Global Model Runs for W.Caribbean Early Season Development

[KWT]

It does sort of look like that Aric though without much better resolution sat.imagery its hard to really know, it could just be a little eddy around the broad circulation in the region or it could be a reformation towards the plusing convection.

[Aric Dunn]

It does sort of look like that Aric though without much better resolution sat.imagery its hard to really know, it could just be a little eddy around the broad circulation in the region or it could be a reformation towards the plusing convection.

right well thats my point actually .. the circulation earlier was really just diffuse i was waiting to see if we could get some sort of small swirl within the larger circulation cause eventually that would begin to take over and spin around doing loops until it became more well defined. that what im looking for.

[vaffie]

Personally, I think it's going to continue to reform to the north and east of the old centers until the shear relaxes due to the serious amount of convection going on. It is something that I've noticed in the past--that the models have a hard time dealing with--they're often off by a large margin when it comes to predicting center reformation over the course of a couple days. It will make for an interesting weekend.

[KWT]

Possibly its a little hard to say to be honest, it may well have jst been a breif eddy, either way everything (including the convection) is being shunted bit by bit to the east, with the convection flaring up then dieing down only to be replaced by new convection further west so expect a rainy spell over the Yucatan.

Still it does need watching just in case.

[cycloneye]

HPC Discussion about Western Caribbean area.


TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
225 PM EDT FRI MAY 30 2008

DISCUSSION FROM MAY 30/0000 UTC. THE MODELS REMAIN SURPRISINGLY
CONSISTENT IN THEIR FORECAST OF THE EVOLVING PATTERN ALOFT...WITH
AN UPPER RIDGE INITIALIZED OVER NORTHERN MEXICO AND ANOTHER OVER
THE WESTERN CARIBBEAN/ CENTRAL AMERICA. THE ONE OVER NORTHERN
MEXICO WILL CENTER ON A HIGH THAT WILL MEANDER BETWEEN
SONORA/CHIHUAHUA. INITIALLY IT IS TO BE NARROW AND ELONGATED...BUT
THROUGH 48-72 HRS IT IS TO STRENGTHEN AS IT BUILDS NORTH INTO THE
WESTERN USA AND IT IS TO ENVELOP MOST OF MEXICO/WESTERN GULF. THE
MID LEVEL SIGNATURE OF THIS FEATURE IS ALSO FORECAST TO GRADUALLY
STRENGTHEN AS THE CYCLE PROGRESSES. THE RIDGE OVER THE
CARIBBEAN...MEANWHILE...IS TO CENTER ON A HIGH OVER THE YUCATAN
EARLY THIS PERIOD...AND IT IS TO EXTEND ACROSS CENTRAL
AMERICA/WESTERN CARIBBEAN. THROUGH 48-60 HRS IT IS TO NEARLY
COLLAPSE OVER CENTRAL AMERICA... AND THE REMNANTS OVER SOUTHERN
MEXICO WILL MERGE INTO THE BROAD RIDGE PATTERN ESTABLISHING OVER
THE REGION.

TS ALMA WEAKENED TO A DISORGANIZED CIRCULATION AS IT WENT INLAND
ACROSS HONDURAS. BUT A BROAD CYCLONIC CIRCULATION IS TO PERSIST
ACROSS HONDURAS-BELIZE-GUATEMALA-YUCATAN-SOUTHERN MEXICO. MEDIUM
AND LONG RANGE GUIDANCE SHOW THIS SYSTEM PERSISTING FOR AT LEAST
FIVE DAYS. EMBEDDED IN THE BROAD CYCLONIC CIRCULATION...THE MODELS
CONTINUE TO SHOW RISK OF A SECONDARY/NEW CYCLONE FORMING OVER THE
WESTERN CARIBBEAN/GULF OF HONDURAS...BUT IT IS A FEATURE THAT
WEAKEN AS IT ENTERS THE YUCATAN/NORTHERN BELIZE. THE SLOW
EVOLUTION/QUASISTATIONARY CHARACTERISTICS OF THIS SYSTEM WILL
RESULT IN A HIGH RISK OF ORGANIZED RAINFALL ACROSS THE PREVIOUSLY
IDENTIFIED AREA. ACROSS CENTRAL/SOUTHERN HONDURAS-EL SALVADOR WE
EXPECT RAINFALL AMOUNTS OF 15-30 MM/DAY AND MAXIMA OF 75-125MM/DAY
THROUGH 36 HRS...AND 15-25MM/DAY AND MAXIMA OF 35-70MM AT 36-60
HRS. OVER NORTHERN BELIZE-QUINTANA ROO AND PORTIONS OF THE YUCATAN
INITIALLY EXPECT RAINFALL MAXIMA OF 75-125MM. THIS IS TO INCREASE
TO 100-200MM BY 48-60 HRS AS THE AFOREMENTIONED VORTEX ENTERS THE
YUCATAN PENINSULA...WITH A GRADUAL DECREASE THROUGH 84 HRS. THE
EVOLVING PATTERN WILL ALLOW FOR ORGANIZED CONVECTION TO AFFECT
TABASCO-CHIAPAS-CAMPECHE IN SOUTHERN MEXICO...WITH ACCUMULATION OF
20-35MM/DAY AND MAXIMA OF 75-150MM/DAY EXPECTED THROUGH 60 HRS.
ACTIVITY IS TO THEN BUILD WEST ACROSS SOUTHERN GUATEMALA TO
SOUTHERN CHIAPAS AND EL SALVADOR/SOUTHERN HONDURAS...WITH
ACCUMULATION OF 20-35MM/DAY AND MAXIMA O 75-125MM.

