Isaac approaching hurricane strength

By: Angela Fritz , 9:14 PM GMT on August 27, 2012

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Isaac is walking the line of hurricane status this afternoon after a hurricane hunter mission investigated the storm and found winds of 80+ mph with the SFMR instrument, which looks down at the surface from the plane and estimates what wind speeds are. This instrument has a notoriously rough time in doing so when there's heavy rain, and since the strongest winds were recorded coinciding with the strongest rain, you can imagine that this region of high wind speed could be suspect. The hurricane hunter mission is still in the storm, so I imagine they will issue a special update if needed. Currently the best estimate of wind speed within the storm is 70 mph. Isaac's pressure has been dropping today as well and is now 981 mb. Isaac is moving northwest at 12 mph--no change since this morning. Satellite loops show that Isaac remains large, though asymmetric, with most of the strong thunderstorm activity on the west and southwest side. Isaac's southeast side continues to struggle with dry air and wind shear, which could help to moderate Isaac's intensity as it approaches the coast.

An oil platform in the northern Gulf of Mexico is reporting sustained winds from the north-northeast at 40 mph this afternoon. A buoy west of Tampa, Florida is recording sustained winds around 30 mph, and platforms south of Louisiana are recording winds from 35-40 mph. The widespread heavy rain of yesterday has lightened up in Florida, but a strong line of thunderstorms in one of Isaac's outer bands is training northward along and offshore of the east coast of Florida, affecting everyone from Miami to Jacksonville.

This afternoon the AP reported that Isaac's death toll in Haiti jumped to 19, which puts Isaac's total death count at 21. It appears most of the deaths in Haiti were due to collapsing structures.


Figure 1. Satellite imagery of Tropical Storm Isaac around 3pm EDT on Monday.

Track forecast:
Models seem to be coming into better agreement today on where Isaac will make landfall, closing in on Louisiana and New Orleans as most likely landfall point. The ECMWF, HWRF, and UKMET all suggest New Orleans as the landfall location. The GFS is only slightly west of that. The GFDL is the farthest west, predicting landfall near the Louisiana-Texas border. Landfall timing remains Tuesday night. Beyond landfall, Isaac is expected to move north toward the Midwest through the rest of this week, however, models are showing that the system will likely slow down around landfall time, prolonging impacts like surge and inland flooding.

Intensity forecast:
The closer Isaac gets to landfall without having formed an eye, the better it is for intensity at landfall. Isaac has strengthened only modestly in the past 24 hours, and is still struggling with a less-than-conducive atmospheric environment. The HWRF remains on the high end of the intensity spectrum, suggesting Isaac will be a weak category 2 upon landfall. Other models suggest it will be a strong category 1, but the difference is splitting hairs. The National Hurricane Center's official forecast is for Isaac to continue strengthening over the next day, reaching category 2 at landfall.


Figure 2. Tide gauge data from St. Petersburg, Florida. The green line shows the storm surge. As Isaac's counterclockwise winds blew offshore this morning, water levels feel two feet at St. Petersburg. The winds switched to onshore this afternoon as the center of Isaac moved more to the northwest, bringing a storm surge of two feet to the city.

Storm surge observations from Isaac
This morning, as Isaac's counter-clockwise winds brought offshore winds to the Tampa/St. Petersburg area, ocean waters fell two feet along the coast. This afternoon, winds have shifted to blow onshore, and a two foot storm surge has been observed at Naples, Fort Meyers, and St. Petersburg on the west coast of Florida. Water levels have also begun to rise along the coast of Louisiana, with a storm surge of 1.5 feet already occurring at Shell Beach on the east side of New Orleans in Lake Borgne.

Angela and Jeff

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Gotta go to work at 9 (no idea why I'm still up -_-), but I thought I'd link to the blog I just finished on Isaac. Didn't have time for Ileana.
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2453. LargoFl
Quoting Patrap:
06z Early Cycle NHC model tracks
Isaac

Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)




Early Model Wind Forecasts

hey pat welcome back, how was cancun?
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Storm is in annoying weak/pathetic shape.

You can see from Mobile and Slidell radar that there are almost no western rains at all this morning.


Oh yeah, Adjusted Euro is 971mb.


I don't know what this is, but the name "Isaac" seems appropriate, because right now it seems like a joke.

