Isaac makes its final approach towards Louisiana

By: Dr. Jeff Masters , 3:29 PM GMT on August 28, 2012

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The winds and water are rising all along the coast from Louisiana to the Florida Panhandle as Tropical Storm Isaac makes its final approach. Two hurricane hunter aircraft in the storm are measuring a steadily lowering pressure and increasing winds aloft, but hurricane-force winds have not yet been observed at the surface. The 8:30 am center fix found a pressure of 976 mb, which is very low for a tropical storm. Top surface winds measured with the SFMR instrument were 70 mph, but the plane measured 102 mph at an altitude of 5,000 feet. It's more typical to see surface winds of 85 mph with a storm with these characteristics. Infrared and visible satellite loops and hurricane hunter reports from this morning have shown that Isaac has developed a 25-mile diameter eye, though the eyewall has not yet formed a full circle around the eye. Heavy thunderstorm activity is lacking on the north side, where light wind shear of 5 -10 knots is still pumping some dry air into the circulation.


Figure 1. Morning satellite image of Isaac. Note how dry air has wrapped into the west side of the storm, causing a lack of heavy thunderstorm activity.

Isaac's rains
One of the most remarkable features of Isaac has been the huge spiral band that parked itself along most of the east coast of Florida and remained there for an entire day, despite the fact the center of the storm moved 400 miles away. This rain band was amplified by a weak trough of low pressure along the East Coast, which pulled away from the coast Monday night, taking the band of heavy rain out to sea (except for a few lingering showers near West Palm Beach.) Isaac's heaviest rains fell along a swath from the east coast of Florida near West Palm Beach to the center of the state, just south of Orlando. The 2-day rainfall total of 9.03" at West Palm Beach brought their monthly rainfall total to 22.28", a new August record (old record: 20.12" in 1995.) Vero Beach's 6.48" of rain was a record for any August day. A possible tornado touched down there, damaging 20 mobile homes. In the Keys, rainfall totals as high as 7.94" (at Upper Matecumbe Key) were measured. Heavy rains from Isaac are lingering over Cuba but have ended in Haiti and the Dominican Republic; flash floods in Haiti from Isaac's torrential rains killed at least 24, and two died in the Dominican Republic. The big concern in Haiti is the heavy damage that was done to crops, and the likelihood that the storm's rains will worsen the cholera epidemic that has killed over 7,000 Haitians.


Figure 2. Radar-estimated rainfall from Miami, Florida radar shows that Isaac has dumped a wide swath of 8+ inches of rain (orange colors) across the state. Rainfall amounts in excess of 20" may have fallen just west of West Palm Beach, though the highest amount reported by a rain gauge was 13.10" at Greenacres in Palm Beach County.

Latest model runs for Isaac
The latest set of 0Z and 06Z (8 pm and 2 am EDT) model runs are fairly unified taking Isaac ashore near Southeast Louisiana late Tuesday night or early Wednesday morning, but continue to show some differences in what happens after that. Isaac may scoot nearly west-northwest just inland along the coast into Texas, as predicted by the ECMWF model, or head straight inland to the northwest and into Arkansas, as predicted by the GFS model. The latest 8-day precipitation forecast from the GFS model calls for 10 - 20 inches of rain over much of Louisiana. It appears likely that Arkansas will see some heavy rains of up to five inches, which would help put a dent in the exceptional drought conditions there.

Intensity forecast for Isaac
Low wind shear of 10 knots or less is likely until landfall, along with very warm ocean temperatures. An analysis of upper level winds from the University of Wisconsin CIMSS shows that Isaac's upper-level outflow is the strongest we've seen, with a solid outflow channel to the south. These conditions favor continued strengthening of Isaac until landfall. However, we've observed in the past many instances of hurricanes suddenly weakening in the final 12 hours before making landfall along the Central Gulf Coast. Katrina, Gustav, Dennis, Ivan, and Rita all did so. A July 2012 paper in the Bulletin of the American Meteorological Society by Rosenfeld et al. titled, AEROSOL EFFECTS ON MICROSTRUCTURE AND INTENSITY OF TROPICAL CYCLONES, theorizes that this may happen because of the impact of small particles that get pulled into the outer circulation of hurricanes, seeding the clouds. These small particles, primarily from air pollution, serve as the seed around which water condenses, increasing the rain in the outer spiral bands. The increase in rain and heat energy at the periphery of the storm comes at the expense of the eyewall and inner core, where the winds tend to weaken. A detailed modeling study by Khain et al. (2010) of Hurricane Katrina in the final day before landfall was able to reproduce the storm's weakening only when this air pollution effect was included. This impact of small particles on hurricanes is not included in any operational hurricane model.


