Hurricane Isaac

[Iceberg]

NHC are worried about this one, taking him through the islands as a hurricane and finishing at 95kt before it heads for the US.

This will be a long and popular one i think

REPEAT...CENTER LOCATED NEAR 15.2N 51.2W AT 21/0900Z

AT 21/0600Z CENTER WAS LOCATED NEAR 15.2N 50.3W

FORECAST VALID 21/1800Z 15.3N 53.8W

MAX WIND 35 KT...GUSTS 45 KT.

34 KT... 40NE 0SE 0SW 40NW.

FORECAST VALID 22/0600Z 15.7N 57.2W

MAX WIND 40 KT...GUSTS 50 KT.

34 KT... 50NE 30SE 20SW 50NW.

FORECAST VALID 22/1800Z 16.0N 60.5W

MAX WIND 50 KT...GUSTS 60 KT.

50 KT... 20NE 0SE 0SW 20NW.

34 KT... 70NE 40SE 30SW 70NW.

FORECAST VALID 23/0600Z 16.3N 63.6W

MAX WIND 65 KT...GUSTS 80 KT.

50 KT... 40NE 30SE 20SW 40NW.

34 KT... 90NE 60SE 40SW 90NW.

FORECAST VALID 24/0600Z 16.9N 69.3W

MAX WIND 80 KT...GUSTS 100 KT.

50 KT... 50NE 30SE 20SW 50NW.

34 KT...110NE 70SE 50SW 110NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 175 NM

ON DAY 4 AND 225 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY

OUTLOOK VALID 25/0600Z 18.0N 74.0W

MAX WIND 95 KT...GUSTS 110 KT.

OUTLOOK VALID 26/0600Z 20.0N 77.3W

MAX WIND 95 KT...GUSTS 110 KT.

[mezzacyclone]

Can we say that`s quite a lethal track Ice? staying off Haiti/DR/ ECuban coast before N turn?

Be interesting watching the max wind probability table in how it changes in the coming days?

[Coast]

Looks like this one is heading towards becoming Tropical Storm Isaac later today:

Tropical Depression #9 forms in the Atlantic and may impact South Florida early next week.

This storm will move toward the west and approach the Leeward Islands by Wednesday. The storm will likely be named Tropical Storm Isaac later today. After that time it will move through the Caribbean, impacting Puerto Rico, and Jamaica before nearing Cuba as a hurricane.

The current model guidance is suggesting that south and central Florida could be impacted by this storm. For right now it looks as though Sunday and into the start of next week could be pretty wet with torrential downpours. This forecast is still uncertain due to fluctuations in the path and intensity of future Isaac. The storm could move into either the eastern Gulf of Mexico and have a greater influence on the west side of Florida, or it could move over the Bahamas, influencing our forecast more directly.

http://www.wptv.com/...y#ixzz24AaMyBRj

At 11:00am ast, the center of the newly formed Tropical Depression 9 was located near latitude 17.6 north, longitude 39.5 west or about 1470 miles, 2365 km, east of the Leeward Islands. The depression is moving toward the west near 16 mph. A general west to west-northwest track is expected during the next day or two. Maximum sustained winds are near 35 mph, with higher gusts.

http://www.wftv.com/...rengthen/nJnR3/

[dallas]

Waters very warm in the GOM, 33 last time I looked (if it takes that route)

[Coast]

Could hurricane wreak havoc at Republican convention? Will it be Isaac?

For three straight simulations, NOAA’s Global Forecast System (GFS) model has tracked a tropical system right over the Florida peninsula through or close to Tampa just as the Republican National Convention is ramping up. Assuming this system - presently a little swirl in the open Atlantic - strengthens some, it will be named Isaac.

Before anyone gets alarmed or excited, consider forecasts of the path and intensity of tropical systems this far out have essentially no skill. As our tropical weather specialist Brian McNoldy said earlier: “In the 5-7 day period and beyond, weather details become fairly unpredictable.†If this model defeats the long odds against it and is somehow right, organizers say they’re ready for the possibility of a hurricane Isaac during the convention according to a report from ABC News: The Republican National Convention, Secret Service and federal, state and local authorities have been planning for a “multitude†of hurricane scenarios for “well over a year,†said Bryan Koon, Florida’s emergency management director. RNC spokesman James Davis would not give details of those plans, saying only that they are “focused completely on having a great convention.â€

Since 1852, the Tampa area been hit by 27 hurricanes including 6 during the month of August the ABC News report said. Colorado State University Tropical Meteorology Project has developed a tool that shows the historic probability of a named storm affecting the region around Tampa is 20 percent in any given season. The odds of a direct hit near Tampa is around 3 percent.

