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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Bermuda may need to keep an eye out on this one.
Member Since: July 12, 2008 Posts: 7 Comments: 383
We have hurricane issac official
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Quoting MississippiWx:


Lol. I don't even care anymore. The strength of the storm won't be determined by the NHC in reality anyway.


How strong do YOU think it is and what its peak will be?
Member Since: July 1, 2008 Posts: 13 Comments: 7334
Quoting SFLWeatherman:
974MB now


It's on or ahead of the adjusted pace, hard to say because the linear projection is effected a lot by 1 vs 2 mb drop, but we could correct the models for current situation and project another 6 hours out and see what we have.

Adjusted landfall forecast:

969mb Adjusted 6z GFDL
971mb Adjusted 6z HWRF
964mb Linear extrapolation (4 hour average).
973mb Adjusted 12z GFS

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NHC site has it as a HURRICANE
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dr knabb this a hurricane now
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Quoting LongGlassTube:


Totally irresponsible for the NHC to call a storm with 976 millibars of pressure a TS.

What is up?

My wife is expected to go to work tomorrow in a nonessential business because it is ONLY a TS.

They are blowing it!

I'm a Fire Fighter and EMS responder here in Ascension Parish. We were told to expect 48 hours of TS force winds and 12 hours of Hurricane force winds within our Parish.
We filled sandbags till our fingers bled last night past midnight and even though winds are picking up here people are still getting sand bags. Most of the public fortunately has taken this seriously.

I just wish at 10:00 they would have called this thing what it is. A hurricane. A hurricane that is approaching CAT 2 strength according to pressure.


There is nothing easy about this.
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Weather Channel just announces Isaac is now a Hurricane! FINALLY
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HURRICANE ISAAC TROPICAL CYCLONE UPDATE
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
1120 AM CDT TUE AUG 28 2012

...RECONNAISSANCE DATA INDICATE ISAAC FINALLY ACHIEVES HURRICANE
STATUS...

REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT
INDICATE THAT MAXIMUM WINDS ASSOCIATED WITH ISAAC HAVE INCREASED
TO 75 MPH...120 KM/H. ON THIS BASIS...ISAAC IS BEING UPGRADED TO
A HURRICANE.

SUMMARY OF 1120 AM CDT...1620 UTC...INFORMATION
-----------------------------------------------
LOCATION...28.1N 88.6W
ABOUT 75 MI...115 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 160 MI...250 KM SE OF NEW ORLEANS LOUISIANA
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...975 MB...28.79 INCHES

$$
FORECASTER STEWART/BEVEN
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000
WTNT64 KNHC 281618
TCUAT4

HURRICANE ISAAC TROPICAL CYCLONE UPDATE
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
1120 AM CDT TUE AUG 28 2012

...RECONNAISSANCE DATA INDICATE ISAAC FINALLY ACHIEVES HURRICANE
STATUS...

REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT
INDICATE THAT MAXIMUM WINDS ASSOCIATED WITH ISAAC HAVE INCREASED
TO 75 MPH...120 KM/H. ON THIS BASIS...ISAAC IS BEING UPGRADED TO
A HURRICANE.

SUMMARY OF 1120 AM CDT...1620 UTC...INFORMATION
-----------------------------------------------
LOCATION...28.1N 88.6W
ABOUT 75 MI...115 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 160 MI...250 KM SE OF NEW ORLEANS LOUISIANA
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...975 MB...28.79 INCHES

$$
FORECASTER STEWART/BEVEN
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For those experiencing the effects of Isaac.

Thanks for posting your observations. +1
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144 hours, notice Isaac's remnants still there.
Member Since: July 12, 2008 Posts: 7 Comments: 383
Quoting hurricanehanna:

and this is why they evacuate Grand Isle...the locals there know to get out.


Exactly!! Everyone I know from there have evacuated... they dont play!
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Quoting flsky:

Thanks so much for this link. Are these just static pix or will they display video as well?
ALready? WOW!
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nice rotating mass of clouds
with some rain and wind
with a little high tide
but its not a hurricane
thats a figment
of our imagination

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Quoting will40:



be safe over there :-)


Thanks Will. Still hoping for the best. But keeping an eye on it. :)
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209. ADCS
Quoting NCHurricane2009:

This is where public understanding and science are at a crossfire with each other. Its a tropical storm because of the broadly-spread pressure gradient that prevents winds despite the low pressure...but not all tropical storms are created equal. They don't want to upgrade...because objective science tells them that the max sustained winds do not meet hurricane status...and the whole classification process for better or worse is based on max sustained winds...not the central pressure...nor the storm surge potential....

