Isaac lashing the Keys; an eyewall is building

By: Dr. Jeff Masters , 3:48 PM GMT on August 26, 2012

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Tropical Storm Isaac is steadily organizing as it lashes the Florida Keys with heavy rain and tropical storm-force winds. Sustained winds of 44 mph and 41 mph have been observed at Molasses Reef and Sombrero Key, respectively, this morning. Radar out of Key West shows an increase in spiral banding, and the beginnings of an eyewall. An Air Force Hurricane Hunter aircraft completed its first pass through the center of Isaac near 11:30 am EDT, and did not find the pressure had fallen, or that the peak winds had increased. Infrared and visible satellite loops show that Isaac is a large and increasingly well-organized storm. An analysis of upper level winds from the University of Wisconsin CIMSS shows that upper-level outflow is quite good and increasing to the north, but is lacking elsewhere. Moderate wind shear and dry air to the south are interfering with heavy thunderstorm development on Isaac's south side. Heavy rains from Isaac are lingering over Haiti and the Dominican Republic; flash floods in Haiti from Isaac's torrential rains killed at least four people.


Figure 1. Morning reflectivity image from the Radar out of Key West radar shows the northwest section of an eyewall beginning to form to the southeast of the city.

Latest model runs for Isaac
The latest set of 0Z and 06Z (8 pm and 2 am EDT) model runs have diverged significantly, and we can no longer be confident we know where Isaac will make landfall on the Gulf Coast. One camp of models, the UKMET and ECMWF, predict that a trough of low pressure moving across the Southeast U.S. will be strong enough to turn Isaac north to a landfall in the Florida Panhandle. The other set of models, the GFDL, GFS, and HWRF, predict the trough will bypass Isaac, and a ridge of high pressure will build in and force Isaac to a landfall over Louisiana. The official NHC forecast averages out these two extremes, calling for a landfall midway between the two solutions. Odds are, one of the two model solutions will turn out to be the correct one, and the NHC will be forced to make a substantial adjustment in their forecast track to the east or the west. Isaac has the potential to drop torrential rains capable of causing serious flooding and drought relief over the South. The latest 8-day precipitation forecast from the GFS model calls for 10 - 20 inches of rain over Southeast Louisiana, where it predicts Isaac will make landfall. The ECMWF model, however, these heavy rains will fall more over the Florida Panhandle, Alabama, and Georgia.


Figure 2. A hurricane forecaster's dilemma: which set of models is correct? The latest set of 0Z and 06Z (8 pm and 2 am EDT) model runs have diverged significantly. Our two top models--the GFS and ECMWF--have 72-hour forecasts that are about 350 miles apart. The ECMWF forecast is not shown here, but lies just to the west of the UKMET forecast (white line.)

Intensity forecast for Isaac
Isaac survived passage over Hispaniola and Cuba relatively intact. It's large size aided this. Isaac is over very warm waters of 31°C (88°F) with high total heat content in the Florida Straits, but is encountering moderate wind shear of 10 - 15 knots due to upper-level winds out of the southwest. This shear is predicted to relax to the light range tonight as an upper-level anticyclone becomes established over the storm. This should allow for more substantial intensification after Isaac passes the Florida Keys. However, the total heat content of the ocean decreases for Isaac Monday morning as it encounters a relatively cool ocean eddy in the Southeast Gulf of Mexico. If Isaac takes a more westerly track, passing due south of the Central Louisiana coast, the storm will encounter a modest warm eddy, which would aid intensification. The intensify forecasts from the various models are very divergent. The latest 06Z (2 am EDT) run of the GFDL model keeps Isaac as a strong tropical storm until landfall in Louisiana. Isaac will undergo rapid intensification into a Category 3 hurricane as it hits New Orleans, says the latest 06Z (2 am EDT) run of the HWRF model. The ECMWF model has Isaac as a strong Category 2 storm with a central pressure near 950 mb as it hits near the Alabama/Florida border.

