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Tropical Depression Ernesto - 35 mph - 1004 mb - W 14 mph


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It is new work so I dont believe a publication has been submitted just yet. I know there is one brewing though. And no, he hasn't made it public on the t-storms list. I guess that might be a reason why no one is talking about it! My apologizes.

Here's the link of his talk at the past AMS trop conf:

https://ams.confex.c...aper205840.html

:lol:

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It looks like some of the models are seeing the weakness in the Gulf in the form of a couple of upper level troughs and doing the NW bend by d5.

Yup... I thought about this yesterday when I saw the weakness approaching the Gulf Coast in the models, but it is still too early to tell just how strong said weakness might be with respect to picking up 05L.

One thing I am intrigued at is how the models have strengthened the ridge/pushed the track of 05L south in the more near term within the eastern and central Caribbean while allowing 05L to respond better to the trough in the NW Caribbean. It's not surprising, of course, but it is interesting to watch the models' evolution of features.

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The trough with current base near the coast of FL could be the key in the path days 4+, as models spin off an ULL and retrogrades it west. If it materializes and is deep enough to affect the mid levels, then yes, future Ernesto could curve to the NW.

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Yup... I thought about this yesterday when I saw the weakness approaching the Gulf Coast in the models, but it is still too early to tell just how strong said weakness might be with respect to picking up 05L.

One thing I am intrigued at is how the models have strengthened the ridge/pushed the track of 05L south in the more near term within the eastern and central Caribbean while allowing 05L to respond better to the trough in the NW Caribbean. It's not surprising, of course, but it is interesting to watch the models' evolution of features.

If I remember correctly, the GFS was the first to catch the more southerly track. It has preformed quite a bit better than the ECMWF with the short term forecast (1-3 days)

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"AFTER LOOKING VERY DISORGANIZED OVERNIGHT...SATELLITE IMAGERY THIS

MORNING SHOWS A MARGINALLY BETTER STRUCTURE WITH EVIDENCE OF

INCREASED CONVECTIVE BANDING."

Tropical cyclones do have a diurnal cycle signature in convection. Jasaon Dunion's most recent work shows that you will often see convection weaken beginning right at sunset and remain in a "suppressed" state through night. Sometimes you get this radially propagating ring of cold cloud tops away from the center of the storm, which has preferable distances from the storm depending on the UTC time. As the sun comes back up- the convection reorganizes near the center of the storm. I'm surprised no one talks about this...

How recent is that research? Do you have a link? It's not been publicized on the TS mailing list and I missed the 2012 conference at Sawgrass.

Sorry if this is a dumb statement, but to me...I always thought the diurnal flare up occurred very late night, but before sunrise. Is this something recently looked at? In developing systems that remain disorganized, I always thought the flare up of convection seemed to occur..say after 06z in the Atlantic basin for instance. Sunrise seems a bit late, but I'll defer to you.

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In the short term it's going to transition from it's current relatively small anticyclone to a bigger one in the Caribbean, this bigger anticyclone will keep the TUTT and associated dry air a bit farther away... convection should increase, but it will still be sheared to the E due to the rather strong low level flow, but shouldn't be destructive...

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Sorry if this is a dumb statement, but to me...I always thought the diurnal flare up occurred very late night, but before sunrise. Is this something recently looked at? In developing systems that remain disorganized, I always thought the flare up of convection seemed to occur..say after 06z in the Atlantic basin for instance. Sunrise seems a bit late, but I'll defer to you.

I think the coldest cloud tops occur between 0400 and 1600 LST. That certainly agrees with what I remember from looking at satellite imagery over the years.

http://www.ssec.wisc.edu/~kossin/articles/Kossin_2002_MWR.pdf

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The arc clouds + the center outrunning the convection makes me think this isn't TD 5's day.

"AFTER LOOKING VERY DISORGANIZED OVERNIGHT...SATELLITE IMAGERY THIS

MORNING SHOWS A MARGINALLY BETTER STRUCTURE WITH EVIDENCE OF

INCREASED CONVECTIVE BANDING."

Tropical cyclones do have a diurnal cycle signature in convection. Jasaon Dunion's most recent work shows that you will often see convection weaken beginning right at sunset and remain in a "suppressed" state through night. Sometimes you get this radially propagating ring of cold cloud tops away from the center of the storm, which has preferable distances from the storm depending on the UTC time. As the sun comes back up- the convection reorganizes near the center of the storm. I'm surprised no one talks about this...

I've read and seen quite a bit about this theory and you got it backwards I think. Convection begins to strengthen right after sunset, and this coincides with the development a ring of cold cloud tops that propagates outwards from the hurricane inner core. It can be tracked through the night and into the next day's afternoon. The best theory for it now (though I am not entirely convinced) is that the development of a cloud top inversion after sunset due to radiative imbalance leads to a favorable environment for an outwards propagating gravity wave, which wouldn't be possible during the day when there is no stable layer at cloud top. This gravity wave may significantly enhance divergence as it moves outwards, so the most rapid intensification would be when it's coupled with the inner core for that brief time and evacuating mass more rapidly. Fortunately they're doing a mission on this so we'll learn more. http://www.aoml.noaa..._TC_Dirunal.pdf

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If I remember correctly, the GFS was the first to catch the more southerly track. It has preformed quite a bit better than the ECMWF with the short term forecast (1-3 days)

Absolutely, although I'm curious about how the Euro saw a stronger weakness in the longer range than the GFS yesterday. It will be interesting to review the 12Z models today.

