Tropical Depression Isaac:

[Andrew]

The cone has become much wider this evening. It now reaches as far west as almost all of LA. This spread just goes to show how uncertain the NHC is about Isaac.

I don't know what you are looking at. Here is the current track:

[srainhoutx]

BULLETIN
TROPICAL STORM ISAAC INTERMEDIATE ADVISORY NUMBER 19A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
800 PM EDT SAT AUG 25 2012

...ISAAC MOVING NORTHWESTWARD JUST OFF THE COAST OF NORTHEASTERN
CUBA...


SUMMARY OF 800 PM EDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...21.7N 76.7W
ABOUT 80 MI...130 KM ENE OF CAMAGUEY CUBA
ABOUT 375 MI...605 KM ESE OF KEY WEST FLORIDA
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 20 MPH...31 KM/H
MINIMUM CENTRAL PRESSURE...997 MB...29.44 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

NONE

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A HURRICANE WARNING IS IN EFFECT FOR...
* THE FLORIDA KEYS INCLUDING THE DRY TORTUGAS
* THE WEST COAST OF FLORIDA FROM BONITA BEACH SOUTHWARD TO OCEAN
REEF
* FLORIDA BAY

A HURRICANE WATCH IS IN EFFECT FOR...
* THE FLORIDA EAST COAST FROM GOLDEN BEACH SOUTHWARD TO OCEAN REEF
* ANDROS ISLAND IN THE BAHAMAS

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* HAITI
* CUBAN PROVINCES OF CIEGO DE AVILA...SANCTI SPIRITUS...VILLA
CLARA...CAMAGUEY...LAS TUNAS...GRANMA...HOLGUIN...SANTIAGO DE
CUBA...AND GUANTANAMO
* THE BAHAMAS
* TURKS AND CAICOS ISLANDS
* THE FLORIDA EAST COAST FROM SEBASTIAN INLET SOUTHWARD TO OCEAN
REEF
* LAKE OKEECHOBEE

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* CUBAN PROVINCES OF MATANZAS AND CIENFUEGOS
* THE FLORIDA EAST COAST NORTH OF SEBASTIAN INLET TO FLAGLER BEACH
* THE FLORIDA WEST COAST NORTH OF BONITA BEACH TO SUWANNEE RIVER

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
SOMEWHERE WITHIN THE WARNING AREA...IN THIS CASE WITHIN THE NEXT
24 TO 36 HOURS. PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD
BE RUSHED TO COMPLETION.

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE
WITHIN THE WATCH AREA...IN THIS CASE WITHIN THE NEXT 24 TO 36 HOURS.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

INTERESTS IN THE REMAINDER OF CUBA...THE REMAINDER OF FLORIDA...AND
ELSEWHERE ALONG THE NORTHERN GULF COAST SHOULD MONITOR THE PROGRESS
OF ISAAC.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED
STATES...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE
MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE
FORECAST OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA OUTSIDE
THE UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL
METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 800 PM EDT...0000 UTC...THE CENTER OF TROPICAL STORM ISAAC WAS
LOCATED NEAR LATITUDE 21.7 NORTH...LONGITUDE 76.7 WEST. ISAAC IS
MOVING TOWARD THE NORTHWEST NEAR 20 MPH...31 KM/H...AND THIS
GENERAL MOTION IS EXPECTED TO CONTINUE DURING THE NEXT 48 HOURS.
ON THE FORECAST TRACK...THE CENTER OF ISAAC SHOULD MOVE ALONG OR
JUST NORTH OF THE CENTRAL COAST OF CUBA TONIGHT...AND MOVE NEAR
OR OVER THE FLORIDA KEYS SUNDAY OR SUNDAY NIGHT. ISAAC IS
FORECAST TO MOVE OVER THE SOUTHEASTERN GULF OF MEXICO BY EARLY
MONDAY.

MAXIMUM SUSTAINED WINDS REMAIN NEAR 60 MPH...95 KM/H...WITH HIGHER
GUSTS. STRENGTHENING IS FORECAST DURING THE NEXT 48 HOURS...AND
ISAAC IS EXPECTED TO BE AT OR NEAR HURRICANE STRENGTH WHEN IT
REACHES THE FLORIDA KEYS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 205 MILES...335 KM
MAINLY TO THE NORTH OF THE CENTER. SUSTAINED WINDS OF 46 MPH...74
KM/H...WITH A GUST TO 61 MPH...98 KM/H...WAS OBSERVED WITHIN THE
PAST FEW HOURS AT GUANTANAMO BAY NAVAL AIR STATION IN EASTERN CUBA.

