekend. There may be brief periods of winds cranking up to 15 to 20 knots on Thursday night through Friday night, but other than that, hazardous marine conditions are not expected. With an inverted mid level trough setting up over the Gulf of Mexico late this weekend, isolated to scattered showers and thunderstorms will also tend to develop across the lower Texas coastal waters.
NOAA Brownsville TX Office: Watches - Warnings - Advisories