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Post Tropical Cyclone Debby


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I do not buy the Euro, now it is the outlier. My forecast is a very slow drift north to the FL panhandle, then a slow exit ENE across north FL and just off the Carolinas. I hope it is faster, just want this crappy system to get out of my hair as soon as possible.

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Simply put, they went Euro over GFS and lost. It wasn't euro going into Big Bend and GFS hitting Tampa/St Pete, it was TX or Fla. They didn't have much room to split the difference.

Again, the GFS wasn't necessarily "right" either. It had Debby going over the middle of the Florida peninsula then way out to sea. This scenario may not happen. If Debby makes landfall in the Florida Panhandle (a la the 12z Euro), neither of the models will have performed well with this, and a "split the difference" idea from yesterday's GFS/Euro would actually have been the way to go... as odd as that is.

EDIT: For yesterday's 12z GFS to verify, we need Debby to head southeast to Tampa Bay over the next couple days (and weaken to almost nothing)...

http://mag.ncep.noaa.gov/GemPakTier/MagGemPakImages/gfs/20120623/12/gfs_namer_084_10m_wnd_precip.gif

Of course, yesterday's 00z Euro had Debby off the Texas coast at that time. In any case, neither model can be said to be the "winner" yet. I would agree that the GFS has outperformed the Euro, but it could still bust big time.

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Here in Bradenton Fla, just South of Tampa Bay, it has been insane for the past couple hrs. Just got back from a ride to the beach, MAJOR flooding across the roads, huge waves in the Gulf, at least 10ft or so. Winds are gusting to about 35 - 40mph or so, I saw several trees down here in town. VERY surprised that we're not under Tropical Storm watches or even warnings, it's really bad out, comes in waves where it'll be pretty calm for a bit, then torrential rain and really gusty winds will hit. Still not at high tide either, I'll be surprised if anyone can even get to the beaches soon, I imagine the Sunshine Skyway must be a pretty brutal drive right about now. Just heard om the local news that Law Enforcement has just asked for people NOT to come out to Anna Maria Island due to flooding...that's where I just was 1/2 hr ago.

Thanks for the update! It's great to see ground reports! This is going to be the main impact of the storm... Lots and lots of rain. Places just offshore of Tampa have picked up 12+ inches. I had to break out my 16" color table to see it all... and it's all moving into the Tampa metro over the next 12 hours..

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And what happens if the shear vector becomes more southerly, or disappears as the upper low to its west continues to retrograde? There's a break in the surface pressure pattern to the system's northwest to north, even if the mid-level break is to its northeast. No wonder its motion is slow. The weak surface ridge is already bridging across the cold front into the subtropical ridge south of Bermuda. Debby is near the col point in the steering flow...which itself will be moving northeast due to increasing heights across the Carolinas, a development already in progress. So which moves faster...the col point or Debby? Debby could easily transcribe an anticyclonic loop due to increasing ridging to its north (a la Elena 1985), if it doesn't accelerate. It's way too early to pat any piece of guidance on the back. No one, at this point, is sure of the steering. We'll know better in a day or two. The guidance (particularly the hurricane guidance) overtrends in the direction the system is currently moving. As another Debbie used to say (spelled differently), anything is possible. =)

I suppose we shall see... I think Debby is already NE enough that it'll slide right into the developing weakness over the east coast (which should be fully opened up to Debby within 24 hours per the GFS), but I agree anything is possible and my forecast could bust just as hard as the yesterday's NHC forecast.

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Again, the GFS wasn't necessarily "right" either. It had Debby going over the middle of the Florida peninsula then way out to sea. This scenario may not happen. If Debby makes landfall in the Florida Panhandle (a la the 12z Euro), neither of the models will have performed well with this, and a "split the difference" idea from yesterday's GFS/Euro would actually have been the way to go... as odd as that is.

EDIT: For yesterday's 12z GFS to verify, we need Debby to head southeast to Tampa Bay over the next couple days (and weaken to almost nothing)...

http://mag.ncep.noaa..._wnd_precip.gif

Of course, yesterday's 00z Euro had Debby off the Texas coast at that time. In any case, neither model can be said to be the "winner" yet. I would agree that the GFS has outperformed the Euro, but it could still bust big time.

This this this. All of the people crying that the GFS scored a coup may end up eating their words.

Ironically, the Canadian may end up being the most accurate medium range forecast.

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This this this. All of the people crying that the GFS scored a coup may end up eating their words.

Ironically, the Canadian may end up being the most accurate medium range forecast.

Yeah exactly..I mean you can use the argument more right than wrong I guess..but scoring a "coup"? I wouldn't go quite that far.

