ATL: DEBBY - Post-Tropical

[gatorcane]

Looking at this WV loop, it certainly seems like the weakness to the north of Debbie is materializing....notice the trough digging over the Great Lakes. In 48 hours the GFS expect this to really create a weakness along the Eastern Seaboard and pull Debbie into it. Going to be interesting to see if this unfolds:

http://www.ssd.noaa.gov/goes/east/eaus/loop-wv.html

[Lane]

Geez i don't think i have ever seen the GFS and EURO so far apart for so long, usually the GFS falls in line with the EURO over time.
How many runs in a row does this make it the GFS has had this type of track for Debby?

This is the 3rd night I have seen it go east with Debby.

[Clint_TX]

Looking at this WV loop, it certainly seems like the weakness to the north of Debbie is materializing....notice the trough digging over the Great Lakes. In 48 hours the GFS expect this to really create a weakness along the Eastern Seaboard and pull Debbie into it. Going to be interesting to see if this unfolds:

http://www.ssd.noaa.gov/goes/east/eaus/loop-wv.html

I see what you see, but the NHC is saying there is a mid-level ridge

[lebron23]

Shocked that NHC nudged the cone a bit south

[HouTXmetro]

I know it can't be but almost looks like the GFS has shown the same runs three nights in a row. Just adjusting how long it stalls before moving east. Since the GFS seems to be the BIG under dog. I can't help but hope it verifies.
I do have a question for whoever can anwer this: What is the GFS seeing or playing out more than the other models to make it still say Debby will head East?

Another Storm developing off the Atlantic Coast creating a weakness in the Ridge.

[Rgv20]

I know it can't be but almost looks like the GFS has shown the same runs three nights in a row. Just adjusting how long it stalls before moving east. Since the GFS seems to be the BIG under dog. I can't help but hope it verifies.
I do have a question for whoever can anwer this: What is the GFS seeing or playing out more than the other models to make it still say Debby will head East?

Comparing the ECMWF and GFS it looks like the GFS is suffering from convective feedback located just east of Florida as the Euro does not show any rain in that area in that time frame. Is just a wild guess by my part tho.

[ozonepete]

00Z GFS is in. Has Debby landfalling at the big bend on Tuesday evening. Still is not backing off at all!

[viberama]

I think if Debby stays weak (due to shear), she has to move east and follow the GFS track. If she strengthens like the EURO suggests, she's going west.

My gut says she stays weak. There's just too much shear in the gulf this time of year.

[Jevo]

I do have a question for whoever can anwer this: What is the GFS seeing or playing out more than the other models to make it still say Debby will head East?

From the 10pm Discussion

THE MAIN REASON THAT THE GFS MOVES DEBBY EASTWARD
ACROSS THE NORTHEASTERN GULF IS DUE TO IT HAVING A WEAKER AND MORE
VERTICALLY SHALLOW STORM DEPICTED IN THE MODEL.

[HurricaneBrain]

Shocked that NHC nudged the cone a bit south

Yes they did, if anything I was expecting a nudge north. It will probably change tomorrow.

[loon]

You guys, Stewart let us know exactly why GFS is acting like it is in the lastest discussion.

quote:
The main reason that the GFS moves Debby eastward
across the northeastern Gulf is due to it having a weaker and more
vertically shallow storm depicted in the model. Given the expected
favorable upper-level flow pattern with weaker vertical shear
forecast to develop after 24 hours...a deeper and more robust
westward moving tropical cyclone as depicted in the
ECMWF...UKMET... NOGAPS models seems a more reasonable scenario.
The official forecast track is just an update of the previous
advisory track.



The "why GFS why!?!?" has been explained =)

[psyclone]

Get ready Pinellas County...for the first time with this system looks like a feeder band is going to come through starting in St. Petersburg in about 30 minutes...the bands have been falling apart south of Tampa Bay this entire afternoon, but looks like this one will stay in tact.

those twin tornadic signatures offshore are impressive. the one to the northwest looks to be on a trajectory that would keep it offshore but the one to the southeast could approach western manatee around anna maria island and then the southern pinellas county region if it holds together.

[bamajammer4eva]

I know it can't be but almost looks like the GFS has shown the same runs three nights in a row. Just adjusting how long it stalls before moving east. Since the GFS seems to be the BIG under dog. I can't help but hope it verifies.
I do have a question for whoever can anwer this: What is the GFS seeing or playing out more than the other models to make it still say Debby will head East?

