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Isaac lashing the Lesser Antilles; TD 10 forms

By: Dr. Jeff Masters, 3:06 PM GMT on August 22, 2012

Tropical Storm Isaac is lashing the entire Lesser Antilles chain of islands with heavy rains this morning, and the winds will be on the increase this afternoon as the storm heads west at 19 mph. Isaac is still a weak and disorganized tropical storm, but that is changing. The Hurricane Hunters are in the storm, and have thus far found no increase in the storm's top surface winds, which remain near 45 mph. In their 7:44 am EDT center fix, an Air Force Reserve aircraft measured a rather unimpressive center pressure of 1007 mb, and top winds at their 1000 foot flight altitude of 56 mph. The plane did not observe an eyewall trying to form, and recent microwave satellite images also show no signs of an eyewall forming. A large area of dry air to the north of the storm, as seen on water vapor satellite loops, continues to interfere with development, and it is unlikely Isaac will become a hurricane today. Satellite loops, however, show that Isaac has developed a Central Dense Overcast (CDO) of high cirrus clouds, the hallmark of a developing storm. These clouds have very cold cloud tops, indicating that the updrafts creating them are quite strong. An analysis of upper level winds from the University of Wisconsin CIMSS shows that upper-level outflow is becoming well-established to the southwest and northwest, but outflow is restricted on the southeast side. A large clump of heavy thunderstorms several hundred miles southeast of the center continues to compete for moisture, and is interfering with the low level inflow and upper level outflow of the storm. The intensification rate of Isaac will increase if the storm is able to integrate this clump of heavy thunderstorms into its circulation, which satellite loops this morning suggest is now beginning to happen. Radar imagery from Barbados and Martinique show plenty of heavy rain showers, mostly on the south side of Isaac where it is moister, but little spiral banding. Hurricane hunter missions are scheduled for Isaac every six hours, and a NOAA hurricane hunter research aircraft will also be in the storm, with missions scheduled every 12 hours. The NOAA jet is first scheduled to fly into the storm on Thursday afternoon, to do a large-scale dropsonde mission to aid model forecasts.


Figure 1. Morning radar image of Isaac taken from the Barbados radar at 10:15 am EDT. Image credit: Barbados Weather Service.

Intensity forecast for Isaac
The latest 8 am EDT run of the SHIPS model shows that wind shear is moderate, 10 - 15 knots, but is expected to relax by this evening to a low 5 - 10 knots. Ocean temperatures have increased to a very warm 29°C, and the storm is now over waters with a high total heat content. The lowering wind shear and warm waters should allow the storm to wall off the dry air that has been interfering with development, and also allow the storm to integrate the thunderstorm clump on its southeast side that has been interfering with low level inflow and upper level outflow. It will take some time for the increase in organization to result in an increase in Isaac's winds, and I still expect top winds of 45 - 60 mph in the Lesser Antilles Islands this evening when the core of the storm moves through. On Thursday, when Isaac will be in the Eastern Caribbean, conditions should be favorable enough to allow steady strengthening to a Category 1 hurricane. The 11 am EDT wind probability forecast from NHC predicted a 47% chance that Isaac will become a hurricane by Friday morning, and a 16% chance it will be a Category 2 or stronger hurricane then. This is a reduction in the odds given in the 5 am advisory.

Impact of Isaac on the Islands
The entire Lesser Antilles Islands chain will have a three-day period of heavy weather Wednesday through Friday. Sustained tropical storm-force winds extend out about 50 miles to the north of the center and 30 miles to the south, so an 80-mile wide swath of the Lesser Antilles will potentially see tropical storm-force winds of 45 - 60 mph this Wednesday evening. Guadaloupe, Antigua and Barbuda, Dominica, Montserrat, and St. Kitts and Nevis at highest risk of these winds.

Winds in St. Croix in the Virgin Islands will likely rise above tropical storm force on Thursday morning, and the south coast of Puerto Rico should see tropical storm-force winds by Thursday afternoon. The San Juan airport may be able to stay open Thursday afternoon and evening, but I think it is more likely they will be forced to shut down.

