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SEPT 28, 2005 /1:30AM - SPECIAL UPDATE

         STRONG WAVE WITH CLOSED CIRCULATION SOUTH OF JAMAICA BUT TIME MAY BE RUNNING OUT

Latest imagery shows that the strong wave in the Caribbean south of Jamaica does have a low level circulation,
but the convection associated with it has diminished -- more than the typical diurnal cycle would produce.
The intense convection of earlier today has weakened, but this is a typical diurnal variation.

The NHC is still planning a RECON - if needed -- for later today. They also issued the below
statement earlier this evening:

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUN SEP 27 2005

...SPECIAL FEATURE...

CENTRAL CARIBBEAN TROPICAL WAVE IS ALONG 77W S OF CUBA WITH A
1009 MB LOW ALONG THE WAVE NEAR 15N. VISIBLE SATELLITE PICTURES
SHOW BANDING FEATURES DEVELOPING ON THE N SIDE OF THE WAVE WITH
SYMMETRIC OUTFLOW. THIS AREA HAS THE POTENTIAL TO BECOME A
TROPICAL CYCLONE WITHIN THE NEXT 36 HOURS. A SLOW MOVEMENT TO
THE WNW IS LIKELY... PLACING THE SYSTEM IN THE W CARIBBEAN LATE
WED/EARLY THU. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION
IS FROM 15N-19N BETWEEN 72W-76W...AND FROM 17N-20N BETWEEN 76W-80W.

they then just updated with:

...SPECIAL FEATURE...

CENTRAL CARIBBEAN TROPICAL WAVE IS ALONG 77W/78W S OF 20N WITH A
1009 MB LOW ALONG THE WAVE NEAR 16N MOVING WNW NEAR 12 KT.
FAIRLY WELL DEFINED LOW/MID LEVEL CIRCULATION WITH AN UPPER
LEVEL HIGH LOCATED JUST TO THE E NEAR 16N74W. THIS AREA HAS THE
POTENTIAL TO BECOME A TROPICAL CYCLONE WITHIN THE NEXT DAY OR
TWO AS THE UPPER LEVEL WINDS BECOME MORE FAVORABLE. ASSOCIATED
DEEP CONVECTION HAS DIED DOWN TONIGHT BUT IS EXPECTED TO
REGENERATE LATER THIS MORNING.

________________________________________________________________
In addition, the NHC did run a few of the specialized tropical cyclone forecast models earlier
today and again this evening (see below).

BUT -- looking at the latest trends on water vapor imagery, there is dry air and very possibly some increased
westerly shears expected to reach into the northwest Caribbean over the next few days. The 00Z GFS no longer
really develops the system, instead opting for a broad area of lower pressure and 'wet weather'. I'm now of the
belief that unless the system develops into a Tropical Depression SOON -- and a Tropical
storm by Thursday -- it may not do either at all!

The reasoning for this is that tropical storms/hurricanes tend to develop a self -sustaining environment -- which
will only then, IMHO, be sufficient to fend off the overall weather pattern now being predicted by the global models.
So if the system doesn't manage to develop into a storm within 48 hours, the predicted synoptic scale pattern may very
well prevent it from doing so.

This kind of reminds me of the 'system' back in mid August that looked so promising to develop into a Hurricane just
northeast of Puerto Rico, and then just failed completely as shear from nearby upper level cyclones inhibited any
further development. Although, a week later it suddenly started to develop -- and ended up becoming a storm
named Katrina. (DO NOT mis-interpret what I just said -- this is NO Katrina -- I'm really just referring to how
so many systems' that 'look' on the verge of intensifying -- suddenly end up falling apart.)

Unless there is a major development, the next full update will be in the late afternoon
Wednesday on the WEATHER UNDERGROUND blog ONLY.