Comparing the ECMWF and GFS it looks like the GFS is suffering from convective feedback located just east of Florida as the Euro does not show any rain in that area in that time frame. Is just a wild guess by my part tho.

[img]http://i61.photobucket.com/albums/h62/cantu5977/Tropical%20Models%202012/0zGFS48hrs_06-24-12.jpg

But there should be rain in that area according to the SPC who btw is at least mentioning the GFS info so I guess they aren't totally throwing it out.

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0219 AM CDT SAT JUN 23 2012

VALID 251200Z - 261200Z

...CAROLINAS/SRN VA...
AN UPPER-LEVEL TROUGH IS FORECAST TO DEEPEN AND REMAIN NEARLY
STATIONARY JUST OFF THE ATLANTIC SEABOARD ON MONDAY. AT THE SFC...A
WELL-DEFINED COLD FRONT IS FORECAST TO MOVE SWD ACROSS THE
CAROLINAS. THE MODELS DEVELOP THUNDERSTORMS ALONG THE BOUNDARY
MONDAY AFTERNOON WITH MODERATE INSTABILITY IN PLACE FROM THE
BOUNDARY SWD. ALTHOUGH THE MODELS DIFFER ON THE AMOUNT OF SHEAR
ACROSS THE SEE TEXT AREA...THE GFS FORECASTS A MINIMUM OF 20 TO 30
KT OF DEEP LAYER SHEAR. THIS COMBINED WITH STEEP LOW-LEVEL LAPSE
RATES SUGGESTS AT LEAST A MARGINAL THREAT FOR WIND DAMAGE WILL BE
POSSIBLE IN THE CAROLINAS AND SRN VA MONDAY AFTERNOON

[Dean4Storms]

Some Hot Towers now with the MLC and it continues north!

http://www.ssd.noaa.gov/PS/TROP/floater ... -long.html

[cycloneye]

A reminder to the members who may want to post model graphics,you can do that on the Debby Models thread.

viewtopic.php?f=59&t=112979&p=2234307#p2234307

[tolakram]

Somebody at the NHC or whoever updated the GFS is going to get fired. I don't know who will turn out to be right (Iv'e learned in the past not to challenge the NHC), but heads will roll. "If" the GFS turns out to be wrong, how embarrassing! People will really question it's future runs.

I think Stewart explained it well. GFS assumes a weaker storm. We know models have a hard time with intensity so this should come as no surprise that with this kind of setup the paths will diverge so much. What separates the professionals from the amateurs is how they view the models ... as tools, not sports teams. They look at all the data, come to understand why a model might be wrong, and discard all or part of the solution.

Once the GFS has the data to come around to a "correct" solution then it may or may not be more accurate than the Euro as far as intensity and landfall. It would never be ignored or discounted because of one bad call. If the GFS is having repeated issues with intensity then that fact would have to be weighed when using the model.

I do agree, though, that the update applied sometime last year appears to have made the GFS worse and I would have thought it would have been corrected by now ... but I don't have any data to back that up as a fact.

Personal Forecast Disclaimer:
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[windnrain]

Please, PLEASE send it our way here in Texas....

WE NEED IT.

[Dean4Storms]

You can clearly see the rotation of the MLC now on long range out of Eglin.......

http://radar.weather.gov/ridge/radar.ph ... 1&loop=yes

[tbstorm]

Get ready Pinellas County...for the first time with this system looks like a feeder band is going to come through starting in St. Petersburg in about 30 minutes...the bands have been falling apart south of Tampa Bay this entire afternoon, but looks like this one will stay in tact.

those twin tornadic signatures offshore are impressive. the one to the northwest looks to be on a trajectory that would keep it offshore but the one to the southeast could approach western manatee around anna maria island and then the southern pinellas county region if it holds together.

Yeah that's a healthy one. Based on what I was watching earlier they seem to last like 30 mins or so, then its quiet (mesocyclone speaking), then another bunch of 'em will spin up in like 1 hour after that.

[vaffie]

Upper level low seems to be weakening and moving ssw quite quickly. conditions should be improving tonight for stacking and intensification. Even with the unfavorable upper level conditions, it has been strengthening all day, it was like 1005 mb yesterday, today below 998 last I saw.