Wave? In Eastern Caribbean

[Rieyeuxs]

Question from the dummy in the audience (that would be me )

Last season was killed by shear and SAL. Now I've read various interpretations on why the shear may relax, but other than the obvious climatology, what signs should we be looking for that the SAL will relax? Is it a slow progression northward? Is it more of a bubbling pattern around the storms? I know Derek has mentioned in the past that a CV storm "pulls" SAL around it coming off of the coast and that instead of pre-moisturing the air, it actually blocks the SAL for a wave/storm to develop _ahead_ of it.

So to make a longer question short, other than time, what feature or trend of the SAL should we be watching to say the train track across is now open? Is is a sudden event? And it is related to shear dropping as in the winds don't carry the SAL as far with it, allowing for SAL subsidence?

NOTE!!!! I am not saying season over! I am just trying to learn from the experts on what they are looking for in conditions for development.

[miamicanes177]

Question from the dummy in the audience (that would be me )

Last season was killed by shear and SAL. Now I've read various interpretations on why the shear may relax, but other than the obvious climatology, what signs should we be looking for that the SAL will relax? Is it a slow progression northward? Is it more of a bubbling pattern around the storms? I know Derek has mentioned in the past that a CV storm "pulls" SAL around it coming off of the coast and that instead of pre-moisturing the air, it actually blocks the SAL for a wave/storm to develop _ahead_ of it.

So to make a longer question short, other than time, what feature or trend of the SAL should we be watching to say the train track across is now open? Is is a sudden event? And it is related to shear dropping as in the winds don't carry the SAL as far with it, allowing for SAL subsidence?

NOTE!!!! I am not saying season over! I am just trying to learn from the experts on what they are looking for in conditions for development.

Yeah I would like to know the answer to this question as well. The answer is probably that nobody knows what will happen for another 6 weeks. We've still got a good bit to go until mid August. I hope 2006 was just a freak year and it wont happen again in 2007. I got tired of looking at all the SAL. It's just so persistent. The past two hurricane seasons I've not been able to look at maps without seeing a massive amount of dry air bulldozing off Africa.

[fci]

I'm actually a big SAL fan.
Let is be a boring year due to the proliferation of SAL as far as I am concerned.
I happen to like "freak" years like 2006.

[flwxwatcher]

Maybe this is the wave the GEM global is picking up on.

http://meteocentre.com/models/glb00_192_e.html

Like the HPC is pointing out, its an outlier with this solution at the moment

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
529 AM EDT THU JUL 12 2007

VALID 12Z MON JUL 16 2007 - 12Z THU JUL 19 2007

00Z MODELS IN GOOD AGREEMENT WITH TROF OVER SERN CANADA DURING THE
MEDIUM RANGE PD...BUT DIFFER ON HOW MUCH INROADS TROF MAKES INTO
NWRN US FROM PAC. GFS IS MOST PROGRESSIVE WITH THIS SYSTEM AND
GEM GLOBAL THE LEAST PROGRESSIVE. OPTED FOR A MIDDLE OF THE ROAD
APPROACH AS PER THE ECMWF/UKMET FOR PRELIM PROGS. USED ECMWF
DETAILS ELSEWHERE AS WELL...BASED ON STABLE SOLUTIONS OVER THE
PAST SEVERAL RUNS AND TYPICAL STRONG PERFORMANCE DURING THE MEDIUM
RANGE. GFS HAS BACKED CONSIDERABLY OFF ITS RETROGRESSION OF ATL
RIDGE INTO THE ERN US IT WAS DEPICTING 24 HRS AGO. GEM GLOBAL
STILL INSISTS ON BRINGING HURRICANE INTO SRN FL AT THE END OF THE
PD...A SOLUTION REJECTED AS AN OUTLIER DESPITE THE MODELS
CONSISTENCY WITH THIS SYSTEM.

[DESTRUCTION5]

Maybe this is the wave the GEM global is picking up on.

http://meteocentre.com/models/glb00_192_e.html

Like the HPC is pointing out, its an outlier with this solution at the moment

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
529 AM EDT THU JUL 12 2007

VALID 12Z MON JUL 16 2007 - 12Z THU JUL 19 2007

00Z MODELS IN GOOD AGREEMENT WITH TROF OVER SERN CANADA DURING THE
MEDIUM RANGE PD...BUT DIFFER ON HOW MUCH INROADS TROF MAKES INTO
NWRN US FROM PAC. GFS IS MOST PROGRESSIVE WITH THIS SYSTEM AND
GEM GLOBAL THE LEAST PROGRESSIVE. OPTED FOR A MIDDLE OF THE ROAD
APPROACH AS PER THE ECMWF/UKMET FOR PRELIM PROGS. USED ECMWF
DETAILS ELSEWHERE AS WELL...BASED ON STABLE SOLUTIONS OVER THE
PAST SEVERAL RUNS AND TYPICAL STRONG PERFORMANCE DURING THE MEDIUM
RANGE. GFS HAS BACKED CONSIDERABLY OFF ITS RETROGRESSION OF ATL
RIDGE INTO THE ERN US IT WAS DEPICTING 24 HRS AGO. GEM GLOBAL
STILL INSISTS ON BRINGING HURRICANE INTO SRN FL AT THE END OF THE
PD...A SOLUTION REJECTED AS AN OUTLIER DESPITE THE MODELS
CONSISTENCY WITH THIS SYSTEM.

CMC called Barry this year..

