Tropical Depression Isaac:

[djjordan]

BULLETIN
TROPICAL STORM ISAAC ADVISORY NUMBER 28
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
1000 PM CDT MON AUG 27 2012

...ISAAC TAKING AIM ON THE NORTHERN GULF COAST...SIGNIFICANT STORM
SURGE AND FRESHWATER FLOOD THREAT EXPECTED...


SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...27.1N 87.0W
ABOUT 190 MI...305 KM SE OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 255 MI...410 KM SSE OF BILOXI MISSISSIPPI
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...979 MB...28.91 INCHES


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

NONE

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A HURRICANE WARNING IS IN EFFECT FOR...
* EAST OF MORGAN CITY LOUISIANA TO THE ALABAMA-FLORIDA BORDER...
INCLUDING METROPOLITAN NEW ORLEANS...LAKE PONTCHARTRAIN...AND LAKE
MAUREPAS

A HURRICANE WATCH IS IN EFFECT FOR...
* INTRACOASTAL CITY TO MORGAN CITY LOUISIANA

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* FROM THE ALABAMA-FLORIDA BORDER TO THE AUCILLA RIVER
* INTRACOASTAL CITY TO MORGAN CITY LOUISIANA

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* EAST OF SABINE PASS TO WEST OF INTRACOASTAL CITY LOUISIANA

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
SOMEWHERE WITHIN THE WARNING AREA. PREPARATIONS TO PROTECT LIFE AND
PROPERTY SHOULD BE RUSHED TO COMPLETION.

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE
WITHIN THE WATCH AREA.

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

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

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


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1000 PM CDT...0300 UTC...THE CENTER OF TROPICAL STORM ISAAC WAS
LOCATED NEAR LATITUDE 27.1 NORTH...LONGITUDE 87.0 WEST. ISAAC IS
MOVING TOWARD THE NORTHWEST NEAR 10 MPH...17 KM/H. THIS GENERAL
MOTION WITH SOME DECREASE IN FORWARD SPEED IS EXPECTED DURING THE
NEXT DAY OR TWO. ON THE FORECAST TRACK...THE CENTER OF ISAAC WILL
MOVE OVER THE CENTRAL GULF OF MEXICO TONIGHT AND APPROACH THE COAST
OF SOUTHEASTERN LOUISIANA AND MISSISSIPPI TUESDAY AFTERNOON OR
TUESDAY NIGHT.

MAXIMUM SUSTAINED WINDS ARE NEAR 70 MPH...110 KM/H...WITH HIGHER
GUSTS. STRENGTHENING IS FORECAST...AND ISAAC IS EXPECTED TO BECOME
A HURRICANE TONIGHT OR EARLY TUESDAY...AND CONTINUE TO STRENGTHEN
UNTIL LANDFALL OCCURS ALONG THE NORTHERN GULF COAST.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 205 MILES...335 KM
FROM THE CENTER.

THE LATEST MINIMUM CENTRAL PRESSURE JUST REPORTED BY AN AIR FORCE
RESERVE RECONNAISSANCE AIRCRAFT WAS 979 MB...28.91 INCHES.


HAZARDS AFFECTING LAND
----------------------
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...

* SOUTHEAST LOUISIANA AND MISSISSIPPI...6 TO 12 FT
* ALABAMA...6 TO 9 FT
* SOUTH-CENTRAL LOUISIANA...3 TO 6 FT
* FLORIDA PANHANDLE...3 TO 6 FT
* FLORIDA WEST COAST INCLUDING APALACHEE BAY...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 LARGE AND DANGEROUS WAVES.

WIND...TROPICAL STORM CONDITIONS ARE EXPECTED TO SPREAD NORTHWARD
INTO THE FLORIDA BIG BEND AREA AND THE FLORIDA PANHANDLE IN THE
TROPICAL STORM WARNING AREA OVERNIGHT AND TUESDAY.

TROPICAL STORM CONDITIONS ARE EXPECTED TO REACH THE NORTHERN GULF
COAST IN THE HURRICANE WARNING AREA OVERNIGHT...WITH HURRICANE
CONDITIONS EXPECTED BY TUESDAY AFTERNOON.

RAINFALL...ISAAC IS EXPECTED TO PRODUCE TOTAL RAINFALL AMOUNTS OF
6 TO 12 INCHES...WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 18
INCHES...IN SOUTHEASTERN LOUISIANA...SOUTHERN MISSISSIPPI...
SOUTHERN ALABAMA AND THE EXTREME WESTERN FLORIDA PANHANDLE.

TORNADOES...ISOLATED TORNADOES ARE POSSIBLE ACROSS WEST-CENTRAL AND
NORTHWESTERN FLORIDA THROUGH TONIGHT...AND ALONG THE NORTHERN GULF
COAST LATE TONIGHT AND TUESDAY.

SURF...DANGEROUS SURF AND RIP CURRENT CONDITIONS WILL CONTINUE TO
AFFECT THE FLORIDA COASTLINE AND THE FLORIDA KEYS DURING THE NEXT
DAY OR SO...AND BEGIN TO AFFECT PORTIONS OF THE NORTHERN GULF COAST
EARLY TUESDAY.