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I would give the NHC track some life as there are signs of a rebound off the strengthening upper ridge and a westward drift setting in later today. This could even accelerate and cancel the stall, but for now would assume the 5-10 knot westward drift solution is most probable, with acceleration 20% outlier (by that I would hold open a slight risk for w LA or e TX landfall in 4-6 days).

Another possible solution would be a WSW rebound drift back towards yesterday's position (say 27.5N 87W) and erratic motion for several days.

It does not look that convincing for a Florida landfall or passage into Atlantic with more development on northwest side and the regional cool trend around Tampa Bay arguing for a wedge of moisture to split off the system and try to move across Florida without the circulation following. That would likely die out around 78W in 2-3 days.

Interesting to see rapid WSW cloud motion south of Texas and almost a ghost-TD formation in low clouds off CRP.

Bottom line is that Debby is likely to be in the northern Gulf for most of the week.

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I would give the NHC track some life as there are signs of a rebound off the strengthening upper ridge and a westward drift setting in later today. This could even accelerate and cancel the stall, but for now would assume the 5-10 knot westward drift solution is most probable, with acceleration 20% outlier (by that I would hold open a slight risk for w LA or e TX landfall in 4-6 days).

Another possible solution would be a WSW rebound drift back towards yesterday's position (say 27.5N 87W) and erratic motion for several days.

It does not look that convincing for a Florida landfall or passage into Atlantic with more development on northwest side and the regional cool trend around Tampa Bay arguing for a wedge of moisture to split off the system and try to move across Florida without the circulation following. That would likely die out around 78W in 2-3 days.

Interesting to see rapid WSW cloud motion south of Texas and almost a ghost-TD formation in low clouds off CRP.

Bottom line is that Debby is likely to be in the northern Gulf for most of the week.

I see this as well. The NHC forecast track as of 11 AM was probably the best forecast to make at the time.

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We are just finishing up our vacation in FL. We are from MD. Spent the past week on Anna Maria Island. Last night out there was interesting. We left the island this morning with some patch street flooding, but heard the same as a previous poster that police out there are asking people to not come out. We have video of the gulf from this morning. Currently we are at my parents in Palmetto and will start our trek North tomorrow. Interesting end to a vacation.

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This. Between these comments and those about how Debby is "crap" and "boring because it's not a hurricane", this thread has suddenly become annoying.

With that said, it is quite possible that both the Canadian and GFS have scored a mild coup with this one. I'm still not convinced that Debby is going to go all-out GFS and go northeast into the Atlantic, as there is still a good chance for a complete stall for a day or so. As I said yesterday, I really like the Lee comparison for the sake of a storm splitting the difference between all models.

It definitely will be interesting to see what Debby does when the shear lets up a bit.

Personally, though everyone else may disagree, I am getting an 'Allisonish' vibe from Debby. Meaning when all is said and done, I think the biggest headlines from Debby will be the wide-spread flash-flooding it generates. Everyone appears to be handing the GFS the trophy on this storm and this may be well deserved. However, I wouldn't be totally shocked if she makes it to the FL panhandle, stalls, and then somehow ducks the trough digging down. Which means she could either sit and spin for days like one of the previous OP GFS runs indicated and/or slide back toward the W or W/SW and eventually threaten areas to the west such as LA & TX in the long range. Thus making her the Allison of 2012. Just some thoughts I've been having the past few days.

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Again, the GFS wasn't necessarily "right" either. It had Debby going over the middle of the Florida peninsula then way out to sea. This scenario may not happen. If Debby makes landfall in the Florida Panhandle (a la the 12z Euro), neither of the models will have performed well with this, and a "split the difference" idea from yesterday's GFS/Euro would actually have been the way to go... as odd as that is.

EDIT: For yesterday's 12z GFS to verify, we need Debby to head southeast to Tampa Bay over the next couple days (and weaken to almost nothing)...

http://mag.ncep.noaa..._wnd_precip.gif

Of course, yesterday's 00z Euro had Debby off the Texas coast at that time. In any case, neither model can be said to be the "winner" yet. I would agree that the GFS has outperformed the Euro, but it could still bust big time.

Good post. This was always going to be a delicate track that was going to be very sensitive to the short term motion. I've been harping against blindly following the Texas track for the past 2-3 days because of the potential for eastward relocations in the track. Both the ECMWF and the GFS were on the opposite sides of the track spectrum. The GFS was so far east because it has the low level circulation continually being affected by eastward vorticity protrusions. Some of those protrusions may have been a result of convective feedback, but some of that was actually realistic last night when we saw the huge blow up of convection to the NE of the circulation center. If the ECMWF was to continue its track, we would have needed to see a NW track prevail without any eastward center relocations. That didn't happen, and thats why the track is now shifting to the east.

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