ralphfl
Weather Master
Reged: Mon
Posts: 435
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I still see wnw and believe that is the 11pm direction also
Edited by ralphfl (Sun Aug 26 2012 10:36 PM)
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Ed Dunham
Meteorologist & CFHC Forum Moderator
Reged: Sun
Posts: 2107
Loc: Melbourne, FL
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Convective blooming makes it difficult to get a good fix on the movement from satellite, but it sure did slow down. Radar and Recon would suggest a decoupled system but it can certainly recover if the convective increase continues. Currently in this area there is not much in the way of a hint regarding the mid level steering for a decoupled system but in this case an old trick provides a clue. Water vapor loop shows the dry air moving up from the SSW under the influence of an upper level low over the Yucatan Peninsula.
Don't rely on the latest forecast bulletin to determine current movement because some of the content is made up early and the movement in the bulletin is usually a 12-hour average - a method that can sometimes get you in trouble. Using the 00Z and 03Z positions from the Forecast bulletin, Isaac has moved about 25 miles - which is a near-term speed of about 7 knots (over 3 hours) and not the 12 knots that is stated in the bulletin. This is why in meteorology the image is always better than the words. Check out the position fix at 06Z and you'll get a better feel for the short term movement.
Cheers,
ED
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sara33
Weather Guru
Reged: Wed
Posts: 135
Loc: St. Pete,
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Ed, Can you post the link to the 06Z please that you are referring to. Thanks!!
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Ed Dunham
Meteorologist & CFHC Forum Moderator
Reged: Sun
Posts: 2107
Loc: Melbourne, FL
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I guess that I should have clarified the position location in the 2am (06Z) Intermediate bulletin.
Cheers,
ED
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dolfinatic
Weather Guru
Reged: Fri
Posts: 103
Loc: St. Petersburg, Fl
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I only see a more northerly component to the movement mainly NW at this time and considerably slower as well. Radar shows the northerly movement cant argue with that. Curious to see the 5 am disco. But probably wont change much. like to keep continuity.
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Bloodstar
Moderator
Reged: Mon
Posts: 397
Loc: Georgia Tech 33.78N 84.40W
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Quote:
I guess that I should have clarified the position location in the 2am (06Z) Intermediate bulletin.
Cheers,
ED
Well, it looks like the latest fix from Dropsonde into the eye is 24.93N 83.52W Which seems to indicate the center has relocated significantly north. (50 miles?)
I'm not sure what 50 miles would do to the model runs, but I hope outside of Louisiana and Mississippi are still paying close attention, because Tomorrow morning might be a shock.
The Hurricane hunters are also picking up a significant swath of 50 - 60 Knot winds aloft in the northeast quadrant. But so far those winds don't appear to be reflected down at the base.
Satellite shows the center fix is right smack in the middle of the most intense convection.
This could be a problem.
--------------------
TD/TS/HU/MH
19/18/0905 <- My prediction (2013 Predictions)
01/01/00/00 <- Year Totals
http://blog.bloodstar.org
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cieldumort
Moderator
Reged: Mon
Posts: 1047
Loc: Texas 30.40N 97.80W
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Here is a snapshot of Mission 24 into Isaac clearly showing the center reformation noted above by Bloodstar.
Tropical Storm Isaac has always been dogged by multiple centers, but it is likely that a core has so far not been able to establish not only because of competing vortices existing since its inception, but also because deep, central convection was never quite that persistent, pervasive and pronounced, having been held in check by repeated injections of dry air from its west and south, land interruptions, and bouts of modest shear.
These inhibiting factors are lessening overnight tonight, and should Isaac finally create a stable core, and provided he remains over water, rapid intensification will become very possible at times during the next 72 hours, likely starting as soon as the present.
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cieldumort
Moderator
Reged: Mon
Posts: 1047
Loc: Texas 30.40N 97.80W
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Pretty conclusive Vortex Message coming out of the new center:
A. Time of Center Fix: 27th day of the month at 5:12:00Z
B. Center Fix Coordinates: 24°55'N 83°31'W (24.9167N 83.5167W)
B. Center Fix Location: 112 miles (180 km) to the WNW (283°) from Key West, FL, USA.
C. Minimum Height at Standard Level: 1,351m (4,432ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 34kts (~ 39.1mph)
E. Location of the Estimated Maximum Surface Wind: 89 nautical miles (102 statute miles) to the SW (217°) of center fix
F. Maximum Flight Level Wind Inbound: From 356° at 31kts (From the N at ~ 35.7mph)
G. Location of Maximum Flight Level Wind Inbound: 99 nautical miles (114 statute miles) to the SW (221°) of center fix
H. Minimum Sea Level Pressure: 990mb (29.23 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 16°C (61°F) at a pressure alt. of 1,527m (5,010ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 25°C (77°F) at a pressure alt. of 1,512m (4,961ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 17°C (63°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 2 nautical miles
Remarks Section:
Maximum Flight Level Wind: 62kts (~ 71.3mph) in the northeast quadrant at 5:24:00Z
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BabyCat
Weather Guru
Reged: Thu
Posts: 150
Loc: New Orleans, La.
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When will there be an updated model run?
If we're lucky, we will see this new information reflected in 12Z model runs (later this morning).