There has literally been stronger 990mb storms before.
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Morning, Pat - glad to see you are back. Probably not as glad as the pup was, though.
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2450. LargoFl
Quoting Fl30258713:


Isaac certainly does score high on the weird-o-meter. I'm in Pensacola near the Alabama border & I-10. I'm wonder if after Isaac turns over land if he will drag his southern half over NW Florida? I know the model show Isaac well to the north of the north central gulf coast before turning but I'm sure there will be moisture being pulled north from the GOM that will bring much rain to NW Florida a Lower Alabama.
issac sure dumped a deluge of rain on eastern florida alright, if nothing else, he is a huge rain maker
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Since we have been enjoying the best Summer weather imaginable here in Maine we are please to see Isaac appear to have lost some of his teeth. That is good news for our Southern friends, although frustrating to the professional meteorologists who do an excellent job with the information fed them.

Really appreciate everyone's insights.
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Quoting GetReal:
Isaac has managed to get into the record books as the first ever 977MB TS.... He is literally a CAT 2 TS....
yes and very large area of low pressure. a big if but if this could go a bit more west and push all the way up to Kansas or Iowa and form a big feeder band like the east coast of Florida had this could bring some much needed drought relief to the Midwest.
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Quoting Chicklit:

Isaac appearance is certainly weird.
It's a hybrid.


Isaac certainly does score high on the weird-o-meter. I'm in Pensacola near the Alabama border & I-10. I'm wonder if after Isaac turns over land if he will drag his southern half over NW Florida? I know the model show Isaac well to the north of the north central gulf coast before turning but I'm sure there will be moisture being pulled north from the GOM that will bring much rain to NW Florida a Lower Alabama.
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2446. FFEMTRQ
Quoting StormThug:
should be a cane by 7


Should have been a 'cane 2 days ago, or was that yesterday, or by 2am, or 5am.....
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2445. HCW
Welcome back Pat How was the trip ? Got your favorite drink ready and on ice for Isaac ?
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Oh yeah, it already has a category 2 hurricane pressure, and it's still not even rated as a category 1.
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2443. Skyepony (Mod)
Quoting bajelayman2:


Makes me wonder if anything has been done to 'adjust' the strom at any point. i.e. seeding or such.


The storm is so big it is going to take a lower pressure to get the same winds. The high in the Atlantic is only ~1024mb as well. You need pressure gradient for winds. It's why the WPAC has a different chart converting mb to winds than the Atlantic.

That being said I traveled from GA to FL yesterday & chemtrails were everywhere in the SGA/NFL area. Another interesting note is how everyone is saying they have never seen a lunar halo or halo around the sun so bright as today in those areas. These sort of sightings are common with certain types of seeding.

If this goes the right way it could save the fall planting up the middle of the country..
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should be a cane by 7
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Quoting FunhouseFX:
I don't generally comment as I usually have nothing to add. Truth be told I really don't have anything useful to add to this discussion either. Other than perhaps this:

The luidicrous hype the experts have participated in over the last few years has consequences far beyond "disappointed" weather fans. Right now, thanks to this nonsense, hundreds-of-thousands of people who are barely making it just spent a lot of money they did not have, buying supplies they did not need, preparing for a storm that has never looked particularly impressive. Businesses are closed, people aren't getting paid, and the folks who spent their money getting ready are discovering that they wasted their cash.

Sadly, ignoring the experts was the RIGHT call. Again.

The end result of all this will be potential victims trained to ignore the warnings -- just as we saw at Joplin with such disasterous and lethal results.

My forecast: Tomorrow this storm is going to come ashore. We will be treated to hillarious overacting as raingear clad reporters ham it up trying to make the thunderstorm force winds and occassional rain look impressive. At least one of these idiots will give his reports while standing knee deep in the water. Another will comment about the horrific force of the storm while kids fly kites or skateboard behind him. And all across America, millions of people will conclude that the best thing one can do is to ignore the paid professionals. After it's all said and done the weather professionals will gather to answer the usual question: did we over-hype this.

Their answer will be a solid no.


Not really the time or place for a political discussion, but that being said, having lived in the North Central Gulf Coast for 47 years and having done my share of preparing for Hurricanes that didn't happen or that didn't come to me as a direct hit, all you can do for any Hurricane or potential hurricane, is plan for the worst and hope for the best.