Comparing Isaac with Ike of 2008
The current situation with Isaac is similar in some ways to that of Hurricane Ike of 2008. Ike spent considerable time over Cuba, weakening from a Category 4 to a Category 1 storm. The storm couldn't put its energy into building a strong inner core, but it was able to build up its outer rainbands that were over very warm waters. This resulted in a major expansion of its wind field, with tropical storm-force winds extending out 275 miles from the center at one point. Ike was able to intensify into a Category 2 storm on its path towards Texas, and had an unusually low pressure for a Cat 2 storm with 100 mph winds--944 mb. That's a central pressure more typical of a Category 3 storm, but Ike could only manage Category 2 winds, since it had such a large chunk of the atmosphere to keep spinning. With Isaac's TS winds already extending out to 205 miles, maybe we'll see another Ike-type situation as it intensifies--the storm will have an unusually low pressure in order to keep a huge wind field spinning, but never make it above Category 2, since it will take so long to spin up such a large wind field.

Storm surge forecast for Isaac
Isaac is a very large storm, with tropical storm-force winds that extend out 205 miles from the center. For comparison, Hurricane Katrina at landfall had tropical storm-force winds that extended out 230 miles from its center. Isaac's large size will enable it to set a large area of the ocean into motion, which will generate a large storm surge once the storm approaches land on the Gulf Coast. The latest 3:30 am EDT Integrated Kinetic Energy analysis from NOAA's Hurricane Research Division put the destructive potential of Isaac's winds near 0 on a scale of 1 to 6, but the destructive potential of Isaacs's storm surge was 2.1 on a scale of 1 to 6. A 2008 paper by Irish et al., The influence of storm size on hurricane surge, found that large storms like Isaac are capable to delivering a 30% larger storm surge to the coast than a smaller storm with the same maximum wind speeds. The angle with which the storm hit the coast is important, too--a storm moving due north or slightly east of north will deliver a storm surge about 10% greater than a storm moving NNW or NW. Consult our Storm Surge pages for detailed information on what the risk is for the coast. I expect that Isaac's storm surge will be about 30% higher than the typical surge one would expect based on the maximum wind speeds.

Invest 97L off the coast of Africa
A tropical wave (Invest 97L) is located about 650 miles west of the Cape Verde Islands off the coast of Africa. 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 50% chance of developing by Tuesday morning. None of the reliable models foresee that 97L will be a threat to the Lesser Antilles Islands. However, both the GFS and ECMWF models predict that a tropical wave that has not yet emerged from the coast of Africa may develop late this week, and potentially take a more westward track towards the Lesser Antilles, arriving around September 2.

Angela Fritz will have a new post here by 6 pm EDT. For the next few days, I plan to do the morning blog post, and Angela will be doing the late afternoon post. I'm in Atlanta to help out The Weather Channel with their on-air hurricane coverage, and will be on either in the afternoon or evening on Sunday, Monday, and Tuesday.

Jeff Masters

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Another east caribbean Storm...let's see if he finds more instability in the atlantic than Isaac

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pressure down winds down.
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Quoting MiamiHurricanes09:
Watching out my window, palm frond just went flying a good 20 yards down the neighborhood. Worst weather I've gotten from Isaac thus far by a great margin.


Wow! Seems you guys are really being hammered by the bands. I have family there too. Stay save.
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Quoting phenomenoloj:
Look time reader, first time poster. I have a question about the hurricane hunter part of the page for Issac, which says:

"Maximum Surface Wind found by Hurricane Hunter: 155 mph"

http://www.wunderground.com/tropical/tracking/at2 01209_hd.html

Does this mean the storm is that powerful? That seems like a mistake.


It appears WU reports all data and does not filter out suspect or contaminated readings.
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Member Since: July 15, 2006 Posts: 165 Comments: 52262


000
WTNT34 KNHC 261747
TCPAT4

BULLETIN
TROPICAL STORM ISAAC INTERMEDIATE ADVISORY NUMBER 22A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
200 PM EDT SUN AUG 26 2012

...ISAAC HAS NOT STRENGTHENED...


