What is the Saffir-Simpson Scale of hurricane categories?

2012-08-28: Update 2: Isaac has attained weak Category 1 status with winds between 74-80mph. Its expected to decrease in strength upon reaching landfall. At 5:30 pm EDT, the eye is approx 87 mi from New Orleans and west of the city. Apparent track puts the eye passing between Houma and New Orleans, on track for Baton Rouge.

2012-08-28: Update: EWR expects Isaac to be barely a category 1 hurricane, if that, at landfall, and drop less rain than expected.

EWR monitoring: TS Isaac from New Orleans KLIX

Visible image. Image switches to infared view at night. Click on image to go to loop.

Aviation Colour Enhancement – As colour moves toward red and gray – indicates colder cloud tops – ie deeper convection, stronger storm. Click for loop

For additional satellite imagery, go to the Tropical Floaters page and select the specific storm (Isaac).

Model Wind Projection – Weatherbell Models (link in sidebar)

HWRF Wind speed projection – ISAAC – see chart for validity period. ©Weatherbell Models

Model track projections – Weatherbell Models

Multiple track projection – ISAAC – Multiple model guidance. ©Weatherbell Models.

BULLETIN
TROPICAL STORM ISAAC ADVISORY NUMBER 37
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
400 AM CDT THU AUG 30 2012

…ISAAC CONTINUES TO WEAKEN SLOWLY OVER LAND BUT STILL PRODUCING
HEAVY RAINS AND SEVERE WEATHER…WATER LEVELS REMAIN HIGH ALONG THE
NORTHERN GULF COAST…

SUMMARY OF 400 AM CDT…0900 UTC…INFORMATION
———————————————-
LOCATION…30.9N 91.6W
ABOUT 55 MI…85 KM SE OF ALEXANDRIA LOUISIANA
ABOUT 110 MI…175 KM NW OF NEW ORLEANS LOUISIANA
MAXIMUM SUSTAINED WINDS…45 MPH…75 KM/H
PRESENT MOVEMENT…NW OR 325 DEGREES AT 8 MPH…13 KM/H
MINIMUM CENTRAL PRESSURE…983 MB…29.03 INCHES

WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY…

THE TROPICAL STORM WARNING WEST OF INTRACOASTAL CITY LOUISIANA TO
CAMERON IS DISCONTINUED.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT…

A TROPICAL STORM WARNING IS IN EFFECT FOR…
* INTRACOASTAL CITY LOUISIANA TO THE MISSISSIPPI-ALABAMA BORDER…
INCLUDING LAKE PONTCHARTRAIN AND LAKE MAUREPAS

FOR STORM INFORMATION SPECIFIC TO YOUR AREA…PLEASE MONITOR
PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST
OFFICE.

DISCUSSION AND 48-HOUR OUTLOOK
——————————
AT 400 AM CDT…0900 UTC…THE CENTER OF TROPICAL STORM ISAAC WAS
LOCATED NEAR LATITUDE 30.9 NORTH…LONGITUDE 91.6 WEST. ISAAC IS
MOVING TOWARD THE NORTHWEST NEAR 8 MPH…13 KM/H. A TURN TOWARD THE
NORTH-NORTHWEST IS EXPECTED LATER TODAY…FOLLOWED BY A TURN TOWARD
THE NORTH ON FRIDAY. ON THE FORECAST TRACK…THE CENTER OF ISAAC
WILL CONTINUE TO MOVE OVER LOUISIANA TODAY…OVER ARKANSAS ON
FRIDAY…AND OVER SOUTHERN MISSOURI FRIDAY NIGHT.

MAXIMUM SUSTAINED WINDS HAVE DECREASED TO NEAR 45 MPH…75 KM/H…
WITH HIGHER GUSTS. THE STRONGEST WINDS ARE PRIMARILY OCCURRING
OVER WATER OR NEAR THE COAST. STEADY WEAKENING IS EXPECTED DURING
THE NEXT 48 HOURS AS ISAAC CONTINUES TO MOVE OVER LAND. ISAAC IS
FORECAST TO BECOME A TROPICAL DEPRESSION BY TONIGHT.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 175 MILES…280 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE BASED ON NEARBY SURFACE
OBSERVATIONS IS 983 MB…29.03 INCHES.

HAZARDS AFFECTING LAND
———————-
EVEN THOUGH ISAAC IS NO LONGER A HURRICANE…LIFE-THREATENING
HAZARDS FROM STORM SURGE…INLAND FLOODING…AND TORNADOES ARE STILL
OCCURRING.

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…

* MISSISSIPPI AND SOUTHEASTERN LOUISIANA…5 TO 10 FT
* ALABAMA…2 TO 4 FT
* SOUTH-CENTRAL LOUISIANA…1 TO 3 FT
* FLORIDA PANHANDLE…1 TO 2 FT

THE DEEPEST WATER WILL OCCUR ALONG THE IMMEDIATE COAST IN AREAS OF
ONSHORE WINDS. 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.