As far as forecasting goes when a system/wanna be Hurricane is headed somewhere at 18 to 20 mph, the models give forecasters a good consensus of what storms will do for the next 2 to 3 day and beyond that time frame, the forecasting is less accurate, but far more accurate than it was 10 years ago.

I always plan based on my conception of the worst parts of the storm reaching me based on forecasting from many different sources to include my own opinion.

You can return unused batteries, 50 ft of unused rope or an unopened tarp and a roll of duct tape, but if you get your butt kicked by a Cat 4 Hurricane or a Tornado during a strong and rather large Tropical Storm, those items could be priceless if you need them.

All local government & media will lean to the side of caution, which happens to be the same side advertising & marketing that was pre-planned in case a storm occurred during hurricane season. It's just pre-planned marketing, not a conspiracy to rip people off.

People have to use common sense when planning for a hurricane's worst case scenario. Otherwise they have hurricane party's at the beach and try to go surfing. History has given us 911 recording of people calling for help in the middle of a hurricane because they didn't heed the warnings. Some of us see that as a pity and want to help but can't in the middle of a storm, others of us see that as a form of stupidity & natural selection.
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2440. Patrap
06z Early Cycle NHC model tracks
Isaac

Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)




Early Model Wind Forecasts

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Projected landfall intensities:

Fixed model intensify projects by correcting their initialization error.

Approximate real rate of intensification over night: 1mb per 3 hours.

Adjusted GFS 972mb
Adjusted GFDL 971mb
Adjusted HWRF 962mb*
Linear Trend 970mb


Still about the same again for HWRF, but looks like everything else has come up by 10mb for now.
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2438. azduck
Barring a stall, Isaac is going to SE LA. Too close to coastline now for any significant change in direction, unless he stops moving altogether.
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2437. GetReal
Member Since: July 4, 2005 Posts: 204 Comments: 8898
Is Isaac still moving NW.. It's been moving wnw the last two frames
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2435. Gearsts
Time: 09:34:00Z
Coordinates: 27.5167N 88.1667W
Acft. Static Air Press: 752.4 mb (~ 22.22 inHg)
Acft. Geopotential Hgt: 2,357 meters (~ 7,733 feet)
Extrap. Sfc. Press: 982.8 mb (~ 29.02 inHg)
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going back too sleep
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2433. azduck
I for one, am pretty happy to see a Cape Verde storm landfalling as a minimal CAT1. Hopefully Isaac doesn't go Allison or Claudette on us.
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Visible of Isaac looks very impressive to me,. Full of rain this storm (as when it passed islands and then also dropped so much on Haiti and DR, and that is NO worst danger. Such a large storm and takes a while to move over, which = flooding.
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Quoting Skyepony:
ISAAC intensity




Taz~ After you threatened cow dropping & left earlier..a few flagged for a banning (it is the 7 year anniversary of Katrina), then a bunch of members from way back that I thought had gone came out in your defense..way to bring out our long lost members:)




some of you guys need too learn too light in up and not start thing on the blogs was this kinding about the cow droping on the nhc



you guys have some in too say too me? will PM me or take it too my own blog not start things up here on the main blog


its off topic and whats keep it clean in here
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I know everyone is very caught up with Isaac right now, understandably.

Note though, that something has just come off the African coast, that is already generating some good spin and is very large.

May not look like much in terms of convection, but that can build fast and has no competition now.
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2429. Skyepony (Mod)
ISAAC intensity




Taz~ After you threatened cow dropping & left earlier..a few flagged for a banning (it is the 7 year anniversary of Katrina), then a bunch of members from way back that I thought had gone came out in your defense..way to bring out our long lost members:)
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Quoting FunhouseFX:
I don't generally comment as I usually have nothing to add. Truth be told I really don't have anything useful to add to this discussion either. Other than perhaps this:

The luidicrous hype the experts have participated in over the last few years has consequences far beyond "disappointed" weather fans. Right now, thanks to this nonsense, hundreds-of-thousands of people who are barely making it just spent a lot of money they did not have, buying supplies they did not need, preparing for a storm that has never looked particularly impressive. Businesses are closed, people aren't getting paid, and the folks who spent their money getting ready are discovering that they wasted their cash.

Sadly, ignoring the experts was the RIGHT call. Again.