Figure 3. Tide gauge data from Shell Beach, located in Lake Borgne just east of New Orleans. The green line shows the storm surge. The red line is the storm tide, the height of the water above Mean Sea Level (MSL.)

Storm surge observations from Isaac
Isaac's storm surge has peaked along the west coast of Florida. As I explain in our Storm Surge Tutorial, we are most interested in the storm tide--the height above Mean Sea Level (MSL) of the tide plus the storm surge. The storm tide is the number given in NHC advisories for how much above ground level the ocean will be at the coast. The storm surge is the extra elevation of the water due to wind blowing on the water, and does not include the action of waves on top of the water, nor the tide. Tide gauges are specially constructed so that transient waves do not impact water level measurements. At Cedar Key on the West Florida coast north of Tampa, a storm surge of 3' and storm tide of 3.8' were observed early this morning. These were the highest water levels measured at any tide gauge along the Florida west coast. Higher storm surges are occurring in the Florida Panhandle. As of 9 am EDT, here were the storm surge/storm tide measurements along the Florida Panhandle:

Apalachicola, FL: 3.5' storm surge, 4' storm tide
Panama City, FL: 2.3' storm surge, 3.3' storm tide
Pensacola, FL: 1.5' storm surge, 2.5' storm tide

A storm surge of 3.5 feet was recorded at 10 am EDT at Shell Beach on the east side of New Orleans in Lake Borgne. This site will have one of the highest surge values during Isaac; a storm surge of 9.5' was measured at Shell Beach during Hurricane Gustav in 2008.


Figure 4. Category 2 Hurricane Gustav of 2008 followed a very similar path to Isaac, and brought a storm tide (the combined effect of the storm surge and tidal levels) of up to 14.5' above ground level to the east side of New Orleans. Isaac's surge may be similar, though probably a little less, than Gustav's.


Figure 5. Track of Hurricane Gustav of 2008, which followed a path very similar to that of Isaac's predicted path.

Isaac: similar to Category 2 Hurricane Gustav of 2008 in destructive power?
Isaac is a huge and slow-moving storm, with tropical storm-force winds that extend out 205 miles from the center. Isaac has cut its forward speed down from 14 mph yesterday to 10 mph today, and a large swath of the coast will be subject to high winds and a large storm surge for an usually long period of time for a hurricane--up to 24 hours. Long duration winds are much more damaging than short duration winds, and a long duration storm surge event allows damage to occur during multiple high tide cycles. The long duration storm event will also allow very high rainfall totals, resulting in greater fresh-water flooding problems than usual. As a result, I expect Isaac's to cause more damage than the typical Category 1 hurricane. The 9:30 am EDT Integrated Kinetic Energy analysis from NOAA's Hurricane Research Division put the destructive potential of Isaac's winds near 2.3 on a scale of 0 to 6, but the destructive potential of Isaacs's storm surge was 4.1 on a scale of 0 to 6. For comparison, the storm surge destructive potential of Category 2 Hurricane Gustav of 2008 was rated at 4.2 on a scale of 0 to 6, and the wind destructive potential was 1.1--which is lower than Isaac's, even though Isaac was just a tropical storm at 9:30 am EDT. Gustav brought a storm tide (the combined height of the storm surge and high tide) of 14.5' to the east side of New Orleans, and 11' to Waveland, Mississippi. However, the destructive potential of Isaac's surge may be overrated by this analysis. Wave heights this morning from buoy and ships in Isaac have mostly been below 15', which is quite unimpressive. One ship report to the SE of the storm had a 19' wave height (thanks to meteorologist Steve Gregory for pointing this out.) With only another 12 - 18 hours over water, Isaac likely won't have time for its slowing increasing winds to build up a storm surge that will reach as high as 14', like Gustav did. The official NHC forecast of maximum storm surge height of 12' looks like a good one. The highest rainfall total observed in Gustav was 21" at Larto Lake, Louisiana, and I expect we'll exceed that for Isaac, since the storm is moving more slowly. Gustav spawned 41 tornadoes--21 in Mississippi, 11 in Louisiana, 6 in Florida, 2 in Arkansas, and 1 in Alabama. The strongest tornado was an EF2 in Evangeline Parish, Louisiana. Isaac will likely produce 10+ tornadoes. The total damage from Gustav in the U.S. was $4.5 billion (2012 dollars.) I expect Isaac's damage total will be in the $500 million - $4 billion range.