On Thursday night, heavy rains and tropical storm-force winds should arrive on the southern coast of the Dominican Republic, and all airports in the D.R. will probably be closed on Friday. Rainfall amounts of 8 - 12 inches will likely affect the Dominican Republic Thursday through Saturday, creating dangerous flash floods and mudslides.

Isaac is potentially a very dangerous storm for Haiti, where 400,000 people still live outside underneath tarps in the wake of the 2010 earthquake. Heavy rains from Isaac will begin on Friday morning in Haiti, and last through Sunday. Rainfall amounts of 8 - 12 inches are possible, which will be capable of causing extreme flooding on the vegetation-denuded slopes of Haiti. It will be a major challenge to keep those Haitians living outside safe, if rainfall amounts of 5 - 10 inches occur.

Impact on Florida, Cuba, Jamaica, and the Bahamas
Florida, Cuba, Jamaica, and the Bahamas are all at high risk of receiving hurricane conditions from Isaac. The latest set of 06Z (2 am EDT) model runs for Isaac are fairly unified for the coming three days, showing a westward track to a point on the south coast of Hispaniola. All of the models then predict a more west-northwest track across the island and into eastern Cuba, as Isaac responds to a trough of low pressure over the Southeast U.S. Most of the models then predict a path for Isaac along the spine of Cuba, then into the Florida Straits off the coast of Miami by five days from now. A notable exception is our best-performing model, the ECMWF, which keeps Isaac just south of Cuba, and takes the storm more to the west between Jamaica and Cuba on Saturday, then into the Yucatan Channel between Mexico and Cuba by Monday. However, this model is keeping Isaac weaker than the other models, and thus predicts the storm will have a weaker response to the trough of low pressure over the Southeast U.S. If the official NHC intensity forecast is right and Isaac becomes a hurricane on Thursday, the more southerly track of the ECMWF is not going to verify, and Isaac will spend considerable time over Cuba on Saturday and Sunday. Where Isaac pops off the coast of Cuba will be critical in determining its future path and intensity. Some models predict a more easterly exit point, allowing Isaac to move up the east coast of Florida, and potentially make landfall in the Southeast U.S. The latest 06Z GFS model run predicts a more westerly track, which would potentially allow Isaac to move up the west coast of Florida towards Tampa. Keep in mind that the average error in a 5-day forecast is 260 miles. The two most recent runs of the GFS model, at 00Z and 06Z (8 pm and 2 am EDT), gave positions for Isaac that were about 250 miles apart--the earlier run putting the center near West Palm Beach, and the more recent run giving a location between Key West and Havana, Cuba. While passage over the high mountains of Hispaniola and then Cuba will substantially disrupt Isaac and probably reduce it below hurricane strength, the storm is quite large, and should be able to re-intensify once it emerges over the Florida Straits. Waters will be very warm, near 30°C, wind shear is predicted to be light, and forecasts of the upper-level winds show the possibility of an upper-level outflow pattern very favorable for intensification. If Isaac spends a day over water, that should be enough time for it to intensify into a Category 1 hurricane, and if the storm takes a longer 2-day track over water up either the east or west coast of Florida, a Category 2 or stronger storm is possible.

Isaac is a threat to affect Tampa during the Republican National Convention, August 27 - 30, and the official NHC forecast now has Tampa in the 5-day cone of uncertainly. The latest 11 am EDT wind probability forecast from NHC gives Tampa a 9% chance of receiving tropical storm-force winds for the 24-hour period ending on the morning of first day of the convention (Monday). I blogged about the climatological chances of a hurricane causing an evacuation of Tampa during the convention in a post last week, putting the odds at 0.2%. I put the odds of an evacuation occurring during the convention in the current situation at 3%.


Figure 2. Morning satellite image of Tropical Depression Ten.

Tropical Depression Ten forms in the Eastern Atlantic
The large tropical wave in the Central Atlantic, midway between Africa and the Lesser Antilles Islands, has become Tropical Depression Ten. The depression has an impressive amount of spin and heavy thunderstorm activity, as seen on visible satellite loops, and should be Tropical Storm Joyce by Thursday. None of the models show that TD 10 will be a threat to the Lesser Antilles Islands.