The end result of all this will be potential victims trained to ignore the warnings -- just as we saw at Joplin with such disasterous and lethal results.

My forecast: Tomorrow this storm is going to come ashore. We will be treated to hillarious overacting as raingear clad reporters ham it up trying to make the thunderstorm force winds and occassional rain look impressive. At least one of these idiots will give his reports while standing knee deep in the water. Another will comment about the horrific force of the storm while kids fly kites or skateboard behind him. And all across America, millions of people will conclude that the best thing one can do is to ignore the paid professionals. After it's all said and done the weather professionals will gather to answer the usual question: did we over-hype this.

Their answer will be a solid no.



Isaac killed 19 people in Haitai and two in the DR. And NO land layout, may be better than Haiti, but is very lowlying as we all know.


So much for 'hype'.
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Isaac is an odd duck. The storm has been contorted and unpredictable. The best we can do at present is use supercomputerized models that indicate where a system is going based upon current observations. It is nobody's 'fault' that Isaac didn't go up the state of Florida as initially the models indicated.

Anyway, sorry about the sour grapes over not getting hit with a storm but believe me, the expense would have been far greater for people had they been hit. And they can now use the supplies for another storm or else consume what they bought.
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Quoting GetReal:
Isaac has managed to get into the record books as the first ever 977MB TS.... He is literally a CAT 2 TS....


Makes me wonder if anything has been done to 'adjust' the strom at any point. i.e. seeding or such.
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Quoting FunhouseFX:
I don't generally comment as I usually have nothing to add. Truth be told I really don't have anything useful to add to this discussion either. Other than perhaps this:

The luidicrous hype the experts have participated in over the last few years has consequences far beyond "disappointed" weather fans. Right now, thanks to this nonsense, hundreds-of-thousands of people who are barely making it just spent a lot of money they did not have, buying supplies they did not need, preparing for a storm that has never looked particularly impressive. Businesses are closed, people aren't getting paid, and the folks who spent their money getting ready are discovering that they wasted their cash.

Sadly, ignoring the experts was the RIGHT call. Again.

The end result of all this will be potential victims trained to ignore the warnings -- just as we saw at Joplin with such disasterous and lethal results.

My forecast: Tomorrow this storm is going to come ashore. We will be treated to hillarious overacting as raingear clad reporters ham it up trying to make the thunderstorm force winds and occassional rain look impressive. At least one of these idiots will give his reports while standing knee deep in the water. Another will comment about the horrific force of the storm while kids fly kites or skateboard behind him. And all across America, millions of people will conclude that the best thing one can do is to ignore the paid professionals. After it's all said and done the weather professionals will gather to answer the usual question: did we over-hype this.

Their answer will be a solid no.



Listen shim/he or she/ there is no value for life. If all you have to do is act like your perfect then go elsewhere. Your the type of person whom doesn't appreciate the EFFORTS other individuals put in to keep us safe. You almost sound depressed. Dizapam! This will be my 18th storm and 11th hurricane. I probably have about 6 false alarms too. Do I care? ummm no. As long as I'm safe and my family is safe that's all that matters to any good worth parent or human being. Shelters are open for a reason. If your that strapped for cash go to the SHELTERS! You appear to be an individual whom just complains all th time and blames others. Well Debbie Downer (or pathetic Pete) go elsewhere. Go cry on your local tv stations site.

Now as far as Isaac. My thoughts are it will make landfall somewhere below Jennings. Either way my family and I are prepared and safe.
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2424. azduck
Taz-

4am CDT is 5am EDT.
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2423. azduck
CCkid00:

The storm is 200 miles wide. Most likely everyone in a swath from Alexandria LA to Mobile AL and inland 100 miles or so will get significant rainfall from this storm. Wind should be less of an issue, hurricane force along the immediate coast, but probably only minor wind damage, if any.
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2422. Gearsts
Time: 09:16:00Z
Coordinates: 27.4167N 86.85W
Acft. Static Air Press: 752.8 mb (~ 22.23 inHg)
Acft. Geopotential Hgt: 2,448 meters (~ 8,031 feet)
Extrap. Sfc. Press: 996.9 mb (~ 29.44 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 176° at 74 knots (From the S at ~ 85.1 mph)
Air Temp: 15.0°C (~ 59.0°F)
Dew Pt: 11.2°C (~ 52.2°F)
Peak (10s) Flt. Lvl. Wind: 74 knots (~ 85.1 mph)
SFMR Peak (10s) Sfc. Wind: 49 knots (~ 56.3 mph)
SFMR Rain Rate: 7 mm/hr (~ 0.28 in/hr)
(*) Denotes suspect data
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2421. GetReal
Member Since: July 4, 2005 Posts: 204 Comments: 8898
Quoting azduck:
5am update is up...

