Southwest Pass of the Mississippi River to Port Fourchon, LA 20 - 60 NM Marine Forecast
|Rest Of Today...Southeast Winds 15 To 20 Knots With Gusts Up To 25 Knots, Becoming South 20 To 25 Knots With Gusts Up To 35 Knots This Afternoon. Seas 3 To 5 Feet, Occasionally To 6 Feet. A Chance Of Showers With A Slight Chance Of Thunderstorms Late This Morning, Then Showers With A Chance Of Thunderstorms This Afternoon.|
|Tonight...West Winds 20 To 25 Knots With Gusts Up To 35 Knots. Seas 4 To 6 Feet, Occasionally To 8 Feet. Showers And Thunderstorms Likely, Mainly In The Evening.|
|Sunday...West Winds 15 To 20 Knots With Gusts Up To 30 Knots, Diminishing To 10 To 15 Knots In The Afternoon. Seas 5 To 6 Feet, Occasionally To 8 Feet, Subsiding To 3 To 5 Feet, Occasionally To 6 Feet In The Afternoon.|
|Sunday Night...West Winds 10 To 15 Knots. Seas 3 To 4 Feet, Occasionally To 5 Feet.|
|Monday...North Winds 5 To 10 Knots, Becoming East In The Afternoon. Seas 2 To 3 Feet.|
|Monday Night...Southeast Winds 10 To 15 Knots. Seas 2 To 4 Feet, Occasionally To 5 Feet.|
|Tuesday...South Winds Around 15 Knots. Seas 3 To 5 Feet, Occasionally To 6 Feet. A Chance Of Showers. A Slight Chance Of Thunderstorms In The Afternoon.|
|Tuesday Night...South Winds 10 To 15 Knots. Seas 4 To 5 Feet, Occasionally To 6 Feet. A Chance Of Showers With A Slight Chance Of Thunderstorms In The Evening, Then Showers Likely With A Chance Of Thunderstorms After Midnight.|
|Wednesday...Southwest Winds 10 To 15 Knots, Becoming North In The Afternoon. Seas 4 To 5 Feet, Occasionally To 6 Feet. Showers Likely With A Slight Chance Of Thunderstorms In The Morning, Then A Chance Of Showers In The Afternoon.|
|Wednesday Night...Northeast Winds Around 15 Knots. Seas 3 To 5 Feet, Occasionally To 6 Feet In The Evening. A Slight Chance Of Showers In The Evening. Winds And Seas Higher In And Near Thunderstorms.|
| Area Forecast Discussion|
...UPDATED National Weather Service New Orleans LA
1011am CST Sat Nov 26 2022
Issued at 938am CST Sat Nov 26 2022
A lot of moving parts this morning. First, stratus build down overnight has left most of the region with some lower visibilities across the region. A warm front along the northern Gulf Coast will allow for overcast skies for most of the region as isentropic upglide and stratiform precipitation continues to advance eastward with the strongest low level forcing.
Taking a look at the 12z RAOB (Radiosonde Observation or Upper-Air Observation) from LIX, the warm front right off the deck is sampled beautifully. There is a small amount of elevated instability, which may be just enough for a rogue embedded lightning strike or two north of the warm front through the morning and into the afternoon. The warm front advancement will be the primary question going into the afternoon in regards to the severe weather potential. At this juncture, expect the surface front to lift along the immediate coast where more surface based instability may be realized this afternoon. Although lackluster insolation and destabilization will be an overall limiting factor, some enhanced upper level forcing will favor slightly stronger updrafts within the warm sector so a severe storm or two will still be possible, especially right along the immediate coast...generally from Houma to Belle Chasse to Gulfport and southeastward. Exact details depend on again the warm front placement. Additionally, hydro concerns will still be around as well, especially in the lower or more urbanized flood prone areas, however, the more transient nature of the system should help mitigate a more widespread hydro concern.