Invest 97L in the Middle Atlantic
A tropical wave (Invest 97L) is located in the Middle Atlantic, about 1250 miles west-northwest of the Cape Verde Islands. The storm has a modest amount of spin and heavy thunderstorms, and is under moderate wind shear. In their 8 am EDT Tropical Weather Outlook, NHC gave 97L a 40% chance of developing by Thursday morning. None of the reliable models foresee that 97L will be a threat to any land areas.

Another tropical wave that moved off the coast of Africa on Sunday is located just southwest of the Cape Verde Islands, and is moving west at 15 mph. Several models develop the disturbance into a tropical depression late this week, and NHC is giving the disturbance a 10% chance of becoming a tropical depression by Thursday morning. The disturbance could begin to affect the Northern Lesser Antilles as early as Saturday night, though our two best models, the GFS and ECMWF, predict the center of the disturbance will pass a few hundred miles north of the islands. The disturbance could be a long-range threat to Bermuda.

Jeff Masters

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Quoting reedzone:


Just receiving info from a friend. The plane is called "Kermit". He says it is surface winds..


Those are flight winds SFMR is turned off.
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Quoting GetReal:



Isaac was having problem with dry air, but NO MORE!!! Look at how this system has put some meat onto its' bones this afternoon. Standby folks the show is just only beginning...


Yup!
Member Since: July 9, 2006 Posts: 184 Comments: 29594
Quoting Tazmanian:



thats noaa recon
NOAA data counts, right?
Member Since: August 1, 2012 Posts: 0 Comments: 436
Quoting Pcolanyc:
Strong gusts and loss of power in Pensacola. My power was only out for a few minutes; my parents' is still out.


Mine hasn't blinked, and that's unusual for Gulf Power. We get a mild t-storm through here, and power's out for hours.
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Quoting Dakster:
Reedzone is that flight level or surface?


Just receiving info from a friend. The plane is called "Kermit". He says it is surface winds..
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1320. atl134
I have a real hard time seeing Isaac strengthen much even with the stalling, anything higher than 85mph would surprise me. The main issue with stalling is the extension of time these areas will get heavy rains.
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Watching the wobbles to the west...may be trying to get live video from New Ibera, LA
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Every time I see that comparison of Typhoon Tip to the US, I get shudders...could you imagine a super-cyclone like that striking the U.S. mainland? That'd be some zombie-apocalypse stuff right there...
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Quoting reedzone:
Recon is now heading towards Isaac, reporting TS winds 500 miles away from the center.



thats noaa recon
Member Since: May 21, 2006 Posts: 5091 Comments: 114712
Quoting Reb74:
Winds in NW FL are strong now and there is no more sun. We had periods of intense sun earlier today but that must be gone. Relative in MS says his pier is underwater. What a long night it will be.


Rain squalls and wind are definitely picking up. Hope the power and internet hold up for the night. Local liquor stores are doing a land office business today. Many businesses were closed around here today (the office I work at included); traffic was very light when I was out earlier. Post office delivered mail, but trash wasn't picked up.

...and that's the report from the Emerald Coast of Florida.
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Quoting Pcolanyc:
Strong gusts and loss of power in Pensacola. My power was only out for a few minutes; my parents' is still out.
Lost power for an hour in Mobile
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1313. Dakster
Reedzone is that flight level or surface?
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Quoting alaina1085:
Is Isaac in any danger of downgrading due to upwelling since he's slowly moving/stalling?


