Marine Weather Net

Port Aransas to Matagorda Ship Channel 20 - 60 NM Marine Forecast


REST OF TODAY

SE
WINDS
10 - 15
KNOTS

TONIGHT

S
WINDS
15 - 20
KNOTS

SUNDAY

W
WINDS
20 - 25
KNOTS

SUNDAY NIGHT

N
WINDS
20 - 25
KNOTS

The Marine Weather Forecast In Detail:
GMZ275 Forecast Issued: 930 AM CST Sat Nov 28 2020

Rest Of Today...Southeast Wind 10 To 15 Knots. Seas 3 To 4 Feet With Occasional Seas Up To 5 Feet. Showers And Thunderstorms Late In The Morning, Then Showers And Thunderstorms Likely In The Afternoon.
Tonight...South Wind 15 To 20 Knots Becoming Northwest 20 To 25 Knots After Midnight. Seas 4 To 5 Feet With Occasional Seas Up To 6 Feet. Showers And Thunderstorms Likely In The Evening, Then A Chance Of Showers And Thunderstorms After Midnight.
Sunday...Northwest Wind 20 To 25 Knots. Seas 5 To 6 Feet With Occasional Seas Up To 8 Feet. A Slight Chance Of Showers In The Morning.
Sunday Night...North Wind 20 To 25 Knots. Seas 7 To 9 Feet With Occasional Seas Up To 11 Feet.
Monday...North Wind 20 To 25 Knots. Seas 8 To 10 Feet With Occasional Seas Up To 13 Feet.
Monday Night...North Wind 15 To 20 Knots Becoming Northeast 10 To 15 Knots After Midnight. Seas 6 To 8 Feet With Occasional Seas Up To 10 Feet Subsiding To 4 To 6 Feet With Occasional Seas Up To 8 Feet After Midnight.
Tuesday...East Wind 5 To 10 Knots Becoming Southeast 10 To 15 Knots In The Afternoon. Seas 3 To 5 Feet With Occasional Seas Up To 6 Feet.
Tuesday Night...Southeast Wind 15 To 20 Knots. Seas 4 To 6 Feet With Occasional Seas Up To 8 Feet. A Slight Chance Of Showers.
Wednesday...Southeast Wind 10 To 15 Knots Shifting East In The Afternoon. Seas 5 To 7 Feet With Occasional Seas Up To 9 Feet. A Chance Of Showers.
Wednesday Night...North Wind 15 To 20 Knots. Seas 8 To 10 Feet With Occasional Seas Up To 13 Feet. A Chance Of Showers.
SHARE THIS PAGE:           
Synopsis for Middle Texas coastal waters from Baffin Bay to Matagorda ship channel - GMZ200
930 AM CST Sat Nov 28 2020

Numerous showers and thunderstorms are expected today. A few storms may be strong with gusty winds, frequent lightning and heavy rainfall. Away from thunderstorm activity, weak to moderate onshore flow is expected today ahead of a cold front. The cold front will move offshore tonight with moderate to strong offshore flow and Small Craft Advisory conditions developing in response. Rain chances will diminish from west to east Sunday morning as drier air arrives. A surge of even drier air by Sunday night will maintain strong offshore flow, before winds finally taper Monday night. There remains additional chances for showers from Wednesday through late week ahead of the next upper disturbance and cold front, but confidence in this system is low at this time. This front may again create strong offshore flow with higher seas from Thursday through Friday.
Area Forecast Discussion
National Weather Service Corpus Christi TX
555am CST Sat Nov 28 2020

SHORT TERM (Today)... Showers and a few thunderstorms are filling in across S TX this morning per radar. This is in response to embedded weak short waves tracking east-northeast across the region and combining with deepening moisture. The heavier rainfall has generally been across the northern portions of the CWA this morning. The better instability per LAPS analysis is currently across the southern coastal bend where minimal precipitation has occurred so far, but the rainfall should increase in this area as well, over the next 2-4 hours.