Jeff Masters of wunderground, who wrote a detailed blog post on the risk of a storm hitting Tampa during the convention, says the risk of a highly disruptive the storm that would trigger evacuations during the convention itself is smaller: “History suggests that the odds of a mass evacuation order being given during the 4-day period that the Republican National Convention is in town are probably around 0.2%,†he wrote. But if powerful hurricane did strike the Tampa Bay region - either during the convention or some other time - the effects could be devastating. Climate Central’s Andrew Freedman ranked Tampa-St. Petersburg the most vulnerable U.S. city to hurricanes ahead of Miami and New Orleans. He noted 125,000 people live below 6.5 feet above high tide, which a large storm surge could overwhelm.

“In St. Petersburg alone, there are more than 45,000 homes that lie below 6 feet in elevation, and would likely be vulnerable to a storm surge of that magnitude or greater,†Freedman wrote. For the most part, the Tampa region has dodged the bullet with landfalling storms in recent years. While a number of storms have brushed the area, the last direct hit from a hurricane occurred in 1946 (a category 1 storm). Not since 1921 has a major hurricane (category 3 or higher) struck the region. The storm of October 20-21, 1921 produced a 10.5 feet storm surge which would cause massive flooding today, including at the convention site.

The bottom line is that Tampa is “due†in a sense to deal with a destructive hurricane. But the odds of a direct hit at any given time are very small. European model simulation of where tropical disturbance or potential “Isaac†could be in 9 days, as illustrated by the different circles. (StormVistaWxModels.com/Matt Rogers) For the moment, all we can say is that there is a small swirl in eastern tropical Atlantic ocean that models generally agree will track towards the northeast Caribbean over the next several days. There’s no telling how strong it will get or where it will go beyond a few days.

The various members of the European forecast model “ensemble†provide a fair representation of where this system might be in 9 days - essentially anywhere from the western Gulf of Mexico to the central Atlantic. There’s a huge spread. In other words, this disturbance could harmlessly turn out to sea, even if it ever earns the name Isaac and becomes a formidable storm. Inauspiciously, several storms beginning with the letter “I†have caused trouble along the Atlantic and Gulf coasts in the last decade, namely Isabel (2003), Ivan (2004), Ike (2008), and Irene (2011). The World Meteorological Organization retired all of these storms due to their toll on life and property.

The odds of a hurricane smacking Tampa during the convention may be long, but chances are if it does, another I-named storm will deliver the blow.

http://www.washingtonpost.com/blogs/capital-weather-gang/post/could-potential-storm-isaac-wreak-havoc-at-republican-convention/2012/08/20/49924d8e-eae8-11e1-a80b-9f898562d010_blog.html

[Somerset Squall]

Some very cold cloud tops directly over the LLC now, I would be very surprised if we didn't have Isaac this afternoon. Another troublesome "I" storm!

[Coast]

Current track

Complete Track & SST

Upon reaching land:

[mezzacyclone]

Some very cold cloud tops directly over the LLC now, I would be very surprised if we didn't have Isaac this afternoon. Another troublesome "I" storm!

etc.

And LOOK where Ivan tracked nearby SS, don`t wanna "little bit of history repeatin"

[Coast]

Haiti again then Cuba??!!!!!

Tropical Depression AL09: Probability of tropical storm winds to 93 hours lead

Tropical Depression AL09: Probability of tropical storm winds to 117 hours lead

Tropical Depression AL09: Storm-centered zoom at 93 hours lead

Tropical Depression AL09: Probability of Cat 1 or above winds to 117 hours lead

[Coast]

A tropical depression that formed in the Atlantic Tuesday morning could rake a string of Caribbean nations, including Haiti and Cuba, over the coming week.

The depression, expected to soon grow strong enough to be named Tropical Storm Isaac, potentially could be a problem for South Florida by early next week – though its track that far out remains uncertain. The large system, with winds of 35 mph, was moving west at a quick 20 mph and many of the Leeward Islands were under tropical storm watches and warnings. Forecasters at The National Hurricane Center expect the system to reach hurricane strength by Thursday as it approaches Puerto Rico.

Forecasters said a subtropical ride to the north will continue steering the system generally west for the next four or five day but Isaac could begin curving more to the northwest by the weekend, a track that would put South Florida at risk by Monday. The timing of that turn remains uncertain, however, and depends on the strength and timing of a trough moving across the Southeastern United States. Atmospheric conditions are favorable for strengthening as well, forecasters said, though the mountainous terrain of Haiti and Cuba could disrupt the system.