THE MINIMUM CENTRAL PRESSURE RECENTLY REPORTED BY AN AIR FORCE
RESERVE HURRICANE HUNTER AIRCRAFT WAS 997 MB...29.44 INCHES.


HAZARDS AFFECTING LAND
----------------------
RAINFALL...TOTAL RAINFALL ACCUMULATIONS OF 8 TO 12 INCHES...WITH
MAXIMUM AMOUNTS OF 20 INCHES...ARE POSSIBLE OVER HISPANIOLA. THESE
RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES.
TOTAL RAIN ACCUMULATIONS OF 4 TO 8 INCHES...WITH MAXIMUM AMOUNTS OF
12 INCHES...ARE POSSIBLE ACROSS JAMAICA...THE CENTRAL AND EASTERN
PORTIONS OF CUBA...THE FLORIDA KEYS AND THE SOUTHERN PENINSULA OF
FLORIDA. TOTAL RAIN ACCUMULATIONS OF 3 TO 5 INCHES ARE POSSIBLE
OVER THE CENTRAL AND SOUTHERN BAHAMAS.

WIND...TROPICAL STORM CONDITIONS ARE OCCURRING OVER PORTIONS OF THE
HAITI...EASTERN CUBA...THE CENTRAL AND SOUTHEASTERN BAHAMAS AND THE
TURKS AND CAICOS ISLANDS. TROPICAL STORM CONDITIONS ARE EXPECTED
OVER THE NORTHWESTERN BAHAMAS BY SUNDAY MORNING. HURRICANE
CONDITIONS ARE POSSIBLE ON ANDROS ISLAND ON SUNDAY. TROPICAL STORM
CONDITIONS ARE EXPECTED OVER CENTRAL CUBA TONIGHT. TROPICAL STORM
CONDITIONS ARE EXPECTED TO REACH NORTHWESTERN CUBA ON SUNDAY.

HURRICANE CONDITIONS ARE EXPECTED IN THE HURRICANE WARNING AREA IN
SOUTHWEST FLORIDA AND THE FLORIDA KEYS ON SUNDAY...WITH TROPICAL
STORM CONDITIONS EXPECTED BY EARLY SUNDAY. HURRICANE CONDITIONS ARE
POSSIBLE IN THE HURRICANE WATCH AREA IN SOUTHEAST FLORIDA ON
SUNDAY...WITH TROPICAL STORM CONDITIONS EXPECTED IN THE TROPICAL
STORM WARNING AREA IN FLORIDA BY EARLY SUNDAY. TROPICAL STORM
CONDITIONS COULD SPREAD NORTHWARD ALONG THE WEST COAST OF FLORIDA IN
THE WATCH AREA BY EARLY MONDAY.

STORM SURGE...THE COMBINATION OF A STORM SURGE AND THE TIDE WILL
CAUSE NORMALLY DRY AREAS NEAR THE COAST TO BE FLOODED BY RISING
WATERS. THE WATER COULD REACH THE FOLLOWING DEPTHS ABOVE GROUND IF
THE PEAK SURGE OCCURS AT THE TIME OF HIGH TIDE...

* SOUTHWEST FLORIDA COAST WITHIN HURRICANE WARNING AREA...5 TO 7 FT
* FLA WEST COAST WITHIN WATCH AREA INCLUDING TAMPA BAY...3 TO 5 FT
* SOUTHEAST FLORIDA COAST AND THE FLORIDA KEYS...1 TO 3 FT
* HISPANIOLA AND EASTERN CUBA...1 TO 3 FT
* THE BAHAMAS AND TURKS AND CAICOS...1 TO 3 FT

THE DEEPEST WATER WILL OCCUR ALONG THE IMMEDIATE COAST IN AREAS OF
ONSHORE FLOW. SURGE-RELATED FLOODING DEPENDS ON THE RELATIVE TIMING
OF THE SURGE AND THE TIDAL CYCLE...AND CAN VARY GREATLY OVER SHORT
DISTANCES. FOR INFORMATION SPECIFIC TO YOUR AREA...PLEASE SEE
PRODUCTS ISSUED BY YOUR LOCAL WEATHER SERVICE OFFICE. NEAR THE
COAST...THE SURGE WILL BE ACCOMPANIED BY DANGEROUS WAVES.

