Baffin Bay to Port Mansfield, TX Marine Forecast
|Tonight...Southeast Winds 15 To 20 Knots Diminishing To 10 To 15 Knots After Midnight. Seas 3 To 5 Feet. Slight Chance Of Showers And Thunderstorms In The Evening, Then Chance Of Showers And Thunderstorms After Midnight.|
|Monday...Southeast Winds 10 To 15 Knots. Seas 3 To 5 Feet. Chance Of Showers And Thunderstorms.|
|Monday Night...Southeast Winds 10 To 15 Knots. Seas 2 To 4 Feet. Slight Chance Of Showers In The Evening. Slight Chance Of Thunderstorms Through The Night. Chance Of Showers After Midnight.|
|Tuesday...East Winds 15 To 20 Knots Becoming Northeast 20 To 30 Knots In The Afternoon. Seas 4 To 6 Feet With Occasional Seas Up To 7 Feet. Showers And Thunderstorms Likely.|
|Tuesday Night...Northeast Winds 15 To 20 Knots Becoming North 5 To 10 Knots After Midnight. Seas 4 To 6 Feet With Occasional Seas Up To 7 Feet. Chance Of Showers And Thunderstorms.|
|Wednesday...North Winds 5 To 10 Knots Shifting Northeast In The Afternoon. Seas 2 To 4 Feet. Slight Chance Of Showers And Thunderstorms.|
|Wednesday Night...East Winds 5 To 10 Knots Shifting Southeast After Midnight. Seas 2 To 4 Feet.|
|Thursday...Southeast Winds Around 5 Knots Becoming East In The Afternoon. Seas 2 To 4 Feet. Slight Chance Of Showers And Thunderstorms.|
|Thursday Night...East Winds 5 To 10 Knots Shifting Southeast After Midnight. Seas 2 To 4 Feet. Chance Of Showers And Thunderstorms.|
|Friday...Northeast Winds 5 To 10 Knots. Seas 2 To 3 Feet. Chance Of Showers And Thunderstorms.|
|Friday Night...Southeast Winds 5 To 10 Knots Shifting South After Midnight. Seas 2 To 3 Feet. Chance Of Showers And Thunderstorms.|
Synopsis for Baffin Bay to Rio Grande out 60 nm: GMZ100|
409 PM CDT Sun May 24 2020
An upper level low pressure system will move into Texas by Monday and persist over the State much of next week. This should maintain a moderate onshore flow with a continuation of elevated seas through at least Tuesday. The pressure gradient weakens mid to late week allowing for lighter onshore flow and subsiding seas. Periodic showers and thunderstorms are expected through much of the period with the best chances late tonight and Monday morning with another good chance Tuesday. Some of the thunderstorms will be strong and produce gusty winds, lightning and poor visibility in heavy rainfall.
Area Forecast Discussion|
...UPDATED National Weather Service Brownsville TX
721pm CDT Sunday May 24 2020
A Severe Thunderstorm Watch has been issued for Zapata, Jim Hogg, Starr and Brooks counties from now until Midnight CDT. Potential threats include large hail up to the size of limes, damaging wind gusts of up to 70 MPH, as well as localized flooding.
Current mesoanalysis shows little to no capping inversion in the northwest ranchlands from Zapata to Laredo. Very strong instability is noted with MLCAPE of around 3500 J/kg. A mid-level wind max is expected to move over South Texas late tonight, increasing shear and steepening mid-level lapse rates, and thus increasing the potential for large hail and damaging winds. High- resolution CAMs indicate 0-6km bulk shear values increasing to 40-50kts, so supercellular or multicellular structures would be anticipated. Some models bring a potential line segment or squall line through Deep South Texas as the convection evolves. With the current 00Z sounding from BRO showing a decent capping inversion, confidence is low on convection reaching into the lower Rio Grande Valley. However, MLCIN may diminish as the mid-level disturbance moves closer overhead, meaning the cap could erode later tonight. Therefore, we will continue to monitor and update as needed.
