Western Caribbean / SW Gulf Development??

[Derek Ortt]

I don't see much of anything in this area. Just scattered convection east of a broad low, which may be onshore

[gatorcane]

Curiously, the 12Z GFS now develops another broad area of low pressure in the WCAR at 120 hours...with a large CONUS trough to the north (which would mean it could get pulled northward). Classic October setup unfolding.

I agree this WCAR area needs watching and I think the GFS is sniffing it out lower pressures in the area (150 hours):

[IvanSurvivor]

Right, your GARP shows a potential for a broad area of low pressure. It needs to slow down before the Yucatan...weak system can develop over the Yucatan though...please, no one throw me under the bus, but I will go into my sat archive on Opal...seem to remember Opal looking a lot like this before it went onshore of the Yucatan...[/quote]

Oddly enough it was September 23, 1995 (today, 14 years ago) that the wave to be known as Opal merged with a broad area of low pressure in the Western Caribbean and moved across the Yucatan (the wave came from Africa). It was classified as a tropical depression on September 27th and moved into the BOC where it was classified as a tropical storm. It underwent RI in the Gulf and moved northward slamming the Pensacola area with 115 mph winds and a 15 ft. storm surge. In the Gulf it reached 150 mph and a pressure of 916 mb (lowest recorded pressure for a storm that did not reach category 5). Also, during an eyewall replacement cycle it went from having an eye with a 6 mile diameter to a 60 mile eye...Yikes!

[IvanSurvivor]

Wow...it got me! Pressure rose 2.3MB in one hour and wind shifted to ESE. I would say outflow boundary, but the winds don't work out...

Yeah, buoy pressures rose in the last hour or two, but general pressures across the region are MUCH lower than in June-August. The "problem" back then was a stronger-than-normal Bermuda High and very strong low-level flow across the Caribbean. That's no longer an issue, it appears.

Right, your GARP shows a potential for a broad area of low pressure. It needs to slow down before the Yucatan...weak system can develop over the Yucatan though...please, no one throw me under the bus, but I will go into my sat archive on Opal...seem to remember Opal looking a lot like this before it went onshore of the Yucatan...

Ooops...I didn't quote right. The top of my last post was a quote from page 1 of this thread, posted by "drezee"...sorry.

[PTrackerLA]

If anything were to develop it would continue moving westward into the Yucatan and then mainland Mexico correct? This is one of the few days this whole season I've seen convection in the western caribbean. It has been extremely quiet there this year.

[HURAKAN]

678
ABNT20 KNHC 231738
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT WED SEP 23 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE NEXT 48 HOURS.

$$
FORECASTER BEVEN

[Nimbus]

The center of rotation looks like it is just off the Honduras Nicaraguan border. I gather from Dereks comment that the center is warm core? With a big anticyclone over the gulf it might be easy to write this off as Pacific bound, but the models apparently either think the steering is going to change or some energy from this area will get pulled up into the Bay of Campeche?

[PTrackerLA]

If anything were to develop it would continue moving westward into the Yucatan and then mainland Mexico correct? This is one of the few days this whole season I've seen convection in the western caribbean. It has been extremely quiet there this year.

[drezee]

Interesting looking over the models...12z NAM indicates a upper high over the GOM at 84 hours and a screaming outflow jet to the SE of the potential system...

http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_084l.gif

For those of us that don't know how to look at these maps, etc....can you give us a little more info as to what that means. Trying to learn as much as possible so that one day I don't have to ask so many dumb questions.

I know this is way too early since this is not anything yet, but with all of the elements combined, which way would this "potential area of concern" be moving...if it crossed the Yucatan and ended up in the BOC or SW Gulf...would it continue to move W, WSW or could it potentially get picked up by something and moved North towards the Gulf Coast?

Good point:

OK, 200MB is typically considered the outflow layer. In 84 hours, you see an anti-cyclonic flow via the wind barbs. To the SE of that area of upper level high pressure you see very strong 50kt+ winds. Upper lows act as vacuums with air getting sucked out of a system...promoting additonal lowpressure. In the image, you see one centered about 16N 80W. If this were to pan out, it would promote air exiting the system and thus make the process of rising air more efficient.

[drezee]

If there is a low pressure forming, then it is still off shore winds along the Caribbean coast have strong N component. Also, pressures offshore are lower. Cozumel has winds gusting to over 15kts out of the NE.

[Nederlander]

The center of rotation looks like it is just off the Honduras Nicaraguan border.

thats where i see the most evidence of rotation on vis... looks like itll be passing over the border soon then on to some more open waters until it reaches the Yuc... Not real impressive yet as a whole though...

[Dean4Storms]

Something to keep an eye on, but it will have to make it to the BOC or southern GOM to become much of anything.

[IvanSurvivor]

Thanks, Drezee!

[Stormcenter]

I'm not concerned at all and just looking forward to the
first "real" cold front.

[Nederlander]

I'm not concerned at all and just looking forward to the
first "real" cold front.

I am right there with you stormcenter! I am ready to see the fog when I exhale!

I gather from Dereks comment that the center is warm core?

I am no expert but it doesnt look like a warm system to me. The cloud tops look rather cold on satellite. If I am wrong about this, please correct me Derek.

[wxman57]

I don't see much of anything in this area. Just scattered convection east of a broad low, which may be onshore

Correct, and I didn't mean to suggest that I see something organizing there. But the mere presence of thunderstorms in the region which has been devoid of thunderstorm activity all season suggests that something is changing there. And that change could result in this feature or the next wave entering the region having a better chance of development than in the previous 3 months. Previously, we could look at the Caribbean Sea and maybe the Gulf of Mexico and say confidently that "no way is something going to be able to develop there in all that shear (low-level or upper-level). But maybe we can't say that as confidently now. Therefore, we need to monitor the region more closely.

[carolina_73]

http://www.ssd.noaa.gov/goes/east/carb/loop-rb.html I see a spin headed NNW just south of the Honduras Nicaraguan border.

[drezee]

Based on what I see with the surface obs and visible sat, I see the following (grain of salt alert):

There are two impulses: one alone 87W moving W and one a bit further SE along 82W moving WNW
Earlier today, they were separated more. The impulse at 82W is moving faster than the one at 87 and should catch it around 90-91W(WAG), if the second system can continue to pull N of West.

I expect a nice blowup of storms over the yucatan tonight in response to the first pulse (outflow boundaries and all), the second system should continue to produce nice convection as moisture seems well established.

Big question is what happens when they meet. I'm not sure....

The playing field is set...you have two areas of latent heat coming together likely over the western Yucatan or BoC in late september...verdict: it must be watched...

[drezee]

I'll go a bit further:

http://weather.msfc.nasa.gov/GOES/goeseastfullir.html

Create a 30 frame loop over the Caribbean...seems like system #2 came from Southern Venezuela!

[Nimbus]

The convection is working its way north toward 17N -81W. Guess we wait for an invest to cut and paste numbers from unless someone has a high resolution surface pressure map..