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Atlantic Tropical Action 2012 - Part II


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Why-- so you can experience a lame, semi-tropical piece o' crap? Hardly seems worth it.

;-) Better than the early autumn zephyr I am currently experiencing...hmm, maybe not. Pretty awesome day here.

No tropical weather in the Atlantic other than a continuously circling fish, another red blob fish and no solar weather while we approach the solar max.

It will change, of course, and all will be well.

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;-) Better than the early autumn zephyr I am currently experiencing...hmm, maybe not. Pretty awesome day here.

No tropical weather in the Atlantic other than a continuously circling fish, another red blob fish and no solar weather while we approach the solar max.

It will change, of course, and all will be well.

:D

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TROPICAL WEATHER OUTLOOK

NWS NATIONAL HURRICANE CENTER MIAMI FL

800 AM EDT WED OCT 3 2012

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

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL

STORM NADINE...LOCATED ABOUT 445 MILES WEST-SOUTHWEST OF THE AZORES.

A TROPICAL DEPRESSION APPEARS TO BE FORMING ABOUT 1000 MILES WEST OF

THE CAPE VERDE ISLANDS...AND IF THIS TREND CONTINUES ADVISORIES

WILL BE INITIATED LATER TODAY. THIS SYSTEM HAS A HIGH CHANCE...90

PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS

AS IT MOVES NORTHWESTWARD AND NORTHWARD AT 10 TO 15 MPH.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE

NEXT 48 HOURS.

$$

FORECASTER AVILA

post-138-0-79528200-1349271096_thumb.jpg

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Models have a piece of the trough that's gonna sweep Nadine and 96L leaving behind from the tail end of the front and dropping SW towards the W Atlantic (close to the Bahamas). Ridging and marginal conditions aloft are shown in the models, with the Euro showing a stronger vorticity center slowly moving W to SW. I'm not expecting much at the moment, but if it can survive for a week or so, the area of disturbed weather could consolidate in a slow brew near home.

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On a related note, there's a distinct planetary wave, especially shown aloft, associated to the MJO currently crossing the Pacific. Models are now in agreement of a resurrection of the MJO into phase 8 in about a week. This could translate to favorable cyclogenesis conditions in the EPac starting 5-6 days from now, and around 10-15 days from now in the Atlantic.

Time sensitive

ALL_emean_phase_full.gif

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On a related note, there's a distinct planetary wave, especially shown aloft, associated to the MJO currently crossing the Pacific. Models are now in agreement of a resurrection of the MJO into phase 8 in about a week. This could translate to favorable cyclogenesis conditions in the EPac starting 5-6 days from now, and around 10-15 days from now in the Atlantic.

Time sensitive

ALL_emean_phase_full.gif

This would be a time where I'd just be cautious with interpreting the RMM signal. There's a way to "dissect" the RMM signal into it's 3 individual components, which we call the fractional contribution of each variable onto the RMM. Matt has this running live on his webpage. If you look at today's fractional contribution, OLR accounts for 18.5%, U850 accounts for 35.6% , and U200 accounts for 45.9% of the full combined PC. Therefore, U200 appears to be the main dog in town and taking a look at the time-longitude plot below of 200 hPa zonal winds averaged from 5S-5N, the strongest area of upper-level diveregence is centered about 150E, hence the West Pac. Unfortunately, this signal is propagating westward and not associated with the MJO. However, the GFS wants to take this westward propagating signal and create and eastward propagating one.. Which may or may not verify, I'm not sure. It's just hard to believe a model-derived forecast of the MJO at the moment.

u.200.anom.30.5S-5N.gif

That being said, I have created an MJO index using space-time filtered 850VP ( I also have 200VP, but it's a very weak MJO signal!). The MJO phase space diagram below shows there is still some MJO signal, which is strongest in the low-levels and is currently already located over the East Pacific. That being said, I do have some feelings there might be some elevated chance for genesis over the Caribbean-GOM once this signal propagates into RMM phases 2-3... however since the signal is weak, I'm not overly too confident.

filterMJO_vp850_Phase.png

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My CFS projections tell a similar story. You can see that the MJO is forecast to flare up a bit in phase 8 moving into phase 1. Notice that from ~10/23 onward, the model is fairly confident (if you measure confidence by ensemble agreement) of a noticeable MJO.