A Hurricane Hunter plane will survey the storm later Tuesday.

http://www.miamiherald.com/2012/08/21/2961268/tropical-depression-could-threaten.html#storylink=cpy

[mezzacyclone]

as expected, NHC have increased the max wind probs across the whole range and Cat1 status for 8am Thurs is 48%, but this is still reserved IMO.

Just about every model now has TD9 tracking between the area slightly N of the Brit virgin Isles to the latitude 14.6N (62.4W) or roughly 100 miles due W of Martinique.

AF307 is headed SE through the outer bands 15.9N 55.9W, MSLP est @ 1010mb so far,,,

[Iceberg]

Having a look at it on visual and avn it's suffering from shear and forward speed still which is displacing any central convective flares.

Recon are in ATM and have as yet not found too much.

Forward speed is due to be a problem until maybe Friday when it should be south of Haiti, shear should lessen more that.

[summer blizzard]

This 94L which we have been following and as said i am pretty excited about this one, especially now it is slowing.

This to me looks like a very good chance of attaining major hurricane status, its track has been continually shifted west and the north easterly shear is evidence that it probably won't gain much latitude soon so i would expect this to avoid Haiti and hit Cuba before its second landfall (probably Louisiana now).

All in all, looking good.

[mezzacyclone]

Noticed a few 42kn (48.3mph) 30 sec. avg. Fl lev winds just NE of LLC,

10 sec. avg. peaks 44knots, 1005mb @ 15.2833N 53.3333W

[Iceberg]

Yep this lot should allow it to be renamed as isaac.

minimum pressure of 1005mb, flight winds of 44kts and surface winds of between 35-40 kts.

185100 1531N 05301W 9847 00197 0071 +230 +230 147041 044 039 005 01

185130 1530N 05302W 9841 00200 0069 +230 +230 148039 042 040 004 01

185200 1529N 05302W 9843 00197 0067 +240 +240 150036 038 039 003 05

185230 1528N 05304W 9838 00202 0065 +230 +230 147035 037 036 002 01

185300 1527N 05305W 9844 00194 0063 +240 +240 149035 036 036 003 01

185330 1526N 05306W 9840 00194 0060 +240 +240 151031 034 035 004 01

185400 1525N 05308W 9846 00188 0059 +240 +240 153030 031 034 001 05

185430 1524N 05309W 9840 00191 0056 +240 +240 153031 032 033 002 01

185500 1524N 05310W 9841 00189 0055 +240 +240 153028 031 031 005 05

185530 1523N 05311W 9842 00187 0053 +250 +250 156024 027 030 005 01

185600 1522N 05313W 9850 00178 0052 +250 +250 160020 021 029 002 01

185630 1521N 05314W 9840 00186 0051 +250 +250 157016 019 025 004 01

185700 1521N 05316W 9840 00186 0051 +250 +250 157011 013 020 006 01

185730 1520N 05317W 9844 00182 0050 +250 +250 174008 010 020 004 05

185800 1520N 05319W 9846 00181 0050 +250 +250 172004 007 019 004 01

185830 1520N 05320W 9840 00184 0049 +250 +250 109001 002 021 002 01

185900 1520N 05322W 9843 00183 0049 +250 +250 025005 006 019 005 01

185930 1519N 05323W 9842 00184 0049 +250 +250 005007 008 015 005 05

[Iceberg]

Heres the latest paths and intensity forecasts. however i would take them with a pinch of salt atm.

Also the ECM which stall isaac near cancun !!! and then steers him into the USA southern belly as a serious monster.

Some convection again near the centre but i still dont have any confidence that will be successful.

[Iceberg]

Confirmation that Nhc have now classified this as a 35kt tropical storm called Isaac, the front page will be updated in the next 90 mins.

Vortex data shows 40kts surface winds as well.

[the gas lad]

im keeping a Eye on this one - im off to florida on Tuesday so more details to me the better

[mezzacyclone]

below VDM Iceb touched on reinforcing that Isaac`s here, soon to slow down & not too fussy over any diminishing shear headaches

Product: Air Force Vortex Message (URNT12 KNHC)

Transmitted: 21st day of the month at 19:17Z

Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 307)

Tropical Depression: Number 9 (flight in the North Atlantic basin)

