Post Tropical Cyclone Debby

[Amped]

GFS still east, but stronger. If that verifies good job ARW srefs.

[Minnesota Meso]

The GFS is often regarded as the flagship of US model's, This will be either a epic win or epic fail, not much in between at this time

[Minnesota Meso]

Hmmm.....RAP model, interesting indeed

[icebreaker5221]

All things considered, Debby is looking quite healthy. The potential was certainly there for diurnal thunderstorms to erupt over the FL peninsula this afternoon generating subsidence over the eastern Gulf, decreasing the favorability of Debby's environment. Instead, more stratiform-type precipitation, semi-associated with Debby developed, and maximum ascent remained over water. Considering we're only slightly past the typical diurnal minimum over the water, Debby looks quite healthy. Tonight's maximum should be telling, but certainly there is the potential for intensification.

[phil882]

Hmmm.....RAP model, interesting indeed

If you are gonna post short-range models... try the HRRR.

http://rapidrefresh....omain=t6&wjet=1

[Alfoman]

CMC at hour 42....FL hit.

btw, for some reason my gut is telling me to stay with the GFS on this one for now.

[phil882]

All things considered, Debby is looking quite healthy. The potential was certainly there for diurnal thunderstorms to erupt over the FL peninsula this afternoon generating subsidence over the eastern Gulf, decreasing the favorability of Debby's environment. Instead, more stratiform-type precipitation, semi-associated with Debby developed, and maximum ascent remained over water. Considering we're only slightly past the typical diurnal minimum over the water, Debby looks quite healthy. Tonight's maximum should be telling, but certainly there is the potential for intensification.

I agree, it looks quite healthy despite the vertical wind shear it has been facing the past 24 hours. I'm still curious with all of the latent heat release ongoing to the east of the mean center if there won't be a llc relocation in the next 12-18 hours. Its really hard to gauge by looking at long range radar reflectivity since we are looking more at the mid-levels of the system as the radar beam is tilted upward on the edge of the radar's range. Still, there does seem to be a developing mid-level circulation embedded in the convection. Its also worth mentioning the llc already appears to be north of the NHC's track in the short term.

[turtlehurricane]

I'd be surprised if the center didn't relocate under the convection tonight, completely throwing off the current NHC forecast. This thing is going to end up on a track that'll rake the entire northern Gulf coast with a northeastwards relocation.

[Amped]

I agree, it looks quite healthy despite the vertical wind shear it has been facing the past 24 hours. I'm still curious with all of the latent heat release ongoing to the east of the mean center if there won't be a llc relocation in the next 12-18 hours. Its really hard to gauge by looking at long range radar reflectivity since we are looking more at the mid-levels of the system as the radar beam is tilted upward on the edge of the radar's range. Still, there does seem to be a developing mid-level circulation embedded in the convection. Its also worth mentioning the llc already appears to be north of the NHC's track in the short term.

At that rate it'll make landfall by 06z Monday.

[Superstorm93]

CMC folds

[Minnesota Meso]

If you are gonna post short-range models... try the HRRR.

http://rapidrefresh....omain=t6&wjet=1

Phill I thought about the HRR, but the RAP initializes the HRR...just a thought, thank you for your comment

[Superstorm93]

Becoming an extremely frustrating system.

Especially if this just meanders into FL like the GFS and CMC have it doing.

UKMET is way east as well:

[phil882]

Phill I thought about the HRR, but the RAP initializes the HRR...just a thought, thank you for your comment

Correct, the RAP does initialize the HRRR. This remains the biggest drawback for the HRRR since the model is run at 3km resolution and the data assimilation (DA) is simply not high enough resolution to provide accurate enough initial conditions. They are working on a 3km DA technique for the future implementation of the HRRR. However, where the HRRR shines is in its lack of a cumulus parameterization which makes it particularly attractive to use in the tropics. This is also the same direction the ECMWF is heading in the next decade.

[Minnesota Meso]

Correct, the RAP does initialize the HRRR. This remains the biggest drawback for the HRRR since the model is run at 3km resolution and the data assimilation (DA) is simply not high enough resolution to provide accurate enough initial conditions. They are working on a 3km DA technique for the future implementation of the HRRR. However, where the HRRR shines is in its lack of a cumulus parameterization which makes it particularly attractive to use in the tropics. This is also the same direction the ECMWF is heading in the next decade.

Thanks Phil, Nice explanation, does that mean in some regards we are ahead of the European Community in short range models? but still lacking in the 2-10 day outlooks???

[Scott747]

0z HWRF through hr 72 -

[phil882]

Thanks Phil, Nice explanation, does that mean in some regards we are ahead of the European Community in short range models? but still lacking in the 2-10 day outlooks???

Well the main problem is that the Europeans have all their resources in medium range forecasting with the ECMWF. NOAA and NCEP have a much larger suite of products of both short and long range models that need to be constantly run. Combine this with the fact that we have a slower supercomputer and you can see why we lag behind in the medium range forecasting division.

You could say we are ahead of the Euros in the short range forecasting area, but thats mainly because nearly all their resources are geared towards medium range forecasting.