http://www.hpc.ncep.noaa.gov/discussions/fxca20.html

[gatorcane]

so basically from the discussion the disturbed weather over the Yucatan and Gulf of Honduras isn't going anywhere for the next 5 days. IMHO it requires a bear watch still because sooner or later a trough should erode the ridge over the GOM.

[cycloneye]

12z EURO



The 12z EURO has something in the Yucatan Channel and Southern GOM but it is at 240 hours,a lot of time that for sure changes will occur.

[KWT]

To be fair though that barely a disturbance yet along a tropical cyclone, the slightest of kinks in the isobars. Still as you say its 240hrs and thats a very very long way out for models to relaly get a good grip on tropical activity, tohugh they did a reasonable job on Alma.

[vaffie]

Roatan Island, Honduras now with a wind of 13 miles per hour from the WSW, pressure of 1008 mb. Implies that the center is just to the north or northnorthwest of the island. Will be interesting to pay attention to this little island's reports.

[NDG]

I can clearly still see the circulation near 17.5N & 87.2W, seems to be getting a little better organized, if it would stay over water during the night, I am sure we will see some development out of this.

[StormspinnerD2]

Whatever circulation there is there is extremely weak and indiscernible on satellite loops. The broad low is moving west and will be back over land soon, so I would not expect any development out of this.

[gatorcane]

There definitely is going to be some kind of weakness in the ridge down the road but the question is what will be left of this low when it happens to allow a path up to the north.

Here is a snippet from the NWS Miami discussion:

IN THE EXTENDED FOR EARLY NEXT WEEK THE GFS, NAM AND ECMWF ALL SHOW
E CST TROUGH CONTINUING TO DEEPEN AS THE MID/UPPER RIDGE RETREATS
WESTWARD AND THROUGH MID WEEK KEEPS THE DEEP LAYER MOISTURE OVER THE
CARIBBEAN. BY THE END OF NEXT WEEK, BOTH THE GFS AND ECMWF INDICATE
THAT AS THE E CST TROUGH CONTINUES TO MOVE EAST INTO THE ATLANTIC, A
SECOND STRONG SHORTWAVE MOVES INTO THE CENTRAL PLAINS WITH THE ECMWF
BEING THE MOST AGGRESSIVE WITH THIS TROUGH. AS THIS HAPPENS, RIDGING
DEVELOPS ACROSS THE ATLANTIC WITH A WEAKNESS IN THE RIDGE ACROSS THE
GULF UNDERNEATH THE MAIN TROUGH. THIS WOULD PUT S FLA UNDER A MORE
FAVORABLE DEEPER SE FLOW TO DRAW THE DEEP LAYER MOISTURE OVER THE
CARIBBEAN NORTHWARD GIVING US A MUCH BETTER CHANCE FOR BADLY NEEDED
RAINFALL, ESPECIALLY ACROSS INTERIOR AND W CST ZONES

[StormspinnerD2]

From the looks of it, Florida could get a shot of moisture if a weakness does develop in the ridge, but it won't be from a tropical cyclone or its remnants. Conditions just don't favour development in the Gulf of Mexico.

[NDG]

Whatever circulation there is there is extremely weak and indiscernible on satellite loops. The broad low is moving west and will be back over land soon, so I would not expect any development out of this.

It has been moving NNW all day very slowly, not W. Not to say that it will not be moving over the Yucatan later on once it starts feeling the ridge to the north.

