Extratropical Isaac Advisories

[Evil Jeremy]

ZCZC MIATCPAT4 ALL
TTAA00 KNHC DDHHMM
BULLETIN
TROPICAL DEPRESSION NINE ADVISORY NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
500 PM EDT WED SEP 27 2006

...NEW TROPICAL DEPRESSION FORMS...NO THREAT TO LAND...

SATELLITE IMAGES INDICATE THAT THE NINTH TROPICAL DEPRESSION OF THE
2006 HURRICANE SEASON HAS FORMED OVER THE CENTRAL ATLANTIC.

AT 500 PM EDT...2100Z...THE CENTER OF TROPICAL DEPRESSION NINE WAS
LOCATED NEAR LATITUDE 26.5 NORTH...LONGITUDE 53.1 WEST OR ABOUT 810
MILES...1305 KM...EAST-SOUTHEAST OF BERMUDA.

THE DEPRESSION IS MOVING TOWARD THE NORTHWEST NEAR 14 MPH...AND THIS
GENERAL MOTION IS EXPECTED TO CONTINUE DURING THE NEXT 24 HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/HR...WITH HIGHER
GUSTS. SOME SLOW STRENGTHENING IS FORECAST...AND THE DEPRESSION
COULD BECOME A TROPICAL STORM DURING THE NEXT 24 HOURS.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1012 MB...29.88 INCHES.

REPEATING THE 500 PM EDT POSITION...26.5 N...53.1 W. MOVEMENT
TOWARD...NORTHWEST NEAR 14 MPH. MAXIMUM SUSTAINED WINDS...35 MPH.
MINIMUM CENTRAL PRESSURE...1012 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
1100 PM EDT.

$$
FORECASTER MAINELLI/PASCH

NNNN

[Evil Jeremy]

ZCZC MIATCDAT4 ALL
TTAA00 KNHC DDHHMM
TROPICAL DEPRESSION NINE DISCUSSION NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
500 PM EDT WED SEP 27 2006

VISIBLE SATELLITE IMAGERY INDICATES THAT THE LOW-LEVEL CIRCULATION
HAS CONTINUED TO GRADUALLY BECOME BETTER-DEFINED IN THE LOW
PRESSURE AREA OVER THE CENTRAL ATLANTIC. ALTHOUGH THE DEEP
CONVECTION DOES NOT WRAP MUCH AROUND THE CENTER...THE SYSTEM HAS
SUFFICIENT ORGANIZATION TO BE DESIGNATED AS A 30 KT TROPICAL
DEPRESSION AT THIS TIME. AN 1800 UTC SHIP REPORT ABOUT 60 MILES TO
THE NORTHWEST OF THE CENTER REPORTED A RATHER HIGH CENTRAL PRESSURE
OF 1016.5 MB...A 21 KT SUSTAINED WIND...AND 13 FT SEAS. BASED ON
THIS SHIP REPORT...12 FT SEA RADII HAVE BEEN INCLUDED IN THE
ADVISORY.

THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 315/12...SINCE THE LOW-
LEVEL CENTER HAS REFORMED AT LEAST ONCE DURING THE PAST 12 TO 24
HOURS. THE DEPRESSION IS CURRENTLY SITUATED BETWEEN AN UPPER-LEVEL
CYCLONE TO ITS WEST AND A LOW- TO MID-LEVEL RIDGE TO ITS EAST. THE
GFS...UKMET... AND NOGAPS MODELS ALL TAKE THE CYCLONE AROUND THE
WESTERN PERIPHERY OF THE RIDGE...THEN ACCELERATE THE SYSTEM AT DAYS
THREE THROUGH FIVE NORTHEASTWARD AHEAD OF A DEEP-LAYER TROUGH FROM
THE WEST. THE OFFICIAL TRACK FORECAST FOLLOWS CLOSELY WITH A
CONSENSUS OF THE AFOREMENTIONED GUIDANCE.

THE CURRENT POOR ORGANIZATION OF THE DEEP CONVECTION AND THE
PRESENCE OF THE UPPER LOW JUST TO THE WEST OF THE TROPICAL CYCLONE
ARGUES AGAINST ANY RAPID STRENGTHENING. HOWEVER...THE VERTICAL
SHEAR IS NOT EXPECTED TO BE STRONG ENOUGH TO PROHIBIT SOME GRADUAL
INTENSIFICATION. THE OFFICIAL INTENSITY FORECAST IS IN REASONABLE
AGREEMENT WITH THE SHIPS GUIDANCE.

FORECAST POSITIONS AND MAX WINDS

INITIAL 27/2100Z 26.5N 53.1W 30 KT
12HR VT 28/0600Z 27.6N 54.5W 35 KT
24HR VT 28/1800Z 29.1N 56.0W 40 KT
36HR VT 29/0600Z 31.0N 57.5W 45 KT
48HR VT 29/1800Z 34.0N 58.0W 50 KT
72HR VT 30/1800Z 39.0N 56.0W 50 KT
96HR VT 01/1800Z 42.0N 50.0W 50 KT...EXTRATROPICAL
120HR VT 02/1800Z 46.0N 40.0W 50 KT...EXTRATROPICAL

$$
FORECASTER MAINELLI/PASCH

NNNN

[Evil Jeremy]

ZCZC MIATCMAT4 ALL
TTAA00 KNHC DDHHMM
TROPICAL DEPRESSION NINE FORECAST/ADVISORY NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
2100 UTC WED SEP 27 2006

TROPICAL DEPRESSION CENTER LOCATED NEAR 26.5N 53.1W AT 27/2100Z
POSITION ACCURATE WITHIN 40 NM

PRESENT MOVEMENT TOWARD THE NORTHWEST OR 315 DEGREES AT 12 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1012 MB
MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT.
12 FT SEAS.. 75NE 0SE 0SW 75NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 26.5N 53.1W AT 27/2100Z
AT 27/1800Z CENTER WAS LOCATED NEAR 26.1N 52.6W

FORECAST VALID 28/0600Z 27.6N 54.5W
MAX WIND 35 KT...GUSTS 45 KT.
34 KT... 30NE 0SE 0SW 30NW.

FORECAST VALID 28/1800Z 29.1N 56.0W
MAX WIND 40 KT...GUSTS 50 KT.
34 KT... 60NE 40SE 30SW 40NW.

FORECAST VALID 29/0600Z 31.0N 57.5W
MAX WIND 45 KT...GUSTS 55 KT.
34 KT... 90NE 75SE 50SW 75NW.

FORECAST VALID 29/1800Z 34.0N 58.0W
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 40NE 40SE 20SW 30NW.
34 KT... 90NE 90SE 50SW 75NW.

FORECAST VALID 30/1800Z 39.0N 56.0W
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 40NE 40SE 20SW 30NW.
34 KT... 90NE 90SE 50SW 75NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 225 NM
ON DAY 4 AND 300 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY

OUTLOOK VALID 01/1800Z 42.0N 50.0W...EXTRATROPICAL
MAX WIND 50 KT...GUSTS 60 KT.

OUTLOOK VALID 02/1800Z 46.0N 40.0W...EXTRATROPICAL
MAX WIND 50 KT...GUSTS 60 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 26.5N 53.1W

NEXT ADVISORY AT 28/0300Z

$$
FORECASTER MAINELLI/PASCH


NNNN

[Evil Jeremy]

[cycloneye]

TCPAT4
BULLETIN
TROPICAL DEPRESSION NINE ADVISORY NUMBER 2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
1100 PM EDT WED SEP 27 2006

...DEPRESSION CLOSE TO TROPICAL STORM STRENGTH...

AT 1100 PM EDT...0300Z...THE CENTER OF TROPICAL DEPRESSION NINE WAS
LOCATED NEAR LATITUDE 27.2 NORTH...LONGITUDE 53.8 WEST OR ABOUT 745
MILES...1205 KM...EAST-SOUTHEAST OF BERMUDA.

THE DEPRESSION IS MOVING TOWARD THE NORTHWEST NEAR 13 MPH AND THIS
GENERAL MOTION IS EXPECTED TO CONTINUE DURING THE NEXT 24 HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/HR...WITH HIGHER
GUSTS. SOME STRENGTHENING IS FORECAST...AND THE DEPRESSION COULD
BECOME A TROPICAL STORM ON THURSDAY.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1012 MB...29.88 INCHES.

