Possible development in the western Caribbean

[MiamiensisWx]

The following posts are not an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including Storm2k.org. For official information please refer to the NHC and NWS products.

I just decided to offer some thoughts on the developing situation with the wave east of the Windward Islands. Although I don't believe that we will observe development over the shorter term, it is possible that the upcoming pattern could play a role if the wave axis survives as it moves into the western Caribbean Sea. I'm not jumping to conclusions, but I believe that the potential for slow development may exist over the next several days.

While the wave axis is visible, I do not expect significant development. Sfc covergence is weak, and mid-level shear is significant. In addition, the wave lacks a defined low-level circulation, and I have not noticed any signs of a sfc low. See the latest visible loop. Although the mid-level environment is more favorable in the eastern Caribbean, there is a significant convective cap in place across that region. In addition, note the mid-level dry air. As the wave is weak, the Windward Islands graveyard may claim another victim.

There is caveat. If the wave axis survives this journey, the prospects may become more interesting within the western Caribbean. A sfc trough (and sfc low) has been established over the Yucatan Peninsula, northern BOC, and southern GOM. As the Southeast trough moves away from the region, ridging may build northward over the course of the next several days. If I am correct, this might reduce shear and provide a better environment for slow development. The chances may increase as the wave axis interacts with the low pressure environment south of Jamaica and Cuba. The Miami NWS mentions the the ridge in their discussion.

.DISCUSSION...SURFACE HIGH PRESSURE RIDGE OVER THE FLORIDA STRAITS
WILL CONTINUE TO MOVE NORTHWARD ONTO SOUTH FLORIDA BY WEDNESDAY.
MOISTURE IS MOVING NORTH WITH THE RIDGE BUT NOT AS FAST AS EARLIER
EXPECTED. GPS WATER VAPOR IS RANGING FROM 1.85" OVER THE KEYS TO 1.7"
OVER MIAMI TO 1.4" NEAR THE LAKE. LOWERED THE POPS A TAD FOR THE
REST OF TODAY. FOR WEDNESDAY, THE GFS40 IS GOING CRAZY WITH THE
POPS WHICH SEEMS TO BE FROM CONVECTIVE FEEDBACK SO LEANED MORE TO THE
NAM/MET DATA. BUT A SHORT WAVE WILL APPROACH THE CWA FROM THE WEST
THROUGH WEDNESDAY. ON THURSDAY, WITH INCREASING EASTERLY FLOW
WITH THE RIDGE MOVING NORTH, THE HIGHEST POPS WILL BE FOCUSED OVER
THE INTERIOR AND WEST. POPS WILL DECREASE STEADILY THROUGH SUNDAY
TO SLGT CHC AS DRIER AIR FINALLY WORKS IN. POPS WILL INCREASE
AGAIN TO CHC FOR MONDAY AND TUESDAY. HUMIDITIES WILL BE HIGHER
THAN THEY HAD BEEN IN PREVIOUS WEEKS.

In addition, the GFS and Euro indicates that we may observe the development of lower pressures over the western Caribbean Sea and southern Gulf of Mexico. The reliable Euro ensembles have been providing some hints of a favorable environment. As I can't find the Euro link, I'll post the latest GFS data.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... _078.shtml

Note the higher sfc pressures over the region. This provides an easterly flow regime and it aids the development of low-level systems. This could reduce low-level shear. What do you think?







Note that the ingredients are in their place. We have low pressures, an adjacent sfc trough, and an upcoming pattern that may favor development. If the wave axis survives into the western Caribbean, we may observe an interesting scenario over the next several days.

[skysummit]

Boooyahhh....what I was thinking! You just described it MUCH better

[Tampa Bay Hurricane]

Looks interesting...will be watching...
whatever forms may give
texas some heavy rains if we
see a trough to the north.

[tropicwatch]

[wjs3]

I'll just say (and I should really look at some actual meteorological data before saying this) that the convection associated with the wave east of the windwards seems to be associated with a jet streak there creating some upper divergence. When I saw it on satellite earlier today I thought it looked interesting. Now after a glance at the upper pattern, I doubt there's really much to it.