Finally, continued the wind advisory through the evening. A few wind gusts will approach 40 mph at times, even outside of storms as the low level jet increasing later today. The southerly winds may impact higher profile vehicles along I10/12 or any east to west highway. Wind become quite gusty right off the deck as the LLJ increases so it wont take much to bring some gusts to the surface, as shown by the latest runs of most raw guidances. Although somewhat borderline, again the heavy travel weekend as well as introduction of holiday decorations was enough to cause some concerns requiring the NPW. Otherwise, the only other change was ended POPs a bit earlier than previously forecast later this evening and overnight again as the system ramps up in forward speed out of the region. (Frye)
.SHORT TERM... (Today through Sunday) Issued at 533am CST Sat Nov 26 2022
Focus will be on the first 24-30 hours. It has been quiet mostly overnight with light showers moving mainly across northwest portions of the CWA (County Warning Area) (BTR to MCB and to the northwest). These showers did struggle to make it far east as the drier low level air helped to erode them but the eastern half of the CWA is moistening up. Main issue overnight has really been more aviation concerns due to low clouds and lowering vsbys.
The next 24 hrs will see numerous impacts, locally heavy rain, strong to maybe an isolated severe storm or two, and gusty gradient winds. Deep closed low over western TX just north of the Big Bend will begin to lift out today and tonight swinging through TX and into the Ozarks and the Lower and Middle MS Valley and into the Ohio Valley by midday Sunday. This path will bring quite a bit of forcing to the region. H5 hgheights will fall around 5-8dm from 18z to 6z while temps will fall by 1-3 degrees C. the middle level jet will swing right through the Lower MS Valley and into the TN Valley. It will also increase with the core going from just under 80kts to possibly topping 95kts as it moves into the TN Valley. Even though the core will be just north of the CWA we will see a pretty good punch with H5 winds surging from around 40kts this morning to possibly topping 80kts along the border of southwest MS and LA. In the upper levels the subtropical jet will also push through the Lower Ms Valley and into the southeastern CONUS along with increasing in intensity. The core of possibly a 110kt jet does push through the area but does so behind the forcing and with that while our best forcing is over the region we will also have decent divergence aloft which will enhance the lift across the region. At the surface we are already beginning to see cyclogenesis across the middle TX coast. This surface low will continue to deepen and surge mostly north along the TX/LA border and into the ARKLATEX (Arkansas/Louisiana/Texas) region by early afternoon and then continue to the NNE into IL/IN by Sunday morning. At 19z the developing surface low was around 1012mb but by late tonight as it moves through the Ozarks it should be below 1000mb. This will drive a cold front through the area late this afternoon through mid-evening. The deepening low will be due to the strong forcing and enhanced lift aloft and this will cause the LL winds to respond with a strong LL jet developing late this afternoon and through the evening. The strongest punch will remain north of the area but winds at H85 will increase to around 40- 50kts across much of the CWA during the time. H925 winds will be quite similar as well. Moisture has already been increasing all night as the showers west of the region have continued to move northeast across the region helping to moisten the LL and by midday we could see pws back around 2" across potions of the CWA. The h85 theta e ridge will also work across the area and all of that will be along and right ahead of the front associated with our surface low.
With the surface low moving more north then northeast it will allow the region to possibly slowly work into the warm sector. Combine that with increasing moisture and cooling mid level temps and we should see some instability, mostly elevated but some none the less. The timing of all of these features will provide a very favorable setup for widespread showers and embedded thunderstorms ahead and along the front this afternoon and the early evening hours. After around 2/3z we will probably start to dry out as the strong forcing likely causes everything to surge to the east and we could be completely dry before 6z, even coastal MS.
As for impacts, first the heavy rain potential. Luckily things should be very progressive and even if there is widespread showers well ahead of the cold front that would likely start to limit some of the instability and lead to slightly less efficient storms. However, with PWs possibly over 2", increasing lift and forcing, along with favorable divergence aloft we will likely see locally heavy rain, especially with any thunderstorm. WPC has placed the region under a Slight Risk for excessive rainfall and this looks good. That said not anticipating much in the way of flash flooding but if we could see another 1-2 inches of rain with locally higher amounts we will likely see a few more river points go into flood.
As for the strong to severe aspect. The whole area is under a marginal risk. This is more of a high shear; low cape environment. Forecast soundings indicate for a moisture loaded profile and all of this would suggest severe weather on the lower end or at least a much less chance a severe weather event and more so an isolated storm or two. As mentioned already we will be lacking instability but there is more than enough forcing and if any storm can become rooted to the surface then the risk for a tornado or two along with damaging winds will increase.