SUMMARY OF 200 PM EDT...1800 UTC...INFORMATION
----------------------------------------------
LOCATION...23.9N 81.5W
ABOUT 50 MI...85 KM SSE OF KEY WEST FLORIDA
ABOUT 75 MI...120 KM NE OF HAVANA CUBA
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 18 MPH...30 KM/H
MINIMUM CENTRAL PRESSURE...994 MB...29.35 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...
* EAST OF MORGAN CITY LOUISIANA TO INDIAN PASS FLORIDA...INCLUDING
METROPOLITAN NEW ORLEANS AND LAKE PONTCHARTRAIN

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* THE CUBAN PROVINCE OF VILLA CLARA
* THE NORTHWESTERN BAHAMAS
* THE FLORIDA EAST COAST FROM SEBASTIAN INLET SOUTHWARD TO OCEAN
REEF
* LAKE OKEECHOBEE
* THE FLORIDA WEST COAST AND THE FLORIDA PANHANDLE FROM NORTH OF
BONITA BEACH TO INDIAN PASS...INCLUDING TAMPA BAY

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

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
SOMEWHERE WITHIN THE WARNING AREA...IN THIS CASE WITHIN THE NEXT 24
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. A WATCH IS TYPICALLY ISSUED 48 HOURS
BEFORE THE ANTICIPATED FIRST OCCURRENCE OF TROPICAL-STORM-FORCE
WINDS...CONDITIONS THAT MAKE OUTSIDE PREPARATIONS DIFFICULT OR
DANGEROUS.

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
THE REMAINDER OF 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 200 PM EDT...1800 UTC...THE CENTER OF TROPICAL STORM ISAAC WAS
LOCATED NEAR LATITUDE 23.9 NORTH...LONGITUDE 81.5 WEST. ISAAC IS
MOVING TOWARD THE WEST-NORTHWEST NEAR 18 MPH...30 KM/H. A WEST-
NORTHWESTWARD TO NORTHWESTWARD MOTION IS EXPECTED DURING THE NEXT
48 HOURS WITH A GRADUAL DECREASE IN FORWARD SPEED. ON THE FORECAST
TRACK...THE CENTER OF ISAAC IS EXPECTED TO MOVE NEAR OR OVER THE
LOWER FLORIDA KEYS LATER TODAY AND TONIGHT...AND MOVE INTO THE
EASTERN GULF OF MEXICO ON MONDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 60 MPH...95 KM/H...WITH HIGHER
GUSTS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 48
HOURS...HOWEVER THE LIKELIHOOD OF ISAAC BECOMING A HURRICANE BEFORE
IT REACHES THE FLORIDA KEYS IS DECREASING.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 205 MILES...335 KM
FROM THE CENTER. A WIND GUST TO 55 MPH...89 KM/H...WAS RECENTLY
REPORTED AT VIRGINIA KEY.

THE MINIMUM CENTRAL PRESSURE BASED ON DATA FROM AN AIR FORCE
HURRICANE HUNTER AIRCRAFT IS 994 MB...29.35 INCHES.


HAZARDS AFFECTING LAND
----------------------
RAINFALL...TOTAL RAINFALL ACCUMULATIONS OF 4 TO 8 INCHES...WITH
MAXIMUM AMOUNTS OF 12 INCHES...ARE POSSIBLE ACROSS THE FLORIDA
KEYS...THE SOUTHERN PENINSULA OF FLORIDA AND PORTIONS OF CENTRAL AND
EASTERN CUBA. TOTAL RAIN ACCUMULATIONS OF 3 TO 6 INCHES ARE
POSSIBLE OVER THE CENTRAL AND SOUTHERN BAHAMAS.

WIND...TROPICAL STORM CONDITIONS ARE OCCURRING OVER PORTIONS OF
EASTERN AND CENTRAL CUBA AND THE BAHAMAS AND THE TURKS AND CAICOS
ISLANDS. TROPICAL STORM CONDITIONS ARE POSSIBLE IN PORTIONS OF
NORTHWESTERN CUBA BY LATE TODAY.

HURRICANE CONDITIONS ARE EXPECTED IN THE HURRICANE WARNING AREA IN
SOUTHWEST FLORIDA AND THE FLORIDA KEYS TODAY.

TROPICAL STORM CONDITIONS ARE OCCURRING IN THE TROPICAL
STORM WARNING AREA ALONG THE FLORIDA EAST COAST. TROPICAL STORM
CONDITIONS ARE EXPECTED TO SPREAD NORTHWARD ALONG THE WEST COAST OF
FLORIDA AND INTO THE EASTERN FLORIDA PANHANDLE IN THE TROPICAL
STORM WARNING AREA TONIGHT AND MONDAY.