Which model should you trust?
Wunderground provides a web page with computer model forecasts for many of the best-performing models used to predict hurricane tracks. So which is the best? Well, the best forecasts are made by combining the forecasts from three or more models into a "consensus" forecast. Over the past decade, NHC has greatly improved their forecasts by relying on consensus forecast models made using various combinations of the GFS, GFDL, NOGAPS, UKMET, HWRF, and ECMWF models. If you average together the track forecasts from these models, the NHC official forecast will rarely depart much from it, and the NHC forecast has been hard to beat over the past few years. The single best-performing model over the past two years has been the ECMWF (European Center model). The GFS model has been a close second. You can view 7-day ECMWF and 16-day GFS forecasts on our wundermap with the model layer turned on. Ten-day ECMWF forecasts are available from the ECMWF web site. The European Center does not permit public display of tropical storm positions from their hurricane tracking module of their model, so we are unable to put ECMWF forecasts on our computer model forecast page that plots positions from the other major models. As seen in Figure 3, the HWRF and GFDL were well behind the ECMWF and GFS in forecast accuracy in 2011, but were still respectable. The BAMM model did very well at 4 and 5-day forecasts. The UKMET, NOGAPS, and CMC models did quite poorly compared to the ECMWF, GFS, GFDL, and HWRF. For those interested in learning more about the models, NOAA has a great training video (updated for 2011.)


Figure 3. Skill of computer model forecasts of Atlantic named storms 2011, compared to a "no skill" model called "CLIPER5" that uses just climatology and persistence to make a hurricane track forecast (persistence=a storm will tend to keep going in the direction it's current going.) OFCL=Official NHC forecast; GFS=Global Forecast System model; GFDL=Geophysical Fluid Dynamic Laboratory model; HWRF=Hurricane Weather Research Forecasting model; NOGAPS=Navy Operational Global Prediction System model; UKMET=United Kingdom Met Office model; ECMWF=European Center for Medium Range Weather Forecasting model; TVCA=one of the consensus models that lends together several of the above models; CMC=Canadian Meteorological Center (GEM) model; BAMM=Beta Advection Model (Medium depth.) Image credit: National Hurricane Center 2011 verification report.

I'll have a new post this afternoon.

Jeff Masters

Hurricane

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

1501. ncstorm
Quoting Chiggy:


NCstorm: But I think bloggers would serve well especially when storms gets close to CONUS to just browse couple of pages to see the new info. Most likely pertinent info would have been covered, especially the major model runs. THis would also speed up the blog page if folks stay away from posting same graphic 20 times :) Thx


I hear ya but people are coming in here between breaks at work and such (myself included)..reading through 1400 comments as this blog currently has would be quite difficult for some..I dont know what happen to courtesy on this blog especially when people should be able to come on here and ask for information and not get told to read back..not everyone can be on the blog all day but I get what ya saying..
1502. keisa90
Quoting Levi32:
12z JMA is a bit farther east, scraping along the Florida coast:



But isn't it further west than it was yesterday?
1503. FOREX
Quoting opal92nwf:
Chief Hurricane Expert at TWC just said that a relocation of the center is possible, and he said that the Euro showed this as well.


Saw that as well.
Now we get the second plane, the NOAA flight. It will be at a different flight level so we will see where they find a center. Also, the tail doppler radar data will go into the HWRF, so it should help that model with intensity, or lack of.
Quoting lottotexas:
on that link click on late and all the AP's are GFS ensambles


OK thanks. Didn't know that. :)
Quoting LargoFl:
..yes i trust him, its going to boil down to how strong that high is to the east


Yep, I saw him earlier today discussing the two scenarios on tv it was very easy to understand.
OH oops gave a plus to AnthonyJKenn before I read the last sentence of his post. I take it back.
1508. LargoFl
Pat..remember..its the Mayan doomsday
Quoting Gearsts:
But the old center has a lower pressure so shouldn't the new 1 get pull towards it?


The pressure in the old center had risen by a millibar. It seems to be losing ground.
RECON has not pout out a vortex message yet on "second fix" they are still traveling WSW-SW there seem possibly to be finding another LLCOC further WSW-SW near Dominica's SSW via the winds wait for more from RECON data to come through
1511. Patrap
If ya step back away from the Monitor like 3-4 feet, one can see the overall taking over easily,as it has been trying to shake out a CoC and has made good headway as to it this afternoon.



