MikeC
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10:00 PM CDT Update 23 October 2011
Tropical Storm Rina develops in the western Caribbean, with tropical storm watches up for coastal Honduras.
Interestingly enough, in the forecast, as it nears the Yucatan, it will be over much warmer water, and conditions are favorable for quite a bit of intensification as it nears the Yucatan. Those in the area will want to pay close attention to Rina as it quite possibly could be stronger than forecast (as per the discussion by Stacey Stewart), the official forecast is currently keeping a category 1 as it nears the Yucatan. With Rina, beyond 3 days or so is very uncertain at the moment. The forecast would have Rina near the Yucatan on Thursday night.
If it goes north of the Yucatan shear will likely increase, and weaken the system, but it is worth watching for those in the northeast gulf (including southwest Florida) into this weekend and early next week to see where Rina eventually winds up.
3:30 PM CDT Update 23 October 2011
Based on recon data and best track forecasts, Tropical Depression 18 has formed in the western Caribbean from what was once being tracked as invest 96L.
Advisories likely will begin at 5PM EDT.
Those in Central America will want to keep a close watch on this system, and some of the more reliable models suggest it may move further north to the gulf before getting ripped apart by shear in the Gulf. Meaning, if it makes it close to the Gulf/Florida it will likely be a weak rainmaker. Still it may have a good shot at strengthening before that, so those in the Yucatan and western Cuba should monitor it closely. It is too soon say how much rain/or threat it would be to elsewhere.
12:30 PM CDT Update 23 October 2011
The small Caribbean low pressure area, Invest 96L, has become more organized today, and a Tropical Cyclone is trying to establish.
As of early this afternoon, deep convection with early stages of banding have developed in the northwest quadrant of the cyclone, and is starting to extend beyond that. Additionally, the low level circulation has tightened up, and looks to be colocating itself better with this expanding and deepening convection.
Conditions
* Small size: 96L is a small system, and this makes it especially sensitive to changes in its environment, both positive and negative.
*Dry air & shear: Dry air and shear are approaching from both its northwest and southeast. 96L may get caught in a squeeze, and shear out if it moves too much, too soon.
*Favorable Sea Surface Temps: Waters over much of the western Atlantic, and particularly so in the western Caribbean, are still very supportive.
Model Runs
Caribbean systems this time of the year can be very challenging for the models, and recon is flying into 96L for the first time just this afternoon. As such, models runs so far have been all over the map, and should be taken with a grain of salt. Runs will probably improve by tomorrow.
Risks
There is a chance that 96L becomes a small, but concentrated, and very strong tropical storm - or even hurricane - in the western Caribbean, which would threaten nations in the region with glancing blows, and possibly even landfalls. The most likely window for such a development would be between Monday through Thursday. While a real possibility, this is not an official forecast. Official forecasts for a Tropical Cyclone have not yet been issued. Stay tuned to the National Hurricane Center, and check back with us frequently for more updates.
Ciel
Original Update
Another area in the west Caribbean is now marked by the National Hurricane Center as having a 30% chance for development, with it likely hanging around in the same spot for a few days.
Systems in the West Caribbean this time of year are notoriously difficult to predict, as seen by this week for those in central Florida. Those in south Florida did receive a lot of rain, and once again the most likely scenario is another near tropical or tropical storm coming near or across parts of Florida mid to late next week, which means more rain for either Central or South Florida.
Another area just east of the Caribbean may be worth watching next week as well as it drifts toward the Central Caribbean.
Neither of these systems are currently being tracked as invest areas, but the one in the west Caribbean likely will be soon.
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weathernet
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The disturbance in the W. Carbibean has been upgraded to an invest and is 96L. Pressures are being reported as "falling", and there already appears to be at least a weak low to mid level circulation. Though quite early, the EURO ( from 0Z ), UK, , and the models to tend to slowly develop this system and eventually move it generally to the north. This a.m. BAM models thus far move the system more westward.
Recon is scheduled to investigate this area tomorrow ( Sat. )
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weathernet
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This morning, 96L appears to be centered close to 13N & 82W, but appears to be experiencing upper level shear and suddenly most models also seem much less "bullish" on development than were shown in yesterday's runs. In addition, today's recon has been cancelled as well. It would appear that if the circulation center were perhaps just north of Honduras rather than its appearant location, than upper level conditions would seem more conducive for development. Though pressures are low throughout that entire area, there may be just enough of a developed center of circulation, that a second center forming farther towards the northwest would appear unlikely. If the current appearant center of 96L were to move westward and disipate over land, than perhaps such a reformation of center and lower pressure could establish itself just north of Honduras.
Other thought on possible reason for 96L having difficulty developing ( and is just speculation ) is perhaps surface inflow issues also exist on the west side of circulation partially due to being a fairly small and tight area of low pressure, and in conjunction with its proximity to the Nicaragua coastline. No doubt there have been many past W. Caribbean storms that have developed in this same general vicinity with little difficulty.