REPEATING THE 1100 PM EDT POSITION...27.2 N...53.8 W. MOVEMENT
TOWARD...NORTHWEST NEAR 13 MPH. MAXIMUM SUSTAINED WINDS...35 MPH.
MINIMUM CENTRAL PRESSURE...1012 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
500 AM EDT.

$$
FORECASTER BROWN/KNABB

[cycloneye]

751
WTNT44 KNHC 280257
TCDAT4
TROPICAL DEPRESSION NINE DISCUSSION NUMBER 2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
1100 PM EDT WED SEP 27 2006

ALTHOUGH THE DEPRESSION IS NOT VERY IMPRESSIVE IN CONVENTIONAL
SATELLITE IMAGERY... MICROWAVE OVERPASSES BY QUIKSCAT AT 2132 UTC
AND SSMIS AT 2309 UTC SUGGEST THAT IT IS NEARING TROPICAL STORM
STRENGTH. LATEST DVORAK INTENSITY ESTIMATES...HOWEVER...REMAIN 30
KT FROM ALL AGENCIES AND THIS WILL BE THE ADVISORY INTENSITY. THE
CENTER OF THE DEPRESSION IS LOCATED JUST SOUTH OF THE PRIMARY AREA
OF DEEP CONVECTION DUE TO SOUTHERLY WIND SHEAR IMPOSED BY AN
UPPER-LEVEL LOW TO THE WEST OF THE DEPRESSION. MOST OF THE GLOBAL
MODELS GRADUALLY WEAKEN THIS FEATURE AND THEREFORE THE SHEAR OVER
THE NEXT DAY OR TWO. THE OFFICIAL FORECAST CALLS FOR GRADUAL
STRENGTHENING DURING THE NEXT 48 HOURS. THEREAFTER...SOUTHWESTERLY
SHEAR IS EXPECTED TO INCREASE AGAIN WHILE SSTS COOL...WHICH SHOULD
INHIBIT FURTHER STRENGTHENING. THE NEW OFFICIAL INTENSITY FORECAST
IS CLOSE TO THE SHIPS AND GFDL INTENSITY GUIDANCE...AND SIMILAR TO
THE PREVIOUS ADVISORY.

THE INITIAL MOTION ESTIMATE IS 315/11. GLOBAL MODEL GUIDANCE
INDICATES THAT THE DEPRESSION WILL BE STEERED AROUND THE WESTERN
PERIPHERY OF A MID-TROPOSPHERIC RIDGE LOCATED TO THE NORTHEAST OF
THE CYCLONE. IN ABOUT 48 HOURS...A LARGE DEEP LAYERED TROUGH IS
PREDICTED TO BE DEPARTING THE EAST COAST OF THE UNITED STATES.
THIS SHOULD ALLOW THE TROPICAL CYCLONE TO TURN NORTHWARD...THEN
NORTHEASTWARD AHEAD OF THIS TROUGH. THE GFS IS ON THE WESTERN EDGE
OF THE MODEL GUIDANCE AS IT DEPICTS A MUCH WEAKER AND MORE SHALLOW
SYSTEM THAN ANTICIPATED BY THE SHIPS AND GFDL. SINCE THE SHIPS AND
GFDL ARE IN SUCH GOOD AGREEMENT ON THE FUTURE INTENSITY OF THE
SYSTEM...THE GFDL TRACK MIGHT BE A MORE LIKELY SOLUTION. THE
OFFICIAL FORECAST IS ADJUSTED WESTWARD AND SLOWER COMPARED TO THE
PREVIOUS ADVISORY TO BE IN BETTER AGREEMENT WITH THE GFDL TRACK.

INITIAL 28/0300Z 27.2N 53.8W 30 KT
12HR VT 28/1200Z 28.2N 55.0W 35 KT
24HR VT 29/0000Z 29.9N 56.5W 40 KT
36HR VT 29/1200Z 31.6N 57.6W 45 KT
48HR VT 30/0000Z 33.6N 58.1W 50 KT
72HR VT 01/0000Z 38.0N 57.0W 50 KT
96HR VT 02/0000Z 42.0N 52.5W 50 KT...EXTRATROPICAL
120HR VT 03/0000Z 46.0N 45.0W 50 KT...EXTRATROPICAL

$$
FORECASTER BROWN/KNABB

[P.K.]

TROPICAL DEPRESSION NINE DISCUSSION NUMBER 3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
500 AM EDT THU SEP 28 2006

SATELLITE IMAGES SHOW THAT THE CENTER OF TROPICAL DEPRESSION NINE
REMAINS MOSTLY EXPOSED TO THE SOUTHEAST OF THE MAIN CONVECTIVE
AREA. SATELLITE INTENSITY ESTIMATES ARE 35 KT FROM TAFB AND
SAB...AND 30 KT FROM AFWA. SINCE THE CENTER IS STILL EXPOSED AND
THE CONVECTIVE TOPS ARE CURRENTLY WARMING...THE SYSTEM WILL REMAIN
A DEPRESSION FOR THIS ADVISORY. THE CENTER SHOULD PASS NEAR A
DRIFTING BUOY DURING THE NEXT FEW HOURS...WHICH SHOULD PRODUCE A
BETTER ESTIMATE OF THE CENTRAL PRESSURE. ALSO...QUIKSCAT DATA
SHOULD BE AVAILABLE IN THE NEXT FEW HOURS.

THE INITIAL MOTION IS 315/10. WATER VAPOR IMAGERY SHOWS THAT THE
DEPRESSION IS SOUTHWEST OF A MID/UPPER-LEVEL RIDGE OVER THE CENTRAL
ATLANTIC...WITH A MID/UPPER-LEVEL LOW NEAR 27N58W. WEST OF THAT...
BROAD DEEP-LAYER TROUGHING COVERS THE WESTERN ATLANTIC AND THE
EASTERN UNITED STATES. IN THE SHORT TERM...FLOW BETWEEN THE
ATLANTIC RIDGE AND LOW SHOULD MOVE THE DEPRESSION GENERALLY
NORTHWESTWARD. AFTER 24-36 HR...THE LARGE-SCALE MODELS FORECAST
THE WESTERN ATLANTIC TROUGH TO AMPLIFY...WHICH IN TURN SHOULD RAISE
HEIGHTS NORTH OF THE DEPRESSION. THIS SHOULD RESULT IN A SLOWER
FORWARD MOTION...AND POSSIBLY A MORE WESTWARD TURN AS FORECAST BY
THE GFS AND GFDL. AFTER 60 HR...THE WESTERN ATLANTIC TROUGH AND
ASSOCIATED SURFACE LOW WILL GET CLOSE ENOUGH TO THE DEPRESSION TO
RECURVE IT NORTHEASTWARD. THE TRACK GUIDANCE IS NOTABLY SLOWER
THAN FOR THE PREVIOUS ADVISORY DURING THE FIRST 72 HR...AND THUS
THE NEW FORECAST TRACK IS SLOWED DOWN AS WELL. THE NEW TRACK IS
ALSO A LITTLE TO THE LEFT OF THE PREVIOUS TRACK.

THE UPPER LOW IS CURRENTLY CAUSING SOUTHERLY VERTICAL SHEAR OVER THE
DEPRESSION. THE LARGE-SCALE MODELS FORECAST THAT THE SHEAR SHOULD
DECREASE DURING THE NEXT 48 HR AS THE CYCLONE MOVES NORTH OF THE
UPPER LOW. THIS SHOULD ALLOW FOR SOME STRENGTHENING AS SHOWN BY
THE GFDL MODEL...WHICH IS REFLECTED IN THE INTENSITY FORECAST. DUE
TO INTERACTION WITH THE UPPER LOW...THERE IS A POSSIBILITY THE
CYCLONE COULD ACQUIRE SOME SUBTROPICAL CHARACTERISTICS AS IT
DEVELOPS. AFTER 48 HR...THE CYCLONE SHOULD ENCOUNTER COOLER WATER
AND INCREASING SOUTHWESTERLY UPPER-LEVEL FLOW ASSOCIATED WITH THE
DEEP-LAYER TROUGH. THIS SHOULD CAUSE WEAKENING...AND EVENTUALLY
LEAD TO EXTRATROPICAL TRANSITION IN 96-120 HR.

FORECAST POSITIONS AND MAX WINDS

INITIAL 28/0900Z 27.8N 54.6W 30 KT
12HR VT 28/1800Z 28.8N 55.7W 35 KT
24HR VT 29/0600Z 30.0N 56.7W 40 KT
36HR VT 29/1800Z 31.1N 57.7W 45 KT
48HR VT 30/0600Z 32.3N 58.4W 50 KT
72HR VT 01/0600Z 36.5N 58.5W 50 KT
96HR VT 02/0600Z 42.0N 54.0W 50 KT...BECOMING EXTRATROPICAL
120HR VT 03/0600Z 47.0N 46.0W 50 KT...EXTRATROPICAL

$$
FORECASTER BEVEN

[cycloneye]

982
WTNT24 KNHC 281433
TCMAT4
TROPICAL STORM ISAAC FORECAST/ADVISORY NUMBER 4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
1500 UTC THU SEP 28 2006

TROPICAL STORM CENTER LOCATED NEAR 28.2N 54.7W AT 28/1500Z
POSITION ACCURATE WITHIN 30 NM

PRESENT MOVEMENT TOWARD THE NORTHWEST OR 320 DEGREES AT 7 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1008 MB
MAX SUSTAINED WINDS 35 KT WITH GUSTS TO 45 KT.
34 KT.......100NE 75SE 0SW 0NW.
12 FT SEAS..100NE 150SE 50SW 100NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 28.2N 54.7W AT 28/1500Z
AT 28/1200Z CENTER WAS LOCATED NEAR 27.9N 54.5W

FORECAST VALID 29/0000Z 28.9N 55.4W
MAX WIND 40 KT...GUSTS 50 KT.
34 KT...100NE 75SE 50SW 50NW.