The WV Loop



Quoting nrtiwlnvragn:
Now we get the second plane, the NOAA flight. It will be at a different flight level so we will see where they find a center. Also, the tail doppler radar data will go into the HWRF, so it should help that model with intensity, or lack of.


Is the theory that the dry slot is the center now?
last frame on Ramdis show a more northwest movement.Any one agrees.?
Quoting opal92nwf:
Chief Hurricane Expert at TWC just said that a relocation of the center is possible, and he said that the Euro showed this as well.


Carl Parker is very good analizing the tropics.
1515. Levi32
Quoting Gearsts:
Levi help! We are lost with whats happening with the center.


Just wait a bit for Isaac to pull himself together. Due to the banding structure he literally can't reform too far south of 16N. The storm is still large and from the beginning has had next to zero westerly winds on the southern side, so he's struggling much the same way Ernesto did near the islands. It goes to show why the NHC original forecast for rapid intensification before Hispaniola was too aggressive.

We'll be able to find the center better later. The global models agree gradual deepening should occur, and they look much more favorably on Isaac than they did on Ernesto, so he isn't going to be a complete mess for long.
Quoting AnthonyJKenn:
And just to remind you, the NAM and NOGAPS and CMC models are just as consistent in moving Issac on the East Coast of FL, if not through the Bahamas towards the OBX and up the East Coast.

Plus, as Dr. Masters noted, the Euro was the most consistent model...but the GFS was a close second. And remember...it was the GFS, not the Euro, who got Debby right when everyone else was moving it towards S Cen TX as a Cat 1 hurricane.

Plus...nothing says that a stronger Issac moving to the S of Hispanola doesn't feel the trough sooner and make an even bigger recurvature N and busts FL from the S or SSW, then rides up the East Coast.

In any event, until the Hurricane Hunters are able to take more detailed readings of the atmosphere and that data is fed into the models, everything is just conjecture now. I believe I'll just rely on the NHC's judgment rather than some fly-by-night armchair I-wanna-play-a-meterologist-on-the-laptop wannabe.



Whatever guy.

CMC is pretty bad with hurricane tracks in general anyway, so I don't know why you'd even mention it. I look at it every update just because, but that's about it. It's almost never even remotely right.
1517. GetReal
IMO the "current" center of Isaac is becoming better organized at this moment... Look at the development over the last three frames.

Link
European model looks like this :



Link
1519. Patrap
Quoting LargoFl:
Pat..remember..its the Mayan doomsday



Yup


The Mayan Atlantic 2012 Swirl-a-Palooza
new center may be at
15.2N
61.0W
1522. Gorty
This Oct. I for one will be watching the models closely to see if it will bring a trough down (cold air) and the remnence of a TC up the coast. I really do not want a repeat of last year.
1523. WxLogic
Based on the latest fix... what I would call the "wooble" in the LLC has now stabilized and resume the original intended position and displacement outlined by NHC so it should be on track.
Quoting GetReal:
IMO the "current" center of Isaac is becoming better organized at this moment... Look at the development over the last three frames.

Link


Yeah def starting to get his act together, if he slows down anytime soon, we have a problem...
1525. hydrus
Quoting GetReal:
IMO the "current" center of Isaac is becoming better organized at this moment... Look at the development over the last three frames.

Link
Thunderstorms appear to be rotating around a center..That would indicate strengthening.
Quoting ncstorm:
Just able to check back..the Euro is taking a major into LA and look at Joyce on this run..


ISAAC is the main focus and for a good reason. But keep an eye on 10...
Quoting HurricaneHunterJoe:


Joe B 8-21-12



Joe B 8-22-12


Normally Joe just goes along with the Euro model so I want to see if he will shift his track to the west of Florida.
1528. FOREX
Quoting tropicfreak:


I CAN'T HEAR YOU, CAN YOU SPEAK A LITTLE LOUDER??????