The large size of Isaac will allow the storm to fight any upwelling effects, also as it moves into shallower water, the water will be warmer with depth than normally deeper water would be, so the upwelling issue would be less.

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1311. kwgirl
Quoting CybrTeddy:
TD 11? That's rather unexpected.

And weird. I looked at computer models and they have it sitting on 0 degrees. Isn't that the equator? Didn't think anything would form on the Equator.
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Recon is now heading towards Isaac, reporting TS winds 500 miles away from the center.
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1309. Dunkman
Quoting LAlurker:
When was the last time recon found Hurricane force winds?
TS at next update????


There hasn't been recon in the storm for like 3 hours.
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Strong gusts and loss of power in Pensacola. My power was only out for a few minutes; my parents' is still out.
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Quoting justsouthofnola:


you put the eye over my house
Sorry about that. With Tip's one-minute sustained winds of 190 mph, there wouldn't be much house left...
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TD 11? That's rather unexpected.

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1305. GetReal
Station 42040
NDBC
Location: 29.212N 88.207W
Date: Tue, 28 Aug 2012 19:50:00 UTC
Winds: SE (130°) at 54.4 kt gusting to 66.0 kt
Atmospheric Pressure: 29.21 in
Air Temperature: 82.4 F
Water Temperature: 83.1 F



Station KMIS
Federal Aviation Administration
Location: 29.296N 88.842W
Date: Tue, 28 Aug 2012 20:15:00 UTC
Winds: SSE (160°) at 52.1 kt gusting to 74.0 kt
Air Temperature: 80.6 F
Dew Point: 78.8 F
Visibility: 0.2 nmi


Station PILL1
NOS
Location: 29.178N 89.258W
Date: Tue, 28 Aug 2012 20:06:00 UTC
Winds: ENE (60°) at 24.1 kt gusting to 33.0 kt
Atmospheric Pressure: 28.99 in
Air Temperature: 81.1 F
Water Temperature: 80.8 F


Station PSTL1
NOS
Location: 28.932N 89.407W
Date: Tue, 28 Aug 2012 20:06:00 UTC
Winds: NE (40°) at 39.0 kt gusting to 45.1 kt
Atmospheric Pressure: 28.98 in
Air Temperature: 81.1 F
Water Temperature: 83.1 F


Station KMDJ
Federal Aviation Administration
Location: 28.643N 89.794W
Date: Tue, 28 Aug 2012 20:15:00 UTC
Winds: NNW (330°) at 55.9 kt gusting to 76.0 kt
Air Temperature: 78.8 F
Dew Point: 78.8 F
Member Since: July 4, 2005 Posts: 204 Comments: 8806
Quoting Neapolitan:
Some have mentioned just how big Isaac is, and there's no doubt that he is larger than many cyclones. But for fun, here's how large 1979's Typhoon Tip would be were it placed in Isaac's location. The entire area under the circle would be subject to at least tropical storm-force winds.

Tip in America

Now, that's a big storm...


you put the eye over my house
Member Since: August 6, 2011 Posts: 0 Comments: 226
Quoting HrDelta:


Ahhh, which Wellington, there are a few of them.


Wellington, FL. Sorry about that, I corrected the post. Thanks for the heads up.
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1302. Skyepony (Mod)
Waveland surge..
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Quoting TomballTXPride:

Almost like it knows where to go to bust the drought. Nature has a fine way of balancing itself out. Always has.


Feel bad for the folks on the coast, but up here in LR we need the rain in a bad way.
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CLICK HERE for THREE live feeds including Tornado Dude and Stormjunkie...and chat room.

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Quoting reedzone:
Isaac appears to have really slowed up or eve stalled. It's also re-organizing itself.. Becoming more round and looks to have mixed out that dry air.

I'm predicting 100 mph. at landfall based on slow movement and strengthening.
These flight level winds will probably collapse down to the surface as Isaac makes landfall sometime tonight or maybe tomorrow morning. The steering pattern has a very slow erratic movement for a good amount of time, which isn't good. Praying that the levees hold in New Orleans or we will have a major disaster in our hands.