FORECAST VALID 29/1200Z 29.9N 56.6W
MAX WIND 45 KT...GUSTS 55 KT.
34 KT...100NE 75SE 50SW 50NW.

FORECAST VALID 30/0000Z 30.9N 57.8W
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 40NE 30SE 0SW 30NW.
34 KT...100NE 75SE 50SW 75NW.

FORECAST VALID 30/1200Z 32.2N 58.8W
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 40NE 30SE 0SW 30NW.
34 KT...100NE 75SE 50SW 75NW.

FORECAST VALID 01/1200Z 35.5N 59.5W
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 50NE 40SE 25SW 40NW.
34 KT...100NE 100SE 50SW 75NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 225 NM
ON DAY 4 AND 300 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY

OUTLOOK VALID 02/1200Z 41.5N 56.0W...EXTRATROPICAL
MAX WIND 50 KT...GUSTS 60 KT.

OUTLOOK VALID 03/1200Z 47.5N 46.5W...EXTRATROPICAL
MAX WIND 50 KT...GUSTS 60 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 28.2N 54.7W

NEXT ADVISORY AT 28/2100Z

$$
FORECASTER BLAKE/STEWART

[cycloneye]

743
WTNT44 KNHC 281433
TCDAT4
TROPICAL STORM ISAAC DISCUSSION NUMBER 4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
1100 AM EDT THU SEP 28 2006

ALTHOUGH THE CURRENT SATELLITE APPEARANCE IS A LITTLE SKELETAL... A
QUIKSCAT PASS NEAR 0845 UTC PROVIDES STRONG EVIDENCE OF AT LEAST 35
KT WINDS IN THE SYSTEM. THUS THE NINTH TROPICAL STORM OF THE
YEAR... ISAAC... IS BORN. THE STORM IS ALSO EXHIBITING SOME
SUBTROPICAL CHARACTERISTICS WITH A RADIUS OF MAXIMUM WINDS LARGER
THAN AVERAGE NEAR 75 NM... AND ALSO AN UPPER LOW IS NEARLY ON TOP
OF THE CYCLONE. FURTHER INTENSIFICATION IS POSSIBLE FOR THE NEXT
COUPLE OF DAYS AS VERTICAL WIND SHEAR REMAINS RELATIVELY LIGHT WITH
UPPER RIDGING NEAR THE STORM. ALTHOUGH SSTS ARE HOVERING NEAR 26C
IN THE PATH OF ISAAC... COLDER-THAN-AVERAGE UPPER-LEVEL
TEMPERATURES ARE ALSO FORECAST... WHICH WOULD ALLOW FOR MORE
INSTABILITY AND MORE CONVECTION. THE INTENSITY FORECAST IS A LITTLE
HIGHER THAN SHIPS AND NOT TOO DISSIMILAR FROM THE FSU
SUPERENSEMBLE.

THE INITIAL MOTION IS 320/7... A LITTLE TO THE RIGHT AND SLOWER THAN
EARLIER. A GENERAL NORTHWESTWARD MOTION SHOULD CONTINUE FOR THE
NEXT 36 HOURS OR SO AS THE STORM IS STEERED BY MIDDLE-LEVEL RIDGING
OVER THE CENTRAL ATLANTIC. THE RIDGE SHOULD STRENGTHEN SOMEWHAT AS
WELL DURING THIS TIME AND COULD PUSH THE SYSTEM A LITTLE MORE TO
THE LEFT THAN THE CURRENT MOTION. THEREAFTER... AN ENORMOUS TROUGH
CURRENTLY OVER THE EASTERN UNITED STATES SHOULD MOVE INTO THE
WESTERN ATLANTIC AND STEER THE STORM AWAY FROM BERMUDA AND NORTH
AMERICA. HOWEVER... MODEL GUIDANCE IS GENERALLY SUGGESTING THAT THE
UPPER RIDGING WILL HOLD A LITTLE LONGER THAN PREVIOUSLY EXPECTED...
AND THE TRACK HAS BEEN SHIFTED WESTWARD IN AGREEMENT WITH NHC
GUIDANCE. THE OFFICIAL FORECAST IS ON THE EASTERN SIDE OF THE MODEL
ENVELOPE... BETWEEN THE UKMET AND THE FSU SUPERENSEMBLE. ISAAC
SHOULD BECOME EXTRATROPICAL IN 3-4 DAYS DUE TO IT PASSING NORTH OF
THE GULF STREAM AND INCREASING VERTICAL WIND SHEAR.

FORECAST POSITIONS AND MAX WINDS

INITIAL 28/1500Z 28.2N 54.7W 35 KT
12HR VT 29/0000Z 28.9N 55.4W 40 KT
24HR VT 29/1200Z 29.9N 56.6W 45 KT
36HR VT 30/0000Z 30.9N 57.8W 50 KT
48HR VT 30/1200Z 32.2N 58.8W 50 KT
72HR VT 01/1200Z 35.5N 59.5W 50 KT
96HR VT 02/1200Z 41.5N 56.0W 50 KT...EXTRATROPICAL
120HR VT 03/1200Z 47.5N 46.5W 50 KT...EXTRATROPICAL

$$
FORECASTER BLAKE/STEWART

[lester]

000
WTNT34 KNHC 281438
TCPAT4
BULLETIN
TROPICAL STORM ISAAC ADVISORY NUMBER 4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
1100 AM EDT THU SEP 28 2006

...NINTH TROPICAL STORM OF THE SEASON DEVELOPS...
...NO IMMEDIATE THREAT TO LAND...

AT 1100 AM EDT...1500Z...THE CENTER OF TROPICAL STORM ISAAC WAS
LOCATED BY SATELLITE IMAGERY NEAR LATITUDE 28.2 NORTH...LONGITUDE
54.7 WEST OR ABOUT 665 MILES...1070 KM...EAST-SOUTHEAST OF BERMUDA.

ISAAC IS MOVING TOWARD THE NORTHWEST NEAR 8 MPH...13 KM/HR...AND
THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 24 HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 40 MPH...65 KM/HR...WITH HIGHER
GUSTS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 115 MILES...185 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB...29.77 INCHES.

REPEATING THE 1100 AM EDT POSITION...28.2 N...54.7 W. MOVEMENT
TOWARD...NORTHWEST NEAR 8 MPH. MAXIMUM SUSTAINED WINDS...40 MPH.
MINIMUM CENTRAL PRESSURE...1008 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
500 PM EDT.

[cycloneye]

292
WTNT34 KNHC 282031
TCPAT4
BULLETIN
TROPICAL STORM ISAAC ADVISORY NUMBER 5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
500 PM EDT THU SEP 28 2006

...ISAAC MOVING OVER OPEN WATERS OF THE CENTRAL ATLANTIC...

AT 500 PM EDT...2100Z...THE CENTER OF TROPICAL STORM ISAAC WAS
LOCATED NEAR LATITUDE 28.9 NORTH...LONGITUDE 54.9 WEST OR ABOUT 635
MILES...1020 KM...EAST-SOUTHEAST OF BERMUDA.

ISAAC IS MOVING TOWARD THE NORTH-NORTHWEST NEAR 8 MPH...13 KM/HR...
AND A TURN TOWARD THE NORTHWEST IS EXPECTED LATER TONIGHT OR
TOMORROW.

MAXIMUM SUSTAINED WINDS ARE NEAR 45 MPH...75 KM/HR...WITH HIGHER
GUSTS. SOME SLOW INCREASE IS STRENGTH IS FORECAST DURING THE NEXT
24 HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 115 MILES...185 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB...29.71 INCHES.

