ATL: DORIAN - Post-Tropical - Discussion

[Blown Away]

ATLANTIC SHIPS INTENSITY FORECAST *
* GOES AVAILABLE, OHC AVAILABLE *
* DORIAN AL042013 07/26/13 12 UTC *

TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
SHEAR (KT) 17 14 15 15 16 17 20 16 16 20 17 15 18


Long range shear values way down from previous forecast, high 20's in to 30's.

[ninel conde]

Dorians in trouble ... looks like the circ is also weakening.. it had better develop some decent convection or it will die...

It's heading into a core of dry air at all levels, worst possible outcome for a developing TC. At least the next one down the line will have a clear view. Whats up with the sudden formation of high-level clouds above Dorian?

you think the dry air is gone for the next one?

[Aric Dunn]

Dorians in trouble ... looks like the circ is also weakening.. it had better develop some decent convection or it will die...

It's heading into a core of dry air at all levels, worst possible outcome for a developing TC. At least the next one down the line will have a clear view. Whats up with the sudden formation of high-level clouds above Dorian?

you think the dry air is gone for the next one?

Dry air comes and goes ... the sal never really stops the systems that make it are lucky to not have a large sal plume... this did not have nearly as bad as chantal but dorian moved right into it.. while chantal for the most part stayed way south.

[Riptide]

Dorians in trouble ... looks like the circ is also weakening.. it had better develop some decent convection or it will die...

It's heading into a core of dry air at all levels, worst possible outcome for a developing TC. At least the next one down the line will have a clear view. Whats up with the sudden formation of high-level clouds above Dorian?

you think the dry air is gone for the next one?

[Aric Dunn]

Taking a look at the TPW.. clearly the air has dried all around dorian however the really dry slot to its west has moistened up some but not enough.. it will have to survive till just north of the islands to find a better environment.. this of course as long as the shear is not too high.

[tolakram]

12Z Euro running. At 48 hours just a wave moving well north of the islands.

[Riptide]

The moisture feed from the ITCZ was really helping Dorian looking back in retrospect, he now must maintain himself as an independent entity.

[Steve H.]

Dorian in deep doodoo. needs to survive at least another 36 hours to have a chance. Seen stranger things happen but............ If it keeps a broad circulation it may still have a chance of regeneration near the Bahamas.

[tolakram]

At 72 hours a little stronger, might be a closed low, about 280 miles north of PR.

[Aric Dunn]

new image in.. the question of it being a open wave is settled .. you can clearly see the small tight LLC last frame completely pop out. though for it to survive it needs convection very soon.

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

[gatorcane]

The MLC (mid-level circulation) and the LLC (low-level circulation) are not vertically stacked. Clearly Dorian is in trouble.

Of course remember intensity guidance by the models is not always correct especially as you go out in time. Forecasting intensity is one of the most challenging parts to forecasting tropical cyclones.

We have seen systems in the past that look awful only to regenerate into strong tropical cyclones once finding better conditions down the road.

Question will be whether Dorian will be one of those systems or not?

Models are also in pretty good agreement Dorian heads west, possibly ending up in the Southeastern Bahamas.

For those reasons, the system will keep my interest until it has completely dissipated.

[ROCK]

the 12Z CMC seems to think the left overs of Dorian will make the Central GOM.....never really closes it off though...

http://moe.met.fsu.edu/cgi-bin/cmctc2.c ... =Animation

[AEWspotter]

Remember, we are near the diurnal minimum for convection, so the recent tower over/near the LLC (what's left of it) is encouraging. We might see this system kinda bounce back and forth in appearance over the next few days as it battles the dry air and shear. Would expect it to hold onto minimal TC values unless the shear gets above 25kts. Not liking the looks of the eroding TPW or the presence of dry air to the south of the Dorian...

[Aric Dunn]

The MLC (mid-level circulation) and the LLC (low-level circulation) are not vertically stacked. Clearly Dorian is in trouble.

Of course remember intensity guidance by the models is not always correct especially as you go out in time. Forecasting intensity is one of the most challenging parts to forecasting tropical cyclones.

We have seen systems in the past that look awful regenerate into strong tropical cyclones once finding better conditions down the road.

Question will be whether Dorian will be one of those systems or not?

For that reason, the system will keep my interest until it has completely dissipated.

exactly I can think of one such system that ran into a lot of dry air and shear.... nearly died then like magic .... that name was ANDREW of course not even remotely saying like that will happen.. but things can change .. its never over till every last bit of energy has dissipated.