HURRICANE CONDITIONS ARE POSSIBLE IN THE HURRICANE WATCH AREA ALONG
THE NORTHERN GULF COAST ON TUESDAY...WITH TROPICAL STORM CONDITIONS
POSSIBLE BY MONDAY NIGHT.

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...

* CRYSTAL RIVER THROUGH THE BIG BEND OF FLORIDA...4 TO 7 FT
* SOUTHWEST FLORIDA COAST WITHIN HURRICANE WARNING AREA...4 TO 6 FT
* FLORIDA WEST COAST FROM BONITA BEACH TO SOUTH OF CRYSTAL RIVER
INCLUDING TAMPA BAY...3 TO 5 FT
* SOUTHEAST FLORIDA COAST AND THE FLORIDA KEYS...1 TO 3 FT
* CENTRAL AND EASTERN CUBA...1 TO 3 FT
* THE BAHAMAS...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...TORNADOES ARE POSSIBLE TODAY OVER CENTRAL AND SOUTHERN
FLORIDA...WITH THE GREATEST THREAT OVER SOUTHERN FLORIDA AND THE
KEYS.

SURF...DANGEROUS SURF AND RIP CURRENT CONDITIONS WILL CONTINUE TO
AFFECT THE CENTRAL AND NORTHWESTERN BAHAMAS...CENTRAL CUBA...THE
FLORIDA PENINSULA 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...500 PM EDT.

$$
FORECASTER PASCH/ROBERTS
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Quoting floridaboy14:
Begin initialization: ECMWF 995mb Perfect 0 hours


Do you have a link you can share please?
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Quoting Grothar:
There have been a number of storms which have taken a similar path. This is not unexpected.








Not from where Isaac came from. This is a first time occurrence.
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The farther west this goes.. the more time Isaac has over water, which means it could strengthen into a Cat 3. I doubt anything higher though. But, still a cat 3 with his size.. could be a similar Katrina situation, if he extends his wind field to the size Katrina did.
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Begin initialization: ECMWF 995mb Perfect 0 hours
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Quoting MiamiFL305:
a nother car accident near hialeah
Yikes! Looks wind-aided...
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...ISAAC HAS NOT STRENGTHENED... ...U.S. Warnings in Effect...
2:00 PM EDT Sun Aug 26
Location: 23.9°N 81.5°W
Moving: WNW at 18 mph
Min pressure: 994 mb
Max sustained: 60 mph
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Quoting seflagamma:


Hi Grothar, been "liking" your posts all weekend but have not given you a shout out yet.
So how are things on east side of town?
Bills, said her power actually flickered a few times but no really stormy weather over there.
We are getting a lot of rain here.. over 3" so far.
ARe you getting rain???



I must pull myself off this computer for a while and go do a few things inside....

will be back later.

Stay safe!


Very windy and heavy rain at time. We are expecting a good one in a few minutes.

I thought our lights were flickering here, but I took my blood pressure medicine and everything seems fine now. A little worried about our neighbors to our North. It seems Florida and the Gulf Coast seems to like to share the same storms.

Any flooding by you?



Member Since: July 17, 2009 Posts: 63 Comments: 23724
Quoting newportrinative:


Drives here drive like sh&t when it rains!!! Blaming on the storm is ridiculous.
that's why you shouldn't be driving in the first place
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POWER'S OUT. Dammit. Posting this on my phone. Will keep you updated; very bad weather.
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Quoting LSU:


Considering the experts aren't predicting rapid intensification, I think you may be the one who is misinformed.

I know, though. You see something they don't.



He isn't saying they are. He's pointing out to the poster that he misunderstands what RI means. Your post is about the most mixed up I've seen on here.
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Look time reader, first time poster. I have a question about the hurricane hunter part of the page for Issac, which says:

"Maximum Surface Wind found by Hurricane Hunter: 155 mph"

http://www.wunderground.com/tropical/tracking/at2 01209_hd.html

Does this mean the storm is that powerful? That seems like a mistake.
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Quoting Grothar:
There have been a number of storms which have taken a similar path. This is not unexpected.










to be fair Gro

none of those came through the Caribbean too
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ECMWF coming out soon. will he join the trend?
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Quoting GetReal:
What do we have here coming out???



