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#96L 's remnants now consolidating into a compact well-defined Low over the Bahamas. May head towards Bermuda eventually.
Days since last H. Landfall - US: Any 38 (Michael) , Major: 38 (Michael) Florida - Any: 38 (Michael) Major: 38 (Michael)
 


General Discussion >> Other Storm Basins

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CoconutCandy
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Tropical Cyclone Formation Alert in the East Pac
      #85606 - Thu Jun 11 2009 06:58 AM

Looks like there is a fair chance for tropical development in the Mid-Easten Pacific.

Technically, this forum (Other Basins) is supposed to be reserved for Depressions and Better (no invests). But, since it's still quite early in the season, and nothing much else is going on, I thought it'd be interesting to see what Invest 91E is up to.

91E has been pretty disorganized the past few days, with little chance of development. But recent trends look much more promising. Nice, deep, sustained convective bursts have been occuring for quite some time and quite near the center of circulation, too, and this has led to the formation of a small, CDO-like feature.

>> "SHOWER ACTIVITY ASSOCIATED WITH THE BROAD AREA OF LOW PRESSURE LOCATED ABOUT 900 MILES SOUTH-SOUTHWEST OF THE SOUTHERN TIP OF BAJA CALIFORNIA CONTINUES TO SHOW SIGNS OF ORGANIZATION. THIS SYSTEM HAS THE POTENTIAL TO BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR SO.

Furthermore, the latest ( 0400Z, Wednesday ) East Pac TWD (tropical weather discussion) goes into a little more detail ...

>> ...SPECIAL FEATURE... A LOW PRESSURE SYSTEM CENTERED NEAR 12N118W HAS IMPROVED IN ORGANIZATION OVER THE PAST SEVERAL HOURS. SATELLITE IMAGES SHOW THE DENSE OVERCAST EXPANDING WITH THE ESTIMATED CLOUD SYSTEM CENTER EMBEDDED IN THE OVERCAST.

>> MEANWHILE ... THE SYSTEM IS ALSO MORE DETACHED FROM THE ITCZ BASED ON ITS OVERALL CLOUD STRUCTURE. RECENT SCATTEROMETER PASSES REVEAL SW 20-25 KT WINDS OVER THE SE QUADRANT AND ENHANCED 20 KT NE TRADES OVER THE N SEMICIRCLE. THERE IS A MEDIUM CHANCE...30 TO 50 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

Here's a Scatterometer image obtained early Wednesday, still showing the banding in the NE quad.



Earlier, non-linear banding arcs were observed in the NE quad. But that has since diminished, only to be replaced with tight, inner banding features much nearer to the LCC center. The CDO has persisted nicely for the past 12 to 18 hours, indicative of sustained, deep layered convection below the CDO canopy.

Because of all these factors, NHC has just upped their 'chances of development' with this system to orange; 30-50 % chance of TC cyclogenesis, and the Joint Typhoon Warning Center (JTWC), based here at Pearl Harbor, has just issued a "Tropical Cyclone Formation Alert" (ATCF) which just went up on the NRL website. Have a looksie.

On the other hand, if the thunderstorms are NOT sufficiently sustained over a period of time, or if they just simply 'fight' amongst themselves for the available precipitable water vapor in the area, and do NOT organize, then no pressure falls will occur. A big blob of convection does not for a tropical cyclone make.

We've all seen instances were, what looks to be so 'promising' during the usual diurnal convective overnight flareup , just 'poofs', like so much cotton candy, upon the dawning of the new day, with little more than cirrus debris blowing off in all directions, from the area where the convective giants did battle the night before.

Cyclones that form around 120W or so and west are of much more significance for Hawaii, standing a much better chance of holding together as they steadily approach the islands from the ESE, all things being equal.

Just have a sort of 'educated hunch' that the East and Central Pacific will see a little more storms this year than normal, compared to the Atlantic, due to a possible mild to moderate ENSO event that still is taking shape, and the fact too that, so far, the upper winds across the Atlantic basin are decidedly not favorable for cyclones, at least not at this time. But all that can change in a hurry, so be astute to sudden changes.

( NOTE: Please see my recent post under "Hurricane Ask/Tell" El Nino Event Taking Shape, for the scoop on a possible El Nino 'event', now shaping up in the equatorial pacific. )

Thanks to all those who follow along and post replies. It's 'our' site, after all, so I encourage everyone to make the most of it, which means contributing often.

We've got a long season ahead of us, and our many 'lurkers' are encouraged to join in on the discussions. Your input is valuable to us, and makes for a better site for everyone. We want to hear from you!



Edited by CoconutCandy (Fri Jun 12 2009 08:09 PM)


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MichaelA
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Re: Tropical Cyclone Formation Alert in the East Pac [Re: CoconutCandy]
      #85607 - Thu Jun 11 2009 09:44 AM

They are waiting for vis sat pics and more mw analysis before declaring it a TD. The IR loop seems to indicate a LL circulation, but it doesn't appear to be symmetrical and not entirely under the convection burst over night. I'm expecting a rather unusual season in both basins.

--------------------
Michael
2018 Actual: 15/7/2


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CoconutCandy
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Tropical Cyclone Formation Looking Less Likely [Re: MichaelA]
      #85608 - Thu Jun 11 2009 05:09 PM

Hmmm ... You're right. Looks to be not very well organized today. Animated visible imagery suggests that there might be several minor circulation centers, in addition to the main one. Microwave imagery doesn't look too pretty, either.

I think the 'window of opportunity' could be closing soon. Even if the convection consolidates tonight (not out of the question) and a TD/storm does form, it's quite likely to be short-lived.

The SST overlay reveals a very complex pattern. One of the strangest I've ever seen. There is a *strong* thermal gradient (tightly packed isotherms) of high amplitude to the NE of the LLC *and* much cooler waters just to the west.



So it now seems to me that development to TD is rather questionable, and even if it does occur, will be short-lived as the SST's in the area just don't really support much development of this system, if at all.

But I concur with Michael that it could be a rather 'unusual season' shaping up for all the basins east of the dateline. More on that later, which I will post to another forum.

Edited by CoconutCandy (Fri Jun 12 2009 07:45 PM)


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CoconutCandy
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TC Formation? Not! [Re: CoconutCandy]
      #85610 - Fri Jun 12 2009 07:39 PM

Nope. It just ain't gonna' happen.

Just as I had surmised, the "broad area of low pressure" and attendant (rather disorganized) thunderstorms never quite got it's act together, due, presumably, to the less-than-favorable SST's in it's path.

For a day or two, it had a shot at it. But a glance at the above SST chart reveals that it was *briefly* over a 'pocket' of warmer SST's with higher oceanic heat content, but essentially corralled by appreciably cooler waters.

But the combination of the disorganized convective activity and, especially, the presence of several LLC's in addition to the main LCC precluded the possibility of this broad low from consolidating sufficiently while it was still over the 'hot pocket'.

I was surprised, in fact, that the JTWC / NRL had *reissued* the Tropical Cyclone Formation Alert, and that the NHC had upped their assessment to Red, greater than 50% probability of genesis, based on the 'new' LLC that had reformed to the NE of the previous LLC, despite rather cool-ish SST and increasingly hostile environment.

All agencies, NHC / NWS TPC / JTWC / NRL, have since dropped the invest as no longer plausible and we now return you to your regular programming. Beautiful tradewind weather this weekend for Hawaii, and hopefully for Florida, too!


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