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WeatherNut
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Its looking much better today and in turn the has upped it to a "high" chance of development. The problem hasn't been dry air from the west but dry air over the Caribbean, but that is changing with upward motion increasing
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Born into Cleo (64)...been stuck on em ever since
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cieldumort
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Recon has closed off a fairly well defined circulation, with maximum surface winds so far at or above 30MPH (and possibly approaching 40 - we will see in subsequent passes).
With this additional information now at hand, Invest 96L has a very high chance of being officially upgraded to 18, and possibly directly to Rina, by tonight.
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Carfax16
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already upgraded to a depression
Edited by danielw (Sun Oct 23 2011 11:11 PM)
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danielw
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URNT12 KNHC 232203
VORTEX DATA MESSAGE AL962011
A. 23/21:40:10Z
B. 15 deg 47 min N
081 deg 54 min W
C. NA
D. 19 kt
E. 143 deg 65 nm
F. 226 deg 20 kt
G. 142 deg 66 nm
H. EXTRAP 1008 mb
I. 23 C / 212 m
J. 25 C / 214 m
K. 23 C / NA
L. NA
M. NA
N. 35 / 1
O. 0.02 / 8 nm
P. AF306 01KKA INVEST OB 17
MAX FL WIND 36 KT SW QUAD 20:55:30Z
MAX OUTBOUND FL WIND 27 KT NW QUAD 21:56:50Z
SLP EXTRAP FROM BELOW 1500 FT
MAX FL TEMP 25 C 143 / 47 NM FROM FL CNTR
Edited by danielw (Sun Oct 23 2011 10:41 PM)
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danielw
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Interest in Southern Florida will need to pay close attention to TD 18 over the next few days as models diverge/ split on the forecast track. See second paragraph below.
TROPICAL DEPRESSION EIGHTEEN DISCUSSION NUMBER 1
NWS National Hurricane Center MIAMI FL AL182011
500 PM EDT SUN OCT 23 2011
THE HURRICANE HUNTER AIRCRAFT INVESTIGATING THE LOW PRESSURE AREA
OVER THE WESTERN CARIBBEAN SEA HAS FOUND A WELL-DEFINED CENTER AND
SATELLITE IMAGERY INDICATES THAT THE DISTURBANCE HAS ACQUIRED JUST
ENOUGH CONVECTIVE ORGANIZATION FOR THE SYSTEM TO BE CLASSIFIED AS A
TROPICAL DEPRESSION. THE INITIAL WIND SPEED IS SET AT 30 KT...
BASED ON A FEW BELIEVABLE 27 TO 28 KT SFMR WIND MEASUREMENTS. THE
DEPRESSION IS OVER WARM WATER BUT IN AN AREA OF MODERATE
SOUTHEASTERLY VERTICAL SHEAR WITH DRY AIR TO THE NORTH AND WEST.
THE ENVIRONMENT DURING THE NEXT COUPLE OF DAYS IS NOT FORECAST TO
BE CONDUCIVE FOR SIGNIFICANT STRENGTHENING...BUT SHOULD NOT BE
HOSTILE ENOUGH TO PREVENT THE SYSTEM FROM BECOMING A TROPICAL
STORM. THE OFFICIAL FORECAST IS JUST SLIGHTLY ABOVE THE
STATISTICAL/DYNAMICAL SHIPS AND LGEM GUIDANCE.
THE INITIAL MOTION ESTIMATE IS A SOMEWHAT UNCERTAIN 335/5. THE
CYCLONE IS FORECAST TO TURN WESTWARD DURING THE NEXT DAY OR
TO THE SOUTH OF A MID-LEVEL RIDGE OVER THE EASTERN GULF OF MEXICO.
THE UNCERTAINTY IN THE TRACK FORECAST INCREASES GREATLY IN THE 3
TO 5 DAY TIME FRAME. THE AND MODELS MOVE THE SYSTEM
INLAND OVER CENTRAL AMERICA IN A FEW DAYS. CONVERSELY...THE
HWRF...ECMWF...AND UKMET MODELS TAKE THE CYCLONE INTO THE
SOUTHEASTERN GULF OF MEXICO IN THE LATTER PART OF THE FORECAST
PERIOD IN RESPONSE TO AN EASTWARD SHIFT OF THE ABOVEMENTIONED
RIDGE. THE OFFICIAL FORECAST LIES BETWEEN THESE EXTREMES...
AND IS CLOSE TO THE TRACK.
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danielw
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Tropical Depression 18 has been upgraded to Tropical Storm Rina.
Rina is forecast to remain in the Western Caribbean for the next 36 to 48 hours. Models split on the storm motion after that.
Intensity forecasts indicate TS Rina may intensify to a Cat 1 Hurricane while in the Western Caribbean, over the next 48 hours.
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