NEXT ADVISORY
-------------
NEXT INTERMEDIATE ADVISORY...100 AM CDT.
NEXT COMPLETE ADVISORY...400 AM CDT.

$$
FORECASTER BROWN/BLAKE

[djjordan]

TROPICAL STORM ISAAC DISCUSSION NUMBER 28
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
1000 PM CDT MON AUG 27 2012

THE SATELLITE PRESENTATION OF ISAAC HAS NOT CHANGED VERY MUCH DURING
THE PAST FEW HOURS. INFRARED AND MICROWAVE IMAGERY SHOW A STRONG
BAND OF CONVECTION...PERHAPS THE BEGINNING OF AN EYEWALL...WRAPPING
AROUND THE SOUTH AND EAST PORTIONS OF THE CIRCULATION. HOWEVER...
AIRCRAFT OBSERVATIONS INDICATE THAT THE CONVECTIVE BAND WAS OPEN TO
THE NORTHWEST AND THAT THE LOW-LEVEL CENTER WAS DISPLACED A LITTLE
TO THE SOUTH OF THE ROTATION SEEN IN SATELLITE PICTURES. THE
MINIMUM PRESSURE HAS NOT FALLEN SIGNIFICANTLY DURING THE PAST
SEVERAL HOURS AND THE NOAA AND AIR FORCE AIRCRAFT HAVE NOT REPORTED
WINDS ANY HIGHER THAN WHAT WAS MEASURED LATE THIS AFTERNOON.
THEREFORE...ISAAC REMAINS A 60-KT TROPICAL STORM FOR THIS ADVISORY.
ISAAC CONTINUES TO HAVE DIFFICULTLY MAINTAINING DEEP CONVECTION
OVER THE NORTHERN SEMICIRCLE LIKELY DUE TO SOME DRY AIR
ENTRAINMENT. OTHERWISE...ENVIRONMENTAL CONDITIONS SHOULD BE
CONDUCIVE FOR STRENGTHENING UNTIL LANDFALL. ISAAC IS FORECAST TO
BECOME A HURRICANE OVERNIGHT AND NHC INTENSITY FORECAST IS SLIGHTLY
HIGHER THAN MOST OF THE GUIDANCE.

ISAAC HAS BEEN MOVING NORTHWESTWARD OR 310 DEGREES AT 9 KT. THE
TRACK GUIDANCE HAS CONTINUED TO COME INTO BETTER AGREEMENT DURING
THE FIRST 36 TO 48 HOURS OF THE FORECAST PERIOD. ISAAC SHOULD MOVE
NORTHWESTWARD TOWARD THE NORTH-CENTRAL GULF COAST WHERE A BREAK IN
THE SUBTROPICAL RIDGE IS LOCATED. AS A MID-LATITUDE TROUGH
BYPASSES ISAAC IN A DAY OR SO...SOME RIDGING BUILDS TO THE
NORTHWEST OF THE CYCLONE. THIS IS EXPECTED TO CAUSE ISAAC TO
SLOW DOWN AS IT MOVES INLAND. AFTER 72 HOURS...THE CYCLONE SHOULD
BEGIN TO MOVE A LITTLE FASTER TOWARD THE NORTH AND NORTHEAST AS IT
MOVES AROUND THE WESTERN SIDE OF A MID-LEVEL RIDGE THAT SLIDES
EASTWARD ACROSS THE OHIO VALLEY AND MID-ATLANTIC REGIONS. THE NEW
NHC TRACK IS SIMILAR TO THE PREVIOUS ADVISORY AND REMAINS BETWEEN
THE ECMWF AND GFS MODELS.

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.
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 28/0300Z 27.1N 87.0W 60 KT 70 MPH
12H 28/1200Z 28.0N 88.0W 70 KT 80 MPH
24H 29/0000Z 29.1N 89.2W 80 KT 90 MPH...ON THE COAST
36H 29/1200Z 29.9N 90.1W 65 KT 75 MPH...INLAND
48H 30/0000Z 30.7N 90.7W 50 KT 60 MPH...INLAND
72H 31/0000Z 33.3N 91.7W 30 KT 35 MPH...INLAND
96H 01/0000Z 37.5N 91.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 02/0000Z 40.5N 87.5W 20 KT 25 MPH...POST-TROP/REMNT LOW

$$
FORECASTER BROWN/BLAKE

[biggerbyte]

I don't see a point in arguing what Isaac is going to do. There is little to debate, due to the fact that things change daily. If we did have a reason to argue, one group is going to be wrong, while another right, or everybody ends up being wrong. I do think, however, there is always room for debate on the possibilities with a live system. To lay down only one possibility is just downright dangerous. Isaac very well could skip town and crawl up the spine of LA, and right now that is the belief. I'm going to leave it at that and start watching again what he is doing, and stop talking about what he might.

Be safe, you guys in LA.


BB

[ticka1]

I don't see a point in arguing what Isaac is going to do. There is little to debate, due to the fact that things change daily. If we did have a reason to argue, one group is going to be wrong, while another right, or everybody ends up being wrong. I do think, however, there is always room for debate on the possibilities with a live system. To lay down only one possibility is just downright dangerous. Isaac very well could skip town and crawl up the spine of LA, and right now that is the belief. I'm going to leave it at that and start watching again what he is doing, and stop talking about what he might.