REPEATING THE 500 PM EDT POSITION...28.9 N...54.9 W. MOVEMENT
TOWARD...NORTH-NORTHWEST NEAR 8 MPH. MAXIMUM SUSTAINED WINDS...45
MPH. MINIMUM CENTRAL PRESSURE...1006 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
1100 PM EDT.

$$
FORECASTER BLAKE/STEWART

553
WTNT44 KNHC 282030
TCDAT4
TROPICAL STORM ISAAC DISCUSSION NUMBER 5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
500 PM EDT THU SEP 28 2006

DURING THE DAY... THE STRUCTURE OF ISAAC HAS BEEN CHANGING. THE
LARGER RADIUS OF MAXIMUM WINDS APPEARS TO HAVE DECREASED WITH
SATELLITE IMAGES SHOWING A MORE COMPACT SYSTEM. AFTER STRUGGLING
MOST OF THE DAY... MODEST CONVECTION HAS BEEN FORMING IN A CURVED
BAND AROUND THE CENTER. THE CONVECTION HAS NOT BEEN AS DEEP AS
TYPICALLY SEEN IN A TROPICAL CYCLONE... POSSIBLY DUE TO THE STORM
MOVING OVER SLIGHTLY COOLER WATER THAT WAS STIRRED UP BY TROPICAL
CYCLONES GORDON AND HELENE. MORE IMPORTANTLY... DRY AIR IS NOTED ON
WATER VAPOR PICTURES NEAR THE CORE OF THE CYCLONE... WHICH ALSO MAY
ACCOUNT FOR THE DESSICATED SATELLITE APPEARANCE. A FURTHER ANALYSIS
OF THE 0845 UTC QUIKSCAT DATA SUGGESTS THAT WINDS OF 40-45 KT WERE
PRESENT AT THAT TIME. THE INITIAL INTENSITY IS THEREFORE BUMPED UP
TO 40 KT TO MATCH THIS ESTIMATE ALONG WITH THE IMPROVED CONVECTIVE
STRUCTURE.

THE INTENSITY FORECAST IS A BIT TRICKY DUE TO THE SOMEWHAT HYBRID
NATURE OF ISAAC. FOR THE NEXT DAY OR SO... THE COLD WAKES OF GORDON
AND HELENE COULD HINDER CONVECTIVE DEVELOPMENT. IN ADDITION...
SOUTHERLY SHEAR FROM AN UPPER LOW DROPPING TO THE SOUTH OF THE
ISAAC... ALONG WITH NEARBY DRY AIR IN THE MIDDLE TO UPPER LEVELS...
SHOULD ALSO HELP TO INHIBIT DEVELOPMENT. HOWEVER BY LATE
TOMORROW... VERTICAL WIND SHEAR IS FORECAST TO BECOME LIGHTER AS
ISSAC BECOMES MORE UNDER THE INFLUENCE OF UPPER RIDGING TO THE
NORTH. THE SHIPS MODEL ALSO DIAGNOSES AN INCREASE IN MIDDLE-LEVEL
HUMIDITY BEYOND 36 HOURS AND THE STORM IS FORECAST TO MOVE OVER
SLIGHTLY WARMER WATERS THAT WERE MOSTLY UNTOUCHED BY OTHER TROPICAL
CYCLONES. THE INTENSITY FORECAST IS REDUCED SOMEWHAT FOR THE FIRST
24 HOURS... BUT THEN BLENDED WITH THE PREVIOUS FORECAST IN THE
LATER-TERM. THIS SOLUTION IS IN REASONABLE AGREEMENT WITH A BLEND
OF THE SHIPS-GFDL-FSSE (FLORIDA STATE SUPERENSEMBLE) GUIDANCE.

DUE TO THE CYCLONE'S INTERACTION WITH AN UPPER LOW... THE MOTION OF
ISAAC HAS SHIFTED EVEN FARTHER TO THE RIGHT... AND IS NOW 330/7. AS
THE UPPER LOW MOVES SOUTHWARD... THE CIRCULATION AROUND THE UPPER
LOW SHOULD HELP TO PULL THE TROPICAL CYCLONE BACK TO THE LEFT.
THEREAFTER... MIDDLE LEVEL RIDGING OVER THE CENTRAL ATLANTIC SHOULD
CAUSE A GENERAL NORTHWESTWARD MOTION UNTIL ABOUT 48 HOURS. A RATHER
LARGE TROUGH IS FORECAST OVER THE WESTERN ATLANTIC BEYOND THAT
TIME... WHICH SHOULD STEER ISAAC NORTHWARD THEN ACCELERATE IT
NORTHEASTWARD. THE FORECAST TRACK HAS BEEN SHIFTED A LITTLE TO THE
RIGHT EARLY ON TO ACCOUNT FOR SHORT-TERM TRENDS BUT IS SIMILAR TO
THE PREVIOUS FORECAST IN THE EXTENDED PERIODS. THE OFFICAL FORECAST
REMAINS JUST TO THE RIGHT OF THE MODEL CONSENSUS.


FORECAST POSITIONS AND MAX WINDS

INITIAL 28/2100Z 28.9N 54.9W 40 KT
12HR VT 29/0600Z 29.7N 55.6W 40 KT
24HR VT 29/1800Z 30.5N 57.0W 45 KT
36HR VT 30/0600Z 31.4N 58.1W 50 KT
48HR VT 30/1800Z 32.8N 59.2W 50 KT
72HR VT 01/1800Z 36.5N 60.0W 50 KT...BECOMING EXTRATROPICAL
96HR VT 02/1800Z 42.0N 56.0W 50 KT...EXTRATROPICAL
120HR VT 03/1800Z 47.0N 47.0W 50 KT...EXTRATROPICAL

$$
FORECASTER BLAKE/STEWART

[cycloneye]

WTNT34 KNHC 290248
TCPAT4
BULLETIN
TROPICAL STORM ISAAC ADVISORY NUMBER 6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
1100 PM EDT THU SEP 28 2006

...ISAAC MOVING SLOWLY NORTHWESTWARD OVER THE CENTRAL ATLANTIC...

AT 1100 PM EDT...0300Z...THE CENTER OF TROPICAL STORM ISAAC WAS
LOCATED NEAR LATITUDE 29.2 NORTH...LONGITUDE 55.2 WEST OR ABOUT 610
MILES...980 KM...EAST-SOUTHEAST OF BERMUDA.

ISAAC IS MOVING TOWARD THE NORTHWEST NEAR 7 MPH...11 KM/HR...AND
THIS GENERAL MOTION IS EXPECTED TO CONTINUE DURING THE NEXT 24
HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 45 MPH...75 KM/HR...WITH HIGHER
GUSTS. SOME SLIGHT STRENGTHENING IS POSSIBLE DURING THE NEXT
24 HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 140 MILES...220 KM
MAINLY TO THE EAST FROM THE CENTER.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB...29.71 INCHES.

REPEATING THE 1100 PM EDT POSITION...29.2 N...55.2 W. MOVEMENT
TOWARD...NORTHWEST NEAR 7 MPH. MAXIMUM SUSTAINED WINDS...45 MPH.
MINIMUM CENTRAL PRESSURE...1006 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
500 AM EDT.

$$
FORECASTER BROWN/KNABB


386
WTNT24 KNHC 290248
TCMAT4
TROPICAL STORM ISAAC FORECAST/ADVISORY NUMBER 6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
0300 UTC FRI SEP 29 2006

TROPICAL STORM CENTER LOCATED NEAR 29.2N 55.2W AT 29/0300Z
POSITION ACCURATE WITHIN 40 NM

PRESENT MOVEMENT TOWARD THE NORTHWEST OR 325 DEGREES AT 6 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1006 MB
MAX SUSTAINED WINDS 40 KT WITH GUSTS TO 50 KT.
34 KT.......120NE 120SE 45SW 75NW.
12 FT SEAS..125NE 150SE 60SW 100NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 29.2N 55.2W AT 29/0300Z
AT 29/0000Z CENTER WAS LOCATED NEAR 29.1N 55.0W

FORECAST VALID 29/1200Z 30.0N 56.0W
MAX WIND 40 KT...GUSTS 50 KT.
34 KT...120NE 120SE 45SW 75NW.

FORECAST VALID 30/0000Z 30.9N 57.3W
MAX WIND 45 KT...GUSTS 55 KT.
34 KT...120NE 120SE 45SW 75NW.

FORECAST VALID 30/1200Z 31.9N 58.5W
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 40NE 30SE 0SW 30NW.
34 KT...120NE 120SE 60SW 90NW.

FORECAST VALID 01/0000Z 33.5N 59.6W
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 40NE 30SE 0SW 30NW.
34 KT...120NE 120SE 60SW 90NW.

FORECAST VALID 02/0000Z 38.0N 59.5W...BECOMING EXTRATROPICAL
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 50NE 40SE 30SW 40NW.
34 KT...150NE 150SE 60SW 90NW.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 225 NM
ON DAY 4 AND 300 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY

OUTLOOK VALID 03/0000Z 44.0N 53.5W...EXTRATROPICAL
MAX WIND 50 KT...GUSTS 60 KT.

OUTLOOK VALID 04/0000Z 49.0N 46.0W...EXTRATROPICAL
MAX WIND 50 KT...GUSTS 60 KT.