Mission Number: 1

Observation Number: 09

A. Time of Center Fix: 21st day of the month at 18:58:40Z

B. Center Fix Coordinates: 15°20'N 53°20'W (15.3333N 53.3333W)

B. Center Fix Location: 448 miles (722 km) to the ENE (70°) from Bridgetown, Barbados.

C. Minimum Height at Standard Level: Not Available

D. Estimated (by SFMR or visually) Maximum Surface Wind: 40kts (~ 46.0mph)

E. Location of the Estimated Maximum Surface Wind: 20 nautical miles (23 statute miles) to the ENE (61°) of center fix

F. Maximum Flight Level Wind Inbound: From 146° at 44kts (From between the SE and SSE at ~ 50.6mph)

G. Location of Maximum Flight Level Wind Inbound: 21 nautical miles (24 statute miles) to the ENE (60°) of center fix

H. Minimum Sea Level Pressure: 1005mb (29.68 inHg) - Extrapolated

I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 24°C (75°F) at a pressure alt. of 304m (997ft)

J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 25°C (77°F) at a pressure alt. of 246m (807ft)

K. Dewpoint Temp (collected at same location as temp inside eye): 25°C (77°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 and Pressure

N. Fix Level: 1,500 feet

O. Navigation Fix Accuracy: 0.02 nautical miles

O. Meteorological Accuracy: 2.5 nautical miles

Remarks Section - Remarks That Were Decoded...

Maximum Flight Level Wind: 44kts (~ 50.6mph) in the northeast quadrant at 18:51:00Z

Sea Level Pressure Extrapolation From: Below 1,500 feet

Remarks Section - Additional Remarks...

SPIRAL BAND

Edited August 21, 2012 by mezzacyclone

[Iceberg]

This did indeed become Tropical Storm Isaac last night at 10am. Latest bit of discussion below.

HERE HAS BEEN NO AERIAL RECONNAISSANCE INTO ISAAC RECENTLY...BUT

THE CLOUD PATTERN OF THE STORM HAS NOT BECOME SIGNIFICANTLY BETTER

ORGANIZED OVER THE PAST FEW HOURS. THE INTENSITY IS HELD AT 35 KT

WHICH IS IN AGREEMENT WITH A DVORAK INTENSITY ESTIMATE FROM TAFB.

ANOTHER HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO INVESTIGATE ISAAC

AT AROUND 0600 UTC.

THERE IS SOME SPREAD IN CENTER FIXES...BUT BASED ON GEOSTATIONARY

AND MICROWAVE IMAGERY THE INITIAL MOTION REMAINS ABOUT THE

SAME...275/16. A WELL-DEFINED MID-TROPOSPHERIC RIDGE TO THE NORTH

OF THE TROPICAL CYCLONE SHOULD MAINTAIN THE WESTWARD TRACK FOR THE

NEXT COUPLE OF DAYS. LATER IN THE FORECAST PERIOD...GLOBAL MODELS

DEPICT ISAAC NEARING A BREAK IN THE RIDGE NEAR FLORIDA.

CONSEQUENTLY THE FORWARD SPEED IS LIKELY TO SLOW...AND THE HEADING

TO GRADUALLY TURN TOWARD THE RIGHT...IN THE LATTER HALF OF THE

FORECAST PERIOD. ALTHOUGH THE GFS HAS SHIFTED JUST A BIT TO THE

NORTH OF ITS PREVIOUS FORECAST...OVERALL THE TRACK GUIDANCE HAS NOT

CHANGED MUCH SINCE THE PREVIOUS CYCLE. THE OFFICIAL FORECAST IS

VERY CLOSE TO THE LATEST HWRF TRACK AND NOT FAR FROM THE DYNAMICAL

CONSENSUS.

[Iceberg]

Recon are currently doing the first pass of the day into isaac and have found pressure is falling with a large area of sub 1004 pressure now. Isaac is showing a very large centre, which is good as it will take him awhile to intensify and but bad as it means he intends on being a biggy if he can manage it.

-90 cloud tops and much better central convective mass also can be seen on sat, although i wouldnt say yet that its a stable cdo.

The size of isaacs moisture shield makes it difficult to see how good the outflow and inflow are as its all very messy. However dry air should not be a problem going forward.

We still have some shear as well effecting the system and displacing the convection to the south and west of the centre, although the centre is covered.