Remember, the Panhandle is part of florida also, not just the peninsula. So a Westward moving cone might still affect the Panhandle, while leaving the Peninsula at a lower risk.
Looks like this system may take a path much like Hurricane Cleo did the last week of August, 1964.  Cleo made a direct hit on Miami and MiamiBeach as a cat-2 Hurricane with 110-MPH winds and gusts up to 135-MPH.
1530. JLPR2
Raining, though not much winds.
Man oh man some people just continue to quote the trolls you can tell who they are rather quickly. Please stop feeding them.
Hi, guys. Could someone post a pic of the latest model tracks? Last I heard this was an east coast Florida storm and then I logged on here. Confused.

Thanks,

GG
Quoting Losttsol:
European model looks like this :



Link

RRRI into CAT 4 now ??? dont think so...
So Isaac is sticking his middle finger out at us. Niceee.

Quoting WxLogic:
Based on the latest fix... what I would call the "wooble" in the LLC has now stabilized and resume the original intended position and displacement outlined by NHC so it should be on track.


Lol...the "fix" showed the center we were following earlier had moved well to the SW and the pressure had risen by a millibar.
Quoting LargoFl:
It's a substantial threat to Florida because of two high pressure systems that will steer the storm if it isn't broken up by mountains on its trek across the Caribbean, Bay News 9 chief meteorologist Mike Clay said.

Although the chances the storm will hit the Tampa Bay area remain relatively low, the prospect of a major storm arriving the same week as the Republican National Convention is creating some anxiety.

"This is going to be the key: How far east and strong will that (east) high be," Clay said.

"So with Isaac (in the Caribbean) eventually, it%u2019s going to find a weakness between (the two highs), and that pretty much assures a track up toward Florida. If this (eastern) high is stronger and is back closer to us, it%u2019ll push Isaac out in the gulf more.

"If this (east) high turns out to be a little weaker, Isaac will come along and go up the east coast and maybe up toward the Carolinas."



Granted. Thanks. Although Isaac looks marginally better than Ernesto going into the eCarib, it's still having similar troubles: some dry air, some light neast quadrant shearing, moving TOO fast, and unable to truly get vertical. It was considerably further west and a bit too much, too late for even a strengthening Ernesto to feel the weakness considerably north of it and it wound up plowing into the Yucatan. Isaac is similar in look and feel, only somewhat stronger, somewhat more organized, but still moving way too fast to get vertical and mature. Consequently, it too, will have similar troubles feeling any similar weakness north of the system.

As long it remains ragged and racing, the movement is likely more westwards than northwards. And, granted, its initial position in the eCarib is somewhat more north than Ernesto and that would tend to eventually assist a northerly movement if/when he gets stronger. However, until then, it's a mostly westwards tracking system. Yes, it is still VERY early, but personally, I think the Carolinas may be on the safer side unless Isaac makes landfall on FL's west coast and emerges back over water off the eastern seaboard. Next 24-36 hours will tell the tale. :)

2 cents worth! ;)
Quoting StormJunkie:


Is the theory that the dry slot is the center now?


There was a second center found to the SE of the first Vortex fix. To me both are weak, so hard to define one as the main center. Waiting to see the NHC take on the situation.
1538. LargoFl
PECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MIAMI FL
410 PM EDT WED AUG 22 2012

FLZ070-222100-
INLAND COLLIER COUNTY FL
410 PM EDT WED AUG 22 2012

...A SIGNIFICANT WEATHER ADVISORY IS IN EFFECT FOR EASTERN COLLIER
COUNTY...FOR FREQUENT TO EXCESSIVE LIGHTNING AND GUSTY WINDS OF 45 TO
55 MPH...

* UNTIL 500 PM EDT

* AT 408 PM EDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
STRONG THUNDERSTORM 5 MILES SOUTH OF BIG CYPRESS NATIONAL
PRESERVE...AND MOVING NORTH AT 15 MPH.

* THE STORM WILL AFFECT...
BIG CYPRESS NATIONAL PRESERVE...
AND SURROUNDING COMMUNITIES.