000
WTNT44 KNHC 280856
TCDAT4

TROPICAL STORM ISAAC DISCUSSION NUMBER 29
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
400 AM CDT TUE AUG 28 2012

REPORTS FROM THE AIR FORCE HURRICANE HUNTER AIRCRAFT INDICATE THAT
THE CENTRAL PRESSURE HAS DROPPED A LITTLE MORE...BUT SO FAR...THE
MAXIMUM FLIGHT-LEVEL AND SFMR-OBSERVED SURFACE WINDS STILL DO NOT
QUITE SUPPORT HURRICANE INTENSITY. THE CURRENT INTENSITY IS HELD
AT 60 KT PENDING ADDITIONAL OBSERVATIONS FROM THE HURRICANE
HUNTERS. ALTHOUGH THE WIND FIELD REMAINS RATHER BROAD AND
RELATIVELY FLAT...RECENT AIRCRAFT DATA SUGGEST THAT THE MAXIMUM
WINDS ARE NOW OCCURRING SOMEWHAT CLOSER TO THE CENTER OVER THE
NORTHERN SEMICIRCLE OF THE CYCLONE. THIS WOULD SUGGEST THAT THE
INNER CORE CIRCULATION IS BECOMING BETTER DEFINED...AND
STRENGTHENING MIGHT BE IMMINENT. UPPER-LEVEL OUTFLOW IS
WELL-ESTABLISHED OVER THE SOUTHERN SEMICIRCLE OF THE SYSTEM...BUT
CENTRAL CONVECTION CONTINUES TO FLUCTUATE. THE LATTER IS
PRESUMABLY DUE TO A CONTINUED INTRUSION OF DRY AIR INTO THE CORE
REGION. THE STATISTICAL-DYNAMICAL GUIDANCE IS A LITTLE LOWER THAN
IN PREVIOUS RUNS...AND THE STORM HAS ONLY ABOUT 12-24 HOURS BEFORE
MOVING INLAND. THE OFFICIAL INTENSITY FORECAST IS JUST SLIGHTLY
LOWER THAN THE PREVIOUS ONE.

CENTER FIXES FROM THE AIRCRAFT INDICATE THAT THE STORM HAS WOBBLED
ON A GENERALLY WESTWARD COURSE OVER THE PAST FEW HOURS. THIS IS
BELIEVED TO BE TEMPORARY...HOWEVER...AND THE LONGER-TERM MOTION
ESTIMATE IS ABOUT 305/10. THE CURRENT AND FORECAST STEERING REGIME
ARE BASICALLY THE SAME AS IN THE PREVIOUS PACKAGE. ISAAC IS
EXPECTED TO MOVE INTO A WEAKNESS IN THE SUBTROPICAL RIDGE NEAR THE
NORTH-CENTRAL GULF COAST...WITH SOME SLOWING OF FORWARD SPEED
DURING THE NEXT COUPLE OF DAYS AS A RIDGE BUILDS A LITTLE TO THE
NORTHWEST OF THE CYCLONE. LATER ON...THE SYSTEM SHOULD TURN
NORTHWARD AND NORTHEASTWARD INTO THE OHIO VALLEY REGION AS IT MOVES
AROUND THE WESTERN PERIPHERY OF A MID-LEVEL ANTICYCLONE.