TORNADOES...ISOLATED TORNADOES ARE POSSIBLE OVER PORTIONS OF
SOUTH FLORIDA AND THE FLORIDA KEYS ON SUNDAY.

SURF...DANGEROUS SURF AND RIP CURRENT CONDITIONS WILL AFFECT
HISPANIOLA...THE BAHAMAS...THE TURKS AND CAICOS...EASTERN AND
CENTRAL CUBA...AND THE EAST COAST OF FLORIDA AND THE FLORIDA KEYS
DURING THE NEXT COUPLE OF DAYS. PLEASE CONSULT PRODUCTS FROM YOUR
LOCAL WEATHER OFFICE FOR MORE INFORMATION.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...1100 PM EDT.

$$
FORECASTER BROWN

[jgreak]

With as ragged as it's looking tonight, is it possible that it weakens and becomes less likely to react to the ridge, therefore shunting it further west?

[unome]

The cone has become much wider this evening. It now reaches as far west as almost all of LA. This spread just goes to show how uncertain the NHC is about Isaac.

BB, that statement is blatently wrong - I suggest you read Bill's blog http://www.click2houston.com/news/Bill- ... index.html or read up on the definition here: http://www.nhc.noaa.gov/aboutcone.shtml

the amount of "uncertainty" in the forecast has absolutely nothing to do with the size of the cone, the parameters don't change during the season.

[srainhoutx]

Convection continues to increase near the center this evening. If we see that convection begin to wrap around the center during D max overnight as it moves further away from Cuba, those Hurricane Warnings for the Keys may well have been warranted. We will see.

[biggerbyte]

The cone has become much wider this evening. It now reaches as far west as almost all of LA. This spread just goes to show how uncertain the NHC is about Isaac.

I don't know what you are looking at. Here is the current track:

Never mind. I did that on my cell phone in a hurry and posted the wrong statement for the wrong graphic.

Oh well!

My bad

[biggerbyte]

The cone has become much wider this evening. It now reaches as far west as almost all of LA. This spread just goes to show how uncertain the NHC is about Isaac.

BB, that statement is blatently wrong - I suggest you read Bill's blog http://www.click2houston.com/news/Bill- ... index.html or read up on the definition here: http://www.nhc.noaa.gov/aboutcone.shtml

the amount of "uncertainty" in the forecast has absolutely nothing to do with the size of the cone, the parameters don't change during the season.

Let's not get carried away, folks. I made an error in my post in haste. Nothing more. Yes, even BB is allowed to have them. And as far as the spread of the cone goes, it has everything to do with the uncertainty of landfall, at least on the part of the models. That is the point I was trying to get across. I'm not sure where you are coming from. It is called, "the cone of uncertainty", for a reason. LOL!

If the newbies would like a link, which is one of many, to read up on what we call the cone of uncertainty, here is a great one:
http://hurricanereport.blogs.heraldtrib ... certainty/

A better explanation is simply a margin of error for their forecasted track to cover themselves.


Enough about BBs snafu. Case AND subject closed. Back to Isaac.

[ticka1]

Track the eye on radar:

[Andrew]

The cone has become much wider this evening. It now reaches as far west as almost all of LA. This spread just goes to show how uncertain the NHC is about Isaac.

BB, that statement is blatently wrong - I suggest you read Bill's blog http://www.click2houston.com/news/Bill- ... index.html or read up on the definition here: http://www.nhc.noaa.gov/aboutcone.shtml

the amount of "uncertainty" in the forecast has absolutely nothing to do with the size of the cone, the parameters don't change during the season.

Let's not get carried away, folks. I made an error in my post in haste. Nothing more. Yes, even BB is allowed to have them. And as far as the spread of the cone goes, it has everything to do with the uncertainty of landfall, at least on the part of the models. That is the point I was trying to get across. I'm not sure where you are coming from. It is called, "the cone of uncertainty", for a reason. LOL!

If the newbies would like a link, which is one of many, to read up on what we call the cone of uncertainty, here is a great one:
http://hurricanereport.blogs.heraldtrib ... certainty/

A better explanation is simply a margin of error for their forecasted track to cover themselves.


Enough about BBs snafu. Case AND subject closed. Back to Isaac.

No one was calling you out BB. We were just correcting your post and making sure all information presented here is as accurate as possible. This is even more imperative now when we have so many viewers checking in about Isaac.

[Andrew]

00z models shifted west:

[sambucol]

That's quite a cluster of tracks trending west.

[Scott747]

Just so everyone understands a bit better....

