ATL: DELTA - Post-Tropical - Discussion

[kevin]

Recon entering the storm now, pressure dropping to 1006 mbar and 21 kts estimated surface level winds.

[cycloneye]

 https://twitter.com/EricBlake12/status/1313196051914985478

[p1nheadlarry]

I haven't heard about the relationship of theta-e with respect to WISHE.
Do you have a reference?

Sure. It's referenced in this article with Michael Montgomery as a coauthor https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/qj.1969
Here's a ppt also that goes into a few TC theories but WISHE is in there and outlines it with second law of thermo which is what I was [trying to] describe. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjB6s_6jJ7sAhUcoHIEHUEbBToQFjABegQIARAC&url=https%3A%2F%2Fwww.usna.edu%2FUsesr%2Foceano%2Fbarrett%2FSO442%2FSO442_Lesson07_TCPotentialIntensity.pptx&usg=AOvVaw1SwqfPar2NGK_2zN-eprZm

Great presentation, much thanks.
Yes, the classic Carnot cycle.
One thing I may want to add is the relationship of Vmax on Tout. Tout being approximately the temperature of the top of the troposphere. Not just dependent on the difference in sea-surface temperature but inversely proportional as well.
So as the upper troposphere seasonally cools off, much stronger TCs are possible. Accounts why such later season TCs are so powerful, case in point Wilma. Delta maybe another case.

Right, MPI is proportional to delta T. Never really looked into how they determined "exhaust" temperature and thought maybe it was the environmental temperature at the furthest T(x,y,z) point along an inner theta-e contour, but I can see how that could be messy.

[aspen]

Recon is getting very close to the core of Delta. Odds are its pressure is lower than the official 998 mbar.

[p1nheadlarry]

Probably the highest RI probabilities i've ever seen from SHIPS

https://pbs.twimg.com/media/Ejll0CDWkAAbMGB?format=png&name=medium

Nearly 60% for 40 kt/24 hr, well then...

[cheezyWXguy]

These probabilities seem justified to me. That core looks really small and tight.

[aspen]

I nearly choked when I saw 985 mbar extrapolated.

[NDG]

Recon finds pressure below 990mb.

RNT15 KWBC 051938
NOAA3 0126A DELTA HDOB 16 20201005
192830 1628N 07943W 8410 01533 0028 +193 -101 046034 034 026 000 00
192900 1626N 07942W 8411 01530 0026 +191 -101 046034 035 025 000 00
192930 1625N 07940W 8413 01525 0022 +193 -100 043034 034 026 000 00
193000 1624N 07939W 8411 01524 0021 +188 -099 042033 034 026 000 00
193030 1622N 07938W 8410 01523 0021 +184 -097 039033 033 028 000 00
193100 1621N 07936W 8411 01519 0017 +186 -096 032033 034 030 000 00
193130 1620N 07935W 8413 01514 0011 +192 -096 030034 035 033 000 00
193200 1619N 07933W 8411 01512 0002 +198 -097 028036 037 034 000 00
193230 1618N 07931W 8412 01508 9997 +198 -097 030041 048 037 000 00
193300 1617N 07929W 8419 01493 9992 +194 -097 030047 049 039 000 00
193330 1616N 07928W 8416 01492 9985 +193 -096 030043 045 039 001 00
193400 1615N 07926W 8420 01476 9974 +195 -095 030048 051 042 001 00
193430 1614N 07924W 8419 01466 9961 +196 -097 030050 051 043 003 00
193500 1613N 07923W 8416 01458 9948 +193 -097 029051 055 047 004 00
193530 1612N 07921W 8430 01423 9922 +204 -095 019050 051 054 003 00
193600 1611N 07919W 8412 01427 9895 +213 -096 022046 049 053 001 00
193630 1610N 07917W 8426 01394 9874 +224 -097 021032 036 040 000 00
193700 1609N 07915W 8416 01395 9858 +231 -098 030017 020 033 000 00
193730 1609N 07914W 8415 01390 9857 +221 -097 059007 013 050 001 03
193800 1607N 07913W 8416 01386 9856 +223 -094 217005 006 020 000 03

[Cataegis96]

985.6 extrap.

[kevin]

Holy moly. Forgot to update for a few minutes and honestly thought something was wrong with the website when I saw 985 mbar .

[Kazmit]

Yup, pressure is about what I expected. This is about to blow up.

[CrazyC83]

I'd guess that Delta will be a hurricane by this evening and a major hurricane sometime tomorrow. I do wonder what a stronger storm sooner will do to the track forecasts - maybe that is what the Euro ensembles are sniffing?

[edu2703]

SFMR winds around 50-55 kts

[NDG]

MH through the Yucatan Channel certainly not out of the question at this point if it continues strengthening this way.
I hope the NE tip of the Yucatan P. is paying attention to it.

[ColdMiser123]

Few key things from this first pass so far:

Pressure is significantly lower than every single model forecast up until now.

This has an inner core, with a significant core temperature spike near the center.

The RMW is already quite small, so this has the potential to spin up quickly.

[CrazyC83]

MH through the Yucatan Channel certainly not out of the question at this point if it continues strengthening this way.
I hope the NE tip of the Yucatan P. is paying attention to it.

That seems quite likely unless ERC's throw a wrench. Weakening probably wouldn't begin until it gets into the central Gulf.

[Hypercane_Kyle]

Over 10 mb stronger than the NHC previously estimated.

[MarioProtVI]

Satellite looks a little ragged then before but I’m sure that’ll fix itself later tonight.

Also this plane usually has a low MSLP bias and the actual pressure is likely 3-4 mb higher then extrapolated. Real pressure is likely 988-989 mb pending dropsonde. This plane also had some issues during Isaias as well.

[NDG]

SFMR winds around 50-55 kts

It should find stronger winds than that in the SE quadrant or NE quadrant.

[kevin]

Lowest pressure measured was 985.3 mbar, Delta really is gonna become something special if its RI is still ahead of us. Also, since pretty much every model initialized this 15 - 20 mbar too weak, we'll have to wait for the new runs to see how this changes the forecast. When will this new data enter the models, 00z?