"Satellite images suggest that Andrew produced deep convection only sporadically for several days, mainly in several bursts of about 12 hours duration. Also, the deep convection did not persist. Instead, it was stripped away from the low-level circulation by the strong southwesterly flow at upper levels. Air Force Reserve unit reconnaissance aircraft investigated Andrew and, on the 20th, found that the cyclone had degenerated to the extent that only a diffuse low-level circulation center remained"

we know what happened after...

[cycloneye]

18z Best Track down to 40kts.

AL, 04, 2013072618, , BEST, 0, 176N, 448W, 40, 1010, TS

[ROCK]

a more recent example... TD10 who opened up only to become TD12 and on to be Katrina....just saying...

[LaBreeze]

the 12Z CMC seems to think the left overs of Dorian will make the Central GOM.....never really closes it off though...

http://moe.met.fsu.edu/cgi-bin/cmctc2.c ... =Animation

Could the "left overs" of Dorian regenerate in the Central GOM? Would there be enough left over and would conditions allow for this?

[Blown Away]

The MLC (mid-level circulation) and the LLC (low-level circulation) are not vertically stacked. Clearly Dorian is in trouble.

Of course remember intensity guidance by the models is not always correct especially as you go out in time. Forecasting intensity is one of the most challenging parts to forecasting tropical cyclones.

We have seen systems in the past that look awful regenerate into strong tropical cyclones once finding better conditions down the road.

Question will be whether Dorian will be one of those systems or not?

Models are also in pretty good agreement Dorian heads west, possibly ending up in the Southeastern Bahamas.

For those reasons, the system will keep my interest until it has completely dissipated.

Mostly agree, but there is almost no model support for Dorian to maintain even as a minimal TS and this intensity reduction occurs w/o the help of the land masses it's targetting. The models over an over must see shear and/or dry air that keeps Dorian very weak at best. We shall see, I love when a storm is against the wall and survives!!

The deep convection looks to be gone in next few frames on IR...
http://www.ssd.noaa.gov/goes/east/tatl/flash-avn.html

[Blown Away]

542
WHXX01 KWBC 261841
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS NATIONAL HURRICANE CENTER MIAMI FL
1841 UTC FRI JUL 26 2013

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE DORIAN (AL042013) 20130726 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
130726 1800 130727 0600 130727 1800 130728 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 17.6N 44.8W 18.5N 49.1W 19.3N 53.1W 19.9N 56.9W
BAMD 17.6N 44.8W 18.1N 47.5W 18.6N 50.1W 18.9N 52.4W
BAMM 17.6N 44.8W 18.2N 48.0W 18.9N 51.1W 19.4N 54.0W
LBAR 17.6N 44.8W 18.0N 48.3W 18.6N 52.1W 19.1N 55.7W
SHIP 40KTS 37KTS 38KTS 39KTS
DSHP 40KTS 37KTS 38KTS 39KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
130728 1800 130729 1800 130730 1800 130731 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 20.7N 60.5W 22.0N 67.1W 22.6N 73.7W 22.5N 79.7W
BAMD 19.0N 54.4W 18.4N 58.2W 17.0N 61.6W 16.2N 64.9W
BAMM 19.9N 56.7W 20.6N 61.6W 21.2N 66.4W 21.9N 70.7W
LBAR 19.6N 59.0W 20.7N 64.6W 22.0N 71.2W .0N .0W
SHIP 43KTS 52KTS 58KTS 62KTS
DSHP 43KTS 52KTS 58KTS 62KTS

...INITIAL CONDITIONS...
LATCUR = 17.6N LONCUR = 44.8W DIRCUR = 280DEG SPDCUR = 19KT
LATM12 = 16.9N LONM12 = 40.7W DIRM12 = 285DEG SPDM12 = 21KT
LATM24 = 16.0N LONM24 = 37.1W
WNDCUR = 40KT RMAXWD = 20NM WNDM12 = 45KT
CENPRS = 1010MB OUTPRS = 1016MB OUTRAD = 120NM SDEPTH = M
RD34NE = 60NM RD34SE = 30NM RD34SW = 0NM RD34NW = 60NM

SHIP/DSHP ALMOST HURRICANE STRENGTH IN 120 HOURS...

[Weatherboy1]

Well, this clearly seems to be a case of dry air intrusion more than "buzzsaw" style shear. Can Dorian fly apart like other systems have done? Sure, I suppose so. But while Dorian is moving along quickly, he's going a couple miles per hour slower than Chantal if memory serves -- 20-22 mph vs. 23-25. So I wouldn't write this off yet. Will have to see if convection blows up again overnight. If so, he still has a fighting chance in my view!