ATL: ISAAC - Post-Tropical - Discussion

[knotimpaired]

For those in PR http://www.elnuevodia.com/envivoemitenv ... 27279.html
is doing minute by minute as to what the Gov is doing.

[HurricaneFan]

00z GFS 18 hour position, well above 15N.

Looks like the GFS is under estimating the Ridge......

http://raleighwx.americanwx.com/models/ ... cal018.gif

How can the GFS still have it east of 55W in 18 hours??

[Tyler Penland]

00z GFS 18 hour position, well above 15N.

Looks like the GFS is under estimating the Ridge......

http://raleighwx.americanwx.com/models/ ... cal018.gif

How can the GFS still have it east of 55W in 18 hours??

0z GFS position. 18 hours from 0z (~8EST) last night meaning ~noon today.

[Portastorm]

IMPORTANT!!

Hey gang, let's not post tracking charts or forecasted tropical cyclone charts from previous storms unless you very clearly mark that it is not the current storm which folks are following. This is confusing and scaring some of our folks unneccesarily. Thanks.

[abajan]

A quick overview of the Storm2K disclaimer policies for those not familiar with them. I know I've tolerated disclaimers in signatures but this practice is in violation of our rules and will need to end.

viewtopic.php?f=37&t=87189

Storm2k.org policy on posting amateur forecasts.. If you post a forecast in any forum it MUST be preceded by the following..

Quote:

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org. For Official Information please refer to the NHC and NWS products.

If a forecast is made without using the disclaimer we will add it for you and send a reminder PM.. If it is "forgotten" repeatedly your posts will be removed, and your membership with storm2k may be removed as well.. This is for the safety of everyone. Please abide by it.

I'm curious about something. Forgive me if it's been asked and answered before (heck, it may even have been asked by me and answered by an S2K admin - my memory could use some improvement lol) but would it not simplify matters if the disclaimer were auto-prepended to each and every post, whether the post is a forecast or not? Would that not solve this perennial problem? Surely, there must be some sort of script (JavaScript or otherwise) that can do that. Perhaps the disclaimer should be edited to make more sense when preceding posts that have nothing to do with forecasts: "If the following post contains information that can be construed as a forecast, that forecast is NOT an official forecast ..."

Just sharing my thoughts.

[Weatherfreak000]

I can't view a loop right now, any vets round here confirm any south of west movement?

[SouthFLTropics]

New track is out and it appears to be an update of the previous one...By 11:00PM tonight South Florida should be in the 5 day cone of error.

SFT

[HurricaneFan]

00z GFS 18 hour position, well above 15N.

Looks like the GFS is under estimating the Ridge......

http://raleighwx.americanwx.com/models/ ... cal018.gif

How can the GFS still have it east of 55W in 18 hours??

0z GFS position. 18 hours from 0z (~8EST) last night meaning ~noon today.

Oh,I see,thanks

[cycloneye]

[Mouton]

It would appear that there is currently a South of due West motion and that could have significant impact to the track and intensity down the road. It is possible that it will keep it South of the big islands and allow it to ramp up faster. Still think it will make the turn to the North at some point but with its current motion it may be more of a sweeping turn versus a sharper turn. Interesting and challenging days ahead for sure. Put the coffee on because I foresee sleepless nights of model watching. What concerns me at this point is even though the potential impact to the CONUS is days away the models have been locked on essentially the same solution for the past 2-3 days.

SFT

Good advice there. My thought yesterday was a slightly south of west trajectory and then a curve to the north over Cuba. I think some models, notably NOGAPS project the storm will hook onto the front now draped over florida and moving to the SE along with some interaction with an ULL. I think the front will pull out to the NE too soon and will miss any interaction with this storm albeit there are more to come too. The ULL may keep some shear on the system and keep the intensity down somewhat but it is a good deal away from the projected path and moving away now too. I don't see any future steering paterns that would force a Charley like turn either which is why I am content with a slow curvature perhaps over the GOM side of Florida, just how far up the coast or into the Panhandle I have no idea. Outside guess would be over Key West and re-land near Panama City or appolachiacola.

Of course this is my unofficial guess not any pronouncement from a reputable source and to not be relied upon.

[Steagle]

What are cisterns doing in P.R ....thought that was a DR Haiti thing...

No mention of any tropical system here on the news this morning....only "Debates"
Guess the DR is in the clear....

Stay safe out on the East islands everyone. !

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org. For Official Information please refer to the NHC and NWS products















People wondering whether to "be prepared" or not, my

[GTStorm]

New track is out and it appears to be an update of the previous one...By 11:00PM tonight South Florida should be in the 5 day cone of error.

