Marine Weather Net

Port Mansfield, TX to the Rio Grande River 20 - 60 NM Marine Forecast


REST OF TONIGHT

S
WINDS
15 - 20
KNOTS

MONDAY

S
WINDS
15 - 20
KNOTS

MONDAY NIGHT

E
WINDS
15 - 20
KNOTS

TUESDAY

N
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
GMZ170 Forecast Issued: 943 PM CST Sun Dec 05 2021

SMALL CRAFT SHOULD EXERCISE CAUTION
Rest Of Tonight...South Winds 15 To 20 Knots. Seas 4 To 6 Feet With Occasional Seas Up To 7 Feet.
Monday...South Winds 15 To 20 Knots Diminishing To 10 To 15 Knots In The Afternoon. Seas 3 To 5 Feet. Slight Chance Of Showers And Thunderstorms In The Afternoon.
Monday Night...East Winds 15 To 20 Knots Shifting North After Midnight. Seas 2 To 4 Feet. Showers Likely In The Evening. Slight Chance Of Thunderstorms Through The Night. Chance Of Showers After Midnight.
Tuesday...North Winds 10 To 15 Knots Diminishing To 5 To 10 Knots In The Afternoon. Seas 2 To 4 Feet. Chance Of Showers And Slight Chance Of Thunderstorms In The Morning, Then Slight Chance Of Showers In The Afternoon.
Tuesday Night...Southeast Winds 5 To 10 Knots Shifting Southwest After Midnight. Seas 2 To 4 Feet.
Wednesday...West Winds 5 To 10 Knots Shifting North In The Afternoon. Seas 2 To 4 Feet. Slight Chance Of Showers.
Wednesday Night...Southeast Winds 5 To 10 Knots Shifting South After Midnight. Seas 2 To 3 Feet.
Thursday...South Winds 10 To 15 Knots. Seas 2 To 3 Feet.
Thursday Night...South Winds 10 To 15 Knots. Seas 2 To 4 Feet.
Friday...South Winds 15 To 20 Knots. Seas 3 To 5 Feet.
Friday Night...South Winds 15 To 20 Knots. Seas 3 To 5 Feet.
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Synopsis for Baffin Bay to Rio Grande out 60 nm: GMZ100
943 PM CST Sun Dec 5 2021

Onshore flow will continue to strengthen tonight as low pressure deepens over the Southern Plains. As a cold front drops into south-central Texas on Monday, winds should slowly weaken while moderate seas persist. The front may move across the coastal waters late Monday night with northerly winds in its wake. The front is expected to return northward late Tuesday or Wednesday with onshore flow resuming. The presence of the front may trigger a few showers or thunderstorms.
Area Forecast Discussion
...UPDATED National Weather Service Brownsville TX
1030pm CST Sunday Dec 5 2021

/issued 532pm CST Sunday Dec 5 2021/

AVIATION...Mainly mid to high level clouds and moderate to gusty southeast winds prevail across deep south Texas early this evening. Winds will continue.nue to diminish this evening as a cold front drops into south Texas, weakening the surface pressure gradient. Another brief round of MVFR (Marginal Visual Flight Rules) ceilings will be possible late tonight into early Monday morning, with skies scattering out by around 15z. Otherwise, VFR conditions are expected through much of the period. MVFR (Marginal Visual Flight Rules) ceilings may develop towards the very end of the period, in the wake of the cold front.

/issued 233pm CST Sunday Dec 5 2021/

Short Term - Tonight through Monday Night
Low pressure deepening over the Central Plains today will maintain an enhanced pressure gradient across Deep South Texas, with breezy conditions resulting for this afternoon. Enhanced southeasterly winds will help keep temperatures very warm, with temperatures this evening only falling into the upper 60s in the ranchlands and the lower 70s in the Lower Rio Grande Valley. The trend of unseasonable warmth continues on Monday with highs reaching the middle to upper 80s across the CWA before a cold front drops into the area late Monday afternoon. Mixed-layer instability of around 1500 J/kg will be in place owing to warmth and abundant surface moisture in advance of the front, so a few thunderstorms are certainly possible Monday evening as the front moves through. Despite the passage of this cold front, low temperatures late Monday night into Tuesday morning will still be a few degrees above seasonal normals, ranging from the middle 50s in the ranchlands to near 60 degrees in the Lower RGV.

Long Term - Tuesday through Sunday
The cold front mentioned in the short term will be stalling south of the Rio Grande River to Tuesday. A few showers will still be possible in the wake of the cold front with the best opportunity over the Gulf waters. There still remains some uncertainty on just how cool we can stay Tuesday afternoon. The 12Z NAM, which keeps a north wind over the region throughout the day, has us several degrees below normal with highs in the upper 50s to lower 60s. Meanwhile, the EURO and GFS switch our winds out of the east Tuesday afternoon, which keeps us a bit milder with upper 60s to lower 70s. Models have trended cooler the past few runs, so have blended a bit of NBM10 with a majority NBM to account for that trend.

A weak coastal trough looks to form off the South Texas coast Tuesday and will lead to a continuation of slight chances for rain over Gulf waters through Wednesday. The cooler air from Tuesday doesn't last long as we see a quick return of the southerly flow by Wednesday afternoon. This pushes temperatures back into the upper 70s to lower 80s Wednesday and even warmer Thursday and Friday. In fact, we could be flirting with record highs across in parts of the region either Thursday and/or Friday with upper 80s to lower 90s expected for many. Latest model guidance even has some middle 90s west of I-69C Friday afternoon. (Are we sure it's December?) This heat is thanks to an H5 ridge over the Yucatan peninsula nudging north in response to a trough moving into the west coast. A gusty south to southwest wind develops as a result, which is typically a very warm wind for us in Deep South Texas.

The good news for fans of cooler weather is the potential for a cold front sometime next weekend. A broad trough across the western third of the country will sharpen as it heads over the Rocky Mountains Friday into Saturday. This will spawn an area of low pressure across the Central Plains and send it east. Models have the trailing cold front arriving sometime late Saturday into early Sunday, but that will likely change between now and next weekend. Temperatures behind next weekend's front ease back closer to seasonal normals.

Marine
ow through Monday Night): Winds will continue.nue to slightly increase this afternoon as low pressure deepens over the Central Plains and strengthens the surface pressure gradient. SCEC criteria winds can be expected for all of the lower Texas coastal waters this evening along with elevated seas. The pressure gradient then weakens on Monday as a cold front drops into Deep South Texas during the afternoon hours. Winds will gradually relax but seas remain moderate during this time. A few showers and thunderstorms are possible as the front moves through late Monday afternoon and evening.

Tuesday through Sunday: Multiple wind shifts are expected Tuesday through Wednesday night as a cold front stalls and washes out over Deep South Texas along with the formation of a coastal trough Tuesday afternoon. This coastal trough will keep rain chances over Gulf Waters through Wednesday afternoon before drier conditions return. The pressure gradient begins to tighten Thursday as an area of low pressure strengthens in the middle of the country. This pushes winds to SCEC criteria from Thursday night through Saturday with a southerly flow at 15 to 20 knots.

NOAA Brownsville TX Office: Watches - Warnings - Advisories
TX...None. GM...None.