..Slight risk of severe weather across northern and western portions of Deep South Texas tonight into Monday morning... ..Heavy rainfall threat continues across Deep South Texas through the rest of the Memorial Day weekend... Short Term - Now through Monday night
A deep mid to upper level trough will edge into the Central U.S. tonight and deepen into the southern plains by the start of the workweek. With ample surface moisture streaming in from the Gulf over the region and conditional instability in place, the nature of the convection that forms will depend primarily on the timing and location of mesoscale interactions...namely, the vort maxes that circulate around base of the trough as well as any surface features including the dry line over West Texas and convective outflows. There is a potential for isolated strong to severe thunderstorms to develop and move into Deep South Texas and the Rio Grande Valley this evening through Monday night. The Storm Prediction Center (SPC) has a slight risk for severe weather across Zapata, Jim Hogg, and Starr Counties and a marginal risk for the rest of Deep South Texas and the Rio Grande Valley for tonight and all of our area in a marginal risk for Monday and Monday night. The primary threats include damaging wind and hail with these storms. While there is generally good agreement between the models on the potential for a wet forecast tonight into early next week because of this general pattern, the exact onset, location, and duration of the showers and thunderstorms that may develop continues to be a challenge. While most models are still indicating significant MCS or MCC development northwest and west of the CWA this evening which may cross portions of or all of our region overnight, some of the CAMs (especially the HRRR) are scaling back the rainfall and thunderstorm potential for tonight.
In addition to the severe weather threat, the Weather Prediction Center (WPC) has included all of Deep South Texas and the Rio Grande Valley in a marginal risk for excessive rainfall tonight through Monday night, with a slight chance for excessive rainfall in Zapata County tonight. This means that localized flash flooding will be possible as some of these storms move through the area during the short term. The better rain chances look like they will be concentrated mostly to our north through the period, but WPC's Day 1- 3 Quantitative Precipitation Forecast shows most of Deep South Texas receiving 1.00" to 3.00" of total rainfall through 7am CDT Tuesday, but locally higher amounts are possible.
Temperatures will depend primarily on the cloud cover and any rain and thunderstorm development, areal coverage and longevity, but will generally be in the lower to mid 70s tonight and Monday night with high temperatures on Monday reaching the lower 90s.
Long Term - Tuesday through Sunday
500mb low/trough across the southern plains/Texas will continue to provide unsettled weather across portions of South Texas Tuesday as the GFS progs an MCS moving from west to east late Monday night into early Tues morning. The model blends are progging considerably high rain chances across the CWA Tuesday as a result. Some drier air aloft is expected to move across south Texas Tues night and this should inhibit convective development Tues night into Wednesday but low to mid level moisture will remain high across northeast Mexico to warrant at least a slight chance of showers and thunderstorms across the Rio Grande Valley. The rest of the forecast period will depend highly on the future position and movement of the 500mb low across northeast Mexico Thursday as the GFS progs the upper level low elongating across the eastern half of the state through the rest of the week into the weekend before retrograding southwest towards southwest Texas Sunday. This scenario will provide a chance of showers and thunderstorms across deep South Texas Friday through Sunday as a result.
Marine - Now through Monday night
Buoy 42020 is reporting seas near 5 feet and southeast winds of 15 knots, gusting to 20 knots. Slighlty elevated seas will continue into tonight and generally subside through the period to 2 to 4 feet. Showers and thunderstorms will be possible tonight through Monday night, and localized winds and seas will be affected by any outflows produced by any strong storms that may develop.
Tuesday through Friday...Moderate to strong east to northeast winds will prevail across the coastal waters Tuesday in the wake of a convective frontal boundary. Small craft advisories will likely be needed for all of the coastal waters Tuesday before the pressure gradient weakens across the lower Texas coast Tues night. Seas will remain elevated offshore the lower Texas coast Tues night and small craft advisories will likely be needed for high seas as winds diminish. Light and variable winds will prevail across the coastal waters Tues night and will be light east to southeast Wednesday with low pressure across the southern plains. The pressure gradient will continue to remain weak across the coastal waters Thursday and light southerly winds will prevail across the western Gulf of Mexico. A weak frontal boundary/surface trough is expected to move through the coastal waters Friday. Winds should shift to the north and increase slightly as a result.
NOAA Brownsville TX Office: Watches - Warnings - Advisories