Global Model Runs for W.Caribbean Early Season Development

[Vortex]

Gator,

While pulses are likely within the developing convection over the SW carribean I think this is the early stages of the environment becoming more conducive for mid-late week development. We know have a general area to focus our attention in "real time" other than just futuristic guidance from the models.


Let the show begin...

[MiamiensisWx]

Personally, I don't think the eastern Pacific area will develop. Most of the greatest low level vorticity is concentrated closer to the coastline of Central America and extends eastward into the southern Caribbean. Westerly shear is greatest across the eastern tropical Pacific, which should also prevent tropical development in the region. As the low level vorticity drifts east, we should observe greater chances of tropical cyclogenesis in the southern Caribbean vicinity, which is supported by anomalously low SLP in the area and over Central America. Upper level divergence should be excellent with the shortwave impulse passing to the north over the northwestern Caribbean Sea and the Bahamas. This is really a classical June pattern that is conducive for Caribbean cyclogenesis at the 500-200 mb level. Although the GFS brings the budding Atlantic TC west toward Mexico, this seems unrealistic in the current pattern with a mean trough over the Midwest/Northeast. In previous cases that involved June tropical cyclones, many models were too far west with the path during the early days of the system. Additionally, the possible cyclone should be on the east side of the ridge over Mexico, and model guidance does indicate a trough should move east over the Midwest during the same time frame over the next several days.

I think the current convection in the southern Caribbean Sea is the first stages of development, and we will likely observe our first Atlantic tropical cyclone in this general region over the upcoming days. I also concur that a weak to moderate system (TS) is most likely, with a possibility of a significant precipitation event over southern Florida as it potentially tracks to the north, which would place the system in the right front quadrant of the upper level divergence. All in all, I expect a classic June event, and we will likely see Arthur from this one. Normally, I would tend to dismiss the model consensus for June cases, but the environment clearly supports them in this case. The operational GFS and others definitely picked up on this one.

...A BEAR WATCH HAS BEEN ISSUED FOR THE SOUTHERN CARIBBEAN BASIN...

[Thunder44]

12z Euro on Plymouth, has development focused in the EPAC again by 72hrs.

[cycloneye]

In general the 12z EURO doesnt have anything of significance in the Caribbean nor GOM.

12z EURO

[MiamiensisWx]

The operational GFS introduced cyclogenesis in the same region of southern Caribbean around this time frame (Monday through Thursday) in previous runs, and it looks like it may have nailed it. It has also performed much better with the pattern than the Euro over North America recently.

[Vortex]

Personally, I don't think the eastern Pacific area will develop. Most of the greatest low level vorticity is concentrated closer to the coastline of Central America and extends eastward into the southern Caribbean. Westerly shear is greatest across the eastern tropical Pacific, which should also prevent tropical development in the region. As the low level vorticity drifts east, we should observe greater chances of tropical cyclogenesis in the southern Caribbean vicinity, which is supported by anomalously low SLP in the area and over Central America. Upper level divergence should be excellent with the shortwave impulse passing to the north over the northwestern Caribbean Sea and the Bahamas. This is really a classical June pattern that is conducive for Caribbean cyclogenesis at the 500-200 mb level. Although the GFS brings the budding Atlantic TC west toward Mexico, this seems unrealistic in the current pattern with a mean trough over the Midwest/Northeast. In previous cases that involved June tropical cyclones, many models were too far west with the path during the early days of the system. Additionally, the possible cyclone should be on the east side of the ridge over Mexico, and model guidance does indicate a trough should move east over the Midwest during the same time frame over the next several days.

I think the current convection in the southern Caribbean Sea is the first stages of development, and we will likely observe our first Atlantic tropical cyclone in this general region over the upcoming days. I also concur that a weak to moderate system (TS) is most likely, with a possibility of a significant precipitation event over southern Florida as it potentially tracks to the north, which would place the system in the right front quadrant of the upper level divergence. All in all, I expect a classic June event, and we will likely see Arthur from this one. Normally, I would tend to dismiss the model consensus for June cases, but the environment clearly supports them in this case. The operational GFS and others definitely picked up on this one.

...A BEAR WATCH HAS BEEN ISSUED FOR THE SOUTHERN CARIBBEAN BASIN...

Nice analysis Miami!

[KWT]

Very good post from MiamiensisWx and I do agree with him. I suspect the voricity will slowly spread further east towards the weak circulation and will drasg moisture in from the region that is currently allowing for widespread convection. In fact I think this process is already occuring with convection increasing in the SW most part of the Caribbean however the circulation isn't amazingly well developed yet and is close to land. If this carries on as the system gets over water then we could well see a TC develop in the Sw Caribbean near central America.

IF it does develop I wouldn't be surprised if the track ends up further east then progged because I've a feeling any intial circulation will die off if it goes inland over the Yucatan and re-develop in the more moist atmosphere to the east.