[boca]

Maybe this wave will make it across if the dry air doesn't kill it off first.

[ronjon]

Looks like the CMC really wants to develop this wave as it approaches the SE bahamas. I think this is the 3rd run (12Z/7/12) in a row now that it has a tropical cyclone approach the SE coast of FL in 6-7 days.

http://moe.met.fsu.edu/cgi-bin/cmctc2.cgi?time=2007071212&field=Sea+Level+Pressure&hour=Animation

[punkyg]

Wah! its not gonna develop even though the models say its gonna make landfall
in florida. if this happens i would be so excited then i can finally use my camera

[windstorm99]

Looks like the CMC really wants to develop this wave as it approaches the SE bahamas. I think this is the 3rd run (12Z/7/12) in a row now that it has a tropical cyclone approach the SE coast of FL in 6-7 days.

http://moe.met.fsu.edu/cgi-bin/cmctc2.cgi?time=2007071212&field=Sea+Level+Pressure&hour=Animation

Yea just saw that its been harping on this for a few runs now...



Pic of the 850mb vort.

[Extremeweatherguy]

Looks like the ridge to the north would keep the wave moving west beyond south Florida too. Could be an issue in the GOM in the very long term (8+ days out). Then again, that is assuming anything even forms at all..which I seriously doubt ATM. I will need to see something definite take shape before I start to worry.

[Aric Dunn]

its definitely something to watch ..... it is the first such low from the models the possible come out of the deep tropics..

[cycloneye]

TROPICAL WAVES...
A HIGH AMPLITUDE TROPICAL WAVE IS ALONG 37W/38W S OF 17N MOVING
W 15-20 KT. BROAD LOW LEVEL INVERTED-V SHAPE PATTERN IS OBSERVED
ON SATELLITE IMAGERY...AND IN ADDITION THE HOVMOLLER DIAGRAM
DEPICTS ITS QUICK WESTWARD MOVEMENT VERY WELL. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS ASSOCIATED WITH THE WAVE
FROM 6N-14N BETWEEN 36W-42W. A LARGE AREA OF AFRICAN DUST IS
BEHIND AND AHEAD OF THE WAVE AXIS. CURRENTLY...AND ACCORDING TO
THE GFS MODEL...MOISTURE FROM THIS WAVE SHOULD BEGIN TO REACH
THE WINDWARD ISLANDS LATE SATURDAY.


http://67.18.196.150/wx/modules.php?nam ... ge&pid=109

2 PM discussion of wave from TPC.Too many words,but no meat.

[ronjon]

From Miami NWS AFD:

BY THE MIDDLE PART OF NEXT WEEK...THE TROPICAL WAVE OVER THE CENTRAL TROPICAL ATLANTIC WILL MOVE WEST MAINLY ACROSS THE CARIB...BUT AXIS COULD EXTEND NORTH NEAR THE AREA...AND MOISTURE COULD INCREASE BEHIND THIS WAVE BY MID WEEK.

[vaffie]

There appears initially to be a hint of it in the GFS model, but it either loses it or it ends up in the Yucatan Channel. Any thoughts.

http://bricker.met.psu.edu/~arnottj/cgi ... =Animation

[vaffie]

Anyway, not that any model is accurate this far out--especially when it's such an outlier as this one is, but the CMC has it crossing south Florida heading wnw to northwest and strengthening into the general vicinity of eastern Louisiana at 240 hours (10 days).

http://meteocentre.com/models/glb00_240_e.html

[Nimbus]

Before a hurricane threatens southern Florida or passes through the Yucatan channel the wave has first to spin up into a depression.

Previous waves have been picking up convection west of 45W but too far south to enter the Caribbean. This wave looks like it may try to fire up a little further north. Just eyeballing the wave it looks like it might focus near 12-14N? The more southern GFS solution looks a little more possible but at this point I would listen to any reasonable prediction including non development due to SAL.

Once the models are initialized with a clear LLC the forecast confidence improves dramatically.

[caribepr]

Too many words,but no meat.

These may be the very best six words I ever read on S2K! And yep, I'm a carnivore Well done, Luis!

[tailgater]

Well we can all follow it a little closer now that RAMDIS has a floater on it.
http://hadar.cira.colostate.edu/ramsdis ... al/173.jpg

[Toadstool]

Did Katrina form out of one of the inverted-V waves? I'm curious since Katrina formed in the same general area the models are indicating, and I'm wondering if most tropical storms come out of the "inverted-V waves". (Also, I'm definitely not stating anything that may form as anything close to what Katrina was.)

[harmclan]

Dennis originated from an Inverted V wave.

The genesis Katrina was influenced by mid-latitude and tropical interactions. The precursor to Hurricane Katrina could be traced to convection along the tail-end of a mid-latitude trough on 14 August. That convection drifted south and then northwestward. Between 17 and 18 August, evidence of a vortex northeast of Puerto Rico could be seen in water vapor image. That upper-level vortex drifted northwestward and then southwestward towards the eastern Bahamas over the next three days. During the same period, a second cyclonic circulation centered at 500hPa over Hispaniola produced several MCSs. A tropical wave entered the eastern Caribbean but weakened as it moved westward. By 21 August, convection over the Caribbean was primarily associated with the mid-level circulation over Hispaniola. Between 22 and 23 August, the northern upper-level circulation merged with the strengthening mid-level circulation. Convection intensified around was now a tropical depression. An interesting feature of the period of intensification was very dry middle-level air mixing into to the west and north of the tropical depression.