A weakening outflow boundary that moved south across the area this morning has led to a surface trough along the coast. The cold front has become less defined as a result due to northeast winds across S TX. However, the colder and drier air will be lagging behind the windshift/trough axis.

The main upper low is moving eastward toward the TX Panhandle and should be crossing the panhandle throughout the day. This will help deepen the surface trough which models prog to occur through the morning and early afternoon, but differ somewhat on just where the trough axis will be located as it waffles across the area later this morning. The overall consensus is that the trough axis should be east of the Brush Country.

A strong upper jet will shift farther southeast and place the RRQ across S TX by late morning into early afternoon. This will provide good upper support for thunderstorms. Weak instability will remain generally across the Coastal Bend with the surface trough providing low level support. The trough is forecast to lift northeast by late afternoon, with colder, drier air building across S TX from northwest to southeast in its wake.

As for the rainfall, the heavier rainfall is forecast to be across the Victoria Crossroads, but could also extend farther south across the Coastal Bend due to the trough. The heavier rainfall may train across eastern portions of S TX which may lead to localized flooding today. Total rainfall amounts today through tonight are expected to range from 1/2 an inch along the Rio Grande to 1 to 2 inches across the eastern portions of the area. Highest amounts are expected to be across the Victoria Crossroads and along the coast with around 2 inch amounts expected. Isolated higher amounts are possible, especially across the Victoria Crossroads where there is a slight risk of excessive rainfall. The slight risk of excessive rainfall extends into Houston's area. Given the dry soils, widespread flooding is not anticipated at this time, but localized flooding is possible.

LONG TERM (Tonight through Friday)... Tonight, the upper low over the TX Panhandle and its attendant trough axis will glide east and in the process accelerate the cold front offshore ahead of markedly drier northerly breezes. However, this drying will initially be confined to a shallow near- surface layer all the while the right rear quadrant of a mid and upper jet streak will maintain some lift likely resulting in at least some light post-frontal showers. Barring a few rogue showers in our southern coastal counties early Sunday morning, this window for post- frontal precipitation should be closed as surface ridging and low theta-E invades the region. What's most dramatic is that exceptionally dry air is set to arrive on Monday from an even stronger surface high. With surface dewpoints cratering into the teens and 20s under deep moisture deficits, models show PWATs (Precipitable Waters) as low as 0.07 inches which is uncommon for this region. This combined with light northerly winds Monday night is looking to set the stage for a widespread freeze for most of our inland counties.

Once dry surface ridging departs on Tuesday, moist isentropic ascent unfolds ahead of the next upper low to our northwest. The behavior of this low remains at odds among the models, but in general the blocky synoptic pattern would tend to favor a slightly slower and more amplified low evident on the CMC and ECMWF, although the ECMWF (European Centre for Medium-Range Weather Forecasts) is a bit of an extreme outlier with its N-S moist axis about 100+ miles west of the CMC. Models are also probably too bullish in moistening the previously bone-dry column, so saturation could easily be delayed in many areas which is why we'll continue to undercut the NBM's generous PoPs. Another cold front will sweep south at some point Wednesday or Thu as the upper low shifts across the Red River, but uncertainty in this front's timing warrants at least some low shower chances as late as Thu before drying out thereafter.

Marine Discussion
Scattered to numerous showers and thunderstorms can be expected today. A few storms may be strong with gusty winds, frequent lightning and heavy rainfall. Outside of the thunderstorms, a weak to moderate onshore flow can be expected ahead of a cold front. The cold front will move offshore this evening with moderate to strong offshore flow and Small Craft Advisory conditions developing overnight. Rain chances will diminish from west to east on Sunday morning as drier air arrives. A surge of even drier air by Sunday night will maintain strong offshore flow, before winds finally taper Monday night. There remains additional chances for showers from Wednesday through late week ahead of the next upper disturbance and cold front, but confidence in this system is low at this time. This front may again create strong offshore flow with higher seas from Thursday through Friday.

NOAA Corpus Christi TX Office: Watches - Warnings - Advisories
TX...None. GM...None.