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 29.2N 55.2W

NEXT ADVISORY AT 29/0900Z

$$
FORECASTER BROWN/KNABB

145
WTNT44 KNHC 290300
TCDAT4
TROPICAL STORM ISAAC DISCUSSION NUMBER 6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
1100 PM EDT THU SEP 28 2006

THE OVERALL CLOUD PATTERN OF ISAAC HAS CHANGED VERY LITTLE THIS
EVENING. A CONVECTIVE BAND HAS WRAPPED AROUND THE WEST AND
SOUTHWEST SIDE OF THE CIRCULATION...WHICH HAS MADE IT A LITTLE
MORE DIFFICULT TO DETERMINE THE CENTER LOCATION WITH INFRARED
IMAGERY. SINCE THE CLOUD TOPS ARE NOT VERY COLD AND THE CONVECTIVE
BAND IS RATHER SMALL...DVORAK DATA T-NUMBERS HAVE DECREASED DURING
THE PAST 6-12 HOURS. THIS IS A CASE IN WHICH THE DVORAK TECHNIQUE
MAY BE UNDERESTIMATING THE INTENSITY...SINCE THE CONVECTION IS NOT
VERY DEEP AND THE CYCLONE HAS SOME SUBTROPICAL CHARACTERISTICS. A
SHIP WELL SOUTHEAST OF THE CENTER AT 0000 UTC REPORTED 33 KT
WINDS...AND STRONGER WINDS COULD BE OCCURRING CLOSER TO THE CENTER.
MAKING THAT ASSUMPTION...THE ADVISORY INTENSITY REMAINS 40 KT. THE
WIND RADII WERE ALSO EXPANDED SLIGHTLY TO ACCOUNT FOR THE SHIP
REPORT.

ISAAC HAS BEEN MOVING ALONG THE EASTERN SIDE OF THE MODEL GUIDANCE
DURING THE PAST DAY OR SO. MOST OF THE DYNAMICAL MODELS TURN THE
CYCLONE WEST-NORTHWESTWARD DURING THE NEXT 12-24 HOURS... IN
BETWEEN AN UPPER-LEVEL LOW JUST SOUTH OF THE TROPICAL CYCLONE AND A
BUILDING MID-TROPOSPHERIC RIDGE TO THE NORTH. IN ABOUT 2 DAYS...A
LARGE DEEP-LAYERED TROUGH MOVING INTO THE WESTERN ATLANTIC SHOULD
TURN ISAAC NORTHWARD ALLOWING THE CYCLONE TO RECURVE INTO THE
WESTERLIES AHEAD OF THE TROUGH. THERE REMAINS A SIGNIFICANT
SPREAD IN THE GUIDANCE DURING RECURVATURE. THE GFS AND NOGAPS
REMAIN ON THE WESTERN SIDE OF THE GUIDANCE WHILE THE UKMET IS TO
THE EAST. GIVEN THIS LARGE SPREAD...THE OFFICIAL FORECAST TRACK
WILL REMAIN CLOSE TO THE MODEL CONSENSUS...WHICH HAPPENS TO BE VERY
NEAR THE PREVIOUS NHC FORECAST.

ISAAC CONTINUES TO BE AFFECTED BY MODERATE SOUTHERLY SHEAR.
HOWEVER...THIS SHEAR IS FORECAST TO DECREASE OVER THE NEXT COUPLE
OF DAYS. THE INTENSITY FORECAST IS MORE PROBLEMATIC SINCE ISAAC IS
PREDICTED TO MOVE OVER WATERS THAT HAVE BEEN COOLED BY
HURRICANES GORDON AND HELENE...WHICH MAY HINDER STRENGTHENING.
THEREAFTER...INCREASING SOUTHWESTERLY SHEAR WILL LIKELY BE AN
ADDITIONAL INHIBITING FACTOR. THE OFFICIAL FORECAST CALLS FOR ONLY
MODEST STRENGTHENING AND IS IN BETWEEN THE SHIPS AND FSU
SUPERENSEMBLE. IT SHOULD BE NOTED THAT THE GFDL MAKES ISAAC A
HURRICANE IN ABOUT 48 HOURS. HOWEVER...THIS MODEL SOMETIMES
OVERESTIMATES THE INTENSIFICATION OF TROPICAL CYCLONES IN A SHEARED
ENVIRONMENT.

FORECAST POSITIONS AND MAX WINDS

INITIAL 29/0300Z 29.2N 55.2W 40 KT
12HR VT 29/1200Z 30.0N 56.0W 40 KT
24HR VT 30/0000Z 30.9N 57.3W 45 KT
36HR VT 30/1200Z 31.9N 58.5W 50 KT
48HR VT 01/0000Z 33.5N 59.6W 50 KT
72HR VT 02/0000Z 38.0N 59.5W 50 KT...BECOMING EXTRATROPICAL
96HR VT 03/0000Z 44.0N 53.5W 50 KT...EXTRATROPICAL
120HR VT 04/0000Z 49.0N 46.0W 50 KT...EXTRATROPICAL

$$
FORECASTER BROWN/KNABB

[Thunder44]

000
WTNT34 KNHC 290831
TCPAT4
BULLETIN
TROPICAL STORM ISAAC ADVISORY NUMBER 7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
500 AM AST FRI SEP 29 2006

...ISAAC SOMEWHAT FARTHER TO THE WEST WITH LITTLE CHANGE IN
STRENGTH...

AT 500 AM AST...0900Z...THE CENTER OF TROPICAL STORM ISAAC WAS
LOCATED NEAR LATITUDE 29.2 NORTH...LONGITUDE 55.6 WEST OR ABOUT 585
MILES...945 KM...EAST-SOUTHEAST OF BERMUDA.

ISAAC IS MOVING ERRATICALLY TOWARD THE NORTHWEST NEAR 5 MPH...
7 KM/HR. THIS GENERAL MOTION IS EXPECTED TO CONTINUE WITH SOME
INCREASE IN FORWARD SPEED DURING THE NEXT 24 HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 45 MPH...75 KM/HR...WITH HIGHER
GUSTS. SLOW STRENGTHENING IS POSSIBLE DURING THE NEXT 24 HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 140 MILES...220 KM
MAINLY TO THE EAST OF THE CENTER.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB...29.71 INCHES.

REPEATING THE 500 AM AST POSITION...29.2 N...55.6 W. MOVEMENT
TOWARD...NORTHWEST NEAR 5 MPH. MAXIMUM SUSTAINED WINDS...45 MPH.
MINIMUM CENTRAL PRESSURE...1006 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
1100 AM AST.

$$
FORECASTER BEVEN



000
WTNT44 KNHC 290843
TCDAT4
TROPICAL STORM ISAAC DISCUSSION NUMBER 7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
500 AM AST FRI SEP 29 2006

ISAAC IS SENDING MIXED STRUCTURAL SIGNALS THIS MORNING. THE
CONVECTION HAS BECOME MORE CONSOLIDATED AROUND THE CENTER...
SUGGESTING THAT THE VERTICAL SHEAR IS DECREASING. ON THE OTHER
HAND...THAT CONVECTION IS VERY WEAK...WITH ONLY A FEW TOPS COLDER
-50C. THIS SUGGESTS THAT THE ONGOING INTERACTION WITH A NEARBY
UPPER-LEVEL LOW HAS HAD AN IMPACT...AND THAT ISAAC MAY HAVE SOME
SUBTROPICAL CHARACTERISTICS. SATELLITE INTENSITY ESTIMATES REMAIN
35 KT FROM ALL AGENCIES...ALTHOUGH THE DVORAK DATA-T NUMBERS REMAIN
LESS THAN THAT. THE INITIAL INTENSITY REMAINS 40 KT...AND THIS
COULD BE A LITTLE GENEROUS.

ISAAC HAS TURNED TOWARD THE LEFT OVER THE PAST 6-12 HR. THE INITIAL
MOTION IS A RATHER UNCERTAIN 305/4...AND OVER THE PAST 3-6 HR THE
CYCLONE SEEMS TO BE MOVING ALMOST DUE WEST. WATER VAPOR IMAGERY
INDICATES A LARGE MID/UPPER-LEVEL RIDGE BUILDING NORTH OF ISAAC IN
RESPONSE TO AN UPSTREAM DEEP-LAYER TROUGH OVER THE EASTERN UNITED
STATES. THIS RIDGE IS LIKELY RESPONSIBLE FOR THE LEFT TURN. THE
U. S. TROUGH IS FORECAST TO MOVE EASTWARD...WITH AN ASSOCIATED
SURFACE LOW FORMING OFF THE U. S. EAST COAST IN 48-72 HR. THIS
DEVELOPMENT SHOULD TURN ISAAC NORTHWARD. AFTER 72 HR...THERE IS
SOME MODEL DIVERGENCE. THE UKMET...NOGAPS...AND CANADIAN MOVE
ISAAC NORTHEASTWARD IN ADVANCE OF THE NEW LOW...WHILE THE GFS AND
ECMWF MERGE ISSAC WITH THE NEW LOW AND BRING THE CENTER NEAR
EASTERN NOVA SCOTIA IN ABOUT 96 HR. FOR NOW...THE NEW FORECAST
TRACK WILL RETAIN THE NORTHEASTWARD MOTION AFTER 72 HR SEEN IN THE
PREVIOUS ADVISORY. THE NEW TRACK IS SHIFTED TO THE LEFT OF THE
PREVIOUS FORECAST...AND AN ADDITIONAL SHIFT TO THE LEFT MAY BE
NECESSARY LATER TODAY IF THE CURRENT WESTWARD TURN CONTINUES.