Ciel
Edited by cieldumort (Mon Aug 27 2012 02:54 AM)
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ftlaudbob
Storm Chaser
Reged: Tue
Posts: 724
Loc: Fort Lauderdale,Fl 26.11N 80.12W
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Quote:
When will there be an updated model run?
The different models all run at different times.
--------------------
Survived:
Gloria,Bob,Katrina,Wilma and a bunch of tropical storms.
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MikeC
Admin
Reged: Sun
Posts: 2798
Loc: Orlando, FL 28.49N 81.47W
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There is an eye (albeit elliptical) forming in Isaac now, so it may get to hurricane strength today.
NOAA 2 recon is finding this as well (see https://twitter.com/HRD_AOML_NOAA )
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MikeC
Admin
Reged: Sun
Posts: 2798
Loc: Orlando, FL 28.49N 81.47W
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Also in Florida, beware, there are still a few nasty bands over the state. One will likely come up from Okeechobee into Central Florida, and Cape Canaveral/Volusia is about to get a bad band as well, another one will near Jacksonville soon too.
Edited by MikeC (Mon Aug 27 2012 07:04 AM)
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Hawkeyewx
Weather Analyst
Reged: Sun
Posts: 53
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Satellite shows increasing banding surrounding the center this morning, as opposed to just a fuzzy blob like late yesterday, which definitely indicates the surface and mid-level centers have finally made the connection and slow intensification has commenced. Landfall should be tomorrow, though, so there isn't a ton of time for any ridiculous strengthening. Gulf coast residents are fortunate Isaac's organization phase was delayed so long.
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WesnWylie
Weather Guru
Reged: Sat
Posts: 155
Loc: 32.59N 96.70W
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After going more NW earlier this AM, Isaac seems to be heading W/NW once again over the last 45 minutes. Unfortunately, the circulation will be out of range of the Tampa radar in a few hours. It does look like it is still trying to organize, though.
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MikeC
Admin
Reged: Sun
Posts: 2798
Loc: Orlando, FL 28.49N 81.47W
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Recon still showing it moving northwest, at this time I'd take that until a visual eye actually shows. I'm not sure if the northwest trend will continue or not, but it has for the past few hours.
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Thunderbird12
Meteorologist
Reged: Thu
Posts: 644
Loc: Oklahoma
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Isaac is finally starting to look like something that could become a hurricane, with at least a partial eyewall evident in the long-range radar and confirmed by recon. Outflow seems to be improving as well. The crucial time for intensification looks like it will be tonight, which is when several model solutions (such as the ) have been implying that most of the strengthening (if any) will occur. It still looks like the environment will become quite favorable, but large storms with ill-defined inner cores like Isaac typically do not undergo rapid intensification, so steady intensification seems like the best bet.
If Isaac can significantly tighten up its circulation in the next 6-12 hours, then something more than steady intensification would be possible. Odds are against it.
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Hawkeyewx
Weather Analyst
Reged: Sun
Posts: 53
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Despite the increasing organization, Isaac is still not doing much. The latest recon report shows no increase in wind and a pressure still stuck a bit below 990 mb. We may have to wait until tonight to see steady strengthening. Heck, it may never strengthen much.
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MikeC
Admin
Reged: Sun
Posts: 2798
Loc: Orlando, FL 28.49N 81.47W
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Central Florida is getting a few very nasty bands coming through, Tornado in Christmas/Chuluota area crossing into Seminole now.
The 11AM advisory has WNW in one spot, and NW in another, movement in the movement section is 305, which is barely considered northwest, but it's splitting hairs.
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Rasvar
Weather Master
Reged: Fri
Posts: 566
Loc: Tallahassee, Fl
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Quote:
The 11AM advisory has WNW in one spot, and NW in another, movement in the movement section is 305, which is barely considered northwest, but it's splitting hairs.
I guess that's what happens when you are trying to figure out where the real center is. Isaac really does seem to have the same level of ability to organize his core that I have to organize my desk - not much.
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Jim
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WesnWylie
Weather Guru
Reged: Sat
Posts: 155
Loc: 32.59N 96.70W
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NHC: "THE LACK OF STRENGTHENING APPEARS TO TO BE DUE TO THE
LARGER-THAN-AVERAGE WIND RADII...WHICH HAVE YET TO CONTRACT
INWARD...ALONG WITH THE PERIODIC ENTRAINMENT OF DRY MID-LEVEL AIR
FROM THE EASTERN SEMICIRCLE INTO THE INNER-CORE REGION. UNTIL THE
DRY AIR MIXES OUT...EROSION OF THE INNER-CORE CONVECTION WILL
LIKELY CONTINUE UNTIL ISAAC APPROACHES THE NORTH-CENTRAL GULF COAST
IN ABOUT 24 HOURS."
This system reminds me of Hurricane Alex back in 2010, regarding the issue with the strengthening wind field (or lack thereof). It also had trouble getting above a Tropical Storm until closer to landfall. It made it to a Cat. 2 with winds of 105mph; however, it's pressure was 946mb - that of a Major Hurricane.
Added at 10:34 AM CDT : Here's a good summary of Alex by the NWS in Corpus Christi: http://www.srh.noaa.gov/crp/?n=hurricanealex
Edited by WesnWylie (Mon Aug 27 2012 11:34 AM)
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