100 mph? Really? Is that after it fails to get west of 85W?

It's gained 10 mph in 2 days, and it's going to go from 75-to-100 in 6 hours?
Member Since: July 25, 2008 Posts: 0 Comments: 596
1298. Dakster
Quoting leelee75k:
Isaac is almost cut off from the portion that went east up Florida and is now near the Carolinas/Georgia. The flow from South Florida seems to be leaning towards the Eastern portion and that portion isn't moving west towards the main body of Isaac anymore. Interesting to observe.


It seems that as soon as that happened Isaac was able to intensify...
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Quoting jeffs713:

Not really. He is over moderately shallow water, and there isn't much cold water between the bottom and the surface. On the south and east side, it is possible - depends on how long he stays there.

Thank you!
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WTNT41 KNHC 282035
TCDAT1

TROPICAL DEPRESSION ELEVEN DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL112012
500 PM AST TUE AUG 28 2012

CONVECTION HAS INCREASED IN ASSOCIATION WITH THE AREA OF LOW
PRESSURE IN THE EASTERN TROPICAL ATLANTIC...AND THE SYSTEM IS NOW
CLASSIFIED AS A TROPICAL DEPRESSION. THE CENTER WAS EXPOSED EARLIER
TO THE SOUTHWEST OF THE DEEP CONVECTION DUE TO ABOUT 15 KT OF
WEST-SOUTHWESTERLY SHEAR...HOWEVER...THE CENTER HAS NOW REFORMED
CLOSER TO THE COLD CLOUD TOPS. THE INITIAL INTENSITY IS SET AT 30
KT FOR THIS ADVISORY IN AGREEMENT WITH THE LATEST DVORAK ESTIMATE
FROM SAB.

RGB AIRMASS IMAGERY FROM MET-9 SHOWS AN AREA OF DRY AIR TO THE WEST
OF THE CYCLONE...WHICH IN COMBINATION WITH THE SHEAR SHOULD RESULT
IN LIMITED INTENSIFICATION IN THE SHORT TERM. HOWEVER...IF THE DEEP
CONVECTION PERSISTS...THE CYCLONE COULD BECOME A TROPICAL STORM
SOON. OVERALL THE ATMOSPHERIC ENVIRONMENT DOES NOT APPEAR CONDUCIVE
FOR INTENSIFICATION DURING THE FORECAST PERIOD...WITH MODERATE
WESTERLY SHEAR EXPECTED TO PERSIST AS AN UPPER-LOW MOVES WESTWARD
AHEAD OF THE DEPRESSION FOR THE NEXT COUPLE OF DAYS. AS THE CYCLONE
MOVES AROUND THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE IN
ABOUT THREE DAYS THE SHEAR SHOULD BECOME MORE SOUTHWESTERLY AHEAD
OF A MID-/UPPER-LEVEL TROUGH MOVING OFFSHORE OF NORTH AMERICA. THE
NHC FORECAST SHOWS LITTLE CHANGE IN INTENSITY DURING THE FORECAST
PERIOD...AND ITS POSSIBLE THE CYCLONE COULD DISSIPATE AT SOME
POINT...AS SHOWN BY THE GFS MODEL.

THE INITIAL MOTION ESTIMATE IS A RATHER UNCERTAIN 285/09...AS THE
CENTER HAS BEEN REFORMING CLOSER TO THE DEEP CONVECTION. A WESTWARD
OR WEST-NORTHWESTWARD MOTION IS EXPECTED OVER THE NEXT 48 HOURS AS
THE CYCLONE WILL BE STEERED BY A NARROW MID-LEVEL RIDGE TO THE
NORTH. THE CYCLONE WILL REACH THE WESTERN EDGE OF THE RIDGE BY 72
HOURS AND A NORTHWARD AND NORTHEASTWARD ACCELERATION AHEAD OF THE
AFOREMENTIONED TROUGH IS EXPECTED AT DAYS 4 AND 5. THE NHC FORECAST
IS CLOSE TO A BLEND OF THE GFS AND ECMWF MODELS THROUGH 72 HOURS
AND IS CLOSE TO THE ECMWF AFTER THAT TIME.