I will no longer be posting 'routine' updates on storms until they become a serious threat to the
U.S. -- or if I wish decide to post a 'general interest' type Diary entry.
(This includes financial, socio/economic and the always popular Polical view of the world commentary

So if you desire to see what's going on in the tropics of sifnificant interest, just visit my
blog there, or subscribe the RSS feed - or better yet, subscribe to my Enhanced Weather
Update Service which includes a lot of 'eductional material I never post on any of the blogs!
For 7 cents a day you can't go too far wrong. br>

Steve Gregory
WeatherInsite
Free RSS wXunderground Feed
For Info on my other FEE Based Services

Water Vapor image shows a closed off upper level cyclone over Florida, and a deep layered TROF over the eastern Caribbean. Between the two, is an anticyclonic flow over the strong tropical wave along 78W with a closed low and mid level circulation near 16N/78W. However -- the deep convection associated with the tropical wave has really decreased tremendously, and, at the same time, the upper low over Florida is pulling down some very dry air into the Gulf of Mexico -- with some of it already nosing into the far northwest Caribbean near the Yucatan channel. So while there are a lot of good reasons for this system to develop into a tropical cyclone -- if it doesn't 'hurry up' -- the environment may not be all that conducive for it in another 48 hours. Outflow is very good in all quadrants -- but it is not at all certain it will last long if the upper low over Florida doesn't move out to the northeast. The GFS, in fact -- brings it eastward -- and this would impose a westerly shear in the north and northwest quadrants, and bring along dry westerly flow across the storm in a couple of days. The 00Z evening model runs track the (presumably) soon to be cyclone to the northern Yucatan by the end of the week. The Intensity forecast brings the system up to a tropical storm and possibly minimal hurricane -- thought the effects of crossing the Yucatan can be seen at 72-96 hours. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
SEPT 27, 2005 / 10:00 AM CDT

         STRONG WAVE LIKELY NEXT T.C. - HEADING FOR NW CARIBBEAN


The strong Tropical Wave
in the Caribbean has slowed down from 15Kts to under 10Kts, and in so
doing, has become considerably more organized in it's overall structure and concentration of
convection -- which has now taken on a circular pattern to the southeast of Jamaica.  The very broad
area of low pressure that dominated the central Caribbean yesterday, as confirmed by numerous
surface reports, appears to have become better defined and is a closed circulation.  
Satellite imagery and surface reports indicate the most likely surface circulation center is near
14.5N/75.1W.  The very latest Buoy report from at 15N/75W indicated winds went from  
ENEat midnight,  to N by 8AM CDT, & just in the past hour, have swung around now to WSW
indicating the passage of a closed low pressure center very close that location.  

The models runs - for some 'unknown reason' have not been run since yesterday afternoon- but the
GFS model continues to develop this system into a cyclone in the NW Caribbean by Thursday.  The
track shown by the GFS has it passing across the far northern end of the Yucatan now, and then
reaching the Gulf of Mexico on Monday. As is typical of newly forming systems, and the GFS
handling of them - each model run bounces back and forth on the track -- and without the aid of the
specialized tropical storm models -- it's rather difficult to determine which track is most likely.  Since
the odds appear much higher today that the system will become a Depression -- once that happens,
the various specialized models WILL become available again.  At the moment, NHC indicates it
may send a RECON out on WED to investigate the system.  But I wouldn't be too surprised to see
that moved up in time depending on the next 6 hours of satellite and surface reports.

There are 2 other significant tropical waves over the central and western Tropical Atlantic -- neither
one of them pose any significant signs of development in the near term.

The next full update will be Wednesday morning -- unless conditions warrant an earlier update

NOTE for Dkos readers: Because I am only permitted 1 Diary entry per day -- and ONLY
if there really is an important reason to add or update to the latest information - if time
permits, I will try simply editing the existing Diary, and add the latest info at the
beginning.  So you might want to check back in the afternoon or evening just to 'see'.

In any event - if you post questions, please check back late at night (I live in Chicago-
11PM?)since I will try and reply to any comments/questions at that time.  I just can't
do it during the day.  If there is a big storm going on, I most likely will not have any time
to reply at all.  But if there is a big storm in progress, the cheapest (free) way to see what
I'm posting is on the Weather Underground - again the once per day limitation. The fastest
and most complete source of my uddates (and cheapest) is tto subscribe to my Enhanced Update
Service.  (One time plug only-please don't send thDkos police after me - I scare off easily)

Steve Gregory        
WeatherInsite
Free RSS wXunderground Feed
For Info on my other FEE Based Services

 

The surface chart from 1AM CDT indicated a low level circulation near 14.5N / 74.5W -- but pressures
are not especially low in the area.  This has shown, however, great continuity from yesterday's estimated
position near 14N/73W.      

By 12Z this morning, or 7AM CDT - the combined surface OBS and IR Image clearly implies a sharp wave,
if not closed low, approaching 75W.  HOWEVER - with the report within  the past hour from the very reliable
Buoy located at 15N/75W showing winds going form due N to WSW leaves no doubt that there is a closed
low at the surface,  and, very well centered on the now circular shaped cloud formation.   Based on the last
24 hours, the system's low level circulation is moving W-WNW (280°) at about  less than 10Kts.

The latest HI-RES VISIBLE image shows deep convection in the eastern semi-circle, and not that far from the low level circulation center.  There is also signs of cirrus outflow as well.

This highly enhanced water vapor image shows a strong concentration of deep moisture associated with
convection, taking on a circular shape surrounding the primary area if developing low and mid level circulation.

As luck would have it, the polar orbiter just missed getting a full
85Ghz scan of the system this AM - however, the very dark brown
areas - both north, and SE of where the the lower level circulation
has been identified -- indicates very strong convection has developed
this morning. in association with this system.  Whether this is just
a 'diurnal cycle' burst of convection remains to be seen.

The outflow from the system is very good in all quadrants but the east -- being slightly enhanced by
the upper low now over Florida.  The closed anticyclone over Puerto Rico yesterday, then over
Hispaniola last night, appears to have begun to weaken, or possibly has dissipated entirely.
Whether the very strong wave has managed to develop it's own anticyclonic flow above the center is
not immediately apparent, except.....

The Shear chart from this morning shows the system has now moved into an area of much lower
shears 5Kts-8kts, and there is a very significant chance this system could intensify into
a depression within 12 -24 hours.  If it does NOT, then it is unlikely that it has managed to form it's
own anticyclone/high pressure system - atop it's lower level circulation center.

 

The steering layer flow forma developing system is generally in a WNW direction, though at a
significantly slower speed than yesterday.  The slower forward motion is also somewhat more
conducive or indicative of a system that is more likely to be intensifying than simply remaining
as a tropical wave.

Originally posted to WeatherInsite on Tue Sep 27, 2005 at 09:06 AM PDT.

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Comment Preferences

  •  re (none)
    Why the caps in the title?

    Steve Holt says "Steve Holt!"

    by cookiesandmilk on Tue Sep 27, 2005 at 09:09:54 AM PDT

  •  Thank you (4.00)
    I'm learning a great deal from reading your diaries!
    •  Agreed (none)
      I greatly appreciate your input.

      ...despite those nets of tuna fleets...we thought that most of your were pretty sweet...

      by moira977 on Tue Sep 27, 2005 at 09:49:38 AM PDT

      [ Parent ]

    •  Hard to think of anything more newsworthy (none)
      in the past month than these 'canes.  And your scientific presentation takes the weather and climate discussion out of the hands of TV blowdrieds and into the realms of public safety, public health and science policy, where we lay dKossacks need to wisen up.

      Steve, if you're plugged into intra-(meteorological) community topic areas like global warming, defunding of NOAA/NWS/NHC, outsourcing/privatising of weather forecasting (to wit, Sen. Santorum's shilling for Accuweather), please consider bringing us up to speed when/if the tropics go quiet.

      Tx!

  •  I heard on the weather this morning (none)
    that there is a lot of cold air that is heading down to the gulf. Will this have an effect on any storms that might be brewing. They said the weather is going to be a lot cooler and it would help thwart off any possible hurricanes that may come our way. Is this a factor?
    •  cold air = no hurricanes (none)
      Yep -- we are quickly approaching time (may even be there...) when the seasonal change will bring cooler and more importantly, much drier air further south.  Most storms in October don't make it to the U.S. -- the winter like pattern that starts to impose itself on us steers these system away from the U.S., and then the enormous wind shear associated with the strong westerlies and  the jet stream' make it impossible for a storm to even form.  By mid to late November -- there simply are no storms at all in the Atlantic basin  or the eastern Pacific.

      Steve Gregory WeatherInsite

      by WeatherInsite on Tue Sep 27, 2005 at 09:57:15 PM PDT

      [ Parent ]

  •  so i guess (none)
    dKos has a weather section now? for big storms i understand the urgency, but for this, at this point?
    •  If you're not interested (4.00)
      Don't read it.  It's one of the more charming aspects of DKos.  You only have to read what you want to read.
    •  Dailykos is full of weather groupies -- who knew? (none)
      Hi my name is Annie and I am a Weather Groupie....

      Reminds me of the tribue special The Weather Channel had when John Hope passed away that included Bill Cosby fondly reminissing watching The Weather Channel in hotel rooms and being a big fan of Dr. Hope.