Be safe, you guys in LA.


BB

Yes i have several friends who went thru Katrina and now are preparing for Isaac. Saying prayers for them that Isaac spares them major damage and that the storm heads west to areas that need rain!

[biggerbyte]

I don't see a point in arguing what Isaac is going to do. There is little to debate, due to the fact that things change daily. If we did have a reason to argue, one group is going to be wrong, while another right, or everybody ends up being wrong. I do think, however, there is always room for debate on the possibilities with a live system. To lay down only one possibility is just downright dangerous. Isaac very well could skip town and crawl up the spine of LA, and right now that is the belief. I'm going to leave it at that and start watching again what he is doing, and stop talking about what he might.

Be safe, you guys in LA.


BB

Yes i have several friends who went thru Katrina and now are preparing for Isaac. Saying prayers for them that Isaac spares them major damage and that the storm heads west to areas that need rain!

Right on.

[biggerbyte]

Looking at this:

http://www.ssd.noaa.gov/goes/east/gmex/flash-wv.html

I swear he looks to be heading west.

[Belmer]

Looking at this:

http://www.ssd.noaa.gov/goes/east/gmex/flash-wv.html

I swear he looks to be heading west.

I don't see a west movement at all. I see a clear NW movement, even a few wobbles in there of a NNW movement.
'check' box the boxes of "L/L" and "Trop Pts" and then follow the center. Maybe you'll see the NW movement a little clearer.

[nuby3]

Looking at this:

http://www.ssd.noaa.gov/goes/east/gmex/flash-wv.html

I swear he looks to be heading west.

I don't see a west movement at all. I see a clear NW movement, even a few wobbles in there of a NNW movement.
'check' box the boxes of "L/L" and "Trop Pts" and then follow the center. Maybe you'll see the NW movement a little clearer.

I agree. To me, it appears to be following the forecasted plot points. Right to New Orleans.

[Scott747]

Looking at this:

http://www.ssd.noaa.gov/goes/east/gmex/flash-wv.html

I swear he looks to be heading west.

I don't see a west movement at all. I see a clear NW movement, even a few wobbles in there of a NNW movement.
'check' box the boxes of "L/L" and "Trop Pts" and then follow the center. Maybe you'll see the NW movement a little clearer.

Correct. It definitely isn't moving W. Latest recon fix show a clear NW movement.

The 10 pm advisory had a track change to the E by about 15 miles and is now over NO metro and Metairie.

0z GFS also shifted to the E.

[biggerbyte]

I'm on my cell. My eyes are playing tricks on me with this small screen. Man, if this is true, those poor folks in NOLA.

[skidog40]

only if thats the low. my low is sw of that low

[biggerbyte]

Wow! That's pretty low.

[Belmer]

One thing to note, Isaac has slowed a bit. Will be interesting if Isaac continues to slow down in forward speed as that could also make a difference in final landfall.

As much as I love Hurricane season and tracking these storms, I am now ready for the 2012 season to be over with after all the headaches it has given me. We had Debby, Ernesto, little bit of Helene and now Isaac. I'm ready to call it quits and bring on our winter discussion ...afterall, this will be a El Nino year.

[biggerbyte]

There is some concern that within 24 hours the way out for Isaac closes and he gets pinned beneath the ridge and heads west again. It is one of those possibilities we talked about earlier. The question is if, then when, and how far northward Isaac is at the time. He is slowing down, so...

[Stormrider]

I'm not taking my eyes off Isaac until he's well onshore, wherever that is. I am feeling for the folks in New Orleans and SE Louisiana. The anxiety there must be pretty high. Memories of Katrina probably still haunt them.

[rselby0654]

There is some concern that within 24 hours the way out for Isaac closes and he gets pinned beneath the ridge and heads west again. It is one of those possibilities we talked about earlier. The question is if, then when, and how far northward Isaac is at the time. He is slowing down, so...

That is probably why Dr. Neil Frank has kept a cautious position on Isaac. Isaac is slowing down and strengthening. It still wouldn't surprise me if Isaac underwent some Rapid Intensification over the next 24 hours or so. The fact that he's slowing down could mean trouble. Hurricanes are sometimes unpredictable and we must always respect mother nature for the diva she really is! LOL

[nuby3]

Convection appears to really be starting to fire around the center...

[Bluefalcon]

Convection appears to really be starting to fire around the center...

Yeah...but the whole N to NE quad. of the storm is nothing but dry air. Looks like someone cut it in half from East to West. 979mb is solid Cat 1 maybe Cat 2 pressure. If it can shake the dry air and the Easterly shear...still a good 24 hours for the winds to catch up to the pressure. Very much like Ike...the wind never really caught up to the pressure.

[Scott747]

Somebody must be playing tricks with the models.

0z Euro shifts a hefty distance W through 24 hrs.

[Scott747]

Now somebody is really playing tricks.

Through 48 hrs the Euro has reversed and now is moving due W along the La coast. S of Abbeville.