THE PRIMARY IMPACTS WILL BE FREQUENT TO EXCESSIVE LIGHTNING AND GUSTY
WINDS OF 45 TO 55 MPH. LIGHTNING IS THE NUMBER ONE WEATHER RELATED
KILLER IN FLORIDA. TREES AND OPEN SHELTERS OFFER NO PROTECTION. THESE
WINDS CAN DOWN SMALL TREE LIMBS AND BRANCHES...AND BLOW AROUND
UNSECURED SMALL OBJECTS. SEEK SHELTER IN A SAFE BUILDING UNTIL THE
STORM PASSES.

LAT...LON 2596 8115 2607 8117 2619 8113 2621 8101
2613 8089 2600 8090 2592 8094 2586 8098
2588 8114
TIME...MOT...LOC 2010Z 192DEG 13KT 2595 8106

$$
1539. hydrus
Quoting prcane4you:
last frame on Ramdis show a more northwest movement.Any one agrees.?
Do not use RAMDIS to deduce storm direction.
1540. kwgirl
Quoting Grothar:


I remember a storm years ago that move west over Cuba then back east then west again. I don't remember the name.
I know I am behind in the blog, but Camille was a huge storm and moved over Cuba three times, knocking it down so it was nothing when it came over the Keys. Then you know the rest of the story.
I recall Dr. Masters saying that the best models for 5 days out are GFS, ECMWF and BAMM. All three are currently calling for a track in the water to the west of southern Florida.
1542. WxLogic
Quoting MississippiWx:


Lol...the "fix" showed the center we were following earlier had moved well to the SW and the pressure had risen by a millibar. Thus, we have no vortex message from the HH.


LOL I think we do now.
1543. LargoFl
Quoting moonlightcowboy:



Granted. Thanks. Although Isaac looks marginally better than Ernesto going into the eCarib, it's still having similar troubles: some dry air, some light neast quadrant shearing, moving TOO fast, and unable to truly get vertical. It was considerably further west and a bit too much, too late for even a strengthening Ernesto to feel the weakness considerably north of it and it wound up plowing into the Yucatan. Isaac is similar in look and feel, only somewhat stronger, somewhat more organized, but still moving way too fast to get vertical and mature. Consequently, it too, will have similar troubles feeling any similar weakness north of the system.

As long it remains ragged and racing, the movement is likely more westwards than northwards. And, granted, its initial position in the eCarib is somewhat more north than Ernesto and that would tend to eventually assist a northerly movement if/when he gets stronger. However, until then, it's a mostly westwards tracking system. Yes, it is still VERY early, but personally, I think the Carolinas may be on the safer side unless Isaac makes landfall on FL's west coast and emerges back over water off the eastern seaboard.

2 cents worth! ;)
yes this is what everyone is afraid of, going much the same flooding route across northern florida to the atlantic as debby did
Isaac; "Changes in Lattitude, Changes in Attitude... nothing remains quite the same"
Strange, the recon put the center fix at 15.8667N 60.7667W. But we there is ac closed circulation at 15.2N, we saw plenty of westerly winds and lowering pressure. I'm thinking the NHC agrees..
Quoting Losttsol:
European model looks like this :



Link


Did Georges come up in the analog package?
Quoting WxLogic:


LOL I think we do now.


Imagine that...they came out with one as soon as I said that. Lol. However, you can tell that center is weakening, nonetheless. Something else is happening elsewhere.
RECON still heading SW-WSW looks like LLCOC may have reformed in the E caribbean S of 15N via RECON's winds
1549. Patrap
Hurricane Camille 1969 Track



The origins of Hurricane Camille were from a tropical wave off the western coast of Africa on August 5. It tracked nearly due westward, eventually becoming clearly identifiable on satellite imagery on August 9. By that time, the thunderstorm activity concentrated into a circular area of convection.

The next day, it moved through the Lesser Antilles, although there was no evidence of a closed circulation. On August 13, the wave passed near or over the southern coast of Jamaica as its convection spread northeastward through the Bahamas. Subsequently it began a slower motion to the northwest. On August 14, the Hurricane Hunters flew to investigate for a closed circulation near the Bahamas as well as near the Cayman Islands.