FORECAST POSITIONS AND MAX WINDS

INIT 28/2100Z 23.8N 43.9W 30 KT 35 MPH
12H 29/0600Z 24.1N 45.3W 35 KT 40 MPH
24H 29/1800Z 24.3N 47.4W 35 KT 40 MPH
36H 30/0600Z 24.6N 49.6W 35 KT 40 MPH
48H 30/1800Z 25.3N 51.7W 35 KT 40 MPH
72H 31/1800Z 27.5N 55.5W 35 KT 40 MPH
96H 01/1800Z 32.5N 55.0W 35 KT 40 MPH
120H 02/1800Z 40.0N 48.0W 35 KT 40 MPH
Member Since: May 21, 2006 Posts: 5091 Comments: 114712
Quoting alaina1085:
Is Isaac in any danger of downgrading due to upwelling since he's slowly moving/stalling?


Possible depending on how long. Waters aren't very deep there. However, there are many other factors involved that are in Isaac's favor which could off set the up welling. Cyclones can usually shrug off some adversity as long as all other parameters are good.
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Some have mentioned just how big Isaac is, and there's no doubt that he is larger than many cyclones. But for fun, here's how large 1979's Typhoon Tip would be were it placed at Isaac's location. The entire area under the circle would be subject to at least tropical storm-force winds.

Tip in America

Now, that's a big storm...
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I just came from outside and the wind is so light I got ate up by mosquitoes. I live in extreme southeast New Orleans, very near Plaquemine Parish.

That's all I have to report as of now.
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Quoting indianrivguy:


and in my opinion, that comment by Neil Frank caused folks to die.


If I remember correctly Neil Frank was pushing for evacuations of areas that were calling for evacuations. The Mayor of Galveston was VERY late in ordering an evacuation but a lot of people had already left. People on the Boliver Peninsula were told to leave. Some didn't move in time and some didn't take the storm seriously. There were remarkably few casualties from Boliver. 48 people died in Texas. Looking at the devastation Ike brought to the coast that is a remarkably small number. A lot of people did evacuate the Cat 2 storm as the NHC bulletin advised that residents living in single-family homes in some parts of coastal Texas faced "certain death" if they did not heed orders to evacuate.

There was also the "Rita" Mindset. I did not run, though most of my neighbors did (which was kind of silly)

These people endured hours and hours of sitting in cars to find out *Nothing* happened in Houston. It would be hard to convince people who went through that to evacuate again. I am talking about people fleeing who were not even close to a mandatory evacuation zone.
Member Since: September 23, 2005 Posts: 6 Comments: 234
1291. HrDelta
Quoting ProgressivePulse:
Areal View Of The Flooding In Wellington below. Reports that septic tanks are backing up and snake infested *STAY OUT OF THE WATER*



Center visible in the bottom left of this image, not really going anywhere.



Ahhh, which Wellington, there are a few of them.
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Quoting alaina1085:
Is Isaac in any danger of downgrading due to upwelling since he's slowly moving/stalling?


It's unlikely because even though he is churning up a lot of ocean, Isaac is not a particularly strong hurricane and has only traversed the area it is in now for 6-9 hours. It usually takes around a day of very slow movement for a hurricane to upwell enough deeper and cooler waters to cause any significant weakening. And despite the likelihood of very slow movement through the next couple of days, he is probably going to officially make landfall later today and thus will feel the effects of land weakening the system anyway.
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000
WTNT31 KNHC 282033
TCPAT1

BULLETIN
TROPICAL DEPRESSION ELEVEN ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL112012
500 PM AST TUE AUG 28 2012