[MiamiensisWx]

I'm sorry, but there is no low level circulation; it dissipated over Central America. It's the surface low that you can observe in the vicinity east of Belize and the Yucatan, but a LLC clearly is not present offshore. The observations indicate some variable winds, which is related to outflow from thunderstorm complexes. It is also typical of a weak surface low in the vicinity, though a closed low level circulation is absent. I think this one has very minimal chances of development before it moves inland over the Yucatan.

I also want to offer some verification for my previous calls over the past few days. I clearly underestimated the strength and amplification of the upper level ridge over Mexico, which led to unexpected intensification of TD 1E to the strong Tropical Storm Alma. Anticyclonic flow was much more conducive for further strengthening and deepening than I originally anticipated; this also resulted in Alma's expansive outflow shearing and "contaminating" the Caribbean system to the east. Low level inflow and convergence was also very excellent in the vicinity of Alma, aiding the TC's intensification. I was far too bullish on the prospects of early Caribbean cyclogenesis, which never materialized and clearly won't occur even with a tropical wave axis in the area. In short, my forecast and original synopsis was a complete bust.

Although some models still indicate development beyond ~160 hours, this is clearly a different system than the current Caribbean mess, and it is unlikely to verify in the end.

[KWT]

No there may not be a LLC but there does appear to be some sort of rotation present in the clouds, maybe a MLC in that case, still its hard to tell without good resolution Sat.imagery. As you say though I do think its heading inland and once its inland the only real shot of anything developing from this area within the next 3-5 days will be over the BoC and thats only if that rotation ends up further north then it is presently and doesn't totally die out, which to be honest is the most likely option.

[NDG]

I'm sorry, but there is no low level circulation; it dissipated over Central America. It's the surface low that you can observe in the vicinity east of Belize and the Yucatan, but a LLC clearly is not present offshore. The observations indicate some variable winds, which is related to outflow from thunderstorm complexes. It is also typical of a weak surface low in the vicinity, though a closed low level circulation is absent. I think this one has very minimal chances of development before it moves inland over the Yucatan.

I also want to offer some verification for my previous calls over the past few days. I clearly underestimated the strength and amplification of the upper level ridge over Mexico, which led to unexpected intensification of TD 1E to the strong Tropical Storm Alma. Anticyclonic flow was much more conducive for further strengthening and deepening than I originally anticipated; this also resulted in Alma's expansive outflow shearing and "contaminating" the Caribbean system to the east. Low level inflow and convergence was also very excellent in the vicinity of Alma, aiding the TC's intensification. I was far too bullish on the prospects of early Caribbean cyclogenesis, which never materialized and clearly won't occur even with a tropical wave axis in the area. In short, my forecast and original synopsis was a complete bust.

Although some models still indicate development beyond ~160 hours, this is clearly a different system than the current Caribbean mess, and it is unlikely to verify in the end.

IMO, I believe it is closed, E winds to the north, N winds to the west, W winds to the S, S winds to the E. Too coinsidental to be outflow bounderies along with satellite images.

[drezee]

I love these situations...you have the three camps:

No development no matter what

Oh my goodness is that an eye

let's wait and see

most are suffering for the "bear watch"...if this thing popped up overnight the board would be going crazy. It is slowly, but quite surely organizing. I for one want this thing onshore soon. This thing will be a TD in less than 24 hours if it stays offshore IMO.

[KWT]

I have to admit NDG that image does make the case for a closed circulation down at lower levels, IF it stays offshore then we may yet see an invest out of this but thats obviously a big if right now. Certainly is going to need watching though it probably will be shunted towards Yucatan fairly shortly unless the center reforms to the east.

Still its a nice little teaser set-up for the start of the season I feel!

[wxman57]

so basically from the discussion the disturbed weather over the Yucatan and Gulf of Honduras isn't going anywhere for the next 5 days. IMHO it requires a bear watch still because sooner or later a trough should erode the ridge over the GOM.

That's not exactly what the discussion says. I.E., that the system will remain over the western Caribbean for 3-5 days. With the building high over northern Mexico and the NW Gulf, the system will track westward over Southern Mexico and the extreme southern BoC where it may linger for a while. By Monday/Tuesday, most of the convection should be moving over the isthmus of Mexico and back out into the East Pac with the NE winds aloft.

As for an LLC, I do discern a broad weak LLC but with no convergence toward a center and with very light winds around the LLC. Without convergence it's hard to build persistent thunderstorms. And without thunderstorms, it's hard to increase convergence. That said, I don't expect any development in the western Caribbean. By late tomorrow, the system should be over the Yucatan. Best chance for any development will be in the southern BoC Sunday into Monday, but chances of a TD/TS forming are only slight.