SFT

Sure is moving fast...any chance that it won't be able to maintain vertical alignment enough to strengthen, and just sort of dies out?

[DESTRUCTION5]

11am track clips the 10k foot mountians...Key factor as time passes with regards to intensity.

[Bocadude85]

New track is out and it appears to be an update of the previous one...By 11:00PM tonight South Florida should be in the 5 day cone of error.

SFT

The new track is a tad to the right... not by much though

[knotimpaired]

What are cisterns doing in P.R ....thought that was a DR Haiti thing...

No mention of any tropical system here on the news this morning....only "Debates"
Guess the DR is in the clear....

Stay safe out on the East islands everyone. !

The following post is NOT an official forecast and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org. For Official Information please refer to the NHC and NWS products

Because water outages are common here. Because we rely on our water to come from PR in a pipe underwater for 8 miles, everyone has one. It's a wise thing to do.

Please I should explain.

Imagine living on an island with one pharmacy for 9,000+ people. We have 2 Drs here and you have to town at about 6 am to sign a sheet to make an appointment.

We have 2 grocery stores owned by the same family but they both carry different items so you are forced to shop at both.

We run out of gas on a weekly basis.

We have no hospital.

Maybe that will make you understand why we have cisterns.









People wondering whether to "be prepared" or not, my

[cycloneye]

The latest discussion with the 11 AM advisory information by Dr Jeff Masters.

Posted by: Dr. Jeff Masters, 10:54 AM AST on August 21, 2012

Tropical Depression Nine has formed in the waters a day's journey from the Lesser Antilles Islands, and is headed west towards the islands at 20 mph. This storm could be trouble for much of the Caribbean, and may affect the mainland U.S. next week. TD 9 is under light wind shear of 5 - 10 knots, and is over waters of 28°C. A large area of dry air lies just to the north, as seen on the latest Saharan Air Layer (SAL) analysis and water vapor satellite loops. This dry air is interfering with development, and will keep development slow today. This morning's visible satellite loops show that TD 9's heavy thunderstorm activity is limited on the north side, due to the dry air. TD 9 has yet to develop a good upper level outflow channel, which will also keep development slow today. An analysis of upper level winds from the University of Wisconsin CIMSS shows that the winds at high levels are blowing fairly uniformly from the east over the storm, and these winds would have to take on a more counter-clockwise pattern over TD 9 to produce the most efficient upper-level outflow. The clump of heavy thunderstorms to the southeast of TD 9 is also a limiting factor; this clump of heavy thunderstorms is competing for moisture and interfering with the low level inflow and upper level outflow of the storm. However, if TD 9 manages to wrap in this extra clump of heavy thunderstorms and add their spin to its own spin, it could become a very large and dangerous storm. Heavy thunderstorms are now attempting to fire up around TD 9's circulation center, but this is being hampered by dry air. The center of TD 9 passed about 20 miles to the north of buoy 41040 at 10 am this Tuesday morning. The buoy recorded top winds of just 18 mph this morning, suggesting that this is not yet Tropical Storm Isaac. The first hurricane hunter mission into TD 9 is scheduled for Tuesday afternoon.


Intensity forecast for TD 9

The latest 8 am EDT run of the SHIPS model predicts that wind shear will be low to moderate, 5 - 15 knots, for the next five days. Ocean temperatures will warm from 28°C this morning to 29°C by Wednesday afternoon, and the total heat content of the ocean will increase sharply during that period. The low wind shear and warm waters will favor strengthening. The main impediment to development through Wednesday will be dry air to the north, though the storm will also have trouble separating from the clump of thunderstorms to its southeast. I expect that TD 9 will continue to struggle with dry air through Wednesday. The official NHC forecast of a 60 mph tropical storm moving through the Lesser Antilles on Wednesday afternoon is on the aggressive side, and I put the most likely range of strengths for TD 9 Wednesday afternoon at 45 - 60 mph. Once TD 9 enters the Eastern Caribbean, wind shear will be low, oceanic heat content high, and the storm should have had enough time to moisten the atmosphere to allow steady strengthening to a hurricane. Intensity forecasts 4 - 5 days out are low in skill, though, and it would not be a surprise at all to see TD 9 struggle like so many other storms have over the past two years, and remain a tropical storm over the next five days. Conversely, rapid intensification into a Category 2 hurricane five days from now, as the official NHC and HWRF model forecasts are suggesting may happen, would also not be a surprise.

