ATL: HERMINE - Post-Tropical - Discussion

[psyclone]

50% TS wind probs on the coast from mid Pinellas north to Dixie county with the 11 PM package

[SeGaBob]

On that track I still wouldn't get rain... we have a slight drought now.

[Aric Dunn]

You know this Depression is looking quite a bit better tonight. And, as has been said, the upper environment (outflow-anti-cyclone) seems much more positive for development. I'm thinking that even without a scheduled recon (and I don't know when that would be), the NHC might upgrade tomorrow morning to Tropical Storm. Wonder what the latest T numbers look like??

recon will be out there before the 5am advisory to see if it strengthened.

[waterworld]

Opinion on the growing chances this storm staying on a westward track?

This storm will stay westward until west of 87

[Stormcenter]

Not surprised one bit, they need to see more consistency before they make any track changes. Though I must say it sure does look like the center is not where they say it is. JMHO

So in a nutshell no changes in track or intensity. trough supposed to still pick it up and dry air to the west and then once storm gets near landfall trough causes shear to keep it in check.

[psyclone]

NHC said they adjusted track south. Must have been just barely.

I couldn't tell it moved at all. We've had multiple forecasts now and the landfall points have all been similar so I'm confident they've got a good handle on the steering... When the models are changing you see them slowly adjust. In this case I think it's pretty much been Dixie or Levy county the whole time...25 miles either side of the Suwannee river is solid consistency thus far..

[RL3AO]

This hasn't updated the most recent forecast yet, but here was the NHC forecast trend through 18Z.



Heres the GFS trend



And the TCVN trend

[rolltide]

Has there ever been a storm that has went completely opposite than what was forecasted?[/quote]

Yes, Elena in 1985 was forecast to turn and hit north of Tampa. It stalled and came back west to landfall in Miss. Check out track below.



https://upload.wikimedia.org/wikipedia/ ... _track.png

[Aric Dunn]

Has there ever been a storm that has went completely opposite than what was forecasted?

Yes, Elena in 1985 was forecast to turn and hit north of Tampa. It stalled and came back west to landfall in Miss. Check out track below.



https://upload.wikimedia.org/wikipedia/ ... _track.png[/quote]

cant forget gordon..

[sponger]

Now that's consistency! Getting a little tired of being down the middle for so long. Glad the intensity forecast is mild.

[psyclone]

My watch guess is Indian pass to Englewood...Tropical storm watch. If that sounds familiar it is...that was the exact breakpoint usage for TS Colin. It might work fine here too.

[sponger]

Where is this trough that is going to counter decades of historical tracks? I have learned long ago to stop doubting the NHC but what am I missing?

"By 48 hours, the depression is
expected to accelerate northeastward across northern Florida ahead
of a shortwave trough that is forecast to dig southeastward into the
southeastern United States and northern Gulf Mexico."

http://weather.unisys.com/satellite/sat ... oop-12.gif

[waterworld]

NHC said they adjusted track south. Must have been just barely.

I couldn't tell it moved at all. We've had multiple forecasts now and the landfall points have all been similar so I'm confident they've got a good handle on the steering... When the models are changing you see them slowly adjust. In this case I think it's pretty much been Dixie or Levy county the whole time...25 miles either side of the Suwannee river is solid consistency thus far..

If you do dot mind me asking, who do you mean "they've got a good handle on the steering" ? I'm learning.

[sponger]

Wiki!

A shortwave or shortwave trough is an embedded kink in the trough / ridge pattern. Its length scale is much smaller than that of longwaves, which are responsible for the largest scale (synoptic scale) weather systems. Shortwaves may be contained within or found ahead of longwaves and range from the mesoscale to the synoptic scale. Shortwaves are most frequently caused by either a cold pool or an upper level front.

An upper front? So it does not reach the ground? Thus would not show on water vapor! Anyone know what heights we need to look at?

[HurriGuy]

After looking at RGB and Shortwave, I think the center is about right. Maybe 23.7N, but that seems good enough. The lower level cloud deck never really changed that much and it is hard for me to see the llc being any further south. As for the presentation, I guess it looks a little better, but honestly the sheer looks like it has only gotten worse on the north and northwest side with that flow from the northwest ULL transferring to the flow to the ULL off the east coast making for one wall of vertical sheer. And seeing that anti-cyclonic flow has really picked up and the circulation is on the outskirts of the anti-cyclonic flow, I would not expect any improvements until the ULL to the northwest starts to move more southwest into Mexico.