Most of Louisiana has been in a 'cone' since as far back as early Thursday morning. It's a cone that reflects on a percentage basis the chances that area sees tropical storm force winds. In fact portions of our area was even in that cone on Thursday afternoon, even if it was only 5%.

http://www.nhc.noaa.gov/archive/2012/gr ... OB34.shtml

[ticka1]

So when will the shift west become a trend - sunday night - monday morning? Just curious....they are really clustered together over New Orleans but will this hold?

[biggerbyte]

Just so everyone understands a bit better....

Most of Louisiana has been in a 'cone' since as far back as early Thursday morning. It's a cone that reflects on a percentage basis the chances that area sees tropical storm force winds. In fact portions of our area was even in that cone on Thursday afternoon, even if it was only 5%.

http://www.nhc.noaa.gov/archive/2012/gr ... OB34.shtml

That is not the "cone" that we are talking about, however. The subject matter was supposed to have been for landfall, not wind probabilities. As of this moment, LA is not in that cone.. At all.

[jgreak]

So when will the shift west become a trend - sunday night - monday morning? Just curious....they are really clustered together over New Orleans but will this hold?

I was wondering the same thing Ticka, it's pretty crazy how clustered they all are right now on NOLA.

[Andrew]

So when will the shift west become a trend - sunday night - monday morning? Just curious....they are really clustered together over New Orleans but will this hold?

I was wondering the same thing Ticka, it's pretty crazy how clustered they all are right now on NOLA.

The NWS is known for not making dramatic shifts (which is very wise as things can change fast). As a result look for a general westward trend in the cone tonight but depending on what the 00z gfs, euro, and other models show tonight.

[Scott747]

Just so everyone understands a bit better....

Most of Louisiana has been in a 'cone' since as far back as early Thursday morning. It's a cone that reflects on a percentage basis the chances that area sees tropical storm force winds. In fact portions of our area was even in that cone on Thursday afternoon, even if it was only 5%.

http://www.nhc.noaa.gov/archive/2012/gr ... OB34.shtml

That is not the "cone" that we are talking about, however. The subject matter was supposed to have been for landfall, not wind probabilities. As of this moment, LA is not in that cone.. At all.

You referred the 'newbies' to the below link which was to an article that later in it contained a reference to a totally different 'cone' that may have confused people that went to it.

If the newbies would like a link, which is one of many, to read up on what we call the cone of uncertainty, here is a great one:
http://hurricanereport.blogs.heraldtrib ... certainty/

Just trying to clarify to avoid further confusion in case any 'newbies' read it and wondered the difference between the 'cones.'

[biggerbyte]

So when will the shift west become a trend - sunday night - monday morning? Just curious....they are really clustered together over New Orleans but will this hold?

I was wondering the same thing Ticka, it's pretty crazy how clustered they all are right now on NOLA.

The NWS is known for not making dramatic shifts (which is very wise as things can change fast). As a result look for a general westward trend in the cone tonight but depending on what the 00z gfs, euro, and other models show tonight.

That is exactly right, Andrew. Very good point. The NHC does not want to flip flop like the models do, so they wait for consistency before doing any dramatic swings.

[sambucol]

NHC 11pm

[Andrew]

WTNT44 KNHC 260244
TCDAT4

TROPICAL STORM ISAAC DISCUSSION NUMBER 20
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
1100 PM EDT SAT AUG 25 2012

SATELLITE AND RADAR DATA FROM CUBA SHOW THAT ISAAC IS MOVING
PARALLEL TO...BUT OFFSHORE OF...THE NORTHERN COAST OF CUBA.
THE HURRICANE HUNTER AIRCRAFT DID NOT FIND ANY STRONGER WINDS
DURING THE LATTER PORTION OF THE FLIGHT AND THE INITIAL WIND
SPEED REMAINS 50 KT. HOWEVER...THUNDERSTORM ACTIVITY HAS
INCREASED IN A BAND TO THE NORTH AND EAST OF THE CENTER DURING
THE PAST FEW HOURS AND ISAAC MAY BE ON THE VERGE OF STRENGTHENING.
THE NEXT RECONNAISSANCE FLIGHT IS EXPECTED TO BE IN THE CYCLONE
AROUND 0600 UTC.