A nice little warm spot, nothing more yet but that is subject to change soon.
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Quoting clickBOOM:


Most likely, started here early this morning. I think it will last until tomorrow though. Big system.
LOL... I keep hoping the winds will stay high enough to make my employer say "No... you should stay home today!".... doubt that'll happen, though... lol

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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
506 AM CDT SUN AUG 26 2012

.HURRICANE WATCH ISSUED FOR THE MISSISSIPPI GULF COAST AND FOR
LOWER ST. BERNARD AND LOWER PLAQUEMINES PARISHES IN LOUISIANA...

MAIN CONCERN...TROPICAL STORM ISAAC. ISAAC
IS LOCATED ABOUT 200 MILES TO THE EAST-SOUTHEAST OF KEY WEST AND
MOVING TOWARDS THE NORTHWEST AT 18 MPH. THE OVERALL STRUCTURE OF
THE STORM CONTINUES TO LOOK RAGGED ON SATELLITE WITH LIMITED DEEP
CONVECTION MAINLY OFF TO THE NORTH AND EAST OF THE CENTER. THAT
SAID...A RECONNAISSANCE FLIGHT HAS FOUND A SLIGHTLY LOWER PRESSURE
OF 995 MB AND WINDS OF 65 MPH. THE NEW FORECAST TRACK FROM THE
NATIONAL HURRICANE CENTER CONTINUES TO SHOW ISSAC MOVING GENERALLY
IN A WEST-NORTHWEST TO NORTHWEST MOTION TOWARDS THE FLORIDA KEYS
AND THE GULF OF MEXICO. IN THE SHORT TERM...THE NEXT 36
HOURS...THE MODEL GUIDANCE IS IN GOOD AGREEMENT ON THAT TRACK.

BY EARLY MONDAY MORNING THE HURRICANE CENTER TRACK PUTS ISSAC
AROUND 100 MILES TO THE NORTHWEST OF KEY WEST AND INTO THE GULF OF
MEXICO. ONCE ISAAC REACHES THE GULF...STRENGTHENING IS FORECAST.
AT THAT POINT...MOST OF THE RELIABLE MODEL GUIDANCE IS STILL IN
DECENT AGREEMENT WITH THE ECMWF...THE GFS...THE NAM AND THE CMC
ALL IN REASONABLE AGREEMENT WITH THE CANADIAN THE FURTHEST WEST.
THAT IS WHERE THINGS START TO GET A LITTLE...OFF. THE DIFFERENCES
IN THE MODEL RUNS HINGE MOSTLY ON HOW THEY HANDLE THE EVOLUTION OF
A SHORTWAVE TROUGH AND HIGH PRESSURE RIDGES TO THE WEST AND THE
EAST OF SAID TROUGH. THE GFS AND THE CMC SHOW THE TROUGH
BYPASSING ISSAC AND THE TWO RIDGES CLOSING THE GAP BETWEEN THEM
LEAVING ISSAC BEHIND TO CONTINUE IN A NORTHWESTWARD MOTION TOWARD
THE CENTRAL GULF COAST. THE NAM AND THE ECMWF BOTH LEAVE ENOUGH OF
A WEAKNESS OVER THE EASTERN FLORIDA PANHANDLE TO ALLOW FOR A
NORTHERLY MOTION TOWARDS THE END OF THE TRACK. DISCOUNTING THE NAM
FOR ITS NOTORIOUS ISSUES IN THE TROPICS...AND WITH THE IDEA THAT
THE ECMWF WAS ONE OF...IF NOT THE BEST...PERFORMING MODELS IN THE
RECENT PAST SOME COMPARISONS WERE DONE ON THE LAST TWO RUNS. THE
12Z RUN YESTERDAY TOOK ISSAC INTO THE FLORIDA PANHANDLE NEAR
APALACHICOLA. THE 00Z RUN FROM A FEW HOURS AGO SHOWS A LANDFALL
POINT NEAR THE FLORIDA/ALABAMA BORDER. THE 00Z RUN OF THE MODEL
DEFINITELY SHOWED A STRONGER ATLANTIC RIDGE WHICH ACCOUNTED FOR
THE PUSH FURTHER WEST AS THERE WAS LITTLE DIFFERENCE IN THE
EVOLUTION OF THE TROUGH IN THE TWO RUNS. THIS WILL BE WATCHED
CLOSELY IN THE NEXT RUN SINCE IT REMAINS ONE OF THE EASTERN MOST
MODELS AT THIS POINT. SHOULD IT SHIFT MORE TO THE WEST AND THE
OTHER MODELS CONTINUE THEIR WESTWARD SHOWING...ADDITIONAL
ADJUSTMENTS TO THE HURRICANE CENTER ARE POSSIBLE.

