HURRICANE ISABEL becomes first Atlantic Category 5 Hurricane since 1998.....

National Hurricane Center ^ | September 11, 2003 | Pasch

[John H K]

BULLETIN HURRICANE ISABEL ADVISORY NUMBER 23 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM AST THU SEP 11 2003

...EXTREMELY DANGEROUS ISABEL NOW AT CATEGORY FIVE INTENSITY...

SATELLITE IMAGES INDICATE THAT HURRICANE ISABEL HAS CONTINUED TO STRENGTHEN...AND HAS REACHED CATEGORY FIVE INTENSITY ON THE SAFFIR-SIMPSON HURRICANE SCALE. ISABEL IS THE FIRST CATEGORY FIVE HURRICANE IN THE ATLANTIC BASIN SINCE MITCH OF 1998.

AT 5 PM AST...2100Z...THE CENTER OF HURRICANE ISABEL WAS LOCATED NEAR LATITUDE 21.6 NORTH... LONGITUDE 55.3 WEST OR ABOUT 500 MILES...805 KM...EAST-NORTHEAST OF THE NORTHERN LEEWARD ISLAND.

ISABEL IS MOVING TOWARD THE WEST NEAR 9 MPH...15 KM/HR...AND THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 24 HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 160 MPH...260 KM/HR...WITH HIGHER GUSTS. SOME FLUCTUATIONS IN INTENSITY ARE LIKELY OVER THE NEXT 24 HOURS.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 60 MILES... 95 KM... FROM THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 185 MILES...295 KM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 921 MB...27.20 INCHES.

LARGE OCEAN SWELLS AND DANGEROUS SURF CONDITIONS ARE LIKELY OVER PORTIONS OF THE LEEWARD ISLANDS...THE VIRGIN ISLANDS...AND PUERTO RICO OVER THE NEXT SEVERAL DAYS.

REPEATING THE 5 PM AST POSITION...21.6 N... 55.3 W. MOVEMENT TOWARD...WEST NEAR 9 MPH. MAXIMUM SUSTAINED WINDS...160 MPH. MINIMUM CENTRAL PRESSURE... 921 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT 11 PM AST.

FORECASTER PASCH

[John H K]

Couple of Notes:

I get the feeling Isabel is regarded as closer to the US than it actually is; it likely would be something like 8-10 DAYS till an actual US landfall, should one occur, which is an eternity in the tropics.

2) It's still quite possible for Isabel to miss the US completely, even though it looks like the chances of a hit are fairly good.

3) It's extremely unlikely for a storm that's a CAT 5 today to be a CAT 5 in 8 days.

[jimkress]

HURRICANE ISABEL becomes first Atlantic Category 5 Hurricane since 1998.....

DemocRATS claim it's all Bush's fault.

[ContemptofCourt]

Yes, but it sure does look pretty.

[John H K]

Here's the NHC discussion, btw:

Hurricane Isabel Discussion Number 23


Statement as of 5:00 PM EDT on September 11, 2003



Isabel has continued to intensify today. Dvorak T-numbers from all
3 agencies...TAFB...SAB...and AFWA are now 7.0 and objective
T-numbers are also about the same value. This supports a current
intensity estimate of 140 kt...a category 5 on the Saffir-Simpson
hurricane scale. Hurricanes rarely maintain such strength for very
long...and Isabel may not stay a Cat 5 for even as long as shown
here. There is an upper-level cyclone about 15 degrees to the
west-northwest of the hurricane but this system appears to be
narrowing and if this trend continues...it should not have much of
an impact on the intensity of Isabel. Another possible factor is
the cooled SST wake produced by Hurricane Fabian in the vicinity of
63w. Since there do not to be any major inhibiting factors in the
environment...internal dynamics such as eyewall replacement cycles
will probably have the greatest influence on intensity change. The
official forecast assumes that we will continue to have a major
hurricane on our hands throughout the forecast period.
Motion continues at about 280/8...along with some minor trochoidal
wobbles. A deep-layer high pressure area to the north of Isabel is
likely to maintain the slow westward to west-northwestward steering
over the next several days. The current NHC forecast is somewhat
slower than the previous one...but faster than the guna consensus.
This is fairly close to the latest U.K. Met office track. The
latter model is the westernmost of the guidance suite.
The big question continues to be what will happen beyond the 5-day
forecast period. It is still impossible to state with any
confidence whether a specific area along the U.S. Coast will be
impacted by Isabel. This will likely depend on the relative
strength and positioning of a mid-tropospheric ridge near the east
coast and a mid-latitude trough to the west or northwest around the
middle of next week. Unfortunately...we have little skill in
predicting the evolution of steering features at these long ranges.
Forecaster Pasch

forecast positions and Max winds

initial 11/2100z 21.6n 55.3w 140 kt
12hr VT 12/0600z 21.7n 56.7w 140 kt
24hr VT 12/1800z 21.9n 58.6w 135 kt
36hr VT 13/0600z 22.4n 60.5w 130 kt
48hr VT 13/1800z 22.9n 62.3w 125 kt
72hr VT 14/1800z 24.0n 65.5w 115 kt
96hr VT 15/1800z 25.0n 68.5w 115 kt
120hr VT 16/1800z 26.0n 71.5w 115 kt

[TexasGunLover]