ISAAC IS A LARGE TROPICAL CYCLONE. A DANGEROUS STORM SURGE...HEAVY
RAINFALL...AND STRONG WINDS EXTEND WELL AWAY FROM THE CENTER AND
ARE EXPECTED TO AFFECT A LARGE PORTION OF THE NORTHERN GULF COAST.
FOR THIS REASON...IT IS IMPORTANT NOT TO FOCUS ON THE EXACT CENTER
LOCATION. THE THREAT OF HEAVY RAINFALL AND FLOODING IS ALSO
EXPECTED TO SPREAD INLAND OVER THE LOWER MISSISSIPPI VALLEY REGION
DURING THE NEXT FEW DAYS.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0900Z 27.5N 88.1W 60 KT 70 MPH
12H 28/1800Z 28.5N 89.1W 70 KT 80 MPH
24H 29/0600Z 29.5N 90.1W 75 KT 85 MPH...NEAR THE COAST
36H 29/1800Z 30.3N 90.9W 55 KT 65 MPH...INLAND
48H 30/0600Z 31.4N 91.5W 45 KT 50 MPH...INLAND
72H 31/0600Z 34.5N 92.5W 25 KT 30 MPH...INLAND
96H 01/0600Z 38.0N 91.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 02/0600Z 40.5N 87.0W 15 KT 15 MPH...POST-TROP/REMNT LOW

$$
FORECASTER PASCH




4am and likey evere one has all ready seen it
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2419. emcf30
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2418. GetReal


Nothing in the way of moisture for Isaac to work with in northern portion of the system this morning... No feeder bands!!!
Member Since: July 4, 2005 Posts: 204 Comments: 8898
2417. CCkid00
Quoting LargoFl:

okay....i live an hour northwest of NOLA (between Baton Rouge and Hammond). if this takes the EURO route, will we still get heavy winds and rain? because all of the convection is on one side, i can't figure what we will get here.
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In the last two frames he moved 1.1 w 0.4 n. Is this a new trend wnw. If it changes movement to wnw at .2 w .1 n it will put the storm T 93.5 w 30.1 n which is right at Texas lo border
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2415. GetReal
Quoting Chicklit:

Isaac appearance is certainly weird.
It's a hybrid.



Good morning and a great observation and point.....
Member Since: July 4, 2005 Posts: 204 Comments: 8898
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2413. azduck
5am update is up...

000
WTNT44 KNHC 280856
TCDAT4

TROPICAL STORM ISAAC DISCUSSION NUMBER 29
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
400 AM CDT TUE AUG 28 2012

REPORTS FROM THE AIR FORCE HURRICANE HUNTER AIRCRAFT INDICATE THAT
THE CENTRAL PRESSURE HAS DROPPED A LITTLE MORE...BUT SO FAR...THE
MAXIMUM FLIGHT-LEVEL AND SFMR-OBSERVED SURFACE WINDS STILL DO NOT
QUITE SUPPORT HURRICANE INTENSITY. THE CURRENT INTENSITY IS HELD
AT 60 KT PENDING ADDITIONAL OBSERVATIONS FROM THE HURRICANE
HUNTERS. ALTHOUGH THE WIND FIELD REMAINS RATHER BROAD AND
RELATIVELY FLAT...RECENT AIRCRAFT DATA SUGGEST THAT THE MAXIMUM
WINDS ARE NOW OCCURRING SOMEWHAT CLOSER TO THE CENTER OVER THE
NORTHERN SEMICIRCLE OF THE CYCLONE. THIS WOULD SUGGEST THAT THE
INNER CORE CIRCULATION IS BECOMING BETTER DEFINED...AND
STRENGTHENING MIGHT BE IMMINENT. UPPER-LEVEL OUTFLOW IS
WELL-ESTABLISHED OVER THE SOUTHERN SEMICIRCLE OF THE SYSTEM...BUT
CENTRAL CONVECTION CONTINUES TO FLUCTUATE. THE LATTER IS
PRESUMABLY DUE TO A CONTINUED INTRUSION OF DRY AIR INTO THE CORE
REGION. THE STATISTICAL-DYNAMICAL GUIDANCE IS A LITTLE LOWER THAN
IN PREVIOUS RUNS...AND THE STORM HAS ONLY ABOUT 12-24 HOURS BEFORE
MOVING INLAND. THE OFFICIAL INTENSITY FORECAST IS JUST SLIGHTLY
LOWER THAN THE PREVIOUS ONE.