FOR THE TIME BEING HAVE GONE WITH A BLEND OF THE ECMWF AND THE GFS
WITH A BIT MORE WEIGHT PLACED ON THE ECMWF SINCE IT IS CLOSER TO
THE CURRENT HURRICANE CENTER FORECAST TRACK. THIS WILL BRING THE
POSSIBILITY OF TROPICAL STORM CONDITIONS INTO THE AREA ON MONDAY
NIGHT ALONG THE EASTERN PARTS OF THE MISSISSIPPI GULF COAST AND
TUESDAY MORNING INTO THE NEW ORLEANS METRO AREA. HURRICANE
CONDITIONS WILL ALSO BE POSSIBLE...ESPECIALLY BY TUESDAY MORNING
ALONG THE MISSISSIPPI COAST. RAIN CHANCES WILL OBVIOUSLY BE
DEPENDENT ON THE EVENTUAL TRACK OF ISAAC...AND THEY CURRENTLY
REFLECT SOME OF THE UNCERTAINTY IN THE FORECAST TRACK AS
MENTIONED IN THE NATIONAL HURRICANE CENTER DISCUSSION.

NEEDLESS TO SAY...THIS IS A DEVELOPING AND FLUID SITUATION THAT
CAN CHANGE GREATLY OVER THE NEXT 24-36 HOURS. THE BOTTOM LINE IS
THAT PARTS OF THE AREA ARE NOW UNDER A HURRICANE WATCH AND IN
THOSE AREA PREPARATIONS SHOULD BE RUSHED TO COMPLETION AS QUICKLY
AS POSSIBLE. OUTSIDE THE HURRICANE WATCH...RESIDENTS SHOULD
CONTINUE TO MONITOR THE LATEST UPDATES ON ISAAC AND BE PREPARED TO
TAKE ACTION IF NEEDED.

AVIATION...

VFR CONDITIONS ARE EXPECTED THROUGH 12Z MONDAY WITH THE POSSIBLE
EXCEPTION OF SOME MVFR VISIBILITIES DUE TO LIGHT FOG AROUND
DAYBREAK.

MARINE...

A HURRICANE WATCH IS NOW IN EFFECT FOR THE MARINE ZONES EAST OF THE
MISSISSIPPI RIVER. EXPECT DETERIORATING CONDITIONS ACROSS THE
COASTAL WATERS BEGINNING MONDAY AND CONTINUING THROUGH TUESDAY AND
WEDNESDAY AS ISAAC IS FORECAST TO STRENGTHEN TO A HURRICANE AS MOVES
INTO SOUTHEAST GULF OF MEXICO AND TRACKS TOWARD THE NORTH GULF
COAST. THE LATEST FORECAST FROM NHC HAS ISAAC MAKING LANDFALL AS A
CATEGORY 2 HURRICANE AROUND MOBILE BAY TUESDAY NIGHT AND EARLY
WEDNESDAY.

DECISION SUPPORT...
DSS CODE...RED.
DEPLOYED...NONE.
ACTIVATION...NONE.
ACTIVITIES...MONITORING TROPICAL STORM ISAAC.