HURRICANE ISABEL DISCUSSION NUMBER 23
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT THU SEP 11 2003

ISABEL HAS CONTINUED TO INTENSIFY TODAY. DVORAK T-NUMBERS FROM ALL
3 AGENCIES...TAFB...SAB...AND AFWA ARE NOW 7.0 AND OBJECTIVE
T-NUMBERS ARE ALSO ABOUT THE SAME VALUE. THIS SUPPORTS A CURRENT
INTENSITY ESTIMATE OF 140 KT...A CATEGORY 5 ON THE SAFFIR-SIMPSON
HURRICANE SCALE. HURRICANES RARELY MAINTAIN SUCH STRENGTH FOR VERY
LONG...AND ISABEL MAY NOT STAY A CAT 5 FOR EVEN AS LONG AS SHOWN
HERE. THERE IS AN UPPER-LEVEL CYCLONE ABOUT 15 DEGREES TO THE
WEST-NORTHWEST OF THE HURRICANE BUT THIS SYSTEM APPEARS TO BE
NARROWING AND IF THIS TREND CONTINUES...IT SHOULD NOT HAVE MUCH OF
AN IMPACT ON THE INTENSITY OF ISABEL. ANOTHER POSSIBLE FACTOR IS
THE COOLED SST WAKE PRODUCED BY HURRICANE FABIAN IN THE VICINITY OF
63W. SINCE THERE DO NOT TO BE ANY MAJOR INHIBITING FACTORS IN THE
ENVIRONMENT...INTERNAL DYNAMICS SUCH AS EYEWALL REPLACEMENT CYCLES
WILL PROBABLY HAVE THE GREATEST INFLUENCE ON INTENSITY CHANGE. THE
OFFICIAL FORECAST ASSUMES THAT WE WILL CONTINUE TO HAVE A MAJOR
HURRICANE ON OUR HANDS THROUGHOUT THE FORECAST PERIOD.

MOTION CONTINUES AT ABOUT 280/8...ALONG WITH SOME MINOR TROCHOIDAL
WOBBLES. A DEEP-LAYER HIGH PRESSURE AREA TO THE NORTH OF ISABEL IS
LIKELY TO MAINTAIN THE SLOW WESTWARD TO WEST-NORTHWESTWARD STEERING
OVER THE NEXT SEVERAL DAYS. THE CURRENT NHC FORECAST IS SOMEWHAT
SLOWER THAN THE PREVIOUS ONE...BUT FASTER THAN THE GUNA CONSENSUS.
THIS IS FAIRLY CLOSE TO THE LATEST U.K. MET OFFICE TRACK. THE
LATTER MODEL IS THE WESTERNMOST OF THE GUIDANCE SUITE.

THE BIG QUESTION CONTINUES TO BE WHAT WILL HAPPEN BEYOND THE 5-DAY
FORECAST PERIOD. IT IS STILL IMPOSSIBLE TO STATE WITH ANY
CONFIDENCE WHETHER A SPECIFIC AREA ALONG THE U.S. COAST WILL BE
IMPACTED BY ISABEL. THIS WILL LIKELY DEPEND ON THE RELATIVE
STRENGTH AND POSITIONING OF A MID-TROPOSPHERIC RIDGE NEAR THE EAST
COAST AND A MID-LATITUDE TROUGH TO THE WEST OR NORTHWEST AROUND THE
MIDDLE OF NEXT WEEK. UNFORTUNATELY...WE HAVE LITTLE SKILL IN
PREDICTING THE EVOLUTION OF STEERING FEATURES AT THESE LONG RANGES.

FORECASTER PASCH

[TheBigB]

WOMEN, MINORITIES, WE'RE PRETTY SURE, TO BE HARDEST HIT

[Centurion2000]

Call me superstitious but I think that if Bush and co stop Israel from killing Arafat this thing is coming straight at us and will stay just as strong.

If arafat is dead in 48 hours then it will miss the US.

[dennis1x]

good points HK.....although based on its location (north of the islands)....and based on the fact that its 8 days away...i would bet on a trough sometime between now and then (its mid-September) that will add another loop to the historical path page.

[HEY4QDEMS]

Isn't she something !!

[TBall]

I've been waiting for someone to post the Isreal storm connection.

[Calpernia]

[ASA Vet]

Here's her twin bearing down on Taiwan.

[GoldMan]

"Call me superstitious but I think that if Bush and co stop Israel from killing Arafat this thing is coming straight at us and will stay just as strong.
If arafat is dead in 48 hours then it will miss the US. "

No, it's not superstitious. It's obsessive compulsive.

[dirtboy]

Here's her twin bearing down on Taiwan.

Actually, that one's heading for Korea...

[showme_the_Glory]

She's a bute.....

[gcruse]

What it looks like is the whirlpool galaxy. There's a lesson there....

[Vigilantcitizen]

New Isabel thread ping.

"3) It's extremely unlikely for a storm that's a CAT 5 today to be a CAT 5 in 8 days."

I wonder what effect, if any, the cold front that currently stretches from Texas to Minnessota will have on the intensity and direction Miss Isabel takes.

I guess it's a matter of timing. I'm still sticking with a Savannah to Myrtle beach landfall.

[John H K]

No, it's not superstitious. It's obsessive compulsive.

I'd cal it moronic, myself.

[Moose4]

"Crikey! Isn't she a beeauuuty?"

Sorry...had a Crocodile Hunter moment there for a sec.

There's great beauty in those pictures, but buddy, no way I'd want to be in that thing's path. Nuh-uh, no how.

Wonder what the odds are on having a Cat 5 hurricane in the Atlantic and a Cat 5 typhoon in the Pacific at the same time?

}:-)4