THE INTENSITY FORECAST IS SOMEWHAT PROBLEMATIC. ISSAC SHOULD BE IN
A LIGHT TO MODERATE VERTICAL SHEAR ENVIRONMENT FOR 36-48 HR...AND
THE NEW FORECAST TRACK TAKES THE SYSTEM OVER SOMEWHAT WARMER SEA
SURFACE TEMPERATURES THAN SEEN EARLIER. NEGATIVE FACTORS INCLUDE
THE CURRENT WEAK CONVECTION AND DRY AIR SEEN IN WATER VAPOR IMAGERY
NEAR AND SOUTH OF THE CYCLONE. THE GFDL RESPONDS TO THESE FACTORS
BY FORECAST ISAAC TO BECOME A HURRICANE IN 72 HR. THE FSU
SUPERENSEMBLE FORECASTS IT TO 48 KT IN 48 HR AND 61 KT IN 84
HR...WHILE THE SHIPS MODEL FORECASTS 44 KT IN 48 HR AND 55 KT IN 96
HR. GIVEN THE CURRENT CONVECTIVE TRENDS...THE NEW INTENSITY
FORECAST WILL CHANGE LITTLE FROM THE PREVIOUS ADVISORY...CALLING
FOR GRADUAL STRENGTHENING DURING THE NEXT 36 HR. AFTER THAT...
INTERACTION WITH THE APPROACHING DEEP-LAYER TROUGH SHOULD STOP
INTENSIFICATION AND LEAD TO EVENTUAL EXTRATROPICAL TRANSITION.

FORECAST POSITIONS AND MAX WINDS

INITIAL 29/0900Z 29.2N 55.6W 40 KT
12HR VT 29/1800Z 29.7N 56.4W 40 KT
24HR VT 30/0600Z 30.5N 57.7W 45 KT
36HR VT 30/1800Z 31.5N 59.0W 50 KT
48HR VT 01/0600Z 33.2N 60.0W 50 KT
72HR VT 02/0600Z 39.5N 60.0W 50 KT...BECOMING EXTRATROPICAL
96HR VT 03/0600Z 46.5N 51.0W 50 KT...EXTRATROPICAL
120HR VT 04/0600Z 49.0N 40.0W 50 KT...EXTRATROPICAL

$$
FORECASTER BEVEN

[cycloneye]

748
WTNT44 KNHC 291429
TCDAT4
TROPICAL STORM ISAAC DISCUSSION NUMBER 8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
1100 AM EDT FRI SEP 29 2006

SATELLITE IMAGES INDICATE THAT ISAAC IS MAINTAINING ITS SMALL CORE
WITH MODERATE CONVECTION IN BANDS AROUND THE CENTER. A QUIKSCAT
PASS AT 0958 UTC THIS MORNING SHOWED THAT THE MAXIMUM WINDS OF
ISAAC REMAIN AROUND 40 KT. QUIKSCAT ALSO INDICATES THE STORM HAS
DECREASED SOMEWHAT IN SIZE AND THE WIND RADII ARE ADJUSTED INWARD.
THERE ARE NO CHANGES TO THE INTENSITY FORECAST PHILOSOPHY THIS
MORNING. LATER TODAY THE TROPICAL CYCLONE WILL BE MOVING OVER
WARMER WATER AND EXPERIENCING ONLY MODEST VERTICAL WIND SHEAR.
THESE FACTORS... PLUS INCREASING MOISTURE ALOFT BASED ON THE SHIPS
MODEL... SHOULD HELP INITIATE A SLOW INTENSIFICATION TREND. BY 36
TO 48 HOURS... SHEAR IS FORECAST TO INCREASE AND LIMIT
STRENGTHENING. THE INTENSITY FORECAST IS BASICALLY THE SAME AS
BEFORE. HOWEVER... IT IS WORTH NOTING THAT SHIPS AND GFDL INTENSIFY
THE CYCLONE MORE THAN THE OFFICIAL FORECAST AFTER RECURVATURE. THIS
SCENARIO SEEMS UNLIKELY GIVEN THE STRONG SHEAR FORECAST AND SHARPLY
DECREASING SSTS.

ISAAC HAS CONTINUED TO TURN MORE WESTWARD AND IS NOW MOVING 290/5.
THE BIGGEST QUESTION IN THE TRACK FORECAST IS HOW LONG DOES THE
WEST-NORTHWESTWARD MOTION CONTINUE BEFORE A TURN BACK TOWARD THE
NORTHWEST BEGINS. THE ECMWF AND NOGAPS MODELS SUGGEST RIDGING WILL
HOLD NORTH OF THE STORM FOR ABOUT 48 HOURS BEFORE STARTING A MORE
NORTHWARD MOTION. THE UKMET CONTINUES TO BE ON THE RIGHT-HAND SIDE
OF THE GUIDANCE BY SUGGESTING A NORTH-NORTHWEST MOTION IN AS LITTLE
AS 24 HOURS. IN GENERAL... GLOBAL MODELS HAVE BEEN TRENDING A
LITTLE TO THE LEFT AND THE OFFICIAL FORECAST IS NUDGED IN THAT
DIRECTION... A TOUCH TO THE WEST OF THE PREVIOUS FORECAST. THE
FORECAST TRACK DURING THE EXTRATROPICAL STAGE REMAINS UNCERTAIN DUE
TO SOME SPREAD IN THE TRACK GUIDANCE. THE COMPUTER MODELS THAT TAKE
THE STORM FARTHEST TO THE WEST ALSO MAKE ISAAC EXTRATROPICAL SOONER
AS IT INTERACTS WITH A DEEP TROUGH IN THE WEST ATLANTIC OCEAN. IN
ADDITION THESE WESTWARD MODELS AND THE GFS ALSO ABSORB ISAAC INTO A
LARGER MID-LATITUDE LOW IN ABOUT 3 DAYS. FOR NOW ISSAC IS FORECAST
TO REMAIN SEPARATE FROM THE OTHER EXTRATROPICAL LOW. HOWEVER IF THE
WESTWARD TREND CONTINUES... THEN THE REMNANTS OF ISAAC COULD BECOME
INDISTINCT FROM THE MID-LATITUDE LOW BY 96 HOURS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 29/1500Z 29.4N 56.2W 40 KT
12HR VT 30/0000Z 29.9N 57.1W 45 KT
24HR VT 30/1200Z 30.7N 58.3W 45 KT
36HR VT 01/0000Z 31.9N 59.6W 50 KT
48HR VT 01/1200Z 33.8N 60.5W 50 KT
72HR VT 02/1200Z 41.6N 58.4W 50 KT...EXTRATROPICAL
96HR VT 03/1200Z 47.0N 49.0W 50 KT...EXTRATROPICAL
120HR VT 04/1200Z 49.0N 37.0W 50 KT...EXTRATROPICAL

$$
FORECASTER BLAKE/STEWART

[Derek Ortt]

CHC keeping Isaac at 40KT

WOCN31 CWHX 291800
TROPICAL STORM ISAAC INFORMATION STATEMENT ISSUED BY THE
CANADIAN HURRICANE CENTRE OF ENVIRONMENT CANADA AT 3.30 PM NDT
FRIDAY 29 SEPTEMBER 2006.

THE NEXT STATEMENT WILL BE ISSUED BY 9.30 PM NDT

... ISAAC POSSIBLY TO AFFECT SOUTHEASTERN MARINE AREAS AND
SOUTHEASTERN NEWFOUNDLAND EARLY NEXT WEEK...

1. CURRENT POSITION, STRENGTH, CENTRAL PRESSURE AND MOTION

AT 3.30 PM NDT... TROPICAL STORM ISAAC WAS LOCATED NEAR LATITUDE
29.6 N AND LONGITUDE 56.5 W... ABOUT 450 NAUTICAL MILES OR 835 KM
EAST SOUTHEAST OF BERMUDA . MAXIMUM SUSTAINED WINDS ARE
ESTIMATED AT 40 KNOTS... 74 KM/H... AND CENTRAL PRESSURE AT 1006
MB. ISAAC IS MOVING WEST AT 5 KNOTS... 9 KM/H.