DECISION SUPPORT SERVICES (DSS) CODE LEGEND
GREEN = NO WEATHER IMPACTS THAT REQUIRE ACTION
BLUE = LONG FUSED WATCH/WARNING/ADVISORY IN EFFECT OR HIGH
VISIBILITY EVENT
YELLOW = HEIGHTENED IMPACTS WITH SHORT FUSED
WATCH/WARNING/ADVISORY ISSUANCES; RADAR SUPPORT
ORANGE = HIGH IMPACTS - SLIGHT TO MODERATE RISK SEVERE; NEARBY
TROPICAL EVENTS; HAZMAT OR OTHER LARGE EPISODES
RED = FULL ENGAGEMENT FOR MODERATE TO HIGH RISK SVR AND/OR
DIRECT TROPICAL THREATS; EVENTS OF NATIONAL SIGNIFICANCE


Link
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Quoting GetReal:
What do we have here coming out???

EYE! EYE!
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Quoting DataNerd:





How does that happen. Yikes.
Car runs light, Car hits SUV, SUV hits curb, SUV rolls over... end of story
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Quoting GetReal:
What do we have here coming out???

A hole?.
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Quoting MiamiFL305:
a nother car accident near hialeah


How does that happen?
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Radar loop of circulation

check this radar out..
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Anyone have a link to the 12z GFDL and HWRF? Also looking for the 12z ECMWF from today. The page I have isn't updating yet. It was yesterday at this time.
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Quoting DataNerd:





How does that happen. Yikes.


Drives here drive like sh&t when it rains!!! Blaming on the storm is ridiculous.
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Quoting GetReal:
What do we have here coming out???



Hmmmm! Are they zeroed-in on Mud Lake now? ;)
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Quoting Hurricanes101:
seems to me that Isaac may take a shot at the middle keys


Is he going Alligator hunting into the Everglades?
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691. JeffM
Isaac just needs time to move further away from Cuba/Florida and then get its huge size moving before it begins to intensify.
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Watching out my window, palm frond just went flying a good 20 yards down the neighborhood. Worst weather I've gotten from Isaac thus far by a great margin.
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Quoting MiamiHurricanes09:
Worst weather I've gotten so far occurring as I type. Torrential rain with a gust of 43kts right now...you can hear the winds howling. Twigs flying around outside of the window and the TV signal flickering. Very bad weather right now. Extremely dark as well.

same im in miami aswell. very gusty winds
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My forecast.
Member Since: September 2, 2011 Posts: 0 Comments: 1140
UT OH, I am in Central LA...so far, it isnt looking good...has any of the officials in LA say anything yet????
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12Z GFDL



HOUR: .0 LONG: -80.19 LAT: 23.26 MIN PRESS (hPa): 994.54 MAX SURF WIND (KNOTS): 43.89
HOUR: 6.0 LONG: -81.33 LAT: 23.79 MIN PRESS (hPa): 991.93 MAX SURF WIND (KNOTS): 44.39
HOUR: 12.0 LONG: -82.47 LAT: 24.63 MIN PRESS (hPa): 988.16 MAX SURF WIND (KNOTS): 61.25
HOUR: 18.0 LONG: -84.02 LAT: 25.25 MIN PRESS (hPa): 982.72 MAX SURF WIND (KNOTS): 57.28
HOUR: 24.0 LONG: -85.21 LAT: 25.73 MIN PRESS (hPa): 984.32 MAX SURF WIND (KNOTS): 52.83
HOUR: 30.0 LONG: -86.28 LAT: 26.33 MIN PRESS (hPa): 983.16 MAX SURF WIND (KNOTS): 49.98
HOUR: 36.0 LONG: -87.38 LAT: 26.71 MIN PRESS (hPa): 981.39 MAX SURF WIND (KNOTS): 53.10
HOUR: 42.0 LONG: -88.47 LAT: 27.00 MIN PRESS (hPa): 979.09 MAX SURF WIND (KNOTS): 56.28
HOUR: 48.0 LONG: -89.29 LAT: 27.29 MIN PRESS (hPa): 975.40 MAX SURF WIND (KNOTS): 65.58
HOUR: 54.0 LONG: -89.73 LAT: 27.60 MIN PRESS (hPa): 967.77 MAX SURF WIND (KNOTS): 83.72
HOUR: 60.0 LONG: -90.07 LAT: 27.89 MIN PRESS (hPa): 965.85 MAX SURF WIND (KNOTS): 78.54
HOUR: 66.0 LONG: -90.57 LAT: 28.22 MIN PRESS (hPa): 963.71 MAX SURF WIND (KNOTS): 79.95
HOUR: 72.0 LONG: -91.13 LAT: 28.60 MIN PRESS (hPa): 962.48 MAX SURF WIND (KNOTS): 83.59
HOUR: 78.0 LONG: -91.59 LAT: 28.90 MIN PRESS (hPa): 963.61 MAX SURF WIND (KNOTS): 72.71
HOUR: 84.0 LONG: -91.97 LAT: 29.20 MIN PRESS (hPa): 964.21 MAX SURF WIND (KNOTS): 74.29
HOUR: 90.0 LONG: -92.66 LAT: 29.74 MIN PRESS (hPa): 968.42 MAX SURF WIND (KNOTS): 61.25
HOUR: 96.0 LONG: -93.30 LAT: 30.36 MIN PRESS (hPa): 974.61 MAX SURF WIND (KNOTS): 54.08
HOUR:102.0 LONG: -93.97 LAT: 31.20 MIN PRESS (hPa): 980.17 MAX SURF WIND (KNOTS): 44.85
HOUR:108.0 LONG: -94.44 LAT: 32.23 MIN PRESS (hPa): 982.54 MAX SURF WIND (KNOTS): 33.01
HOUR:114.0 LONG: -95.06 LAT: 33.42 MIN PRESS (hPa): 984.70 MAX SURF WIND (KNOTS): 34.28
HOUR:120.0 LONG: -95.26 LAT: 34.80 MIN PRESS (hPa): 987.47 MAX SURF WIND (KNOTS): 32.05
HOUR:126.0 LONG: -95.11 LAT: 36.34 MIN PRESS (hPa): 989.33 MAX SURF WIND (KNOTS): 25.09
Member Since: September 23, 2005 Posts: 13 Comments: 10466
There have been a number of storms which have taken a similar path. This is not unexpected.