To bring this back on topic, I think its a very ominous sign that both the UKMET and GGEM are further east tonight. We will see if the ECMWF holds serve. I continue to remain steadfast that a large system such as this is more susceptible to even marginal weaknesses. All it needs to do is move a touch too far north and it will be difficult for the mid-level ridge to capture the circulation beyond that point. The ECMWF had difficulty in the medium range with Lee last year, and this could be a repeat performance if the system continues to drift northward without any substancial westward component.

[Minnesota Meso]

CMC is now showing what the GFS has been insisting on for the last two days.Waiting on the ECMWF and EkMET...my guess the Hurricane Hunters info has helped to bring this system into a stronger focus, along with the 0z/24 upper air analysis, all of a sudden this looks like a GFS win IMO. I'm a little red faced now, was leaning strongly towards a non GFS solution.

[wxmeddler]

I'm just glad I'm not in the hot seat tonight. IE. "Miami we might have a problem here" or the MIC at TLH who's previous forecast shift put out 15-20 mph winds and 1-2" of rain for the Apalachicola bay area today.

[thewxmann]

Yeah, I get the feeling the GFS camp has merit. Still pretty 50-50 about it, but as Phil has stated, center relocations will be crucial, and the trend has been weaker with the central U.S. ridge.

P.S. Also, the ULL to Debby's west may have an additional short-term effect of steering Debby slightly more northward, or delay the ridge building back, both of which would favor a GFS scenario.

[Cheeznado]

Euro rolling, to 60- has shifted east but not as far as the GFS. Similar to the new Ukie- stalled just SE of the mouth of the Mississippi

[Hoosier]

Euro rolling, to 60- has shifted east but not as far as the GFS. Similar to the new Ukie- stalled just SE of the mouth of the Mississippi

Looks like it should go in around southeast LA on this run.

[Cheeznado]

This would NOT be good for new Orleans, even if it is pretty weak the very slow movement would really pile up the water along with the rainfall

[Alfoman]

ITS OFFICIAL: THE ECMWF TURNS BACK ON ITS WESTWARD TRACK AND MOVES DEBBY NW TO LA.

[turtlehurricane]

This would NOT be good for new Orleans, even if it is pretty weak the very slow movement would really pile up the water along with the rainfall

Tides were 1 ft above normal in eastern Louisiana during the day yesterday due to gusts in the 20s mph from the east. Just a preview.

[wxmeddler]

Well... Good thing they hoisted those tropical storm warnings...

[Minnesota Meso]

Thinking about this, I'm not sure this could be a straight GFS win. Will this system be picked up by the NE trough and lift it out ? And where will the south eastern edge of the ridge set up. So in other words will Betty sit and just stew in the NE gulf area? waiting for the steering winds to effect it? This looks very interesting to me. Hopefully there is a weakness that it finds and moves on instead of sitting in Gulf and strengthening

[tmagan]

06Z Observations

[Scott747]

WITH INFRARED IMAGERY THE CENTER...ALTHOUGH PARTIALLY EXPOSED...HAS

BECOME A LITTLE MORE DIFFICULT TO LOCATE AND THE FIXES FROM TAFB

AND SAB ARE ABOUT 50 MILES APART. MY BEST ESTIMATE OF INITIAL

MOTION IS SLOWLY NORTHWARD...OR 360/3. THE TRACK FORECAST FOR THIS

STORM IS EXTREMELY CHALLENGING. THE SYNOPTIC REASONING IN PREVIOUS

ADVISORIES WAS BASED ON A MID-LEVEL RIDGE BUILDING TO THE NORTH OF

THE TROPICAL CYCLONE...WHICH WOULD CAUSE DEBBY TO MOVE TOWARD THE

NORTHWEST GULF OF MEXICO COAST IN SEVERAL DAYS. THAT TRACK

SCENARIO WAS SUPPORTED BY THE ECMWF MODEL...WHICH HAS BEEN THE

BEST-PERFORMING GUIDANCE OVER THE PAST FEW YEARS. HOWEVER...THE

0000 RUN OF THAT MODEL HAS SHIFTED SUBSTANTIALLY TO THE NORTH AND

EAST OF THE PREVIOUS RUNS. THE U.K. MET. OFFICE MODEL HAS ALSO

SHIFTED SIGNIFICANTLY TO THE RIGHT. IN FACT...ONLY THE HWRF MODEL

IS CLOSE TO THE PREVIOUS OFFICIAL FORECASTS...AND EVEN IT IS TO THE

NORTH OF THEM. THEREFORE AN UNUSUALLY LARGE RIGHTWARD ADJUSTMENT

TO THE NHC FORECAST IS REQUIRED...AND ADDITIONAL SHIFTS TO THE

NORTH AND EAST MAY BE NECESSARY IN SUBSEQUENT ADVISORY PACKAGES.

[HurricaneJosh]

This might be one of those situations where the NHC has to make some awkwardly abrupt changes to the forecast track. The key question is whether the right shift is for real or just some windshield wiping. It is interesting how rigidly consistent the GFS has been with the FL solution-- and how the Euro has now "blinked".

[bic]

She looks to be getting better organized as convection begins to wrap around to the N/NNW: