dem05
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I found this exerpt of the TWD to be fairly insightful/interesting...
THE TRACK GUIDANCE IS TIGHTLY CLUSTERED
THROUGH 36 HR...THEN SOME SPREAD OCCURS. THE HWRF AND THE SHALLOW
AND MEDIUM MEAN LAYER BAM MODELS FORECAST A MORE NORTHWARD MOTION
TO A 120 HR POSITION NEAR THE YUCATAN CHANNEL...WHILE THE REMAINDER
OF THE GUIDANCE TAKES THE CYCLONE TO BELIZE AND THE SOUTHERN
YUCATAN PENINSULA. THE HWRF SHOWS THE STORM DISSIPATING DURING THE
FORECAST PERIOD...WHICH MAY ACCOUNT FOR ITS MORE NORTHWARD FORECAST
TRACK. THE TRACK FORECAST IS DOWN THE MIDDLE OF THE REMAINDER OF
THE GUIDANCE AND IS SIMILAR TO THE PREVIOUS FORECAST.
Traditionally, I have been used to seeing the models demonstrating a more westward biased when they see the system as weaker (shallower)...and a more northward biased when a stronger storm is forecast. In this case, the models are apparently showing the opposite (Per this discussion blurb). I'd love to hear opinions on this, but my take is that a stronger system in this circumstance will strengthen the low/mid level ridge to the north and result in a more westward course....WIll be interesting to see if the other models move more toward the BAMS, BAMM, and the HWRF (Yucatan Channel)...or to see if the exact opposite will occur. Overall, the pattern does look like Dean revisited...but I'm sure there will be some interesting tracking differences in the coming days.
Edited by dem05 (Fri Aug 31 2007 11:39 PM)
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typhoon_tip
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Quote:
Some of the models are showing a more northern track after four days. Is it possible the high won't build as far as it is supposed to or that
there will be a weakness somewhere? I suppose it is still too early to tell. It looks like it is headed straight for Belize but a lot can
happen in four days so I do not think the Gulf Coast should dismisss the storm just yet.
Anything is possible, first off...
Much of this HAS to be probabilistically derived.
That being said, I refer you back to post # 77637 of this thread.
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Storm Hunter
Veteran Storm Chaser
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Loc: Panama City Beach, Fl.
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***just a side note... *** Update your bookmarks 
Was launched tonight from cira at colostate (RAMSDIS Online)
http://rammb.cira.colostate.edu/ramsdis/online/index.asp
Beta Test of the New RAMSDIS Online
Welcome to the new version of RAMSDIS Online. We're in the process of transferring all the products to the new streamlined version, starting with all the tropical products.
Using new coding for faster access to products on the web site....
--------------------
www.Stormhunter7.com ***see my flight into Hurricane Ike ***
Wx Data: KFLPANAM23 / CW8771
2012== 23/10/9/5 sys/strms/hurr/majh
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flahurricane
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Loc:
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Satellite imagery of the TD looks impressive over the last few hours. I wouldn't be surprised if the intermediate advisory upgrades it to a tropical storm.
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typhoon_tip
Meteorologist
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Posts: 576
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Quote:
I found this exerpt of the TWD to be fairly insightful/interesting...
THE TRACK GUIDANCE IS TIGHTLY CLUSTERED
THROUGH 36 HR...THEN SOME SPREAD OCCURS. THE HWRF AND THE SHALLOW
AND MEDIUM MEAN LAYER BAM MODELS FORECAST A MORE NORTHWARD MOTION
TO A 120 HR POSITION NEAR THE YUCATAN CHANNEL...WHILE THE REMAINDER
OF THE GUIDANCE TAKES THE CYCLONE TO BELIZE AND THE SOUTHERN
YUCATAN PENINSULA. THE HWRF SHOWS THE STORM DISSIPATING DURING THE
FORECAST PERIOD...WHICH MAY ACCOUNT FOR ITS MORE NORTHWARD FORECAST
TRACK. THE TRACK FORECAST IS DOWN THE MIDDLE OF THE REMAINDER OF
THE GUIDANCE AND IS SIMILAR TO THE PREVIOUS FORECAST.
Traditionally, I have been used to seeing the models demonstrating a more westward biased when they see the system as weaker (shallower)...and a more northward biased when a stronger storm is forecast. In this case, the models are apparently showing the opposite (Per this discussion blurb). I'd love to hear opinions on this, but my take is that a stronger system in this circumstance will strengthen the low/mid level ridge to the north and result in a more westward course....WIll be interesting to see if the other models move more toward the BAMS, BAMM, and the HWRF (Yucatan Channel)...or to see if the exact opposite will occur. Overall, the pattern does look like Dean revisited...but I'm sure there will be some interesting tracking differences in the coming days.
There is likely some "inside" info they are leaving out. This is a complex question, actually.
In general, your observations are correct for the longer view. There is a tendency for weaker systems to align more westerly...
However, there is also a bit of an on-going anomaly in the respective layers at those time intervals in question; namely, the low-level and mid-level steering fields. The ridge is in the process of migrating west through the Gulf by the time this system reaches the western Caribbean... If "Felix" beats the ridge to those longitudes, there is some prospect that the low level steering would be more NW if it is a weaker system. Why? Because the steering level will tend to turn W at low levels last for retrograding low-latitude ridges.
The modeled steering fields do have a W component nearing the longitudes of the western Caribbean at the time intervals in question; however, the low-level (H850) is pointing NW, and when combined with Beta Drift, and a weaker system, that could easily mean a northerly position.
However, if a stronger system is there, integrating more in the deeper layers where the majority of mass is blowing almost due W, this resumes a westerly course.
You have to look at the actual pattern for each individual circumstance. In this case, the complexities of all are dictating a bit of an anticorrelary correction need.
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Storm Hunter
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well... unless recon is out there tonight, which i don't think they are until the morning... and sats are going into Eclipse from about 400utc to about 600utc... we really want know anything about TD6 for a couple more hours... and last few images from sats, showed the cloud tops were warming a little, so looks like the round of covection has sustained itself for a bit, but will see what it looks like in the morning...
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www.Stormhunter7.com ***see my flight into Hurricane Ike ***
Wx Data: KFLPANAM23 / CW8771
2012== 23/10/9/5 sys/strms/hurr/majh
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dem05
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Loc: Port Charlotte, FL
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I see...Last time (During Hurricane Dean) I payed more attention to the Water Vapor loops...This time, since the overall pattern seems to be "straight forwardly similar to Dean"...I'm gonna be watching each of the models more closely this time...from run to run. Just to see if I learn something new.
Hmmm...Does seem to me that the (9/1 0Z) is maybe having even a bit more trouble in maintaining TD6 than the 18Z run did...With that said, the new run is just a smidge further to the north. Of no significance really though.
The 0Z NAM, which is not one of the reliable models, appears to be pointing toward the Yucatan Channel on this run...Compared to a Nicaragua/Hondoras option that was identified in the 18Z.
Maybe there will be a bit more northward bias in the 00Z model runs...Will have to wait for the reliable models to finish their runs...Let the windshield wiper action begin...
Link to and Models: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/index_carib.shtml
Edited by dem05 (Sat Sep 01 2007 12:36 AM)
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typhoon_tip
Meteorologist
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Also, keep in mind, there are larger scale teleconnectors that suggest the more westerly track; BUT, teleconnectors can change, doing so slower than a point-in-time model output. What that really means is that there are on-going permutation-based possibilities in these matters.
Edited by typhoon_tip (Sat Sep 01 2007 12:42 AM)
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dem05
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Loc: Port Charlotte, FL
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Hmmm...Well, the 06Z runs of the BAMS, BAMM, BAMD, and the Clipper (Climo and persistance model...not a reliable model) should be out soon. Mean time, I am very interested in seeing the 00Z when it comes out. The 00Z has moved north a fair amount in the last run. Indicating a landfall about 50 miles north of whare Dean came in, but south of Cozumel. General tendancy is toward a subtile recurvature at the end of the track. The UKmet is much faster (probably too fast)...and a bit more concerning if it remains persistent in future runs. It is now showing a recurvature toward the NW and NNW into the central Gulf. With the coming in at 00Z about 50-100 miles north of the at 00Z...if the moves northward on the 00Z...Then the 11PM forecast track will be totally outside the guidance envelope (With particular respect to the "reliable models") on the southern end and a track update may be required at 5AM... We should know more about that soon...Like I mentioned earlier...the Windshield wipers are on! 
In general, the compromise of the BAMS, BAMM, and BAMD have not bee bad in recent years as far as a consensus track...If they do not shift further north on the 06Z runs...the combination of them, the , the UKMET, and someothers may place a new track more towards Cozumel (a touch south of there)...with the as a Southern Outlier and the as an extreme southern outlier...But the does not get as much attention for its track as the other big models.
Edited by dem05 (Sat Sep 01 2007 02:41 AM)
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scottsvb
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Dem, for the 11pm track, the does the track based on the 18Z runs and which model they prefer compared to the satellite data they review.
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Storm Hunter
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Dem05, i think the 00Z has been out for a bit... hasn't converted it yet..
but i think this is it below... looks to me it moved just a tad?
https://www.fnmoc.navy.mil/wxmap_cgi/cgi...;dtg=2007090100
*go here, https://www.fnmoc.navy.mil/wxmap_cgi/cgi-bin/wxmap_DOD_area.cgi?area=ngp_namer
its not doing to well with the system though... keeps it weak.
Edited by Storm Hunter (Sat Sep 01 2007 02:46 AM)
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dem05
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Yes, that is correct Scott. For the 5AM advisory package, they will be looking at the 00Z information as well as the information for the 06Z on the BAM suite. If the trend persists with the 06Z ...Everything else is placing the 11PM advisory Forecast on the Southern extent and/or outside of the guidance envelope...as such, we may see a subtle move in the forecast track to the north on days 4 and 5 in the 5AM advisory...
Mean time, speaking of satellites, the satellite eclipse is over for tonight. TD6 must have sped up a bit this evening, cuase it is significantly further to the west. That coordinate estimate for 2AM advisory probably should have been further west, but they were flying a bit blind with no recon or satellite. That is, unless TD6 is suffering from easterly shear and the mid level center has been displaced to the west...which I seriously doubt. Not their fualt at the for this though...as I mentined a minute ago, they were flying a bit blind tonight and that was an excellent extrapolation on their part for the 2AM coordinates.
Edited by dem05 (Sat Sep 01 2007 03:09 AM)
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Storm Hunter
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06z BAMS are all together now in the norther Yucatan... one north of Cancun and others just to the south... but does look like a few more models are well north of the 11pm track, so there may be a SLIGHT adjustment made, or they may hold on it... also just glanced at lastest few sat shots... some weak shear? Looks like it fixing to pass close to that island soon! Also notice now the front/weak low is now just off shore of me (PC, Fl) from that front that is over the SE.
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www.Stormhunter7.com ***see my flight into Hurricane Ike ***
Wx Data: KFLPANAM23 / CW8771
2012== 23/10/9/5 sys/strms/hurr/majh
Edited by Storm Hunter (Sat Sep 01 2007 03:27 AM)
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dem05
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I'd been watching for that BAM package to come out...I notice that has basically updated all the other models as well. In that I also notice that the ensemble (CONU) is now well north of the 11PM as well...In fact, it is the southern outlier compared to BAM, , , HWRF, and UKMET...but it is also north of where Dean slid on shore and it has a greater northern component than Dean did.
I will not model monger as things will likely windshield wiper a bit over time...but for now, the philosophy for track has changed from a westward mover into Belize to one that may be moving in an almost NW heading on approach to the Yucatan...As such, the models are currently seeming to center around the area south of Cozumel (around the BAMD)...Actually, right about where the CONU is pointing as of 6Z. Coincidently, if TD6 is gonna be a stronger storm (i.e. hurricane), I found it interesting that it moved north once again on this run of the BAMD...closer to the BAMM and the BAMS.
At 5AM, I would suspect that the track change will be subtle due to many changes in the overall appearances of the models. I wouldsay the 5AM will be smack in the middle between the 11PM and the 06Z BAMD track. Justin case the models do windshield wiper back.
Also interesting to note that none of the models have decided to grab the reigns and make TD6 ahurricane...Even though it is forecasted...and quite possible that it will do so. I wouldn't put 100% stockinto the major global models just yet.
Edited by dem05 (Sat Sep 01 2007 03:42 AM)
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Storm Hunter
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hmm.. i think we have a TS now?
Storm Location
Date: Sep. 1, 2007 6Z
Coordinates: 12.2N 61.2W
Wind Speed: 35 knots
MSLP: 1006 mb
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0704 UTC SAT SEP 1 2007
TROPICAL CYCLONE SIX (AL062007) 20070901 0600 UTC
...INITIAL CONDITIONS...
LATCUR = 12.2N LONCUR = 61.2W DIRCUR = 280DEG SPDCUR = 16KT
LATM12 = 11.6N LONM12 = 57.9W DIRM12 = 281DEG SPDM12 = 14KT
LATM24 = 11.3N LONM24 = 55.4W
WNDCUR = 35KT RMAXWD = 30NM WNDM12 = 30KT
CENPRS = 1006MB OUTPRS = 1014MB OUTRAD = 150NM SDEPTH = D
RD34NE = 40NM RD34SE = 0NM RD34SW = 0NM RD34NW = 40NM
--------------------
www.Stormhunter7.com ***see my flight into Hurricane Ike ***
Wx Data: KFLPANAM23 / CW8771
2012== 23/10/9/5 sys/strms/hurr/majh
Edited by Storm Hunter (Sat Sep 01 2007 04:08 AM)
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dem05
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5AM Discussion...They must be picking up on the potential for model windshield wiper action with Felix based on their updated forceast path...or, and without meaning this with anegative tone...they are coming off of a high confidence with Dean and they may want to watch that Mother Nature does not chomp some finger tips down there...
For the very first time that I can think of, the has absolutely abandoned the models here. In fact, they went as far to say that they dropped the forecast farther south, even though the whole model group generally moved north. The , which they identify as the southern model package is in fact...north of the 11PM forecast as well as even farther north of the 5AM forecast. I'm pretty surprised, but I also know that they know what they are doing...Unfortunately, the discussion did not mention their reasoning for going southward in any way that really backs the models, or why they are using independant thought...but if you look at the site for the 00Z runs and Clark's page of the model plots for 06Z...I am sure you will agree. No knock on them, but they sided against conventional practice here. With that said, they must be really on to something....Therefore, in Belize, please note that they have Felix approaching Category 3 strength before landfall...Something to consider in preparations if the track does hold up. Mean time, further north in the Yucatan...you guys know the Hurricane drill too...
Edited by dem05 (Sat Sep 01 2007 05:26 AM)
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CoconutCandy
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Good Morning All. TD-6 has been upgraded to Tropical Storm Felix at the 5am advisory.
The convection continues to expand with continuing organization of the feeder bands, several of which are now in evidence in the western semi-circle, with more beginning to take shape in the S and SE quads.
Also, the deep convection has maintained very cold cloud top temps of -70 to -80, all the while continuing to organize better, implying that gradual intensification is underway. And upper level outflow is quite good and only improving.
From 's 5am discussion:
"THE CONVECTIVE PATTERN OF THE CYCLONE HAS CONSOLIDATED SOMEWHAT OVERNIGHT...WITH THE COLDEST CLOUD TOPS NOW FOCUSED ON A CLUSTER VERY NEAR THE ESTIMATED LOW-LEVEL CENTER LOCATION ... AND THE ADVISORY INTENSITY IS RAISED TO 35 KT ... SO THE DEPRESSION IS UPGRADED TO TROPICAL STORM FELIX."
Moving a little faster now, it seems that Felix is destined to be, like Dean, a 'Straight Shooter' type system, with high confidence in taking it directly towards Central America, with a possible landfall in Belize nearing Cat 3 strength.
Shear is expected to remain low, so an even stronger hurricane wouldn't be out of the question by the end of the forecast period. Remember that mid and long range *intensity forecasts* have a much greater degree of error than do those regarding location, and all factors appear to be favorable, certainly not inhibitive.
All in all, it would appear that Felix could become a quite 'respectable' Caribbean Hurricane, which fortunately, should not effect US interests.
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