      I must confess though that my lifelong interest in weather comes about because my dad was a "hurricane hunter" back in the 50s and later was an expert in acid rain. Also my dad's younger brother is a meterologist.

    •  At this point? (none)
      What point might that be? Oh yes, at this point during the hurricaine season, which is not over yet.

      For every complex problem there is a simple solution that is completely wrong.

      by MarkInSanFran on Tue Sep 27, 2005 at 11:35:31 AM PDT

      [ Parent ]

    •  It's fascinating and (none)
      is in keeping with the spirit of the "citizen journalist."  As in:   Go to the source and get your own weather news, unfiltered.

      Plus it gives us an idea of the resources that are available to our government and are not always properly used!

      Fitting in all ways for dkos, I say.

    •  To post or not to post--that's a FOR REAL question (none)
      If you noticed, I have not posted anything since the big storms until this SIGNIFICANT wave appeared, and I have spent no time discussing the other 3 tropical waves across the Atlantic basin.  Nonetheless, if people would prefer I only post my Weather updates only for named or really BIG storms -- that's fine.  I probably will end up doing that anyway.

      This reminds me of a very real world issue with private forecast services.  Is it really worth the time and $$$ for a daily, 7x24 forecast service when in fact, the NWS does perfectly fine (and free) whenever the weather is just plain old 'nice'.  In fact, they do fine even in bad weather.  But because the NWS needs to be `everything for everyone', for certain specialized applications and operations, there are certain types of weather events they just don't do as well as the private sector can.  If that was not true, then there would not be a private sector.

      Seriously, who needs to pay for a forecast that says 'clear skies and no wind today' when you can get that all for free in a zillion different places?
      And this includes places like  Denver where that is broadly speaking, the weather out there  about 95% of the time.

      Personally, I hoping this thing self destructs - I've got a lot of other things to catch up on -- this 'disturbance' is really disturbing me too.  :-)

      Steve Gregory WeatherInsite

      by WeatherInsite on Tue Sep 27, 2005 at 09:51:03 PM PDT

      [ Parent ]

  •  Hmmm, (none)
    I know Steve Gregory is very good at what he does but when I run the GFS dynamic model, I don't see the development he talks about.  The National Hurricane Center also doesn't seem very alarmed about this system.  Here are the relevant sections of the Tropical Weather Outlook:

    CENTRAL ATLC TROPICAL WAVE IS ALONG 44W/45W S OF 21N WITH A 1010 MB LOW ALONG THE WAVE NEAR 14N MOVING W 15 KT. BROAD HIGH AMPLITUDE WAVE WITH A LOW/MID LEVEL TURNING ALONG THE AXIS NEAR 14N. WAVE IS BENEATH S UPPER FLOW AROUND THE BASE OF AN UPPER HIGH LOCATED TO THE E OF THE WAVE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 60/75 NM OF LINE 15N39W-17N42W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 17N-23N BETWEEN 44W-49W.  

    and:

    CARIBBEAN...
    THE AREA IS SPLIT BETWEEN THE UPPER TROUGH EXTENDING ACROSS CUBA NEAR 22N82W OVER THE NW CARIBBEAN TO N OF THE GULF OF HONDURAS NEAR 17N85W AND AN UPPER RIDGE ANCHORED OVER HISPANIOLA COVERING THE CARIBBEAN W OF 80W. TROPICAL MOISTURE IS ABUNDANT OVER MOST OF THE CARIBBEAN GENERATING CLUSTERS OF SCATTERED
    SHOWERS/ ISOLATED THUNDERSTORMS OVER THE AREA E OF 65W WITH THE GREATEST INTENSITY ENHANCED BY THE TROPICAL WAVE ALONG 74W/75W.

    •  I was surprised by this too... (none)
      ...but the Trop. wx outlook seems a bit more cautious.

      A VIGOROUS TROPICAL WAVE CENTERED A COUPLE HUNDRED MILES SOUTHEAST
      OF JAMAICA IS PRODUCING CLOUDINESS AND THUNDERSTORMS OVER MUCH OF
      THE CENTRAL CARIBBEAN SEA. THIS SYSTEM HAS BECOME BETTER ORGANIZED
      TODAY... AND UPPER-LEVEL WINDS HAVE ALSO BECOME MORE FAVORABLE FOR
      A TROPICAL DEPRESSION TO DEVELOP DURING THE NEXT DAY OR SO. AN AIR
      FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT IS SCHEDULED TO
      INVESTIGATE THE SYSTEM TOMORROW... IF NECESSARY.  INTERESTS IN
      JAMAICA... THE CAYMAN ISLANDS... AND IN THE NORTHWESTERN CARIBBEAN
      SEA SHOULD CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM OVER THE
      NEXT FEW DAYS AS IT MOVES WEST-NORTHWESTWARD AT ABOUT 10 MPH.