WJS3

[MiamiensisWx]

I'll just say (and I should really look at some actual meteorological data before saying this) that the convection associated with the wave east of the windwards seems to be associated with a jet streak there creating some upper divergence. When I saw it on satellite earlier today I thought it looked interesting. Now after a glance at the upper pattern, I doubt there's really much to it.

WJS3

I definitely agree with your point, but a closer view indicates a pronounced wave axis to the east of the convective activity. While the upper-level divergence (jet streak) has been enhancing convection, the wave axis typically survives a journey through hostile conditions (unless unfavorable thermodynamics or adjacent systems take their toll). Many waves cross the Caribbean (and Atlantic) while they feature very little convection. The dry air (and mid-level cap) poses a challenge ahead of the wave, but you should observe the large anticyclone in the southwest Caribbean. This sfc ridge is expected to move northward and cover the western Caribbean Sea within the next few days. By this time, the wave axis (if it survives) may develop south of Cuba (as tropical waves are steered by the low-level flow).

While the current pattern may appear to be unfavorable, the upcoming trends support a favorable environment. The low-level ridge should migrate northward (per the current setup, model guidance, and Miami NWS), and this should reduce low-level shear over the next few days. At the same time, a weak sfc trough should linger in the vicinity, and this could provide lower pressures. In addition, we have a falling QBO. This easterly stratospheric regime should provide an increasingly favorable environment for western Caribbean convective initiation. Sfc convergence should improve as the ridge builds over the region. In a general sense, the "spark of life" may be stirring in the region over the next several days.

I apologize if this description is too vague. Here is some detailed information with respect to the QBO (Quasi-Biennial Oscillation). The current position of the westerlies is further north over the western CONUS, and this favors an easterly QBO stratospheric setup over the eastern Pacific. This could provide a favorable low-level environment (and favorable upper-level pattern) over portions of the Atlantic Basin. We could observe a favorable convergence of westerly and easterly sfc winds in the western Caribbean, and the variations of the QBO could foster Caribbean development.

I hope this helps. I'm eager for your comments, WJS.

Edit: I'm unsure with respect to the QBO. This is a relatively new field for me. Which phase would be more favorable for Atlantic TC development? Thanks for your patience.

[ronjon]

Long range GFS stirring up western carribean development again in 9 days. On the 18Z run, it develops another low pressure system off of Yucatan and moves it NE across S FL. Have to see if remains persistent in later runs or gets any other model support later on.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_216m.gif

[MiamiensisWx]

Long range GFS stirring up western carribean development again in 9 days. On the 18Z run, it develops another low pressure system off of Yucatan and moves it NE across S FL. Have to see if remains persistent in later runs or gets any other model support later on.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_216m.gif

I'm discussing a different development. I believe that the next four or five days might hold potential for development. This largely depends on the tropical wave's axis east of Windward Islands. If the axis holds together as it transverses the Caribbean over the next few days, we might watch the conditions become favorable as ridging builds over the area.

[windstorm99]

Iam not so sure that wave will enter the caribbean as it looks to be getting pulled to the north.

[Cyclenall]

I had similar thoughts in the "When and where will Chantel form" thread:

Western Carribean - June 7 to June 13 - affects parts of Cuba as a mid tropical storm.

[skysummit]

Iam not so sure that wave will enter the caribbean as it looks to be getting pulled to the north.

But the axis is moving west.

[SouthFloridawx]

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 52W SOUTH OF 12N MOVING
WEST 10-15 KT. AN INVERTED-V LOW CLOUD SIGNATURE IS NOTED ON
THE LATEST SATELLITE IMAGES. WIDELY SCATTERED MODERATE
CONVECTION IS FROM 5N-12N BETWEEN 47W-54W.

[Praxus]

[meteorologyman]

what is inverted-V I don't understand that, and I don't see anything that is an inverted V

[MiamiensisWx]

what is inverted-V I don't understand that, and I don't see anything that is an inverted V

The east and west extension of an easterly wave forms an inverted V cloud pattern.