2. FORECAST POSITION, CENTRAL PRESSURE AND STRENGTH

DATE TIME LAT LON MSLP MAX WIND
NDT MB KTS KMH
SEP 29 3.30 PM 29.6N 56.5W 1006 40 74
SEP 30 3.30 AM 30.3N 57.7W 1003 45 83
SEP 30 3.30 PM 31.3N 59.0W 999 50 93
OCT 01 3.30 AM 32.9N 60.2W 999 50 93
OCT 01 3.30 PM 35.8N 60.7W 999 50 93 BECOMING POST-TROPICAL
OCT 02 3.30 AM 39.8N 59.7W 999 50 93 BECOMING POST-TROPICAL
OCT 02 3.30 PM 43.3N 56.6W 999 50 93 BECOMING POST-TROPICAL
OCT 03 3.30 AM 46.1N 51.7W 999 50 93 BECOMING POST-TROPICAL
OCT 03 3.30 PM 47.7N 46.3W 999 50 93 POST-TROPICAL
OCT 04 3.30 AM 48.7N 40.2W 999 50 93 POST-TROPICAL
OCT 04 3.30 PM 49.0N 33.9W 999 50 93 POST-TROPICAL

3. PUBLIC WEATHER IMPACTS AND WARNINGS SUMMARY
RAIN ASSOCIATED WITH ISAAC MAY AFFECT SOUTHEASTERN NEWFOUNDLAND
MONDAY OR TUESDAY BUT IT IS TOO EARLY TO PROVIDE DETAILS.

4. MARINE WEATHER IMPACTS AND WARNINGS SUMMARY
SOUTHEASTERN WATERS... NAMELY LAURENTIAN FAN AND THE GRAND BANKS...
WILL LIKELY EXPERIENCE GALES AND POSSIBLY STORM FORCE WINDS AS ISAAC
TRACKS THROUGH THOSE AREAS MONDAY OR TUESDAY. IT IS TOO EARLY
FOR WARNINGS TO BE ISSUED.

5. TECHNICAL DISCUSSION

A. ANALYSIS

FOLLOWING NHC LEAD ON INTENSITY. POSITION BASED ON VISIBLE IMAGERY
WHICH SHOWS OPEN AREA IN CIRCULATION.

B. PROGNOSTIC

WE HAVE FOLLOWED THE NHC TRACK AND INTENSITY ALMOST VERBATIM AT THIS
POINT. THE UKMET NOGAPS AND FSU MM5 ARE BEGINNING TO OFFER CONVERGING
SOLUTIONS... ALBEIT WITH INTERESTING DIFFERENCES. IT IS THE VARIOUS
DIFFERENCES AND UNCERTAINTIES THAT CONCERN US.

ISAAC HAS BEEN MOVING ALMOST DUE WEST FOR THE LAST FEW HOURS. THIS
TREND MAY CONTINUE AS THE RIDGING TO THE NORTH IS FORECAST TO
STRENGTHEN OUT TO AT LEAST 36-48 HOURS.

CMC REPORTS ISAAC INITIALIZED 1 DEGREE TOO FAR SW IN TRIAL FIELD.
FOR THE MOST PART THE SMALL SIZE OF ISAAC IS PROBLEMATIC FOR THE
INITIALIZATION ON MANY OF THE DYNAMICAL MODELS.

THERE IS AGREEMENT IN THE MODELS THAT BAROCLINIC CYCLOGENESIS TAKES
PLACE OFF THE EAST COAST AS THE LARGE UPPER TROUGH PUSHES THROUGH
ATLANTIC CANADA BEYOND 60 HOURS. THE GFS INITIATES CYCLOGENESIS
AFTER 60 HOURS WHICH THEN DEVELOPS SO SIGNIFICANTLY THAT
THE STORM SIZE SWAMPS THE DOMAIN AND ISAAC IS EITHER LOST OR
ABSORBED. THE UKMET HOWEVER KEEPS ISAAC AS AN IDENTIFIABLE SURFACE
LOW IN AN ELONGATED SURFACE FEATURE FOLLOWING THE CYCLOGENESIS AND
HAS A TRACK THAT IS SLIGHTLY NORTH OF THE NHC TRACK AT 72 HRS...
BEYOND WHICH IT MOVES FASTER AND EVEN FARTHER NORTH. THE NOGAPS AND
FSU MM5 MODELS HAVE A SIMILAR SOLUTION TO THE UKMET BUT KEEP IT
FARTHER SOUTH ONCE IT PASSES NEWFOUNDLAND. MEANWHILE THE VORTICITY
AND QPF OUTPUT ON THE CANADIAN MODEL INDICATES THAT ISAAC NEVER GETS
SUFFICIENTLY CLOSE TO THE TROUGH FOR MARKED INTERACTION.

IT IS ALSO WORTH MENTIONING THAT IF THE APPROACHING TROUGH IS NOT
AS LARGE AND IF ISAAC RETARDS ITS MOTION TO THE NORTHWEST FOR TOO
LONG IT COULD ACTUALLY BECOME ORPHANED IN THE SUBTROPICS...
RESULTING IN HUGE TRACK ERRORS FOR DAYS 3-5. HENCE WE REFRAIN FROM
BEING TOO DEFINITIVE AT THIS POINT BUT SIMPLY WATCH FOR A GREATER
CONCENSUS OF MODELS... WHICH WE DOUBT WILL OCCUR UNTIL AT LEAST 48
HOURS FROM NOW.

C. PUBLIC WEATHER
NONE.

D. MARINE WEATHER

PREDICTED WIND RADII (NM)
TIME GALES STORMS HURRICANE
NE SE SW NW NE SE SW NW NE SE SW NW
29/18Z 120 90 45 60 0 0 0 0 0 0 0 0
30/06Z 120 120 60 75 0 0 0 0 0 0 0 0
30/18Z 120 120 60 75 40 30 0 0 0 0 0 0
01/06Z 120 120 60 90 40 30 0 0 0 0 0 0
01/18Z 120 120 60 90 40 30 0 0 0 0 0 0
02/06Z 120 120 110 90 50 40 0 0 0 0 0 0
02/18Z 150 150 140 90 90 90 0 0 0 0 0 0
03/06Z 210 240 150 90 90 90 0 0 0 0 0 0
03/18Z 240 360 150 120 90 90 0 0 0 0 0 0
04/06Z 240 400 150 120 90 90 0 0 0 0 0 0
04/18Z 240 400 150 120 90 90 0 0 0 0 0 0

THESE RADII REFLECT THE TRANSITION OF ISAAC IN THE LONGER RANGE AND
ARE ONLY INTENDED TO SHOW A CONCEPTUAL RATHER THAN DETERMINISTIC
TREND.

END BOWYER

[cycloneye]

WTNT34 KNHC 292030
TCPAT4
BULLETIN
TROPICAL STORM ISAAC ADVISORY NUMBER 9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
500 PM EDT FRI SEP 29 2006

...ISAAC INTENSIFYING OVER THE CENTRAL ATLANTIC OCEAN...

AT 500 PM EDT...2100Z...THE CENTER OF TROPICAL STORM ISAAC WAS
LOCATED BY SATELLITE IMAGERY NEAR LATITUDE 29.7 NORTH...LONGITUDE
56.8 WEST OR ABOUT 505 MILES...815 KM...EAST-SOUTHEAST OF BERMUDA.

ISAAC IS MOVING TOWARD THE WEST-NORTHWEST NEAR 7 MPH...11 KM/HR...
AND THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 24
HOURS WITH A GRADUAL INCREASE IN FORWARD SPEED.

MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 60 MPH...95
KM/HR...WITH HIGHER GUSTS. SOME ADDITIONAL STRENGTHENING IS
FORECAST DURING THE NEXT 24 HOURS... AND ISAAC COULD BECOME A
HURRICANE OVER THE WEEKEND.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 115 MILES...185 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB...29.53 INCHES.