Impact of TD 9 on the Islands

The entire Lesser Antilles Islands chain will have a three-day period of heavy weather Wednesday through Friday, as TD 9 and the associated area of heavy thunderstorms to its southeast passes through. Sustained tropical storm-force winds of 40 - 60 mph will occur in the islands only on Wednesday, with Guadaloupe, Antigua and Barbuda, Martinique, Dominica, Montserrat, and St. Kitts and Nevis at highest risk of these winds.

TD 9 will make its closest approach to the Virgin Islands and Puerto Rico on Thursday, and heavy rains from the storm will affect these islands Thursday through Saturday. Tropical storm-force winds should remain just south of these islands.

On Thursday night, heavy rains and tropical storm-force winds should arrive on the southern coast of the Dominican Republic. If the center of TD 9 remains offshore, as appears likely, heavy rains from TD 9 will still be a danger to the country. Rainfall amounts of 4 - 8 inches will likely affect the Dominican Republic Thursday through Saturday, creating flash floods and mudslides. We can't rule out a direct hit on the Dominican Republic on Thursday evening or Friday morning, since the country is well within the NHC cone of uncertainty.

TD 9 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 TD 9 will begin on Friday morning in Haiti, and last through Sunday. Rainfall amounts of 5 - 10 inches are possible, which will be capable to causing extreme flooding on the vegetation-denuded slopes of Haiti.

Longer-range outlook for TD 9

Heavy rains from TD 9 will begin in Jamaica and eastern Cuba on Friday night, but our vision of where the storm might be headed after Friday gets blurry. The official NHC track forecast at long ranges is heavily weighted towards the GFS and ECMWF models, which have done the best job predicting TD 9's path so far. In general, the models have been predicting a track too far to the north for TD 9, and I expect the storm will remain south of Hispaniola, avoiding the disruptive impact of that island's high mountains. While the current NHC forecast has TD 9 hitting Cuba just north of Jamaica five days from now, keep in mind that the average error in a 5-day forecast is 260 miles. Given the tendency of the models to predict a track too far to the north for this storm, and this season's general steering pattern that has already taken two storms into Mexico's Yucatan Peninsula, we should not be surprised if TD 9 takes a more southerly path than the official NHC forecast, and potentially become a threat to western Cuba or Mexico's Yucatan Peninsula. A trough of low pressure capable of pulling TD 9 to the north enters Western Canada Thursday, and the exact timing and amplitude of this trough as it crosses the U.S. this weekend will determine the ultimate landfall location of TD 9. The ECMWF model has a more northwards position for the trough, and thus keeps TD 9 moving more slowly and father south than the GFS. Both of these models predict an eventual landfall for TD 9 over Florida, and TD 9 is a threat to affect Tampa during the Republican National Convention, August 27 - 30. 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%. The odds in the current situation are higher, somewhere in the 1% - 3% range. It would take a "perfect storm" sort of conditions to all fall in place to bring TD 9 to the doorstep of Tampa as a hurricane during the convention, but that is one of the possibilities the models have been suggesting could happen.

[Javlin]

Masters explanation about the trend of late for a more S route makes sense just this early arrival of Fall?The WV does loops show the WCarib to have alittle more moisture than the current location.

[Steagle]

Thanks knotimpaired for that information...i really had no idea it was like that there.
Cycloneye...and everybody out over the blue waters...keep us posted whenever you can..we rely on it !

[wxwatcher1999]

Is there any possibility this goes to the west of Florida?

[Gustywind]

WEATHER GUADELOUPE

Yellow vigilance until Isaac

franceantilles.fr 21.08.2012

http://www.microsofttranslator.com/bv.a ... 183571.php

5 p.m. local, the center was located about 1150 km east of Guadeloupe. The depression is expected to strengthen to tropical storm stage today. Its planned trajectory through the Guadeloupe, the centre of the phenomenon should reach our archipelago in afternoon or evening of Wednesday.

The depression is expected to strengthen to tropical storm stage today. Its planned trajectory through Guadeloupe, the center of the phenomenon should reach our archipelago in afternoon or evening of Wednesday. 5 P.m. local, the center was located about 1150 km east of Guadeloupe.
The next night, heavy rains take place. They will intensify to culminate on the night of Wednesday to Thursday and Thursday day. Accumulations of rainfall may exceed 100 mm / 24 hours at many points, as well Wednesday as Thursday.
The winds will strengthen to reach their maximum after the passage of the center, on the night of Wednesday to Thursday. They will then be in direction South-East and sustained average 60 km/h, gusting to 100 km/h or more.
The sea will grow gradually and average lows should approach 3 m during the day Thursday, with maximum hollow 6 m. More cross-swell phenomena make the chaotic sea.