But general public understanding is that all tropical storms are created equal when they are NOT:

There are tropical storms that are slow and bring more rain....there are tropical storms that move fast and bring less rain...

There are tropical storms that can produce a huge storm surge because of the wind field size....there are tropical storms that produce not so much surge because they are puny or weaker...


Seems like it might be advisable to only release SSHS ratings in conjunction with the associated IKE surge rating.
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Water is also already over Hwy 90 in Biloxi!
Member Since: July 9, 2006 Posts: 184 Comments: 29594
Quoting alaina1085:


Grand Isle, LA

and this is why they evacuate Grand Isle...the locals there know to get out.
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Quoting Elena85Vet:
Has anyone said cane at 2pm yet? lulz


Lol. I don't even care anymore. The strength of the storm won't be determined by the NHC in reality anyway.
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Quoting moonlightcowboy:


Mere sample, just getting started!

MLC <-------------shakes head! :(


I know :/
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Isaac seems to have lost all connection to the deep moisture source in the Caribbean. How can he mix out the dry air without that ? Just wondering.
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Quoting Felix2007:
126 hours


Kirk a fish ?
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Looks like he's going out to sea. Too early to tell though.
Member Since: July 12, 2008 Posts: 7 Comments: 383
Quoting alaina1085:


Grand Isle, LA


Mere sample, just getting started!

MLC <-------------shakes head! :(
Member Since: July 9, 2006 Posts: 184 Comments: 29594
Quoting AtHomeInTX:


I don't know. we'll have to see. We haven't ever been in the cone here. Guess we'll see soon if the NHC agrees with the models.



be safe over there :-)
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Grand Isle, LA
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132 hours
Member Since: July 12, 2008 Posts: 7 Comments: 383
Quoting ckeusa:
In a previous blog post, Dr. Masters noted that the ideal situation to break the drought in the U.S. would be a big, wet category 1 hurricane making landfall along the Gulf Coast. TS Isaac is the exact scenario that was described (only with slightly weaker winds!), yet this storm is certainly not being treated as a good thing. What gives?


Once it clears the Gulf Coast, it will be a good thing. The one bad element is the models (for what they are worth) have the remnants of Issac curving northeast, away from the areas with the worst drought. The other thing that remains to be seen is how big a rainmaker Isaac will be. So far, the heaviest rains have been on the east coast of Florida well after Isaac was in the Gulf.
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126 hours
Member Since: July 12, 2008 Posts: 7 Comments: 383
Quoting LongGlassTube:


Totally irresponsible for the NHC to call a storm with 976 millibars of pressure a TS.

What is up?

My wife is expected to go to work tomorrow in a nonessential business because it is ONLY a TS.

They are blowing it!

I'm a Fire Fighter and EMS responder here in Ascension Parish. We were told to expect 48 hours of TS force winds and 12 hours of Hurricane force winds within our Parish.
We filled sandbags till our fingers bled last night past midnight and even though winds are picking up here people are still getting sand bags. Most of the public fortunately has taken this seriously.

I just wish at 10:00 they would have called this thing what it is. A hurricane. A hurricane that is approaching CAT 2 strength according to pressure.

This is where public understanding and science are at a crossfire with each other. Its a tropical storm because of the broadly-spread pressure gradient that prevents winds despite the low pressure...but not all tropical storms are created equal. They don't want to upgrade...because objective science tells them that the max sustained winds do not meet hurricane status...and the whole classification process for better or worse is based on max sustained winds...not the central pressure...nor the storm surge potential....

But general public understanding is that all tropical storms are created equal when they are NOT:

There are tropical storms that are slow and bring more rain....there are tropical storms that move fast and bring less rain...

There are tropical storms that can produce a huge storm surge because of the wind field size....there are tropical storms that produce not so much surge because they are puny or weaker...
Member Since: Posts: Comments:
The rain that went through Florida has arrived in Charleston, SC. The storm drains at work where blowing water 3 feet into the air LOL.

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHARLESTON SC
1203 PM EDT TUE AUG 28 2012

SCC015-019-281830-
/O.CON.KCHS.FF.W.0007.000000T0000Z-120828T1830Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000 Z.OO/
CHARLESTON SC-BERKELEY SC-
1203 PM EDT TUE AUG 28 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 230 PM EDT FOR SOUTH
CENTRAL BERKELEY AND CENTRAL CHARLESTON COUNTIES...