That leads me to my next problem. That ULL to the northwest was supposed to move southwest getting over northern Mexico, but if you look on the GFS, it has trended the path of that ULL more and more to the south and east barely each run. Putting that ULL more towards the B.O.C. or just over the Gulf in general will only cause more problems bringing in more dry air and not letting the anti-cyclonic flow really get a chance to expand and grow in size. That was the original trends by the HWRF was having a big dominant upper high over the Gulf leaving plenty of room for our system to get under it out of the sheer. Having a smaller upper high would mean TD 09 needs to get directly over the center or else the sheer will continue.

So in summary, if the ULL in the northwest Gulf does not start moving more west, I am expecting more unfavorable conditions because the upper high will not get a chance to expand north with TD 09. This is just my take.

[TheProfessor]

Where is this trough that is going to counter decades of historical tracks? I have learned long ago to stop doubting the NHC but what am I missing?

"By 48 hours, the depression is
expected to accelerate northeastward across northern Florida ahead
of a shortwave trough that is forecast to dig southeastward into the
southeastern United States and northern Gulf Mexico."

http://weather.unisys.com/satellite/sat ... oop-12.gif

I believe it's that trough that's digging in the northeast right now.

[chaser1]

All I know is, that based on TD9 having its LLC at about 25N & 85.5W... I'd say it looks like crap lol?! It really is shocking to see such a humongous upper anticyclone over the general area, yet in spite of 30° C SST's, TD9 just can't seem to find an adequate supply of inflow to be popping convection from here to kingdom-come! At this point I'm practically stymied that a dropsound really found a 1005mb pressure (yes, I heard they were extrapolating 1003mb due to 20mph winds at the drop). Whether upgrading to a T.S. is prudent given Watches needing to be placed, or simply because the next recon actually measures 39 1/2 mph on their next run... TD9's window for potentially reaching hurricane strength will likely start closing in about 24 hours if it can't simply find a way to expand a CDO over center. Fortunately for the N. Florida coastline, the same convective surge and shear cycles continue to occur. Not unlike 2015 where many tropical systems gasped and wheezed, and barring TD9 being inserted with a tropical pacemaker I have little reason to think that anything much more organized than some broad training of tropical slop will ultimately approach the coastline up there.

[Aric Dunn]

All I know is, that based on TD9 having its LLC at about 25N & 85.5W... I'd say it looks like crap lol?! It really is shocking to see such a humongous upper anticyclone over the general area, yet in spite of 30° C SST's, TD9 just can't seem to find an adequate supply of inflow to be popping convection from here to kingdom-come! At this point I'm practically stymied that a dropsound really found a 1005mb pressure (yes, I heard they were extrapolating 1003mb due to 20mph winds at the drop). Whether upgrading to a T.S. is prudent given Watches needing to be placed, or simply because the next recon actually measures 39 1/2 mph on their next run... TD9's window for potentially reaching hurricane strength will likely start closing in about 24 hours if it can't simply find a way to expand a CDO over center. Fortunately for the N. Florida coastline, the same convective surge and shear cycles continue to occur. Not unlike 2015 where many tropical systems gasped and wheezed, and barring TD9 being inserted with a tropical pacemaker I have little reason to think that anything much more organized than some broad training of tropical slop will ultimately approach the coastline up there.

they didn't mention the obvious multiple vorts in the discussion which is odd but next recon will take care of that.

[hipshot]

Where is this trough that is going to counter decades of historical tracks? I have learned long ago to stop doubting the NHC but what am I missing?

"By 48 hours, the depression is
expected to accelerate northeastward across northern Florida ahead
of a shortwave trough that is forecast to dig southeastward into the
southeastern United States and northern Gulf Mexico."

http://weather.unisys.com/satellite/sat ... oop-12.gif

Well, from that link, I don't see a trough but I am a rank amateur.

[SeGaBob]

Aric, does this still look like it's going to strengthen to you?