The crew observed a developing center in the western Caribbean, and winds quickly reached tropical storm status. It is estimated Tropical Storm Camille developed late on August 14 with winds of 60 mph (95 km/h), about 50 miles (80 km) west-northwest of Grand Cayman.
Quoting CybrTeddy:
Strange, the recon put the center fix at 15.8667N 60.7667W. But we there is ac closed circulation at 15.2N, we saw plenty of westerly winds and lowering pressure. I'm thinking the NHC agrees..


The 18z Best Track has not been released yet waiting for the data from recon.

Isaac looks like a wild and wooly Pacific storm already!
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 22nd day of the month at 20:17Z
Storm Name: Isaac (flight in the North Atlantic basin)
A. Time of Center Fix: 22nd day of the month at 19:50:00Z
B. Center Fix Coordinates: 15°52'N 60°46'W (15.8667N 60.7667W)
D. Estimated (by SFMR or visually) Maximum Surface Wind: 30kts (~ 34.5mph)
H. Minimum Sea Level Pressure: 1005mb (29.68 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 18°C (64°F) at a pressure alt. of 1,529m (5,016ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 20°C (68°F) at a pressure alt. of 1,524m (5,000ft)
L. Eye Character: Not Available
M. Eye Shape: Not Available


-----

Shorter Vortex: We know where we observed the lowest pressure, but we haven't the first clue what we're looking at overall.
Quoting CaicosRetiredSailor:
Isaac; "Changes in Lattitude, Changes in Attitude... nothing remains quite the same"


If we weren't all crazy we would go insane
Quoting wunderkidcayman:
RECON still heading SW-WSW looks like LLCOC may have reformed in the E caribbean S of 15N via RECON's winds


That's somewhat consistent with RGB satellite and the Antilles radar.

Any talk of 16N is absurd, and the RAMMB site is just stupid bugged.
1555. wpb
B. Center Fix Coordinates: 15°52'N 60°46'W (15.8667N 60.7667W

recon flying 147 feet above the ocean trying to get answers quite an effort by them
Quoting redwagon:

Hey! off-topic, are you following what's building off our coast? TCFP sees it, my 10day fcst doesn't.


Oh wow! No I didn't even see that. I can't tell what level that's on. The upper level winds didn't look like they went west or south. Where'd it come from? lol
1557. Levi32
If you ask me the "center" due east of the gap between Gaudeloupe and Dominica is the more defined one, not that that's saying much. I agree with placing the location there instead of to the southwest.

1558. Patrap
Quoting MississippiWx:


Imagine that...they came out with one as soon as I said that. Lol. However, you can tell that center is weakening, nonetheless. Something else is happening elsewhere.


It has been all day, as a mean center is forming in the Overall and tracking those embedded swirls as a new Center, or a center re-locate are futile.

1559. LargoFl
1560. Patrap
I'm with Levi on those ob's as well.

1561. WxLogic
A little 18Z NAM @36HR action:

Quoting CloudGatherer:
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 22nd day of the month at 20:17Z
Storm Name: Isaac (flight in the North Atlantic basin)
A. Time of Center Fix: 22nd day of the month at 19:50:00Z
B. Center Fix Coordinates: 15°52'N 60°46'W (15.8667N 60.7667W)
D. Estimated (by SFMR or visually) Maximum Surface Wind: 30kts (~ 34.5mph)
H. Minimum Sea Level Pressure: 1005mb (29.68 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 18°C (64°F) at a pressure alt. of 1,529m (5,016ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 20°C (68°F) at a pressure alt. of 1,524m (5,000ft)
L. Eye Character: Not Available
M. Eye Shape: Not Available


-----

Shorter Vortex: We know where we observed the lowest pressure, but we haven't the first clue what we're looking at overall.


40-50 MPH storms don't have an "eye" that's why it says not available.
Quoting Patrap:
If ya step back away from the Monitor like 3-4 feet, one can see the overall taking over easily,as it has been trying to shake out a CoC and has made good headway as to it this afternoon.



The WV Loop




Looks moist... Dry air to N what will happen dry air ingested or not??
Quoting wunderkidcayman:
RECON still heading SW-WSW looks like LLCOC may have reformed in the E caribbean S of 15N via RECON's winds


Overall organization on visible looks south of NOAA fcst points.
Quoting nrtiwlnvragn:


There was a second center found to the SE of the first Vortex fix. To me both are weak, so hard to define one as the main center. Waiting to see the NHC take on the situation.


