ATL: INVEST 91L - Discussion

[ouragans]

At least PTC to issue TS Warnings.

[ouragans]

 https://twitter.com/DrRickKnabb/status/1395839230413262852

[wxman57]

PTC advisory requires a "High" (70%+) chance of development and/or a need for a TS watch within 48 hrs. This weak low isn't meeting those criteria. Less than 12 hrs remaining over water. Convection very sparse near the center. Lots of shear and dry air in its path. Probably no PTC advisory. Of course, those are just their guidelines. The NHC could issue a PTC advisory if they think chances of it becoming a TD are increasing since their 18Z assessment.

[psyclone]

Naked swirl advisory. Still too soon but an indication that we're getting close

[InfernoFlameCat]

Convection has increased ever so slightly. Still would not call it a TC yet. If both systems get named, we have a real shot at 3 ns in MAY.
Also this system strongly reminds me of TS Cindy in 2017.

[captainbarbossa19]

Convection has increased ever so slightly. Still would not call it a TC yet. If both systems get named, we have a real shot at 3 ns in MAY.
Also this system strongly reminds me of TS Cindy in 2017.

This is definitely similar. Cindy was a little more towards the east, but her appearance was about the same.

[jasons2k]

From Jeff Lindner, hot off the press:

There has been little change today with the organization of the area of low pressure over the NW Gulf of Mexico.

Since this morning surface observations and satellite images indicate that a surface low pressure system has formed with the disturbance over the NW Gulf of Mexico. While surface low pressure has formed, deep convection is lacking across the system and certainly near the center with a plume of dry air helping to minimize deep convection. There are some banding features to the east and southeast of the center and an area of showers and thunderstorms to the west and well to the north stretching into SE TX.

The system is moving toward the NW and this motion is expected to continue as the system is being steered by high pressure over the SE US. On this track 91L will make landfall along the middle TX coast near Matagorda Bay early Saturday morning. The system will continue to track NW and then NNW well inland over TX on Saturday. This is a high confidence forecast track. While the overall organization of the system remains poor, it would only take a brief burst of deep convection near/over the center to likely result in tropical storm formation. This will be possible as the system nears the coast later tonight, but any sustained intensification is unlikely, and even if the system becomes a weak tropical storm, the impacts will be the same as if it were to remain in its current state.

Impacts:

Main the impacts continue to be rainfall with amounts of 1-3 inches and a few higher isolated totals. Overall, the dry air wrapping into the system and the overall lack of organization should keep rainfall totals in the manageable range. With that said, much of the area will fall on the east side of the center track and we will have to be watchful for any sort of sustained bands that may attempt to setup and train for a period of time which would locally increase the rainfall totals. Creeks and bayous should be able to handle the forecasted rainfall.

Tides are elevated and will remain elevated into the weekend with water levels near 3-4 feet above (MLLW). At times of high tide, minor coastal flooding will be possible along the Gulf beaches and in the inland bays, but significant coastal flooding is not expected.

Some gusty winds of 25-35mph may occur near the center tonight along the Gulf beaches, but not expecting any significant wind concerns.

[wxman57]

Convection is almost all gone now. Doesn't look like it will make it to a TD before it moves ashore in about 8 hrs.

[DestinHurricane]

Convection is almost all gone now. Doesn't look like it will make it to a TD before it moves ashore in about 8 hrs.

True, but it is nearing Dmin, so convection could increase later tonight.

[cycloneye]

A well-defined low pressure area is located over the western Gulf of
Mexico about 150 miles east-southeast of Corpus Christi, Texas.
Earlier satellite wind data and buoy observations indicated that the
system is producing winds of 30-35 mph near and to the east of its
center but recent satellite and radar imagery shows that shower and
thunderstorm activity remains limited. Although environmental
conditions are not particularly favorable for significant
development, only a slight increase in thunderstorm activity could
result in the formation of a tropical depression or storm before the
system moves inland along the Texas coast overnight. Regardless of
development, the system could produce heavy rainfall over portions
of southeastern Texas and southwestern Louisiana through Saturday.
Given the complete saturation of soils with ongoing river flooding
along the Texas and Louisiana coastal areas, heavy rain could lead
to flash, urban, and additional riverine flooding across this
region. Additional information on the rainfall and flooding
potential can be found in products issued by your local National
Weather Service Forecast Office.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 5 days...medium...50 percent.

[Monsoonjr99]

Likely to come ashore before DMax. 50% seems way too high for this thing.

[DorkyMcDorkface]

Got as high as 60% because of the well-defined circulation, but with marginal to borderline unfavorable thermodynamics preventing it from producing and sustaining persistent convective activity the window is likely closing on this one barring some last-minute shenanigans on final approach. You could probably think of this as an "if only it were a month later" type of situation.

[Sciencerocks]

bye

[JW-_-]

http://products.hfip.org/nhc-display/#


https://noaa.maps.arcgis.com/apps/MapSe ... d97e7ae35b

[cycloneye]

Surface observations and radar data indicate that the area of low
pressure previously over the northwestern Gulf of Mexico has moved
inland over southeastern Texas. Therefore, tropical cyclone
formation is not expected. However, the system could produce heavy
rainfall over portions of southeastern Texas and southwestern
Louisiana today. Given the complete saturation of soils with
ongoing river flooding along the Texas and Louisiana coastal areas,
these rains could lead to flash, urban, and additional riverine
flooding across this region. Additional information on the rainfall
and flooding potential can be found in products issued by your
local National Weather Service Forecast Office.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...near 0 percent.

[cycloneye]

Looks better inland.

 https://twitter.com/JimCantore/status/1396130099293048835

[captainbarbossa19]

Looks better inland.

https://twitter.com/JimCantore/status/1396130099293048835

I have heard that land friction can often tighten the vorticity of tropical lows. I would not be surprised if this is happening with this low.

[cycloneye]

NHC taking note of the structure inland.

 https://twitter.com/pppapin/status/1396149762630459392




 https://twitter.com/pppapin/status/1396151738105679874