CENTER FIXES FROM THE AIRCRAFT INDICATE THAT THE STORM HAS WOBBLED
ON A GENERALLY WESTWARD COURSE OVER THE PAST FEW HOURS. THIS IS
BELIEVED TO BE TEMPORARY...HOWEVER...AND THE LONGER-TERM MOTION
ESTIMATE IS ABOUT 305/10. THE CURRENT AND FORECAST STEERING REGIME
ARE BASICALLY THE SAME AS IN THE PREVIOUS PACKAGE. ISAAC IS
EXPECTED TO MOVE INTO A WEAKNESS IN THE SUBTROPICAL RIDGE NEAR THE
NORTH-CENTRAL GULF COAST...WITH SOME SLOWING OF FORWARD SPEED
DURING THE NEXT COUPLE OF DAYS AS A RIDGE BUILDS A LITTLE TO THE
NORTHWEST OF THE CYCLONE. LATER ON...THE SYSTEM SHOULD TURN
NORTHWARD AND NORTHEASTWARD INTO THE OHIO VALLEY REGION AS IT MOVES
AROUND THE WESTERN PERIPHERY OF A MID-LEVEL ANTICYCLONE.

ISAAC IS A LARGE TROPICAL CYCLONE. A DANGEROUS STORM SURGE...HEAVY
RAINFALL...AND STRONG WINDS EXTEND WELL AWAY FROM THE CENTER AND
ARE EXPECTED TO AFFECT A LARGE PORTION OF THE NORTHERN GULF COAST.
FOR THIS REASON...IT IS IMPORTANT NOT TO FOCUS ON THE EXACT CENTER
LOCATION. THE THREAT OF HEAVY RAINFALL AND FLOODING IS ALSO
EXPECTED TO SPREAD INLAND OVER THE LOWER MISSISSIPPI VALLEY REGION
DURING THE NEXT FEW DAYS.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0900Z 27.5N 88.1W 60 KT 70 MPH
12H 28/1800Z 28.5N 89.1W 70 KT 80 MPH
24H 29/0600Z 29.5N 90.1W 75 KT 85 MPH...NEAR THE COAST
36H 29/1800Z 30.3N 90.9W 55 KT 65 MPH...INLAND
48H 30/0600Z 31.4N 91.5W 45 KT 50 MPH...INLAND
72H 31/0600Z 34.5N 92.5W 25 KT 30 MPH...INLAND
96H 01/0600Z 38.0N 91.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 02/0600Z 40.5N 87.0W 15 KT 15 MPH...POST-TROP/REMNT LOW

$$
FORECASTER PASCH
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2412. GetReal


Luckily it appears Isaac maybe cutting off that trining of dry air from the east. He will not be able to take advantage of it, running out of time and water.
Member Since: July 4, 2005 Posts: 204 Comments: 8898
2411. Skyepony (Mod)
Quoting StormThug:
They found flight level winds around 90mph I don't see how this isn't a hurricane


Because the surface winds is what counts.
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Winds are sustained 16 knots on my boat in just outside of galveston in the gom, seas are starting to slowly build...
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All times in GMT. Derived from NHC_ATCF data for TropicalStormIsaac for 28August6am
27Aug.12am , 24.0n82.5w
27Aug.06am , 24.9n83.7w , 309.6*NW @26.2km/h (16.3mph) 14.2knots , 50knots , 990millibars , TS
27Aug.12pm , 25.8n84.8w , 312.2*NW @24.8km/h (15.4mph) 13.4knots , 55knots , 987millibars , TS
27Aug.06pm , 26.1n85.9w , 287.0*WNW@19.2km/h(11.9mph)10.4knots , 60knots , 984millibars , TS
28Aug.12am , 26.7n86.5w , 318.1*NWest@14.9km/h (9.3mph) 8.0knots , 60knots , 981millibars , TS
28Aug.06am , 27.4n87.7w , 303.4*WNW@23.7km/h(14.7mph)12.8knots , 60knots , 978millibars , TS
2TA5-PortO'Connor :: HUM-Houma :: 17LA-Venice :: 5LA6-SouthwestPass,MississippiRiver
The unconnected unlabeled dot covers FortJefferson :: EYW-KeyWest

The kinked line is TS.Issac's path on its 6th day as a TropicalStorm
The southeasternmost dot on the longest straight line is TS.Isaac's most recent position

