ATL: DELTA - Post-Tropical - Discussion

[tolakram]

A farther west track means that Delta would avoid the cold pool south of the mouth of the Mississippi as well. The water is a bit warmer farther west.

May also encounter more shear?

I think that's the big unknown. Upper level winds from the SW favor intensification as they vent the system, but as an amateur I need someone else to interpret if this will be a benefit the the system or a hindrance, and does moving further west increase or decrease that?

[aspen]

Recon is descending down to flight level. If Delta’s center is off of the coast by now, we should have a center fix within 45-60 minutes.

[CrazyC83]

 https://twitter.com/CC_StormWatch/status/1313887290847096838

[hipshot]

A farther west track means that Delta would avoid the cold pool south of the mouth of the Mississippi as well. The water is a bit warmer farther west.

May also encounter more shear?

I think that's the big unknown. Upper level winds from the SW favor intensification as they vent the system, but as an amateur I need someone else to interpret if this will be a benefit the the system or a hindrance, and does moving further west increase or decrease that?

I think Levi indicated that the shear from the SW was in the upper atmosphere caused by a trough over Texas. As such, it would help to steer the
storm back towards the NE toward its current projected target. As to its affect on the strength of the storm, I'm not sure like you. Maybe in Levi's
notes this evening he will tell us.

[mpic]

https://twitter.com/CC_StormWatch/status/1313887290847096838

So thankful that we now get warning far in advance.

[Steve]

May also encounter more shear?

I think that's the big unknown. Upper level winds from the SW favor intensification as they vent the system, but as an amateur I need someone else to interpret if this will be a benefit the the system or a hindrance, and does moving further west increase or decrease that?

I think Levi indicated that the shear from the SW was in the upper atmosphere caused by a trough over Texas. As such, it would help to steer the
storm back towards the NE toward its current projected target. As to its affect on the strength of the storm, I'm not sure like you. Maybe in Levi's
notes this evening he will tell us.

Yeah, it's likely to have an eastern component after 27 or 28N. One of the modeled changes yesterday was the smoothing out of any sharper turns to the NE in favor of landfall with only a gentle slope to the east (essentially N to NNNE)

[FLpanhandle91]

Eye seems to be warming. May see it clear soon.

[MBryant]

I have my reservations to evacuate to Tyler again. This is a decision partially driven by the debris piles still on the streets which will become deadly objects if we have a RITA type wind. If I go, it will need to be tomorrow. There's no chance I'd try to outrun a storm.

[Rail Dawg]

I think that's the big unknown. Upper level winds from the SW favor intensification as they vent the system, but as an amateur I need someone else to interpret if this will be a benefit the the system or a hindrance, and does moving further west increase or decrease that?

For the record Mark I look at you as far from an amateur lol.

Keep up the good work.

Chuck

[Rail Dawg]

For the record the airlines and our government pay big bucks to overfly other countries. It is a big boost to their bottom line and it happens thousands of times a day.

Our government routinely gets permission to overfly countries to hunt hurricanes. I'm quite sure NOAA got the right permissions and paid the right amount of money.

Chuck

[TheProfessor]

A farther west track means that Delta would avoid the cold pool south of the mouth of the Mississippi as well. The water is a bit warmer farther west.

May also encounter more shear?

I think that's the big unknown. Upper level winds from the SW favor intensification as they vent the system, but as an amateur I need someone else to interpret if this will be a benefit the the system or a hindrance, and does moving further west increase or decrease that?

For the most part the specific setup hasn't changed much because the whole pattern has shifted westward, including the upper level anticyclone. The GFS still has the storm riding the western edge of the upper ridge, but further west overall. The ULL in the Caribbean is also further west so the environment is very similar. What will be vital in knowing just how much of an affect that shear will have on the storm is how strong the core is, how long the storm moves over cooler waters, and whether or not dry air gets entrained.



The GFS seems to keep dry air out of the core of the storm, however I imagine the further west the storm gets the more likely that gets entrained, even with the setup shifted west. If the dry air is able to disrupt the core we're probably looking at a strong cat-1 landfall, if the core stays intact, the storm likely won't weaken as quickly. Dry air and shear may also play a part in tornadoes in feeder bands as well, so there could potentially be more significant impacts outside the core of the storm compared to some of the other storms not named Isaias.


It should be noted that weakening will likely happen just before landfall and even if the storm is hitting as a Cat-1 hurricane, it will likely still be packing a Cat-3like surge as it takes prolonged weakening for the surge to drastically reduce.

Edit: Click on the image to get the loops playing.

[MBryant]

There still appears to be about a 200 mile divergence in the models for center of landfall. But anybody that thinks that won't change in the next 24 hours would be foolish. If you live anywhere along the Gulf Coast, Pay Attention. It doesn't cost a dime.

[supercane4867]

May also encounter more shear?

I think that's the big unknown. Upper level winds from the SW favor intensification as they vent the system, but as an amateur I need someone else to interpret if this will be a benefit the the system or a hindrance, and does moving further west increase or decrease that?

I think Levi indicated that the shear from the SW was in the upper atmosphere caused by a trough over Texas. As such, it would help to steer the
storm back towards the NE toward its current projected target. As to its affect on the strength of the storm, I'm not sure like you. Maybe in Levi's
notes this evening he will tell us.

Upper level pattern before the system making the turn to NE favors intensification. When Delta approaches the coastline it will start to get embedded in westerlies and that will eventually weaken the storm. Overall setup is similar to what Laura had in the Gulf, albeit more south.

[Gums]

Salute!

Good poop, Dawg.

I would not ride out in Morgan City for this one. Seems like Lafayette.

Problem is the law closes many roads along I-10 for the folks getting out.

Good luck, man, and keep us posted.

Gums sends...

[aspen]

Almost every SFMR measurement so far is flagged.

[NDG]

[ColdMiser123]

Another wildcard could potentially be any kind of favorable interaction between the jet to the northwest resulting in enhanced upper level divergence in the right-entrance region of the jet over Texas, close to where Delta would be.

However, at this time it doesn't appear as though this part of the jet will be strong enough to where the jet streak model would apply. But if this ends up being a bit stronger than forecast, it may be related to a favorable jet dynamic interaction.

[Sciencerocks]

[kevin]

New recon center pass gives an Extrapolated Sfc. Pressure of 973.3 mbar. Does anyone know why pretty much all wind measurements are flagged?

Edit: Looking at the overlay of the plane track and the sat image of the storm I don't think it was a clear center pass, so the actual central pressure might be a few mbar lower. Or maybe Delta doesn't have a true clear center atm.

[Sciencerocks]

Damage seen in Cancun appears to be the worst since Wilma.

And Delta can't be retired! It wouldn't matter if it ran down the center of New orleans as a cat5 and killed 100,000 people.