Member Since: July 17, 2009 Posts: 63 Comments: 23724
Quoting misscoast:
After reading Dr. Masters blog it sounds as if he is saying one of the two models consensus will be correct and the NHC will have a large correction to make instead of blending the two solutions and splitting it down the middle. Being that a Hurricane warning has to be issued 36 hours ahead of the onset of tropical force winds I would think if this model difference continues the NHC will have to flip a coin or so to speak. Anyone have a take on this?


Based on history, they will continue near the middle of the guidance and truly hope that the subsequent model runs come into better agreement, particularly the GFS, European and UKMET. If that doesn't happen by tonight, they are going to put their 'trust' in the guidance that they feel is depicting the current and future large scale pattern better than the others.
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system is moving NW per radar

I think the NHC had the center wrong at 11am
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681. LSU
Quoting pipelines:


RI=Rapid intensification.

While I respect your opinion, you are clearly misinformed.


Considering the experts aren't predicting rapid intensification, I think you may be the one who is misinformed.

I know, though. You see something they don't.

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Quoting MiamiFL305:
a nother car accident near hialeah





How does that happen. Yikes.
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Time: 17:28:00Z
Coordinates: 24.5167N 82.0667W
Acft. Static Air Press: 843.0 mb (~ 24.89 inHg)
Acft. Geopotential Hgt: 1,495 meters (~ 4,905 feet)
Extrap. Sfc. Press: 1001.3 mb (~ 29.57 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 33° at 52 knots (From the NNE at ~ 59.8 mph)
Air Temp: 17.1°C (~ 62.8°F)
Dew Pt: 15.1°C (~ 59.2°F)
Peak (10s) Flt. Lvl. Wind: 52 knots (~ 59.8 mph)
SFMR Peak (10s) Sfc. Wind: 46 knots (~ 52.9 mph)
SFMR Rain Rate: 2 mm/hr (~ 0.08 in/hr)



Nope not a hurricane. IE To the west we go.
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Quoting BahaHurican:
BTW, clickBOOM, welcome to the blog... hope you hang around for the rest of the season!


Thanks, been here for years (2005) but was only lurking.
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Worst weather I've gotten so far occurring as I type. Torrential rain with a gust of 43kts right now...you can hear the winds howling. Twigs flying around outside of the window and the TV signal flickering. Very bad weather right now. Extremely dark as well.

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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.