...NEW TROPICAL DEPRESSION FORMS OVER THE EASTERN ATLANTIC...NO
THREAT TO LAND...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...23.8N 43.9W
ABOUT 1270 MI...2045 KM ENE OF THE LESSER ANTILLES
ABOUT 1400 MI...2250 KM SW OF THE AZORES
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 500 PM AST...2100 UTC...THE CENTER OF TROPICAL DEPRESSION ELEVEN
WAS LOCATED NEAR LATITUDE 23.8 NORTH...LONGITUDE 43.9 WEST. THE
DEPRESSION IS MOVING TOWARD THE WEST-NORTHWEST NEAR 10 MPH...17
KM/H...AND A WESTWARD TO WEST-NORTHWESTWARD MOTION IS EXPECTED TO
CONTINUE FOR THE NEXT COUPLE OF DAYS.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/H...WITH HIGHER
GUSTS. A LITTLE STRENGTHENING IS POSSIBLE...AND THE DEPRESSION COULD
BECOME A TROPICAL STORM IN THE NEXT DAY OR SO.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB...29.77 INCHES.

HAZARDS AFFECTING LAND
----------------------
NONE


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...1100 PM AST.

$$
FORECASTER BRENNAN
Member Since: August 1, 2012 Posts: 0 Comments: 436
Quoting mobilebayal:


I am not smelling anything right now. It started raining so maybe it washed the smell away.
I'm waiting for the roar that sounds like a jet overhead.
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000
WTNT31 KNHC 282033
TCPAT1

BULLETIN
TROPICAL DEPRESSION ELEVEN ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL112012
500 PM AST TUE AUG 28 2012

...NEW TROPICAL DEPRESSION FORMS OVER THE EASTERN ATLANTIC...NO
THREAT TO LAND...


SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...23.8N 43.9W
ABOUT 1270 MI...2045 KM ENE OF THE LESSER ANTILLES
ABOUT 1400 MI...2250 KM SW OF THE AZORES
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 500 PM AST...2100 UTC...THE CENTER OF TROPICAL DEPRESSION ELEVEN
WAS LOCATED NEAR LATITUDE 23.8 NORTH...LONGITUDE 43.9 WEST. THE
DEPRESSION IS MOVING TOWARD THE WEST-NORTHWEST NEAR 10 MPH...17
KM/H...AND A WESTWARD TO WEST-NORTHWESTWARD MOTION IS EXPECTED TO
CONTINUE FOR THE NEXT COUPLE OF DAYS.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/H...WITH HIGHER
GUSTS. A LITTLE STRENGTHENING IS POSSIBLE...AND THE DEPRESSION COULD
BECOME A TROPICAL STORM IN THE NEXT DAY OR SO.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB...29.77 INCHES.

HAZARDS AFFECTING LAND
----------------------
NONE


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...1100 PM AST.

$$
FORECASTER BRENNAN
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Quoting TropicalAnalystwx13:

Recon isn't out there..



but noaa recon is so we got some in at lest
Member Since: May 21, 2006 Posts: 5091 Comments: 114712
1285. Reb74
Winds in NW FL are strong now and there is no more sun. We had periods of intense sun earlier today but that must be gone. Relative in MS says his pier is underwater. What a long night it will be.
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Quoting huntsvle:


At this point, it really wont make much different if he upwells or not...the damange is already in progress and he would not fall apart THAT quickly.

Thank you! I was just curious.
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1283. Patrap
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000
FXUS64 KHGX 282029
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
329 PM CDT TUE AUG 28 2012