AT 1157 AM EDT...EXTREMELY HEAVY RAINFALL CONTINUES ACROSS AREAS
FROM WEST ASHLEY...TO NORTH CHARLESTON...DOWNTOWN CHARLESTON...AND
MOUNT PLEASANT. TRAINED WEATHER SPOTTERS AND LOCAL LAW ENFORCEMENT
OFFICIALS REPORT NUMEROUS ROADS AS IMPASSABLE IN THESE AREAS.
FURTHERMORE...THERE ARE MULTIPLE REPORTS OF STALLED VEHICLES AND
RESCUES TAKING PLACE. THIS IS AN EXTREMELY DANGEROUS AND LIFE
THREATENING SITUATION AND ANYONE IN AND AROUND DOWNTOWN CHARLESTON
SHOULD TAKE IMMEDIATE ACTION NOW.

RAINFALL AMOUNTS OF 3 INCHES OR MORE HAVE ALREADY FALLEN AND AN
ADDITIONAL 2 TO 4 INCHES WILL BE POSSIBLE THROUGH THE EARLY
AFTERNOON.

FLASH FLOODING IS EXPECTED IN AND AROUND BOONE HALL PLANTATION...
CAINHOY...CHARLES TOWNE LANDING...CHARLESTON NAVAL COMPLEX...DANIEL
ISLAND...DON HOLT BRIDGE...DOWNTOWN CHARLESTON...FOLLY BEACH...FORT
JOHNSON...FORT SUMTER...I-26/I-526 INTERCHANGE...ISLE OF PALMS...
JAMES ISLAND...JAMES ISLAND COUNTY PARK...MAYBANK BRIDGE...MOUNT
PLEASANT...MOUNT PLEASANT REGIONAL AIRPORT...MOUNT PLEASANT TOWNE
CENTRE...NORTH CHARLESTON...SHADOWMOSS...SULLIVANS ISLAND...WANDO AND
WEST ASHLEY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THE MAJORITY OF FLOOD DEATHS ARE DUE TO PEOPLE DRIVING INTO WATER OF
UNKNOWN DEPTH. JUST ONE FOOT OF FLOWING WATER IS POWERFUL ENOUGH TO
SWEEP VEHICLES OFF THE ROAD. EVEN MODERN SPORT UTILITY VEHICLES ARE
VULNERABLE TO FLOODING. TO AVOID THE RISK OF DEATH...FIND AN
ALTERNATE ROUTE IF THE ROAD IS FLOODED.

HOMES AND BUSINESSES WILL BEGIN TO FLOOD DUE TO THE TORRENTIAL
RAINFALL. IF YOU ARE IN A LOW-LYING AREA...BE PROACTIVE. RAISE
SENSITIVE ITEMS OFF THE GROUND BEFORE FLOODING BEGINS.

TO REPORT SIGNIFICANT FLOODING...PLEASE CONTACT THE NATIONAL WEATHER
SERVICE IN CHARLESTON TOLL FREE AT 1-888-383-2024 OR EMAIL YOUR
REPORTS TO CHS.SKYWARN@NOAA.GOV. REPORTS CAN ALSO BE SENT THROUGH
TWITTER USING #WXREPORT.
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Patrap Jr. here for now.





SEL1

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 591
NWS STORM PREDICTION CENTER NORMAN OK
945 AM CDT TUE AUG 28 2012

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

SOUTHWEST ALABAMA
WESTERN FLORIDA PANHANDLE
SOUTHEAST LOUISIANA
FAR SOUTHEAST MISSISSIPPI
COASTAL WATERS

EFFECTIVE THIS TUESDAY MORNING AND EVENING FROM 945 AM UNTIL 700
PM CDT.

TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 55 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 15 MILES WEST OF NEW ORLEANS
LOUISIANA TO 20 MILES EAST OF PANAMA CITY FLORIDA. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU1).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

DISCUSSION...A SLOW INCREASE IN CONVECTION HAS BEEN NOTED THIS
MORNING ON OUTER PERIPHERY OF ISAAC WHERE BREAKS IN THE CLOUDS ARE
SUPPORTING AIR MASS DESTABILIZATION. THIS TREND SHOULD CONTINUE
THROUGH THE REMAINDER OF THE MORNING AND THIS AFTERNOON WITH AN
INCREASED RISK FOR MINI SUPERCELLS AND AN ASSOCIATED TORNADO THREAT.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
450. MEAN STORM MOTION VECTOR 11040.


