ATL: IOTA - Remnants - Discussion

[ElectricStorm]

No longer forecast to be a major. That shear may be a bigger issue than we thought it would be. It is November after all...

[Kazmit]

Iota looks odd this morning.

[chaser1]

Just read the 10:00am discussion and the reference to unanticipated shear as a result to proximity to Columbia. Not sure I see that as an issue but rather vertical shear that I see occurring as a result of a TUTT-like feature to the north of the storm and extending WSW over Cuba and Jamaica. If looking at the water vapor loop, it appears that the storm is presently at the base of this feature however as deep layer ridging begins to expand over and to the east, this mid to upper perturbance should weaken and move westward. It seems that as a result of this mid/upper trough to the north, vertical shear has allowed the LLC to progress westward and is essentially now rotating with a temporary SW motion around it's own core circulation. I think we'll probably see the LLC rotate back under the MLC during today and tonight, or possibly even be ejected altogether with a new LLC developing under the MLC. Anyway, that's my take on the present.

[aspen]

Well today’s HMON/HWRF runs should be interesting, with all of the model defiance Iota has exhibited.

[chaser1]

Seems to me that all models have underplayed the strength of mid/upper level trough to the north of Iota, however all models to suggest that the upper air will become more diffluent in about 24 hours and this I suppose would lessen the vertical shear presently affecting the storm. Seems reasonable enough but I'm not sure that conditions will improve quite that quickly unless Iota temporarily stalls and reorganizes where it is. Conversely, NHC is calling for an increased forward motion and to me this might retard it's development and only prolong the storm's reorganization until much closer to the Central American coastline. As I see Iota progressing toward 82W, a faster motion would suggest a weaker and more westward track resulting in a landfall further south over Nicaragua while fighting vertical shear most of the way. A significantly slower then forecast motion would result in a significantly stronger storm prior to reaching 82W, that would track more WNW near or even north of the Honduran border. Seems that the ultimate outcome determining Iota's final intensity will be most reliant on the storm's position relevant to upper level conditions continuing to impact vertical shear or Iota's timing to allow more diffluent upper conditions to better assist it's vertical organization and increased diffluent upper outflow.

[chaser1]

Well today’s HMON/HWRF runs should be interesting, with all of the model defiance Iota has exhibited.

True enough. I'd guess that both models will become less bullish on intensity while suggesting a track well south of their 0Z forecasts.
Edit: If not in the model 6Z update, then certainly later today in their 12Z model run.

[tolakram]

Center (mid or llc, hard to tell) clearly visible now.

https://whirlwind.aos.wisc.edu/~wxp/goe ... o1_60.html

source: https://www.aos.wisc.edu/weather/wx_obs/GOES16.html

[bp92]

Well, Matthew blew up all the way to Cat.5 in pretty much the same location.
There's an isolated massif with some massive mountains in northern Colombia which can easily disrupt storms, but if the circulation's small, it shouldn't be that big of an issue. I understand that the issue is, indeed, an unrelated shear system nearby.
Regardless, it's raining cats and dogs over here in northern Colombia. Hope the flooding isn't too bad in risk areas .

[kevin]

I know this isn't the models thread, but considering the talk about possible track it feels relevant to mention here. Now HMON has joined the other models with a Nicaragua landfall. It landfalls at 63 hours as a high end cat 4 (136 kts). HWRF is still running, but it is also further south and it seems like it will also make landfall in Nicaragua or otherwise Honduras.

[aspen]

Well today’s HMON/HWRF runs should be interesting, with all of the model defiance Iota has exhibited.

True enough. I'd guess that both models will become less bullish on intensity while suggesting a track well south of their 0Z forecasts.
Edit: If not in the model 6Z update, then certainly later today in their 12Z model run.

Both 12z runs have a 930s system at landfall, with the HMON right on the cusp of a Cat 5 hurricane.

[aspen]

Iota is 40-45 kt based on this first pass.

[cycloneye]

...AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT FINDS IOTA A LITTLE
STRONGER...
...HURRICANE WATCH ISSUED FOR PROVIDENCIA ISLAND AND PORTIONS OF
THE COASTS OF NICARAGUA AND HONDURAS...


SUMMARY OF 100 PM EST...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...12.6N 76.4W
ABOUT 375 MI...600 KM S OF KINGSTON JAMAICA
ABOUT 485 MI...780 KM ESE OF CABO GRACIAS A DIOS ON NIC/HON BORDER
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...WSW OR 255 DEGREES AT 5 MPH...7 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES

[supercane4867]

NHC dropping major intensity out of their forecast in the advisory this morning was clearly a mistake.

[kevin]

Recon just measured 998.3 mbar, already 4 mbar stronger than the recent NHC advisory. While it still looks like it needs to get its act together on visual, the pressure drop seems to indicate that it's busy getting there right now.

[aspen]

Iota has a really compact core, but maximum winds are pretty far from the enter. This might eventually lead to a core expansion or EWRC/eyewall meld like the HWRF is forecasting. We’ll have to see if hot towers begin firing over the CoC and force those max winds closer.

[kevin]

Maybe they missed the 'real' core on the first pass, but otherwise this seems to be deepening quite rapidly already. First NHC with 1002 mbar, then the first pass 998 mbar and just an hour later 994 mbar.

[aspen]

994 mbar from the dropsonde this pass. Iota also appears to have stalled again, as this pass is slightly NE of the last one.

[underthwx]

994 mbar from the dropsonde this pass. Iota also appears to have stalled again, as this pass is slightly NE of the last one.

shizaam....that is not good Iota stalling....I hope it's not fixin to strengthen alot...

[cycloneye]

The mission is over. The next one departs at 9 PM EST.

[supercane4867]

Very broad circulation. Looking WPAC-ish on satellite