.DISCUSSION...
A VERY HOT DAY ACROSS SOUTHEAST TEXAS WITH TEMPERATURES NEARING
100 DEGREES OVER THE NORTHWEST ZONES. HEAT INDEX VALUES ARE
BETWEEN 100 AND 105 DEGREES. ISOLATED SHRA WERE BEGINNING TO
DEVELOP OVER THE WESTERN THIRD OF THE REGION. ALL EYES ARE ON THE
NORTHERN GULF AS ISAAC GAINS IN STRENGTH. HURRICANE ISAAC IS STILL
EXPECTED TO MOVE INTO SOUTHERN LOUISIANA AND THEN TRACK NORTHWEST.
SYNOPTIC SCALE MODELS STILL DIFFER RATHER SIGNIFICANTLY ON THE
POSITION OF ISAAC AFTER LANDFALL WITH THE NAM AND GFS FURTHER WEST
THAN THE OFFICIAL HURRICANE TRACK AND THE ECMWF. STILL NOT
COMPLETELY COMFORTABLE DISCOUNTING THE THE NAM AND GFS SOLUTIONS.
WILL EXPAND LOWISH POPS A BIT FURTHER WEST ON WEDNESDAY AS MSTR
LEVELS INCREASE TO NEAR OR JUST ABOVE 2.00 INCHES BY LATE WEDS
AFTN. WINDS WILL INCREASE ON WEDNESDAY...ESPECIALLY NEAR THE
EXTREME UPPER TEXAS COAST. WIND SPEEDS WILL APPROACH WIND ADVISORY
CRITERIA ON WEDS AFTN. WILL DEFER TO MIDNIGHT SHIFT ON THE WIND
ADVISORY. PW VALUES INCREASE TO BETWEEN 2.2 AND 2.3 INCHES WED
NIGHT INTO THURSDAY. THE NAM AND GFS HINT AT SOME MODERATE TO
STRONG LOW LEVEL SPEED AND DIRECTIONAL CONVERGENCE ALONG THE COAST
AS THE REMNANTS OF ISAAC MOVE INLAND. CONFIDENCE IN THIS
CONVERGENCE ZONE OCCURRING IS LOW BUT STILL WORTH A MENTION IN
THE ZFP. WILL GO WITH CHANCE POPS WED NIGHT THROUGH THURSDAY. HPC
QPF VALUES ARE BETWEEN 2 AND 3 INCHES OVER THE EXTREME EASTERN
ZONES BY FRIDAY NIGHT. WITH THE EXPECTED CLOUD COVER AND
RAIN...WILL TRIM MAX TEMPS A BIT ON THURSDAY. COULD BE QUITE A
CONTRAST IN TEMPS BETWEEN THE EASTERN AND WESTERN ZONES.
CONDITIONS WARM UP FRIDAY THROUGH SUNDAY WITH MAX TEMPS BACK INTO
THE MID 90S. PW VALUES BRIEFLY PEAK NEAR 2.0 INCHES AGAIN OVER THE
WEEKEND...SO WILL MAINTAIN SLT CHANCE POPS BOTH SAT/SUN. UPPER
LEVEL RIDGING WILL BUILD INTO TEXAS EARLY NEXT WEEK SO WILL LEAN
VERY WARM AND DRY MON THROUGH WEDS. 43
Member Since: August 18, 2011 Posts: 0 Comments: 598
1281. Reb74
Quoting PRweathercenter:
English Version of Blog Update



Skip to 2:16

Thank you so much for always posting these. They are truly helpful and the reporter does not seem "excited" as much as informative!
Member Since: Posts: Comments:
Quoting Patrap:
This is going to get out of control..easily, toward Dark.


We're thinking of ya, man. All y'all.

Winds whipping off and on here through squalls in P-cola.
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Quoting emcf30:
I apologize if this has already been posted but Surge is rising FAST at Shell Beach, Louisiana, which is East of The Big Easy. 6 ft of surge now, water level at 7.2 ft when you include tide.

Link

Been looking at it all morning.
Historical Maximum Water Level: Sep 1 2008, 8.78 ft
Wind Speed: 40 knots Gusts: 52 knots Direction: 27°
Just south of there on Pilot's station the pressure is 980mb.


Member Since: Posts: Comments:
Quoting LAlurker:
When was the last time recon found Hurricane force winds?
TS at next update????


There isn't any plane in the air atm for some reason..last plane left like 2 hours ago..
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Quoting alaina1085:
Is Isaac in any danger of downgrading due to upwelling since he's slowly moving/stalling?

Not really. He is over moderately shallow water, and there isn't much cold water between the bottom and the surface. On the south and east side, it is possible - depends on how long he stays there.
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Quoting huntsvle:


Well, the large consensus of models tends to agree with that...we'll see what forecasters say. HGX usually releases their forecast discussion between now and the next hour, we'll see what they say about it.

No they don't. Stop spreading misinformation!


Member Since: Posts: Comments:
Quoting alaina1085:
Is Isaac in any danger of downgrading due to upwelling since he's slowly moving/stalling?


At this point, it really wont make much different if he upwells or not...the damange is already in progress and he would not fall apart THAT quickly.
Member Since: Posts: Comments:

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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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