Atlantic Tropical Action 2013 - Part 2

[Superstorm93]

OSCAT 

 

[phil882]

This is a serious question as I have been busy with a lot of non-weather things over the last week that have distracted my attention.  How have the global models done handling the genesis in the EPac associated with the MJO enhancement in that basin, e.g. Ivo, Juliette, Kiko?

 

By my subjective point of view... they have done decent. Most of the models picked up on Ivo pretty early on and had the correct evolution. Juliette and Kiko developed out of the same feature (monsoon gyre/trough). If anything they were too aggressive with genesis of this feature into a robust and strong TC. Instead it remained pretty broad and spawned multiple TCs but on the weak side as they propagated on the southern and eastern periphery of the mean circulation.  

[am19psu]

This is a serious question as I have been busy with a lot of non-weather things over the last week that have distracted my attention.  How have the global models done handling the genesis in the EPac associated with the MJO enhancement in that basin, e.g. Ivo, Juliette, Kiko?

both models handled those genesis events well

[Derecho!]

Despite the uptick in support of genesis from the GFDL and HWRF, I'd much rather see a global model not named in the CMC come on board as well. 

 

If this becomes a TC (and I suspect it will) I hope people don't see it as some sort of validation of the CMC as useful. If one believed the CMC this should already be a strong hurricane a good distance northeast of the Carribiean.

 

Any primitive model filled with boguscanes is going to be the the "first" to show a TC now (as someone earlier mentioned about Sanddy)  and then by dumb luck.   If the main criteria was not to miss tropical cyclogenesis then we should abandon the GFS and run the AVN/MRF from the late 90s, because it didn't miss anything (as long as you could stand every single wave becoming a TC.)

 

Also, the rare occasions where CMC happens to have the best track forcecast (and this will be sporadically, for a couple of runs) are again simply the result of having a poor-quality model running every 12 hours spitting out tracks - by dumb luck one of those runs will happen to be more accurate at a few forecast periods than useful models.

[Sunny and Warm]

[Sunny and Warm]

Early guidance center fix:

 

At 1800 UTC, 01 September 2013, LOW INVEST (AL97) was located in the North Atlantic basin at 14.6°N and 59.7°W. The current intensity was 30 kt and the center was moving at 7 kt at a bearing of 270 degrees. The minimum central pressure was 1008 mb

[wxsmwhrms]

Thanks guys for the info on the EPac...

[Ed Lizard]

As long as it appears tied to a trough, with Westerly winds South of that trough about 10 degrees of latitude wide, I think development will be slowed.

 

I see what may be arcus clouds well North of it, but the NHC mention of dry air, I think it'll moisten up the atmosphere as long as showers and storms keep firing, and it is pushing cirrus ahead of itself on the South side, but I still think this could be Pacific-ish, where until it becomes distinct from a monsoon trough like feature, it'll have a hard time organizing.

 

Slow development isn't all bad, unless it never develops at all, GFS shows Eastern trough axis as rather progressive, the farther West 97L comes before being a deeper system, the better the chance it misses that trough and becomes chaseable.  If it develops.  HWRF may not be right for several reasons, but it is obvious a path along the Cuban coast is why it doesn't have 97L as a significant storm.  Has to develop, but avoid a trough moving through the East Coast, and avoid significant land interaction, quite the gauntlet, but if it does that, over 7 years, 10 months since a Florida hurricane.

[Indystorm]

At least 97L is developing far enough west that SAL issues seem rather minimal.  Looking impressive on WV loop with respect to moisture.  I am cautiously optimistic with this one.

[icebreaker5221]

Convection looks to really be drifting southeastward recently towards where CIMSS has the greatest LL convergence.  This suggests that the system has not yet developed any substantial inflow at the low levels, so convection is just following environmentally-favored regions within the environment.  We're really going to want to see convection fire up again much closer to the LL vorticity maximum if we want to see 97L have a shot at developing.

[wxmeddler]

There is a near direct overhead TRMM pass at 22:17UTC. Should allow us to take a peek at the near surface environment and see if anything is cooking under the hood.

[Amped]

GFS has no surface pressure drop but  shows a strong mid level vortex. Also note 2 competing vortices only a few hundred miles apart. This maybe what's preventing TC formation on some of the model runs. GGEM and NOGAPS have 2 storms.

 

[Ed Lizard]

Based on no analyzed low level convergence where CIMSS analyzes the best low level vorticity, I think 97L is in no hurry whatsoever to organize.

[HurricaneJosh]

The 8 pm TWO has two slight buzzkills:  1) convection has decreased and 2) they're expecting it to take the Shredderola track.