THE INITIAL MOTION ESTIMATE IS 305/15 KT. ISAAC SHOULD CONTINUE ON
A WEST-NORTHWESTWARD TO NORTHWESTWARD MOTION DURING THE NEXT 24
HOURS OR SO BETWEEN A LARGE LOW/MID-LEVEL LOW PRESSURE SYSTEM OVER
THE NORTHWESTERN CARIBBEAN SEA AND A MID-LEVEL RIDGE OVER THE
WESTERN ATLANTIC. THE MODEL GUIDANCE IS TIGHTLY CLUSTERED DURING
THIS TIME AND SHOWS A TRACK OVER THE STRAITS OF FLORIDA AND NEAR OR
OVER THE FLORIDA KEYS. IN ABOUT 48 HOURS...ISAAC WILL BE NEARING
THE WESTERN PORTION OF THE RIDGE AND SHOULD MOVE IN A GENERAL
NORTHWESTWARD HEADING OVER THE EASTERN GULF OF MEXICO...BUT LARGE
DIFFERENCES EXIST BETWEEN THE LATEST ECMWF AND GFS MODELS AFTER
THAT TIME. THE ECMWF RECURVES ISAAC AHEAD OF A MID-LATITUDE
TROUGH OVER THE EASTERN UNITED STATES...WHILE THE GFS SLOWS ISAAC
DOWN AS THE TROUGH BYPASSES THE SYSTEM AND THE MODEL THEN TURNS
THE CYCLONE WESTWARD TO THE SOUTH OF A DEVELOPING MID- TO
UPPER-LEVEL RIDGE. THIS BIFURCATION IS ALSO SEEN IN THE MOST RECENT
ECMWF AND GFS ENSEMBLES WITH ABOUT AN EQUAL NUMBER OF MEMBERS
SHOWING RECURVATURE VERSUS A CONTINUE NORTHWESTERLY TRACK TOWARD
THE NORTHERN GULF COAST. SINCE THE UNCERTAINTY IS LARGE AND EITHER
OF THESE SCENARIOS ARE POSSIBLE AT THIS TIME...THE NHC FORECAST IS
LIES BETWEEN THEM. THE UPDATED TRACK IS VERY CLOSE TO THE PREVIOUS
ADVISORY THROUGH 36 HOURS. AFTER THAT TIME...THE TRACK HAS BEEN
ADJUSTED WESTWARD...BUT IT REMAINS EAST OF THE DYNAMICAL MODEL
CONSENSUS TO RETAIN SOME CONTINUITY WITH THE PREVIOUS FORECAST.

THE UPPER-LEVEL ENVIRONMENT IS EXPECTED TO BECOME MORE CONDUCIVE FOR
STRENGTHENING DURING THE NEXT COUPLE OF DAYS AS ISAAC MOVES OVER
THE WARM WATERS OF THE FLORIDA STRAITS AND EASTERN GULF. STEADY
STRENGTHENING IS EXPECTED AND ISAAC IS EXPECTED TO BE AT OR NEAR
HURRICANE STRENGTH WHEN THE CENTER REACHES THE FLORIDA KEYS.
ADDITIONAL STRENGTHENING IS LIKELY WHILE THE CYCLONE MOVES OVER THE
EASTERN GULF OF MEXICO. THE NEW INTENSITY FORECAST IS A LITTLE
HIGHER THAN THE PREVIOUS ADVISORY AND IS BETWEEN THE SHIPS/LGEM
GUIDANCE AND THE MORE AGGRESSIVE HWRF MODEL.

IT IS IMPORTANT NOT TO FOCUS ON THE EXACT FORECAST TRACK SINCE
SIGNIFICANT HAZARDS EXTEND WELL AWAY FROM THE CENTER. SINCE LARGE
UNCERTAINTIES REMAIN IN THE EXTENDED PORTION OF THE FORECAST...IT
IS TOO EARLY TO DETERMINE EXACTLY WHERE AND WHEN ISAAC WILL MAKE
LANDFALL ALONG THE GULF COAST.

FORECAST POSITIONS AND MAX WINDS

INIT 26/0300Z 22.1N 77.2W 50 KT 60 MPH
12H 26/1200Z 23.4N 79.4W 55 KT 65 MPH
24H 27/0000Z 24.6N 81.8W 65 KT 75 MPH...NEAR FLORIDA KEYS
36H 27/1200Z 25.8N 83.7W 75 KT 85 MPH
48H 28/0000Z 27.2N 85.2W 85 KT 100 MPH
72H 29/0000Z 29.5N 86.5W 90 KT 105 MPH
96H 30/0000Z 31.5N 86.5W 50 KT 60 MPH...INLAND
120H 31/0000Z 34.0N 86.0W 25 KT 30 MPH...INLA