      I guess it depends on the forecaster issuing the discussion or outlook.  Given the buoy data, there is evidence of surface circulation, and if the upper level winds get their act together, this could strengthen significantly, given the incredible heat content and convection over the W Carribean.

      In any case, my guess is we'll see 2-3 more hurricanes this year, maybe 1 more major, and we'll run out of names, up to TS Beta.

      People should not be afraid of their governments. Governments should be afraid of their people.

      by viget on Tue Sep 27, 2005 at 09:54:09 AM PDT

      [ Parent ]

    •  Recon scheduled for tomorrow (4.00)
      They have scheduled two recon flights for tomorrow, and potentially 6-hour fixes after that, so obviously their interest in this system is increasing.

      NOUS42 KNHC 271630
      WEATHER RECONNAISSANCE FLIGHTS
      1230 PM EDT TUE 27 SEP 2005
      SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
      VALID 28/1100Z TO 29/1100Z SEP 2005
      TCPOD NUMBER.....05-122

      I. ATLANTIC REQUIREMENTS
      1. SUSPECT AREA CENTRAL CARRIBEAN
      FLIGHT ONE FLIGHT TWO
      A. 28/1800Z A. 29/0500Z
      B. AFXXX 01HHA INVEST B. AFXXX 0219A CYCLONE
      C. 28/1345Z C. 29/0000Z
      D. 17N AND 80W D. 18N AND 81.5W
      E. 28/1700-2300Z E. 29/0400-0800Z
      F. SFC TO 10,000FT F. SFC TO 10,000FT
      2. OUTLOOK FOR SUCCEEDING DAY: BEGIN 6 HRLY FIXES AT 29/18Z
      IF SYSTEM DEVELOPS.

    •  Is it or isn't it of interest (none)
      The below is NHC's latest Tropical Discussion:

      TROPICAL WEATHER OUTLOOK
      NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
      1030 PM EDT TUE SEP 27 2005

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

      A TROPICAL WAVE OVER THE CENTRAL CARIBBEAN SEA IS PRODUCING
      CLOUDINESS AND A FEW THUNDERSTORMS NEAR JAMAICA AND HAITI... AND
      OVER ADJACENT CARIBBEAN WATERS. EVEN THOUGH THE THUNDERSTORM
      ACTIVITY HAS GREATLY DECREASED THIS EVENING... UPPER-LEVEL WINDS
      ARE EXPECTED TO BECOME MORE CONDUCIVE FOR DEVELOPMENT... AND THIS
      SYSTEM COULD BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR
      TWO. AN AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT IS SCHEDULED
      TO INVESTIGATE THIS SYSTEM TOMORROW... IF NECESSARY. INTERESTS IN
      THE NORTHWESTERN CARIBBEAN SEA AND ADJACENT LAND AREAS SHOULD
      CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM DURING THE NEXT FEW
      DAYS AS IT MOVES WEST-NORTHWESTWARD AT 10 TO 15 MPH.

      ****
      My job is to forecast weather, and mitigate risk for clients who near to hedge their operation - and to that end - everything is probabilities.  NHC's job is that plus Public Relations. A real conflict of interest at times.

      NHC started running the special hurricane models for this 'system' this morning, shortly after I posterd the morning diary.

      Half the models make this into a hurricane in 72-96 hours, 2 of them develop it and then kill it.

      I could wake up tomorrow and find the system has broken down and will never do anything - or, about as likely, we may see a Tropical Depression.  

      Steve Gregory WeatherInsite

      by WeatherInsite on Tue Sep 27, 2005 at 07:56:53 PM PDT

      [ Parent ]

  •  Heading to NOLA? (none)
    If this storm is on a northeastern track, that could put it heading towards New Orleans, right?  Is that what you are trying to get at with this update?
  •  hey kos how about a weather slug on front page (none)
    where weatherinsite can post

    "90% of everything is crud" - Sturgeon's Law.

    by newore on Tue Sep 27, 2005 at 10:19:27 AM PDT

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