 

Ugh.

[TropicalAnalystwx13]

The 8 pm TWO has two slight buzzkills:  1) convection has decreased and 2) they're expecting it to take the Shredderola track.

 

Ugh.

Not sure why the discrepancy. NHC TAFB has it southeast of Jamaica in 72 hours, which would make sense if this hasn't developed by then like it shouldn't.

[HurricaneJosh]

Not sure why the discrepancy. NHC TAFB has it southeast of Jamaica in 72 hours, which would make sense if this hasn't developed by then like it shouldn't.

 

Yeah, we should basically be hoping for no development right now, I guess-- so it can scoot W.

[TropicalAnalystwx13]

   

 

TIME (HR) 0 6 12 18 24 36 48 60 72 84 96 108 120
V (KT) NO LAND 30 33 37 41 46 57 67 78 86 89 96 99 101
V (KT) LAND 30 33 37 41 46 57 67 78 86 89 96 99 101
V (KT) LGE mod 30 31 33 36 40 49 63 78 94 106 114 115 113
Storm Type TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP TROP

 

[Derecho!]

More weenie pr0n:

 

[wxmeddler]

^^ Intresting every dynamic model hits the gas after 36 hrs. This one just may need time to cook.

[wxmeddler]

There is a near direct overhead TRMM pass at 22:17UTC. Should allow us to take a peek at the near surface environment and see if anything is cooking under the hood.

Meh...Not much going on down there.

[TropicalAnalystwx13]

System will probably change little in organization over the next 2 days it passes through the central/eastern Caribbean. Might have something to watch as it nears Jamaica.

[thewxmann]

Because the LGEM/SHIPS are statistical models, they don't see the physical processes that will hinder organization (like misalignment of mid/low-level vorticity, etc.). They use some regression on some physical parameters but it's an incomplete picture of what's going on.

 

Trust the globals.

[Ed Lizard]

Still looks like an enhanced area of vorticity on the end of a low level trough on CMSS 850 and 700 mb analysis.  Also entering an area of accelerating low level flow, which is divergent and not favorable for development.  Maybe in about 3 days when the flow starts slowing/becomes somewhat convergent.  Probably not before then.

[Eyewall2005]

Blah...

[AutoPenalti]

More weenie pr0n:

Kinda supports the idea that by 24 hrs most models sort of puts it as a TS or a weak Cat 1 before shredding into bits.

[icebreaker5221]

Because the LGEM/SHIPS are statistical models, they don't see the physical processes that will hinder organization (like misalignment of mid/low-level vorticity, etc.). They use some regression on some physical parameters but it's an incomplete picture of what's going on.

 

Trust the globals.

 

The statistical models still out-perform the dynamical models once you have a storm.  Right now, they're still running SHIPS and LGEM for a 30 kt invest where the statistics have been run for all 30 kt TDs, so they aren't much use right now. 

 

I wouldn't really trust the statistical or the dynamical models.  They're just tools that can either be used correctly or used incorrectly.  But in this situation, I agree, the global most likely have a better handle of the system. 

[Derecho!]

GFS has a closed low that sort of spontaneously develops behind 97L and goes N of the Carribean

[GaWx]

 Unofficially, the MJO on 8/31/13 reached its highest near the peak of the season since 1989 and 4th highest since at least 1975 and it continues to rise. However, it isn't official yet.

[Ed Lizard]

Sort of untested, but 18Z FIM-9 combines 97L with wave behind it into one disturbance, a 35-40 knot TS that was heading Northwest, but heights starting to build ahead of at hour 168, maybe to turn it back across the Gulf Stream and towards Florida.

 

Trying to keep positive thoughts.  The concept of the wave right behind it competing has also shown up on some GFS and even Euro runs the last couple of days.

[Ed Lizard]

GFS has a closed low that sort of spontaneously develops behind 97L and goes N of the Carribean

It hasn't just been the GFS doing it.  Two runs of the Euro also show more love for the disturbance behind 97L.

 

 

Edit

 

NHC disco

 

TROPICAL WAVE IN THE CENTRAL TROPICAL ATLC EXTENDS FROM 18N46W

TO A 1011 MB LOW NEAR 11N48W MOVING W NEAR 10 KT. WAVE IS

EMBEDDED WITHIN A SURGE OF DEEP MOISTURE AS DEPICTED ON THE

TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED CLUSTERS OF

SCATTERED MODERATE CONVECTION ARE FROM 10N-15N BETWEEN 43W-50W.