BASED ON AN OBSERVATION FROM A NATIONAL OCEAN SERVICE TIDE GAUGE AT
NEW CANAL STATION LOUISIANA…A STORM SURGE OF 6.3 FEET IS STILL
OCCURRING ON THE SOUTHERN SHORE OF LAKE PONTCHARTRAIN.

WIND…TROPICAL STORM CONDITIONS WILL CONTINUE ACROSS THE WARNING
AREA THROUGH THIS MORNING.

RAINFALL…ISAAC IS EXPECTED TO PRODUCE TOTAL RAINFALL AMOUNTS OF 7
TO 14 INCHES…WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 25
INCHES…OVER MUCH OF LOUISIANA…MISSISSIPPI…SOUTHWEST ALABAMA
AND ARKANSAS THROUGH FRIDAY. THESE RAINS COULD RESULT IN
SIGNIFICANT LOWLAND FLOODING.

TORNADOES…ISOLATED TORNADOES ARE POSSIBLE ALONG THE CENTRAL GULF
COAST REGION AND PARTS OF THE LOWER MISSISSIPPI RIVER VALLEY
THROUGH TODAY.

SURF…DANGEROUS SURF AND RIP CURRENT CONDITIONS WILL CONTINUE TO
AFFECT THE WEST COAST OF FLORIDA AND THE NORTHERN GULF COAST FOR THE
NEXT DAY OR SO.

TROPICAL STORM ISAAC DISCUSSION NUMBER 37
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
400 AM CDT THU AUG 30 2012

ISAAC IS SLOWLY WEAKENING AS MORE OF ITS LARGE CIRCULATION MOVES
OVER LAND. BASED ON THE LATEST SURFACE WIND OBSERVATIONS NEAR THE
NORTHERN GULF COAST…THE MAXIMUM WINDS HAVE DIMINISHED TO NEAR 40
KT. THESE WINDS ARE OCCURRING PRIMARILY OVER WATER OR ALONG THE
COASTLINE. CONTINUED GRADUAL WEAKENING IS EXPECTED…AND ISAAC IS
LIKELY TO BECOME A TROPICAL DEPRESSION BY THIS EVENING. THE
OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ONE…AND IS
MORE OR LESS IN AGREEMENT WITH THE STATISTICAL-DYNAMICAL GUIDANCE.

CENTER FIXES USING SURFACE SYNOPTIC DATA AND NATIONAL WEATHER
SERVICE DOPPLER RADAR IMAGERY INDICATE THAT ISAAC IS MOVING
NORTHWESTWARD AT A SLIGHTLY FASTER PACE…325/7. THE TRACK
FORECAST AND PROGNOSTIC REASONING REMAIN ESSENTIALLY UNCHANGED.
OVER THE NEXT SEVERAL DAYS…THE PRIMARY STEERING MECHANISM SHOULD
BE THE FLOW BETWEEN THE MID-LATITUDE WESTERLIES AND A RIDGE OVER
THE SOUTHEASTERN UNITED STATES. AS A RESULT THE CYCLONE IS
EXPECTED TO TURN NORTHWARD…NORTHEASTWARD…AND EASTWARD DURING
THE FORECAST PERIOD. THE OFFICIAL TRACK FORECAST IS VERY CLOSE TO
THE PREVIOUS ONE…AND ALSO CLOSE TO THE LATEST DYNAMICAL MODEL
CONSENSUS.

HEAVY RAINFALL AND A SIGNIFICANT FLOOD THREAT ARE EXPECTED TO SPREAD
INLAND ACROSS PORTIONS OF THE CENTRAL UNITED STATES DURING THE NEXT
SEVERAL DAYS. WATER LEVELS ALONG THE NORTHERN GULF COAST WILL
REMAIN ELEVATED THROUGH AT LEAST THIS MORNING. TORNADOES REMAIN A
THREAT AS WELL FROM THIS SYSTEM TODAY.

FORECAST POSITIONS AND MAX WINDS

INIT 30/0900Z 30.9N 91.6W 40 KT 45 MPH
12H 30/1800Z 31.9N 92.3W 35 KT 40 MPH…INLAND
24H 31/0600Z 33.8N 93.2W 30 KT 35 MPH…INLAND
36H 31/1800Z 36.0N 93.5W 25 KT 30 MPH…INLAND
48H 01/0600Z 38.0N 93.0W 20 KT 25 MPH…POST-TROP/REMNT LOW
72H 02/0600Z 39.5N 90.0W 15 KT 15 MPH…POST-TROP/REMNT LOW
96H 03/0600Z 40.0N 86.5W 15 KT 15 MPH…POST-TROP/REMNT LOW
120H 04/0600Z 40.5N 82.0W 15 KT 15 MPH…POST-TROP/REMNT LOW