[cycloneye]

[Derek Ortt]

I will not be the happiest of people if this thing forms before Contador crosses the Passo di Aprica Saturday morning (and if he somehow is trailing, before the final TT on Sunday)

[gatorcane]

Very good post from MiamiensisWx and I do agree with him. I suspect the voricity will slowly spread further east towards the weak circulation and will drasg moisture in from the region that is currently allowing for widespread convection. In fact I think this process is already occuring with convection increasing in the SW most part of the Caribbean however the circulation isn't amazingly well developed yet and is close to land. If this carries on as the system gets over water then we could well see a TC develop in the Sw Caribbean near central America.

IF it does develop I wouldn't be surprised if the track ends up further east then progged because I've a feeling any intial circulation will die off if it goes inland over the Yucatan and re-develop in the more moist atmosphere to the east.

One should also note that late May/early June climatological tracks for a Western or SW Caribbean systems would favor the eastern GOM and/or peninsula Florida (as opposed to the Western GOM and Bay of Campeche). Tracks well SE of Southern Florida through Cuba or the Bahamas are also climatologically favored.

I'm very interested to see how the Northwest Pacific system should impact any ridging that wants to build over the central and northern GOM. Jeff Master's mentions this system in his blog.

[MiamiensisWx]

THE CARIBBEAN SEA...
A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN SEA WITH NO
SHOWERS OR THUNDERSTORMS OVER THE CARIBBEAN SEA. SEE ABOVE.
A 1010 MB LOW IS LOCATED N OF HAITI NEAR 21N73W. A COLD COLD
FRONT EXTENDS SW FROM THE LOW TO N OF JAMAICA NEAR 19N78W.
SCATTERED SHOWERS ARE WITHIN 60 NM OF THE FRONT. ELSEWHERE...
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS N OF PANAMA
FROM 9N-12N BETWEEN 78W-83W. SCATTERED SHOWERS ARE ALSO OVER
THE LEEWARD ISLANDS N OF 15N BETWEEN 60W-70W. IN THE UPPER
LEVELS...ZONAL FLOW PREDOMINATES. SIGNIFICANT UPPER LEVEL
MOISTURE IS OVER CENTRAL AMERICA AND THE SW CARIBBEAN SEA S OF
16N AND W OF 78W. EXPECT... THE COLD FRONT TO DISSIPATE OVER THE
CARIBBEAN SEA WITHIN 24 HOURS.

http://www.nhc.noaa.gov/text/refresh/MIATWDAT+shtml/261737.shtml?

Italicized portion is another key to the bolded synoptic puzzle, especially in the lower levels. This should leave a broad trough in the southern Caribbean and serve as the genesis of a cyclone.

[Eyewall]

If there is a high in place then it would not be able to go into florida it would follow a more southern to west track. Then form there who knows what will happen.

[wxman57]

The continued delaying of the development of this "storm" is a classic sign of a "modelcane". First it was the 25th, then 27th, then 30th. It's always just a little be further down the road.

[MiamiensisWx]

If there is a high in place then it would not be able to go into florida it would follow a more southern to west track. Then form there who knows what will happen.

Although tracks into the Bay of Campeche/Texas/Mexico and northeasterly paths into the eastern GOM/Florida peninsula are climatologically common for late May/June tropical cyclones, models have recently displayed an initial west bias prior to the actual genesis of June tropical cyclones. For example, I believe some model runs took the system that became Arlene much further west than the actual path. This bias was common before the system featured a closed low level circulation. Given the recent pattern with a trough over the Midwest and Northeast, some models may be displaying a similar bias in this situation. Although there will be an upper ridge over Mexico, this possible system will be on the southeastern flank of the ridge as a trough moves east over the Midwest. Remember that we do not have a closed low level circulation; development will occur slowly.

Additionally, the typical "delay" (initial setbacks) in some models have stopped; consensus generally argues for development over the next several days (today through Thursday).

[cycloneye]

[x-y-no]

The continued delaying of the development of this "storm" is a classic sign of a "modelcane". First it was the 25th, then 27th, then 30th. It's always just a little be further down the road.

Yes that's true, but the delay is getting shorter ... we're no longer talking 200+ hours out, we're talking ~100 hours out.

I don't give it high odds, but I think there's a real chance.

[KWT]

Not so sure about that Wxman, the GFS never really did much with the area of low pressure till the 28-29th in the first place, sure it developed weak looking center but nothing too concentrated till the time period above when it starts to develop a better defined center...indeed the GFs has slowly been bringing this system closer.

[Ed Mahmoud]

The continued delaying of the development of this "storm" is a classic sign of a "modelcane". First it was the 25th, then 27th, then 30th. It's always just a little be further down the road.

maybe, but it has creeped a little closer in time to the current.

The NOGAPS solution (assuming it is generally correct but the model, because of coarser resolution of a global isn't underestimating the strength) is the perfect solution to end wildfire season in Florida and ensure a 1998 style fire- out of the then Pepsi 400 (now the Coke Zero 400) doesn't repeat with a not to strong tropical storm that rains a lot on Florida. Not that I'd wishcast that or anything.

[cycloneye]

Ed,image does not work.

[x-y-no]

:uarrow: Ed,image does not work.

Works for me.