ATL: DELTA - Post-Tropical - Discussion

[NDG]

I am still in awe on how small the eye is, only 5-6 nautical miles wide

[NDG]

Pressure down to 957mb.

948
URNT12 KWBC 061346
VORTEX DATA MESSAGE AL262020
A. 06/13:03:36Z
B. 17.93 deg N 082.26 deg W
C. 700 MB 2759 m
D. EXTRAP 957 mb
E. NA
F. CLOSED
G. C6
H. 83 kt
I. 049 deg 7 nm 13:01:53Z
J. 139 deg 102 kt
K. 049 deg 7 nm 13:01:50Z
L. 95 kt
M. 223 deg 4 nm 13:04:44Z
N. 302 deg 87 kt
O. 223 deg 6 nm 13:05:03Z
P. 13 C / 3060 m
Q. 18 C / 3079 m
R. 13 C / NA
S. 12 / 7
T. 0.01 / 1 nm
U. NOAA2 0426A DELTA OB 19
SLP EXTRAP FROM 700 MB
MAX FL WIND 102 KT 049 / 7 NM 13:01:50Z
MAX FL TEMP 20 C 049 / 6 NM FROM FL CNTR

[BYG Jacob]

An honest to god pinhole

[USTropics]

 https://twitter.com/MJVentrice/status/1313474538429206532




 https://twitter.com/AndyHazelton/status/1313473903499542536




 https://twitter.com/splillo/status/1313466903407390721




 https://twitter.com/JakeCarstens/status/1313451717992873985

[GCANE]

[Hypercane_Kyle]

VDM shows a 6 nautical mile wide eye, closed eyewall.

[us89]

113 knots on the dropsonde but likely a gust. However, this supports an upgrade to 100 knot major hurricane status when considering reduction from gusts.

I dunno about "likely a gust-" note that winds averaged 115 kt in the lowest 150 m and 112 kt in the lowest 500 m. If this was just a gust I don't imagine you'd see such a deep layer of strong winds, however I do think that surface wind is still a bit too high/should not be taken literally. I'd say 105-110 kt.

According to a tweet from Daniel Brown back when everyone was annoyed Dorian didn't get upgraded to a cat 5 right away, the NHC doesn't use surface winds from dropsonde data, but they do use reduction from the mean boundary layer and mean wind in the lowest 150 meters.

Mean wind in the lowest 150 m was 115 kt, and the mean boundary layer wind was 112 kt (not sure what the reduction factor is, but assuming it's 90%, that translates to 101 kt at the surface). If I were the NHC, I would probably go with 100 or 105 kt out of respect for the lower flight-level and SFMR data reported by the plane.

[tailgater]

OHC is actually slightly higher closer to the Yucatán. Absolutely bonkers rocket fuel for the next 18-24 hours.
https://rammb-data.cira.colostate.edu/tc_realtime/products/storms/2020al26/ohcnfcst/2020al26_ohcnfcst_202010060600.gif

Some “good” news: models show relatively high background pressures in the N Gulf, meaning smaller-than-average size, hence lower surge. Add lower OHC, mid-level shear, and continental dry air. This system will be rather tame vs. other N-Gulf hurricanes, especially in terms of fetch, given the high background pressures (= reduced fetch). Furthermore, given the other negative factors, Delta is likely to weaken significantly prior to landfall on the N Gulf Coast. While a Category-5 impact to the Yucatán Peninsula is quite plausible, I can’t envision anything stronger than a weakening Cat-2 in Louisiana. But time will tell.

Thanks Shell Mound, I was going to ask about the size of Delta’s wind field as it enters the GOM. Hopefully we won’t half a huge (area wise) storm surge, EWR’s could have some effect on it and it will likely enlarge somewhat after it ingest Gamma’s leftovers.

[PTrackerLA]

This is not looking good for my area. Starting preparations today but I feel a big sense of complacency around here regarding Delta. That will probably change after it strikes Cancun tonight.

[StormPyrate]

Now that we're talking about ACE, does anyone have a link to a place where we can find the ACE of all or at least many storms? It will be interesting to compare Delta to other Caribbean cruisers like Wilma later on.

I've been working on this project. I have all the ibtracs uploaded to Google Sheets, and have created the ACE formula and a pivot table to look at each season/system. I haven't 100% confirmed every system is accurate (there was quite a bit of filtering work that went in to it), so let me know if anyone sees any errors.

https://docs.google.com/spreadsheets/d/ ... sp=sharing

That is interesting, thank you.
People keep comparing this to 2005 but I just do not see the comparison.
Yes we got into the Greek names. But I think we are seeing and naming storms today that were barely a blip on the radar a decade ago. Look at the Ace for 2005 vs this year.

[GCANE]

Still interacting with the PVS

[tiger_deF]

Now that we're talking about ACE, does anyone have a link to a place where we can find the ACE of all or at least many storms? It will be interesting to compare Delta to other Caribbean cruisers like Wilma later on.

I've been working on this project. I have all the ibtracs uploaded to Google Sheets, and have created the ACE formula and a pivot table to look at each season/system. I haven't 100% confirmed every system is accurate (there was quite a bit of filtering work that went in to it), so let me know if anyone sees any errors.

https://docs.google.com/spreadsheets/d/ ... sp=sharing

That is interesting, thank you.
People keep comparing this to 2005 but I just do not see the comparison.
Yes we got into the Greek names. But I think we are seeing and naming storms today that were barely a blip on the radar a decade ago. Look at the Ace for 2005 vs this year.

I have to disagree, while we have more tools nowadays and 2005 was no comparison to this season, there has been a concrete case for every single named storm this season. I would say background conditions just haven't been as conductive for very intense cyclones, but the mojo spawning systems from every possible area of interest is similar to 2005. Plus the season has been fairly quiet in the MDR, where storms usually churn across for days generating a majority of ACE

[xironman]

The land interaction when Delta hits the Yucatan will probably increase the wind field quite a bit.

[plasticup]

The land interaction when Delta hits the Yucatan will probably increase the wind field quite a bit.

If. Core could definitely stay off shore, as a stronger-than-expected Gamma would favor

[Keldeo1997]

Feeder band connected to the eyewall

[kevin]

Latest IR loop.

[ScottNAtlanta]

The only thing with a small pinhole eye is that you need to start looking for an EWRC. If one of those completes it will expand the wind field dramatically

[ScottNAtlanta]

Now that we're talking about ACE, does anyone have a link to a place where we can find the ACE of all or at least many storms? It will be interesting to compare Delta to other Caribbean cruisers like Wilma later on.

I've been working on this project. I have all the ibtracs uploaded to Google Sheets, and have created the ACE formula and a pivot table to look at each season/system. I haven't 100% confirmed every system is accurate (there was quite a bit of filtering work that went in to it), so let me know if anyone sees any errors.

https://docs.google.com/spreadsheets/d/ ... sp=sharing

That is interesting, thank you.
People keep comparing this to 2005 but I just do not see the comparison.


Yes we got into the Greek names. But I think we are seeing and naming storms today that were barely a blip on the radar a decade ago. Look at the Ace for 2005 vs this year.

http://tropical.atmos.colostate.edu/Rea ... thatlantic

[kevin]

'Est. Sfc. Wind (30 sec. Avg.) Using Est. Red. Factor' of 96.9 kts measured on the latest pass, supports a minimal cat 3. No center fix yet this pass, but pressure is already down to 959.9 mbar.

[mpic]

Will the front that's suppose to come through Houston come in time to spare us?