[wjs3]

I definitely agree with your point, but a closer view indicates a pronounced wave axis to the east of the convective activity. While the upper-level divergence (jet streak) has been enhancing convection, the wave axis typically survives a journey through hostile conditions (unless unfavorable thermodynamics or adjacent systems take their toll). Many waves cross the Caribbean (and Atlantic) while they feature very little convection. The dry air (and mid-level cap) poses a challenge ahead of the wave, but you should observe the large anticyclone in the southwest Caribbean. This sfc ridge is expected to move northward and cover the western Caribbean Sea within the next few days. By this time, the wave axis (if it survives) may develop south of Cuba (as tropical waves are steered by the low-level flow).

While the current pattern may appear to be unfavorable, the upcoming trends support a favorable environment. The low-level ridge should migrate northward (per the current setup, model guidance, and Miami NWS), and this should reduce low-level shear over the next few days. At the same time, a weak sfc trough should linger in the vicinity, and this could provide lower pressures. In addition, we have a falling QBO. This easterly stratospheric regime should provide an increasingly favorable environment for western Caribbean convective initiation. Sfc convergence should improve as the ridge builds over the region. In a general sense, the "spark of life" may be stirring in the region over the next several days.

I apologize if this description is too vague. Here is some detailed information with respect to the QBO (Quasi-Biennial Oscillation). The current position of the westerlies is further north over the western CONUS, and this favors an easterly QBO stratospheric setup over the eastern Pacific. This could provide a favorable low-level environment (and favorable upper-level pattern) over portions of the Atlantic Basin. We could observe a favorable convergence of westerly and easterly sfc winds in the western Caribbean, and the variations of the QBO could foster Caribbean development.

I hope this helps. I'm eager for your comments, WJS.

Edit: I'm unsure with respect to the QBO. This is a relatively new field for me. Which phase would be more favorable for Atlantic TC development? Thanks for your patience.

Hey, Miamiensiswx. Always enjoy a good conversation.

First, on the QBO, I saw your post in "got a question" too. I am not sure to what degree easterly or weterly winds in the stratosphere affect tropical cyclones, if at all. Since weather takes place in the troposphere (I know you know this!) I'm not sure that the stratosphere has a whole lot to do with the tropics--or any other weather--but that is just a educated guess and not based on any research or reading. I bet I'm wrong and someone will correct me. Let's watch over in the other forum and see if anyone can help. Have you read anything about how the QBO affects the troposphere?

I agree that there is a wave axis there, I was just noting that the convection with it seems to be firing not becasue of tropical mechanics (something about potential vorticity that I am trying to supress keeps flashing back into my brain), but because of more typical mid latitude (jet streak) effects.

I do think that this wave--with or withourt convection--can make it into the Caribbean, and it could flare up once there, depending on what else is going on when it gets there. However, a quick glance at models (OK...a quick look at the 12z gfs) I do think that the subtropical jet still looks pretty active (speaking in a broad, general sense ) even 7 days or so out. That means shear, even if the low level easterlies relax. You raise a good point that as the surface ridge retreats, by definition, pressures will lower.

Sorry...sort of rambling...so while I kind of agree with you re: the surface evolution, I am not sure about the pattern aloft....if there's any kind of westerly aloft, the shear in the area is going to inhibit any kind of development.

We'll keep an eye on it. It's certainly possible given climatology.

Sorry I can't give you a better response. Long day and I haven't had time to look at a ton of stuff.

Thanks!

WJS3

[Extremeweatherguy]

Looks like an interesting wave. IF it can survive the Caribbean and blow up in the western Caribbean, then I think it has some shot at development. There are a lot of open seas ahead though, and being early in the season the chances seem low. However, it is still worth watching as the Caribbean seems more favorable earlier than normal this season...so something could possibly try to spin up.

[boca]

I have a question if that wave along 52w continues west can it keep on going west even though all the convection is being pulled northward into the Central Atlantic?
http://www.ssd.noaa.gov/goes/east/catl/loop-avn.html

Essentially it would be a naked wave until it enters the western Caribbean,as what Miamiensiswx was eluding to.

[StormTracker]

Whew, that's just due east of Hebert Box #1!!!

[Javlin]

I think it only has to worry about the Graveyard if it is something when it enters the Graveyard,otherwise it should be OK?The pull to the N well,wouldn't it have to develop some to feel the tugs of the Upper ATM?otherwise it is steered by a lower set of conditions?