054230 1524N 05650W 8434 01531 0044 +180 +180 314014 016 017 003 01

054300 1525N 05649W 8428 01534 0038 +188 +183 321012 015 014 002 00

054330 1526N 05648W 8429 01531 0040 +186 +179 327008 012 015 003 00

054400 1527N 05647W 8430 01527 0040 +180 +180 342007 008 015 003 01

054430 1528N 05645W 8432 01528 0038 +180 +180 351007 008 011 005 01

054500 1529N 05644W 8424 01534 0036 +180 +180 344006 008 010 002 01

054530 1530N 05642W 8433 01527 0039 +180 +180 009002 004 006 002 01

054600 1531N 05641W 8432 01527 0036 +188 +187 071003 004 003 002 00

054630 1532N 05639W 8430 01528 0036 +180 +180 093006 008 003 003 01

054700 1532N 05638W 8431 01527 0035 +188 +186 101010 011 003 003 00

054730 1533N 05636W 8430 01529 0036 +188 +182 100012 012 003 004 00

054800 1534N 05635W 8428 01532 0037 +180 +180 114020 022 006 004 01

054830 1535N 05634W 8430 01529 0034 +194 +182 118024 025 016 003 00

Edited August 22, 2012 by Iceberg

[Iceberg]

recon have been playing around trying to get a fix on the centre and i've put on the below where is is(to within 10 miles or so).

It helps to show that the convective mass is actually completely over the centre, but much stronger to the sw.

Winds have still be around the 35kts mark so nothing yet to justify an upgrade, however given the size of its pressure field winds will likely take a while to respond.

Pressure is down to 1003.2mb, whether this is down to them finally getting a clear pas of the centre, or whether its down to falling pressure in unclear. However given the agressive precip, strengthening should be occuring imho.

pressure of sub 1003mb might be found in the next run and maybe sub 1000 by the time recon depart.

Models: the globals are to the west of the guidance and tropicals to the east. Most agree on a hit to florida, after passing over some islands, ECM yet again goes to the far west as it keeps a much stronger ridge in place.

At the 72+ range i would not be going against the ecm tbh with big hemisphere building blocks like this and the globals should have a much better handle.

[Iceberg]

ecm finally all the way out and leaves the recurve north until after its gone under cuba, with the resulting monster which would be Katrina in style as it hits LA.

[Coast]

Tropical Storm Isaac, the ninth named storm of the Atlantic hurricane season, was heading toward the Lesser Antilles and is forecast to emerge over the eastern Caribbean Sea within two days.

Isaac, about 435 miles (700 kilometers) east of Guadeloupe, is moving west at 17 miles per hour, the Miami-based National Hurricane Center said in an advisory before 8 p.m. New York time. The storm, with maximum sustained winds of 40 mph, formed earlier today about 500 miles east of Guadeloupe. The system is forecast to move through the Leeward Islands tomorrow evening and emerge over the eastern Caribbean Sea the next morning, the hurricane center said. It is predicted to strengthen over the next 48 hours. Tropical storm warnings have been issued for islands including Dominica, Guadeloupe, St. Kitts, Nevis, Antigua and Barbuda.

Tropical storm conditions are expected to reach warning areas by tomorrow afternoon, “making outside preparations difficult or dangerous,†the center said. A system becomes a tropical storm when sustained winds reach 39 mph and a hurricane when they reach 74 mph. The center’s tracking map shows the system crossing Haiti as a hurricane on Aug. 25 and striking Cuba the next day.

Two computer models are suggesting a Florida landfall that may affect the Republican National Convention, Jeff Masters, co- founder of Weather Underground in Ann Arbor, Michigan, said on his blog. The convention, at which the party will officially nominate Mitt Romney as its candidate for president, is Aug. 27 to Aug. 30 in Tampa, Florida. Storm Watches

“It would take a ‘perfect storm’ sort of conditions to all fall in place†for the system to reach Tampa as a hurricane during the convention, Masters said. “But that is one of the possibilities.â€

Storm watches were posted for Puerto Rico and the U.S. Virgin Islands, among others. A warning means storm conditions are expected within 36 hours. A watch means tropical storm impact is possible within 48 hours. As much as eight inches (20 centimeters) of rain may fall over the Leeward Islands and the northern Windward Islands, the center said. A storm surge may raise water levels as much as 3 feet (0.9 meters) above normal tide levels in the northern Leeward Islands, “accompanied by dangerous waves†near the coast.

The center is tracking two other Atlantic systems. A low- pressure area over the far western Gulf of Mexico has a 20 percent chance of becoming a tropical system in the next two days. Another, 550 miles southwest of the Cape Verde Islands, has a 60 percent probability of becoming tropical.

http://www.businessw...ne-in-caribbean

Tropical Storm ISAAC: Storm-centered zoom at 93 hours lead

[Iceberg]

pressure now 1002mb. rain contaminated winds of 40-50kts.

Persistant cdo looks like it has/is forming.

However their is still decoupling due to the forward speed of low and mid circulations, however the are coming together, when that happens with the cdo and very cold cloud tops we should go bang.