The longest line is a straightline projection through TS.Isaac's 2 most recent positions to its closest approach (within 18miles or 29kilometres) to an inhabited coastline
27Aug.6am: TS.Isaac had been headed for passage just southwest of the SouthwestPass shipping entrance/exit for the MississippiRiver (bottom,2TA5blob) on its way to GrandIsle,Louisiana
27Aug.12pm: TS.Isaac had been headed for passage over Venice,Louisiana (middle,17LAblob)
27Aug.6pm: TS.Isaac had been headed for passage over Seadrift(PortO'Connor)Texas (not shown)
28Aug.12am: TS.Isaac had been headed for passage 7.6miles(12.3kilometres)NEast of Venice (top,17LAblob)
28Aug.6am: TS.Isaac was heading for a 9:30pm passage 17.8miles(28.7kilometres)SSWest of Dulac in ~12hours from now (when this was posted)

Copy&paste hum, 24.627n82.873w, 5la6-28.894n89.436w, 17la-29.268n89.322w, 17la-29.347n89.263w, eyw, 23.9n81.5w- 24.0n82.5w- 24.9n83.7w- 25.8n84.8w- 26.1n85.9w, 26.1n85.9w-26.7n86.5w, 26.7n86.5w-27.4n87.7w, 26.7n86.5w-29.161n90.868w, 29.382n90.714w-29.161n90.868w into the GreatCircleMapper for a larger map and other information
The previous mapping for comparison
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2408. GetReal
Quoting tomas5tex:
By all information from recon Isaac is moving WNW....Dont understand why they said NW. They are the professional so we just have to take their word.



Product: Air Force Temp Drop (Dropsonde) Message (UZNT13 KNHC)
Transmitted: 28th day of the month at 09:00Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 309)
Storm Number: 09
Storm Name: Isaac (flight in the North Atlantic basin)
Mission Number: 29
Observation Number: 23

Part A...

Date: Near the closest hour of 9Z on the 28th day of the month
Highest Mandatory Level For Which Wind Was Reported: 850mb
Coordinates: 27.4N 88.0W
Location: 215 miles (347 km) to the SSW (193) from Pensacola, FL, USA.
Marsden Square: 081 (About)

Level Geo. Height Air Temp. Dew Point Wind Direction Wind Speed
977mb (28.85 inHg) Sea Level (Surface) 28.2C (82.8F) 27.3C (81.1F) 170 (from the S) 2 knots (2 mph)
1000mb -204m (-669 ft) This level does not exist in this area of the storm above the surface level.
925mb 490m (1,608 ft) 25.0C (77.0F) 24.7C (76.5F) 220 (from the SW) 2 knots (2 mph)
850mb 1,234m (4,049 ft) 21.6C (70.9F) 21.4C (70.5F) 335 (from the NNW) 4 knots (5 mph)





On the last HH fly through they found the center to the north of the previous HH fix.
Member Since: July 4, 2005 Posts: 204 Comments: 8898
2407. unc70
How far out will that outer band reach when it rotates 180 degrees?
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I don't generally comment as I usually have nothing to add. Truth be told I really don't have anything useful to add to this discussion either. Other than perhaps this:

The luidicrous hype the experts have participated in over the last few years has consequences far beyond "disappointed" weather fans. Right now, thanks to this nonsense, hundreds-of-thousands of people who are barely making it just spent a lot of money they did not have, buying supplies they did not need, preparing for a storm that has never looked particularly impressive. Businesses are closed, people aren't getting paid, and the folks who spent their money getting ready are discovering that they wasted their cash.

Sadly, ignoring the experts was the RIGHT call. Again.

The end result of all this will be potential victims trained to ignore the warnings -- just as we saw at Joplin with such disasterous and lethal results.

My forecast: Tomorrow this storm is going to come ashore. We will be treated to hillarious overacting as raingear clad reporters ham it up trying to make the thunderstorm force winds and occassional rain look impressive. At least one of these idiots will give his reports while standing knee deep in the water. Another will comment about the horrific force of the storm while kids fly kites or skateboard behind him. And all across America, millions of people will conclude that the best thing one can do is to ignore the paid professionals. After it's all said and done the weather professionals will gather to answer the usual question: did we over-hype this.

Their answer will be a solid no.
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Quoting GetReal:
Isaac has managed to get into the record books as the first ever 977MB TS.... He is literally a CAT 2 TS....

Isaac appearance is certainly weird.
It's a hybrid.
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Is this western movement just a jog in the last two frames or a trend
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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