One advantage to this particular RMM index is that it only factors in variables that are on the MJO timescale and which propagate eastward. Therefore, the intersection of other equatorial modes is much less likely to create a false MJO signal.

post-1078-0-20283100-1349275518_thumb.pn

In a Hovmoller sense, the CFS is forecasting fairly significant (1.5 sigma) MJO OLR anomalies around 10/23 as well.

http://www.atmos.albany.edu/student/macritch/plotfilteredhovs_trans_normalized.php?lat=75S75N

I doubt we'll see any significant MJO activity before 10/23, though, and this corresponds well with what Mike and the GFS are predicting.

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Keep an eye on this feature expected to dive southward over the next 24-48 hours, the global models are hinting that it might try to develop just north of Puerto Rico by day 3.

Yep, that's the feature I was talking about a few posts back. New Euro is bullish, developing a TC in the Bahamas. By the way, the same Euro run is now leaving Nadine's associated vorticity back to where it is now by day 5

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Yep, that's the feature I was talking about a few posts back. New Euro is bullish, developing a TC in the Bahamas. By the way, the same Euro run is now leaving Nadine's associated vorticity back to where it is now by day 5

Sorry I missed your post earlier. Even though both the GFS and ECMWF hang the vorticity around the Bahamas in the longer range, I think its more likely it gets picked up by the mid-latitude trough or sheared out rather than pose a legitimate US threat.

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Yeah, something N of Puerto Rico in October is essentially fish food. Can't believe this is the best we have to discuss on 03 Oct. The garbage continues.

Although for this time of the year, anything N of Puerto Rico climo favors recurving, 0z Euro and now the 18z GFS favor a SW continuation track into the NW Caribbean...but shear from the building deep layered ridge in the GOM proves too strong before it shears out the budding disturbance. 12z Euro digs the East coast trough a bit deeper, and snatches the better organized disturbance to the NE.

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Although for this time of the year, anything N of Puerto Rico climo favors recurving, 0z Euro and now the 18z GFS favor a SW continuation track into the NW Caribbean...but shear from the building deep layered ridge in the GOM proves too strong before it shears out the budding disturbance. 12z Euro digs the East coast trough a bit deeper, and snatches the better organized disturbance to the NE.

Fish or sheared-- climo prevails. Oct disturbance N of Puerto Rico = crap.

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Nadine single handedly boosted TNA temps, which are near record warm for this time of the year. Not that it matters much, since the region is almost dead until next season. Any activity in the basin will probably have to wait for the 2nd half of the month, other than any subtropical spawns or the Bahamas thingie.

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Finally something shows in the long range modeling (12z GFS). Remember, the long range models won't verify verbatim, but they could be signaling a change in the pattern for the 2nd half of the month.

Most Ensemble show a storm somwhere near Cuba at 384hrs. The MJO should be coming into a more active phase at that time.

A mid-late October storm in the Caribbean is almost a yearly event, although it is stronger some years than others depending on shear and interaction with land.

So I guess there is one more chance for a major hurricane. If we miss that, we're stuck with the C- season we have now.

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Bahamas Low: code yellow 10%

It looks like a small re-curve, but depending how slow/fast it moves it could be a potential threat.

ZCZC MIATWOAT ALL

TTAA00 KNHC DDHHMM

TROPICAL WEATHER OUTLOOK

NWS NATIONAL HURRICANE CENTER MIAMI FL

800 PM EDT SAT OCT 6 2012

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

1. A WEAK LOW PRESSURE SYSTEM LOCATED ABOUT 250 MILES EAST OF THE

SOUTHEASTERN BAHAMAS IS PRODUCING A LARGE AREA OF DISORGANIZED

CLOUDINESS AND SHOWERS. DEVELOPMENT...IF ANY...OF THIS

DISTURBANCE IS EXPECTED TO BE SLOW TO OCCUR. THIS SYSTEM HAS

A LOW CHANCE...10 PERCENT...OF BECOMING A TROPICAL CYCLONE

DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE

NEXT 48 HOURS.

$$

FORECASTER BROWN

NNNN

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Don't hold your breath. Anything forming in or crossing that area in October has about a 1% chance of making news in the USA.

The only exception I can think of is Hazel 1954, which formed in the Caribbean and moved N, passing a bit W of where that lemon is and hitting the Carolinas as a strong 'cane. But that was highly unusual.

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