Yeah, I hear you. Will also be nice to get the other plane in there. It really is a mess of a system right now. Has never truly developed a CDO, if it ever does it may find its center.
NOAA,s P-3 hurricane hunter have just took off and is in the air
1568. LargoFl
ok we sure dont want it going into the straights, not with these water temps huh
Isaac's odd shape could keep him from establishing a true, well-defined center for a while.


Anyone else notice that the ECMWF is now developing another tropical wave into a system by 144 hours? And by 240 hours.. one would think this is Joyce, but Joyce actually dissipates on the run. This would be "Kirk" if it where to happen.
Looks to me like a WNW motion is beginning to take place.
1572. Levi32
NOAA flight from Barbados is on its way. You can observe both flights simultaneously from my recon page.

So what's "Kermit" doing in air near Isaac?
JeffMasters has created a new entry.
Quoting Patrap:


It has been all day, as a mean center is forming in the Overall and tracking those embedded swirls as a new Center, or a center re-locate are futile.



The multiple swirls on infrared seem like the energy is well distributed, but changing to an area farther south.
1576. LargoFl
This nogaps track has changed since this morning
Quoting Bluestorm5:
So what's "Kermit" doing in air near Isaac?

They are running all hands on deck for Issac, and flying the HH through the storm near constantly.
Are those Kermit reading legit??? 999.8??
1579. LargoFl
Quoting LargoFl:
This nogaps track has changed since this morning
........the nogaps is now where the gfs was yesterday, putting issac right up the middle of florida
Quoting Patrap:


It has been all day, as a mean center is forming in the Overall and tracking those embedded swirls as a new Center, or a center re-locate are futile.



The LLC and MLC seem to be trying to come to terms of agreement; but having a little difficulty agreeing on where they would like to do that.
Am I correct in saying that the Euro is now coming into more agreement with GFS? Yesterday the Euro had Isaac going to the Yucatan, GFS has consistently been in the same area. Just curious why the big change in the Euro when its been said that its the top model.
1582. keisa90
So basically, not enough information to make much of a change for the 5pm discussion. If there are any major changes, we probably won't see it until at least the 11pm.
Quoting VAbeachhurricanes:
Are those Kermit reading legit??? 999.8??


Yes, but only at static air pressure (plane height).
Quoting Losttsol:
European model looks like this :



Link


Shifted north and east but the end result remains NOLA dont buy into these until the NOAA jets go out there.
1585. Patrap
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1586. ARiot
Either way, I speculate we have a big raker. I also suspect a hook path in the out days, let's hope it's a hook away from people, out into the atlantic...
Quoting VAbeachhurricanes:
Are those Kermit reading legit??? 999.8??

the plane has not been used for a while I don't think they are and plane is is riding at 10,000 ft too
1588. TXCWC
Quoting medic2luv:
Am I correct in saying that the Euro is now coming into more agreement with GFS? Yesterday the Euro had Isaac going to the Yucatan, GFS has consistently been in the same area. Just curious why the big change in the Euro when its been said that its the top model.


No - Euro is still wayyy west of GFS by still taking Isaac to Louisiana - if anything GFS has ever so gradually shifted further west of the Florida Coast before making a turn to the NE.
Quoting medic2luv:
Am I correct in saying that the Euro is now coming into more agreement with GFS? Yesterday the Euro had Isaac going to the Yucatan, GFS has consistently been in the same area. Just curious why the big change in the Euro when its been said that its the top model.


12Z Euro shifted slightly eastward but it's still very far from the GFS, and still shows a strong hurricane going into the Lousiana/Misisipi area.
1590. Grothar
Quoting nrtiwlnvragn:


If we weren't all crazy we would go insane


"Tryin' to reason with hurricane season".....

Link
Quoting StuartLurker:


"Tryin' to reason with hurricane season".....

Link


New Blog
According to the 5 pm NHC advisory, Isaac's center is located at 16.0 N. I personally think that it is much further south, but this system is so disorganized right now that even trying to determine a center is a joke.