Last but likely just as strong of an impact will be the gradient winds. First overall this is not the greatest setup for a strong wind at the surface day. Timing is not ideal as the time frame the best mixing due to daytime heating is, well during the day. The main time frame to see LL winds increase will be from 21-6z. But with widespread rain that will likely limit the sun breaking through to the surface which would aid in mixing down the strong winds. In addition the winds will not be unidirectional from the surface to H85. That will also impact the efficiency in mixing. However, winds will try to become more unidirectional around and shortly after 23/00z. Winds in the H925 and H85 levels will increase through the afternoon and could approach 40-50kts. This is only 2500-5k ft off the deck and it may not take much to mix down at least a few wind gusts to or even greater than 40 mph, especially along and north of the 10/12 corridor. The other aspect that will be favorable in leading to a windy day will be the deepening surface low and its trajectory which could lead to a gradient that is possibly as high as 6mb across the CWA. With all of this there is a good chance much of the area will gust to around 35 mph but it is likely that a few sites gust above 40 mph. Now, with Thanksgiving having occurred this past Thursday there are likely many people have started or already finished putting up a lot of outside decorations. In addition there is people going to be a lot of people on the road traveling back home or doing shopping. The strongest winds will also be perpendicular to our major roads providing a strong cross wind. So combine the decorations, number of travelers on the road, conditions on the roads due to heavy possibly blinding rain leading to slick roads occurring with a strong cross wind, we felt it prudent to issue a wind advisory to alert people of the possible hazardous conditions. Again it is likely that most of the area will not "OFFICIALLY" hit criteria but it will be close enough an isolated areas likely will so we have issued a wind adv for the entire area through this evening. Winds should back off enough at least at the surface by midnight tonight.
Much quieter forecast heading into Sunday and the beginning of the work week. We will see drier conditions and temperatures will likely just remain steady for the next 60-72 hours. /CAB/
(Sunday night through Friday) Issued at 533am CST Sat Nov 26 2022
It looks like we will see another system impact the region during the middle of the week but overall not extremely confident in the forecast nor the impacts we could see. With that we stuck very close to the NBM.
As we move into Tuesday generally zonal flow will become more southwesterly as a ridge builds over Cuba and the next s/w system works southeast over the continental divide. There are some rather distinct differences in the strength of the next system. That also leads to differences in timing and potential for severe weather. Right now Storm Prediction Center has portions of the area outlooked at 15% (basically a Slight Risk) in the day 4 which is 12Z Tuesday through 12z Wed. The main timing would be overnight and through the Wednesday for our impacts. A stronger deeper s/w would suggest a better chance of strong to severe storms but also favor a slightly slower speed (later time frame possibly going a little deeper into Wednesday and not mainly an overnight Tuesday night episode). That said either solution looks like the bulk of the forcing will remain north of the region and thus the greatest impacts should as well. Still anticipate showers and thunderstorms at the least but we will wit a little longer and for us to get through todays systems before we really dive into the details on the mid week system. /CAB/
Issued at 533am CST Sat Nov 26 2022
Right now the coastal zones are only seeing minimal impacts and that is actually from slightly reduced visibilities but conditions should change rather quickly this morning as winds begin to ramp up. SCY conditions are expected to rapidly develop after sunrise across the waters west of the mouth of the river and then expand east through the morning and midday hours. By late this afternoon as the surface low begins to deepen and trek north near the TX/LA border the gradient will tighten and strong scy conditions will impact all of the coastal waters. The cold front is expected to traverse the waters overnight tonight and winds will quickly veer around to the west and southwest overnight but SCY conditions will remain in place through midday Sunday and possibly later. /CAB/
NOAA New Orleans LA Office: Watches - Warnings - Advisories
LA...Wind Advisory until midnight CST tonight for LAZ034>037-039- 046>048-056>060-064>071-076>090.
GM...Small Craft Advisory until 1pm CST Sunday for GMZ530-532-534- 536-538-550-552-555-557-570-572-575-577.
Dense Fog Advisory until 11am CST this morning for GMZ532.
MS...Wind Advisory until midnight CST tonight for MSZ068>071-077- 080>082.
GM...Small Craft Advisory until 1pm CST Sunday for GMZ532-534-536- 538-550-552-555-557-570-572-575-577.