ATL: HERMINE - Post-Tropical - Discussion

[SeGaBob]

It has the classic look of a developing td right now...of course it may fizzle out.

[USTropics]

Most recent past from about 45 minutes ago caught the western half of 99L:



Nice burst of convection this evening, we'll see if it can maintain into the morning:

[northjaxpro]

Well folks 99L has apparently found its clothes this morning. This system looks rather healthy early this morning. Deep convection has blossomed in and near where a LLC may be coalescing now. Tbis is as good a satellite appearance I have seen to this juncture of 99L. I would go as far as stating that if the current trends continue with 99L to what is I am seeing at this juncture, we may see a TD found by Recon later today.

[Chris_in_Tampa]

Satellite image at 3:45am EDT on Tuesday of Fiona, Gaston and 99L (which if named, would be Hermine)

[jlauderdal]

Good to see Capt Stewart on the overnight shift. He bumped TWO up to 60/60. He can real satellites/obs pretty well and interpret globals pretty damn well too.

avial will knock it down 10-20% on his shift just because thats what he does...

its looking good on IR...this continues then the plane will be a go..impressive on IR doesnt mean impressive at the surface
we have seen some very impressive systems on IR with nada at the surface

[Alyono]

I have a major bone to pick with the NHC probabilities

How are the 48 and 120 hour chances the same if conditions become more favorable after 48 hours?

[northjaxpro]

Good to see Capt Stewart on the overnight shift. He bumped TWO up to 60/60. He can real satellites/obs pretty well and interpret globals pretty damn well too.

its looking good on IR...this continues then the plane will be a go..impressive on IR doesnt mean impressive at the surface
we have seen some very impressive systems on IR with nada at the surface

This is true. But if the trend continues with the convection persisting and the system trying to organize, Recon will fly out later today.

[RL3AO]

I have a major bone to pick with the NHC probabilities

How are the 48 and 120 hour chances the same if conditions become more favorable after 48 hours?

I was wondering the same thing.

[jlauderdal]

I have a major bone to pick with the NHC probabilities

How are the 48 and 120 hour chances the same if conditions become more favorable after 48 hours?

i agree but the rationalization could be...there is a larger error rate in the future so even though its expected to be more favorable there is also a greater chance that is wrong so that brings down the final percentage...similar to the cone of uncertainty

[Alyono]

I am not impressed with the convection this morning.

No signs of banding. I suspect this will largely dissipate in the coming hours. It has already weakened quite a bit. I would not send recon into this. Development may take 3-4 days

[northjaxpro]

Well up to now that had been the trend with 99L, seeing these convective bursts only later to die off. You may be correct with your assessment. We shall see as the morning progresses.

[RL3AO]

I'd agree with Alyono. This still needs a few days. When you get these bursts at night, it will ingest more dry air. Takes the rest of the day to mix it out and then restart the cycle.

[stormwise]

Going solely off the 06 i think its likely a recon may find TS, having said that i respect Alyono's opinion.

[Frank2]

The wildcard would be 99L becoming another Earl - per this view it is possible: http://www.ssd.noaa.gov/goes/east/tatl/wv-animated.gif

[cycloneye]

Plane is going this morning.

An Air Force Reserve
Hurricane Hunter aircraft is scheduled to investigate this system
later this morning.

[RL3AO]

It's scheduled for take off at 13Z. I still don't think it needs to go today but maybe they want data.

[abajan]

Excerpt from latest TWO:

"... A tropical wave located about 400 miles east-southeast of the
Leeward Islands is producing widespread cloudiness and
thunderstorms. Conditions are marginally conducive for gradual
development while the disturbance moves west-northwestward to
westward at 15 to 20 mph. Environmental conditions are expected to
become more conducive for a tropical depression to form by late this
week when the system is forecast to move near Hispaniola and Puerto
Rico, and the southeastern and central Bahamas. An Air Force Reserve
Hurricane Hunter aircraft is scheduled to investigate this system
later this morning. Interests in the central and northern Lesser
Antilles, the Virgin Islands, and Puerto Rico should monitor the
progress of this system.
* Formation chance through 48 hours...medium...60 percent
* Formation chance through 5 days...medium...60 percent ..."

Okay, so how is it that the previous TWO (at 8 PM) advised those in the southern and central Bahamas to monitor the progress of 90L and this one doesn't? After all, the system is closer to the Bahamas now than it was at 8 PM. Is its forward speed expected to decelerate?

[AJC3]

Excerpt from latest TWO:

"... A tropical wave located about 400 miles east-southeast of the
Leeward Islands is producing widespread cloudiness and
thunderstorms. Conditions are marginally conducive for gradual
development while the disturbance moves west-northwestward to
westward at 15 to 20 mph. Environmental conditions are expected to
become more conducive for a tropical depression to form by late this
week when the system is forecast to move near Hispaniola and Puerto
Rico, and the southeastern and central Bahamas. An Air Force Reserve
Hurricane Hunter aircraft is scheduled to investigate this system
later this morning. Interests in the central and northern Lesser
Antilles, the Virgin Islands, and Puerto Rico should monitor the
progress of this system.
* Formation chance through 48 hours...medium...60 percent
* Formation chance through 5 days...medium...60 percent ..."

Okay, so how is it that the previous TWO (at 8 PM) advised those in the southern and central Bahamas to monitor the progress of 90L and this one doesn't? After all, the system is closer to the Bahamas now than it was at 8 PM. Is its forward speed expected to decelerate?

You're misremembering. Here's the quote from the 8:00 PM TWOAT

http://www.nhc.noaa.gov/archive/text/TW ... 222343.txt

"Interests in the Lesser Antilles, the Virgin Islands, and Puerto Rico should monitor the progress of this system."

[abajan]

You're quite right. I could've sworn they advised the Bahamas to monitor it's progress in the 8 PM TWO. I tried to delete the post but since you had already replied, that wasn't possible. The weird thing is, I can't find mention of what I thought was stated in any of the recent TWOs!

[northjaxpro]

It's scheduled for take off at 13Z. I still don't think it needs to go today but maybe they want data.

Yes. We definitely need to get a better sampling of data with the environment surrounding 99L. Any new data imputed to the models should help give us better insight to what will evolve with this system hopefully down the road, especially for the next 5-7 days.