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I may be just a humble amateur, but I wasn't mistaking outflow for narrow little low cloud bands racing away from 05L.

The overall organization is looking better, that is all that I take from it; and probably more in the future when another Hurricane Carla comes crashing into your backyard. All kidding aside; it may struggle but will be dangerous down the road.

600px-Carla_1961_track.png

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It is new work so I dont believe a publication has been submitted just yet. I know there is one brewing though. And no, he hasn't made it public on the t-storms list. I guess that might be a reason why no one is talking about it! My apologizes.

Here's the link of his talk at the past AMS trop conf:

https://ams.confex.c...aper205840.html

This is absolutly amazing work. I've noticed this before from time to time in different storms but to see all this information all together is just mind-blowing.

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Since it's virtually dead in here, here's the 18z SHIPS output.

Steady decrease in shear over the next 24 hours, then virtually no shear (at least in the 850-200mb range)

*   ATLANTIC SHIPS INTENSITY FORECAST	   *
			    * GOES AVAILABLE,	   OHC AVAILABLE	   *
			    *	    FIVE  AL052012  08/02/12  18 UTC   *
TIME (HR)		  0	 6    12    18    24    36    48    60    72    84    96   108   120
V (KT) NO LAND    30    31    33    35    39    45    51    56    58    62    70    74    80
V (KT) LAND	   30    31    33    35    39    45    51    56    58    62    70    74    80
V (KT) LGE mod    30    30    31    32    33    36    41    47    53    59    68    79    89
Storm Type	  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP  TROP
SHEAR (KT)	    15    16    11	 5	 2	 5	 3    10	 4	 4	 0	 4	 3
SHEAR ADJ (KT)	 0	 1    -1	 0    -1	 0	 6    -2	 0	 0	 2    -3    -1
SHEAR DIR	    264   255   263   263   229   226   235   256   273   294   246   277   104
SST (C)		 28.1  28.1  28.1  28.0  27.9  28.2  28.4  28.0  28.3  28.4  28.4  28.6  28.8
POT. INT. (KT)   141   141   141   139   138   142   144   138   142   143   143   145   148
ADJ. POT. INT.   147   145   144   142   140   144   146   137   140   139   137   138   139
200 MB T (C)   -53.4 -53.4 -53.7 -53.8 -53.2 -53.3 -52.7 -52.7 -52.7 -52.6 -52.5 -52.5 -52.2
TH_E DEV (C)	   8	 9	 9	 9    10	 9    11	 9    10	 8	 9	 9	 9
700-500 MB RH	 61    59    59    60    61    60    60    62    63    67    63    68    69
GFS VTEX (KT)	 10    11    11    12    13    13    13    12    10	 9    12    11    12
850 MB ENV VOR    18    31    40    42    48    53    62    86    92    89    70    67    65
200 MB DIV	    42    70    60    37    44    61    46    39    28    45    47    45    48
700-850 TADV	  -8    -7    -6    -7    -1    -3    -1    -4    -5    -5    -5    -2    -3
LAND (KM)	    628   469   346   295   322   381   312   274   295   178   176   341   301
LAT (DEG N)	 12.8  13.1  13.3  13.5  13.6  14.0  14.7  15.2  15.5  16.1  17.1  17.8  18.4
LONG(DEG W)	 55.6  57.4  59.1  60.8  62.5  65.6  68.9  72.0  74.8  77.3  79.5  81.5  83.4
STM SPEED (KT)    18    17    17    17    16    16    16    14    13    12    11    10	 9
HEAT CONTENT	  27    46    54    52    40    33    68    46    59   112   125    85    96

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LOL Euro. I'm feeling shades of Debby with this Euro/GFS battle going on. Now the Euro has gone way to the left of the GFS, slamming a weak 05L into southern Belize after skimming the coast of Honduras.

Ridging over the central CONUS is actually weaker, but more zonal, with no weaknesses...that and the weak nature of the cyclone makes it go west undisturbed. IMO TD 5 (or Ernesto or whatever) will be stronger...but the ULL being strong enough to be able to create a weakness, that's what will be the big question and headache the next few days.

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Not sure the shear will subside that much after hr 12....IMO it will be close to 10-15 kts for at least 2-3 days.

Yeah, recon is showing that this has multiple low-level centers now. While the traditional shear will lower in 24 hours, this will only be able to organize at a gradual pace until it reaches the region near Jamaica.

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Ridging over the central CONUS is actually weaker, but more zonal, with no weaknesses...that and the weak nature of the cyclone makes it go west undisturbed. IMO TD 5 (or Ernesto or whatever) will be stronger...but the ULL being strong enough to be able to create a weakness, that's what will be the big question and headache the next few days.

The LOL is more how the Euro and GFS just refuse to get on the same page with each other... yesterday the situation was almost entirely reversed.

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