...MEAD


Member Since: July 3, 2005 Posts: 414 Comments: 125613
120 hours
Member Since: July 12, 2008 Posts: 7 Comments: 383
Kirk strengthening, 144 hours
Member Since: July 12, 2008 Posts: 7 Comments: 383
Quoting Dunkman:


There was no public awareness to be gained by upgrading now. That would have needed to be done at 5am this morning at the latest. It is too dangerous for people in SE LA to start trying to evacuate now...that would be a disaster waiting to happen.



Sorry, but I'm all about the truth. You may be full well right. Politics and lies enter absolutely everything! Sort of hardened to that now at my age. You just expect it. Totally why personal responsibility is imperative!
Member Since: July 9, 2006 Posts: 184 Comments: 29594
Thanks for the update Levi!!! We here in SELA appreciate it!
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I think I spy more of a wobble to the NNW?
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Quoting ckeusa:
In a previous blog post, Dr. Masters noted that the ideal situation to break the drought in the U.S. would be a big, wet category 1 hurricane making landfall along the Gulf Coast. TS Isaac is the exact scenario that was described (only with slightly weaker winds!), yet this storm is certainly not being treated as a good thing. What gives?


I'm terrified in the collective American-PTSD-because-of-Katrina sense because this storm is hitting New Orleans...

But I live in severely drought stricken Missouri, and Isaac is coming here by the end of the week. I'm welcoming him with open arms. Give us RAIN!
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Has anyone said cane at 2pm yet? lulz
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Quoting yoboi:


i wonder if it will stall at swla and setx????


I don't know. we'll have to see. We haven't ever been in the cone here. Guess we'll see soon if the NHC agrees with the models.
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Quoting ckeusa:
In a previous blog post, Dr. Masters noted that the ideal situation to break the drought in the U.S. would be a big, wet category 1 hurricane making landfall along the Gulf Coast. TS Isaac is the exact scenario that was described (only with slightly weaker winds!), yet this storm is certainly not being treated as a good thing. What gives?
Maybe he meant a fast moving hurricane zipping over the midwest, not a life-threatening slow-moving flood-maker.

Floods do not help break droughts as well as a series of gentle rains. Dry soil tends to repel water, heavy rains run off quickly and erode the soil without sinking into the subsoil. The main benefit is refilling of lakes and reservoirs.
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Great webpage for monitoring bouys
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181. flsky
Quoting Fl30258713:
Gulf Shores, Al web cam

Link

Thanks so much for this link. Are these just static pix or will they display video as well?
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Quoting moonlightcowboy:


+++++++, great post, Sully! Thanks.

That makes sense to me too...I understand how directional wind shear can add to the tornado threat.....
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Quoting Chicklit:
From Moonlight Cowboy:
Sat presentation is better, looks like a duck, walks like duck, quacks like a duck, well...it's probably a duck! That's the way it needs to be treated. Isaac may sneak up on folks, 80 mph winds with higher gusts is no walk in the park.

I think you're right.

Isaac is a VERY serious storm still. It's lack of further classification has likely generated considerable apathy. Mistake. There will be very long periods of hurricane force winds on land. He will not be a "passing-thru" system. There will be lots of rain and flooding. And, there will be above estimated surge, imo, as well.

Right again. It's awful to say but am suspecting there will be deaths with this storm for the very reasons cited above.


Totally irresponsible for the NHC to call a storm with 976 millibars of pressure a TS.

What is up?

My wife is expected to go to work tomorrow in a nonessential business because it is ONLY a TS.

They are blowing it!

I'm a Fire Fighter and EMS responder here in Ascension Parish. We were told to expect 48 hours of TS force winds and 12 hours of Hurricane force winds within our Parish.
We filled sandbags till our fingers bled last night past midnight and even though winds are picking up here people are still getting sand bags. Most of the public fortunately has taken this seriously.

I just wish at 10:00 they would have called this thing what it is. A hurricane. A hurricane that is approaching CAT 2 strength according to pressure.
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Finally the water vapor and radar images are showing a lot of storminess in the right front quadrant. The hurricane force winds might be detected, in this case, 90 miles to the northeast before any hurricane force winds are detected at the center.

At 11:20am:



At 12:05pm:



LOOP
Member Since: December 28, 2010 Posts: 0 Comments: 134
What does the potential storm surge look like for the "land mass" between Mobile and New Orleans?
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176. VR46L
Quoting Patrap:


Dunno,..as I struggle just to make a decent Margarita myself.

; )


Perhaps you should have a Chamomile Tea might be a calming influence :)

Issac in rainbow in the gulf

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Isaac is finally pulling that moisture around to his N/NE quadrants.

It's been stuck on his south side for a couple days while his north side had been taking in the dry air.
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.