ATL: DEBBY - Models

[LarryWx]

Does the stubborn 12Z GFS have support from its ensembles offshore the SE? Yes as 75% of members go back NW into the SE coast CHS south. This is similar to prior GEFS.

[LarryWx]

12Z Euro: LF 50 miles SW of 0Z Euro or 15 miles SW of Myrtle Beach then moving NNW. This is also 100 miles N of the 12Z UKMET hour 96.
Then to Florence followed by Fayetteville as it weakens.
Extremely heavy rain CHS to MYR.

[aspen]

There’s one member on the 12z GEFS that takes Debby back out into the Gulf, blows it up into a 937mb Cat 4, and then sends it into southern Texas at peak intensity. Basically due west across the Gulf.

[LarryWx]

12Z Euro ens: only ~25% curve back NW CHS south (similar to 0Z) vs ~75% doing that on the 12Z GEFS.
Compared to recent Euro ens going NW CHS S: ~33% did on 0Z and ~75% did on yesterday’s 12Z

[OuterBanker]

GFS last holdout on west into Ga and dying. All others are now east coast riders.

CMC did go from dying in Ga to east cost rider from 00z to 12z.

Icon has a cat 3 on the OBX. By far the most aggressive due to more time over the ocean.

TPC track does not include GFS path'.

GFS and Hwrf smoking crack in the basement again.

[Steve]

You knew it had to happen. 18Z NAM 3km broke 950 and hits 947 before landfall. Seeing how absurdly low it can drop pressure has become a side treat for me tracking landfalling storms. The takeaway that although of course it’s wrong, it maintains intensification to landfall. In reality world, NAM 12km gets it to 987 with only minimal intensification into landfall.

Rainfall 12km through almost 3 days:
https://www.tropicaltidbits.com/analysi ... 0418&fh=75

[aspen]

18z GFS pushes back landfall by a good several hours. Looks to be closer to 16z or 17z Monday afternoon, instead of 12z Monday morning. If this actually happens, those additional 4-5 hours could make a world of a difference for Debby’s landfall intensity, depending on how its structure evolves tonight.

[Steve]

18z GFS pushes back landfall by a good several hours. Looks to be closer to 16z or 17z Monday afternoon, instead of 12z Monday morning. If this actually happens, those additional 4-5 hours could make a world of a difference for Debby’s landfall intensity, depending on how its structure evolves tonight.

Debby’s getting high enough in latitude we can watch the rapid models and test verification like HRRR to see what’s good with the models. Only 4x a day for long runs but you get 18 hours every hour. 18z had it progressing through southern GA at least to that point. Lots of solutions lots of possibilities which is whack for day out landfalls except this part of the country where the there can be part 2s and 3s.

[Category5Kaiju]

Wow, if that ICON run were to verify even remotely, then North Carolina is going to get quite a lashing.

[tolakram]

18Z ICON run

[tiger_deF]

GFS is playing ping-pong with Debby at 30N.

Debby bounces from the SE US coast to eastern LA to the coast again over the course of 8 days. I can't even imagine how catastrophic the flooding would be, especially if Debby is able to maintain it's structure. At hour 200 high pressure dives south and shows Debby some mercy.

[tolakram]

18Z GFS


Total Rainfall

[Steve]

Wow, if that ICON run were to verify even remotely, then North Carolina is going to get quite a lashing.

Cat 3 landfall there and lots of impacts in FL, GA, SC, NC, VA and pretty much all along the coast. 18z only shows 5 days but you can assume if it comes off the coast near Maryland a bunch of weather is going up into PA NJ Long Island CT and Rhode Island with a possible nother landfall or scrape on the MA cape.

Big test for the ICON. It’s hit on a few storms over the years and most recently did incredible with Beryl locking in early. Looking forward to the full duration 7.5 day run around 10 tonight to see if stays with the rake the hell out of the whole east coast as a hurricane+. If it hits, props to the model, but Debby is gonna cause some historic damage along the coastal Atlantic particularly in the scope of the vast areas that would be affected which is the down side of it verifying. Better for the country if it took that general track 100 miles off the east coast.

[Hypercane_Kyle]

18z HWRF has the system at 975mb at landfall.

[AnnularCane]

GFS is playing ping-pong with Debby at 30N.

Debby bounces from the SE US coast to eastern LA to the coast again over the course of 8 days. I can't even imagine how catastrophic the flooding would be, especially if Debby is able to maintain it's structure. At hour 200 high pressure dives south and shows Debby some mercy.

I don't think Debby would appreciate that kind of treatment.

[Steve]

18z HWRF has the system at 975mb at landfall.

Is that run even believable? Goes in comes back and hits south Mississippi. I don’t know. GFS has been on that sort of trajectory but it seems outlier scenario to me. Not hating on the 975 but I’d bet more 982ish. But the track is wack.

[Hypercane_Kyle]

18z HWRF has the system at 975mb at landfall.

Is that run even believable? Goes in comes back and hits south Mississippi. I don’t know. GFS has been on that sort of trajectory but it seems outlier scenario to me. Not hating on the 975 but I’d bet more 982ish. But the track is wack.

Seems pretty reasonable to me, we've got a solid 12+ hours before landfall and recon already has this thing at ~988 mb.

[Steve]

18z HWRF has the system at 975mb at landfall.

Is that run even believable? Goes in comes back and hits south Mississippi. I don’t know. GFS has been on that sort of trajectory but it seems outlier scenario to me. Not hating on the 975 but I’d bet more 982ish. But the track is wack.

Seems pretty reasonable to me, we've got a solid 12+ hours before landfall and recon already has this thing at ~988 mb.

Right. The pressure does but not the track. Probably HWRF uses some of the same data as GFS but idk for sure.

[ScottNAtlanta]

Wow, if that ICON run were to verify even remotely, then North Carolina is going to get quite a lashing.

Cat 3 landfall there and lots of impacts in FL, GA, SC, NC, VA and pretty much all along the coast. 18z only shows 5 days but you can assume if it comes off the coast near Maryland a bunch of weather is going up into PA NJ Long Island CT and Rhode Island with a possible nother landfall or scrape on the MA cape.

Big test for the ICON. It’s hit on a few storms over the years and most recently did incredible with Beryl locking in early. Looking forward to the full duration 7.5 day run around 10 tonight to see if stays with the rake the hell out of the whole east coast as a hurricane+. If it hits, props to the model, but Debby is gonna cause some historic damage along the coastal Atlantic particularly in the scope of the vast areas that would be affected which is the down side of it verifying. Better for the country if it took that general track 100 miles off the east coast.

I'm starting to get Agnes '72 vibes with this

[Steve]

HRRR out to 36 hours and at GA Coast. More like ICON but it only goes out to 48h at 00. Looks realistic but it only goes out 12 more hours so it’s not really a clue beyond Tuesday evening. Got to wait for the globals. Also NAMS probably running so I’ll check them in 20 minutes or so.

HRRR in progress.
https://www.tropicaltidbits.com/analysi ... 0500&fh=36