REPEATING THE 500 PM EDT POSITION...29.7 N...56.8 W. MOVEMENT
TOWARD...WEST-NORTHWEST NEAR 7 MPH. MAXIMUM SUSTAINED WINDS...60
MPH. MINIMUM CENTRAL PRESSURE...1000 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
1100 PM EDT.

$$
FORECASTER BLAKE/STEWART

377
WTNT44 KNHC 292029
TCDAT4
TROPICAL STORM ISAAC DISCUSSION NUMBER 9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
500 PM EDT FRI SEP 29 2006

CONVECTION HAS BEEN INTENSIFYING AND ATTEMPTING TO FORM A RING
AROUND THE CENTER OF ISAAC. IN ADDITION THE OUTFLOW HAS BEEN
EXPANDING AND BECOMING MORE SYMMETRIC. THESE ARE ALL SIGNS OF AN
INTENSIFYING SYSTEM. DVORAK T-NUMBERS HAVE INCREASED MARKEDLY...
AND SINCE AN EARLIER QUIKSCAT PASS SUPPORTED WINDS OF 40-45 KT
TWELVE HOURS AGO... THE INITIAL INTENSITY IS RAISED TO 50 KT. ISAAC
IS LEAVING THE COOLER WATERS PREVIOUSLY UPWELLED BY GORDON AND
HELENE AND MOVING INTO WARMER SSTS. IN ADDITION... THE DRY AIR IN
THE MIDDLE TO UPPER LEVELS NEAR THE SYSTEM'S CORE HAS BEEN REDUCED
AND THERE IS LITTLE SHEAR APPARENT ON SATELLITE IMAGES. THESE
FACTORS SUPPORT INTENSIFICATION FOR THE NEXT 36 HOURS OR SO. THUS
THE INTENSITY FORECAST IS RAISED FROM THE PREVIOUS ONE AND SHOWS
ISAAC BECOMING A HURRICANE. THE FORECAST IS HIGHER THAN THE
PREVIOUS ONE AND IN BEST AGREEMENT WITH A BLEND OF THE SHIPS/FSSE.

THE INITIAL MOTION IS VIRTUALLY UNCHANGED FROM EARLIER AND IS ABOUT
295/6. MIDDLE-LEVEL RIDGING OVER THE CENTRAL ATLANTIC SHOULD BE THE
PRIMARY STEERING MECHANISM FOR THE NEXT ONE OR TWO DAYS... SENDING
THE STORM ON A WEST-NORTHWEST TO NORTHWESTWARD HEADING. THEREAFTER
ISSAC WILL REACH THE WESTERN PERIPHERY OF THE RIDGE AND LIKELY
ACCELERATE TO THE NORTH IN FRONT OF A MASSIVE TROUGH FORECAST TO
PROGRESS EASTWARD ACROSS THE WESTERN ATLANTIC. THE UKMET HAS
SHIFTED ITS TRACK WESTWARD FROM EARLIER BUT IS STILL ON THE EASTERN
SIDE OF THE MODEL ENVELOPE. OTHER MODELS ARE MOSTLY UNCHANGED OR
SLIGHTLY FARTHER WEST OF THE PREVIOUS GUIDANCE. THE OFFICIAL
FORECAST IS NUDGED WESTWARD BUT STILL LIES JUST EAST OF THE MODEL
CONSENSUS. GLOBAL MODELS SUGGEST THAT ISAAC WILL BECOME RAPIDLY
EXTRATROPICAL BETWEEN 48 AND 72 HOURS FOLLOWED BY ABSORPTION INTO A
LARGER EXTRATROPICAL LOW IN 4 TO 5 DAYS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 29/2100Z 29.7N 56.8W 50 KT
12HR VT 30/0600Z 30.1N 57.8W 55 KT
24HR VT 30/1800Z 31.1N 59.1W 60 KT
36HR VT 01/0600Z 32.5N 60.3W 65 KT
48HR VT 01/1800Z 34.7N 61.0W 60 KT
72HR VT 02/1800Z 43.5N 57.0W 55 KT...EXTRATROPICAL
96HR VT 03/1800Z 50.0N 48.0W 50 KT...EXTRATROPICAL
120HR VT 04/1800Z...ABSORBED

$$
FORECASTER BLAKE/STEWART

[cycloneye]

625
WTNT34 KNHC 300232
TCPAT4
BULLETIN
TROPICAL STORM ISAAC ADVISORY NUMBER 10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
1100 PM AST FRI SEP 29 2006

...ISAAC NEARING HURRICANE STRENGTH...EXPECTED TO PASS WELL EAST OF
BERMUDA...

AT 1100 PM AST...0300Z...THE CENTER OF TROPICAL STORM ISAAC WAS
LOCATED NEAR LATITUDE 30.1 NORTH...LONGITUDE 57.4 WEST OR ABOUT 465
MILES...745 KM...EAST-SOUTHEAST OF BERMUDA.

ISAAC IS MOVING TOWARD THE WEST-NORTHWEST NEAR 8 MPH...13 KM/HR...
AND THIS MOTION IS EXPECTED TO CONTINUE ON SATURDAY WITH A GRADUAL
TURN TO THE NORTHWEST.

MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 70 MPH...110
KM/HR...WITH HIGHER GUSTS. ISSAC COULD BECOME A HURRICANE ON
SATURDAY.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 115 MILES...185 KM
FROM THE CENTER.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 MB...29.38 INCHES.

REPEATING THE 1100 PM AST POSITION...30.1 N...57.4 W. MOVEMENT
TOWARD...WEST-NORTHWEST NEAR 8 MPH. MAXIMUM SUSTAINED WINDS...70
MPH. MINIMUM CENTRAL PRESSURE...995 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
500 AM AST.

$$
FORECASTER AVILA

624
WTNT44 KNHC 300232
TCDAT4
TROPICAL STORM ISAAC DISCUSSION NUMBER 10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092006
1100 PM EDT FRI SEP 29 2006

THE SHAPE OF THE CLOUD PATTERN HAS BECOME A LITTLE BETTER ORGANIZED
AND MORE TYPICAL OF A TROPICAL STORM. I DID NOT MAKE ISAAC A
HURRICANE BECAUSE THE CONVECTION SURROUNDING THE CENTER IS NOT VERY
STRONG AT THE TIME OF THIS ADVISORY...BUT I WAS VERY TEMPTED. A
QUIKSCAT PASS OVER THE CYCLONE SHOWED A FEW VECTORS OF 60 KNOTS
JUST TO THE NORTH OF THE CENTER. HOWEVER...I AM NOT SURE IF THESE
VECTOR ARE REPRESENTATIVE OR NOT OF THE INTENSITY OF ISAAC...SINCE
THERE IS ALWAYS A LOT OF GOOD DEBATE ABOUT THE SUBJECT AMONG THE
QUIKSCAT EXPERTS. HOWEVER...THESE WINDS ARE ONLY 5 KNOTS ABOVE THE
DVORAK INTENSITY ESTIMATES...AND I AM NOT GOING TO ARGUE OVER 5
KNOTS. SO LET'S USE THE VECTORS AND INCREASE THE WINDS TO 60 KNOTS.
UNANIMOUSLY...ALL INTENSITY MODELS BRING ISAAC TO HURRICANE STATUS
BEFORE THE SHEAR INCREASES AND THE OCEAN COOLS...AND SO DOES THE
OFFICIAL FORECAST. ISSAC SHOULD BECOME EXTRATROPICAL IN 3 DAYS AND
BECOME ABSORBED BY A LARGER FRONTAL SYSTEM IN 5 DAYS OR EARLIER.

ISAAC IS MOVING TOWARD THE WEST-NORTHWEST ABOUT 7 KNOTS BUT IS
ALREADY REACHING THE WESTERN PORTION OF THE SUBTROPICAL RIDGE AND
THE SOUTHERLY FLOW ASSOCIATED WITH A STRONG MID-LATITUDE TROUGH.
THIS PATTERN SHOULD STEER ISAAC NORTHWARD AND PASS WELL EAST OF
BERMUDA IN THE NEXT DAY OR TWO. IT SHOULD THEN TURN TO THE
NORTH-NORTHEAST WITH INCREASING FORWARD SPEED. ISAAC IS EXPECTED TO
BE AN EXTRATROPICAL STORM WHILE APPROACHING SOUTHEASTERN
NEWFOUNDLAND IN ABOUT 3 DAYS. THIS IS CONSISTENT WITH TRACK
GUIDANCE WHICH IN FACT HAS SHIFTED TO THE LEFT A LITTLE BIT...AND
THE MAIN ENVELOPE IS OVER EXTREME SOUTHEASTERN NEWFOUNDLAND AND
ADJACENT WATERS.


FORECAST POSITIONS AND MAX WINDS

INITIAL 30/0300Z 30.1N 57.4W 60 KT
12HR VT 30/1200Z 30.5N 58.4W 65 KT
24HR VT 01/0000Z 31.5N 59.7W 65 KT
36HR VT 01/1200Z 33.5N 61.0W 65 KT
48HR VT 02/0000Z 36.5N 61.0W 60 KT
72HR VT 03/0000Z 46.0N 55.0W 55 KT...EXTRATROPICAL
96HR VT 04/0000Z 51.0N 45.0W 45 KT...EXTRATROPICAL
120HR VT 05/0000Z...ABSORBED BY A FRONTAL SYSTEM

$$
FORECASTER AVILA

[Ptarmigan]

Isaac could be a hurricane by tomorrow.

[Evil Jeremy]

only 5 more MPH strengthening? i think that this could intensify well over 75 MPH!!!!!

[Ptarmigan]

only 5 more MPH strengthening? i think that this could intensify well over 75 MPH!!!!!

I'd say around 85 to 100 mph.