11 am discussion--Question Please!

[Deenac813]

000
WTNT43 KNHC 131439
TCDAT3
HURRICANE ISABEL DISCUSSION NUMBER 30
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT SAT SEP 13 2003

ISABEL HAS COMPLETED AN EYEWALL REPLACEMENT CYCLE BASED ON A
13/1102Z SSMI OVERPASS SHOWING A CLOSED 35 NMI DIAMETER EYE. THE
INTENSITY IS MAINTAINED AT 130 KT BASED ON CONTINUITY WITH THE
PREVIOUS DATA...A CONSENSUS SATELLITE INTENSITY ESTIMATE OF 127
KT...RAW ODT VALUES OF T6.5...OR 127 KT...AND THE FACT THAT THE EYE
HAS CLEARED OUT NICELY AND SURROUNDING EYEWALL CLOUD TOPS HAVE
COOLED TO -70C AND COLDER ONCE AGAIN. NEXT RECON MISSION IS AT 18Z.

THE INITIAL MOTION IS 280/08. OVER THE PAST 72 HOURS...ISABEL HAS
BEEN MOVING AT 275 DEGREES. THE HURRICANE MADE A SLIGHT NORTHWARD
WOBBLE DURING THE EARLIER EYEWALL REPLACEMENT CYCLE...BUT IT NOW
APPEARS TO HAVE RESUMED A 275-280 DEGREES MOTION. ALL OF THE GLOBAL
AND REGIONAL MODELS HAVE HAD A DISTINCT RIGHT-OF-TRACK BIAS BY AS
MUCH AS 10 DEGREES...AND EACH MODEL RUN HAS BEEN A LITTLE FARTHER
WEST AND SLOWER. THE EXCEPTION IS THE 06Z GFDL RUN WHICH MADE A
MAJOR SHIFT WESTWARD BY MORE 200 NMI IN THE LATER FORECAST PERIODS
...WHILE THE 06Z NOGAPS MODEL ACCELERATED ISABEL AND HAS THE
HURRICANE ONSHORE THE SOUTHEAST COAST OF NORTH CAROLINA IN 120
HOURS. HOWEVER...THE MODEL CONSENSUS IS SLOWER AND FARTHER WEST
BEFORE A TURN TO THE NORTHWEST OCCURS IN THE LATER PERIODS. THE
MODELS OBVIOUSLY HAVE NOT BEEN HANDLING THE STRONG RIDGING TO THE
NORTH OF ISABEL VERY WELL. THIS MAY BE DUE TO THE OUTFLOW ON THE
NORTH SIDE BEING DRAWN NORTHWARD AND SINKING ALONG 30N-33N...WHICH
MAY HAVE HELPED TO STRENGTHEN THE SUBTROPICAL RIDGE. WATER VAPOR
IMAGERY INDICATES THIS PATTERN HAS PERSISTED FOR MORE THAN 72 HOURS
AND CONTINUES TO SHIFT WESTWARD WITH ISABEL. THEREFORE...A GENERAL
WESTWARD MOTION SHOULD CONTINUE FOR ANOTHER 36 HOURS OR SO.
AFTERWARDS...THERE REMAINS CONSIDERABLE DIVERGENCE AMONG THE MODELS
AND HOW THEY HANDLE THE CURRENT SHORTWAVE TROUGH/LOW OVER THE
SOUTHEASTERN U.S. WATER VAPOR IMAGERY INDICATES THE TROUGH HAS
BECOME NEGATIVELY TILTED IN AN EAST-WEST ORIENTATION. THIS WOULD
SUGGEST THAT THE LOW SHOULD BEGIN TO LIFT OUT AND ALLOW THE RIDGE
NORTH OF ISABEL TO GRADUALLY BUILD WESTWARD...WHICH IS SIMILAR TO
THE 06Z GFS...GFDL...AND ETA...AND 00Z UKMET SOLUTIONS. THE KEY
WILL BE HOW THE CENTRAL U.S. TROUGH EVOLVES AND HOW DEEP IT DIGS
INTO THE SOUTHERN U.S. AND GULF OF MEXICO. THE OFFICIAL FORECAST
WAS ADJUSTED SLIGHTLY TO THE LEFT OF AND SLOWER THAN THE PREVIOUS
FORECAST...WHICH IS CONSISTENT WITH THE GUNA MODEL CONSENSUS.
HOWEVER...IT IS STILL TOO EARLY TO DETERMINE WHEN OR WHERE ISABEL
WILL MAKE LANDFALL. HOPEFULLY...THE NOAA GULFSTREAM-IV SYNOPTIC
DATA MISSION AT 14/00Z WILL PROVIDE BETTER MODEL CONVERGENCE.

ALTHOUGH ISABEL HAS A RATHER LARGE EYE DIAMETER...CONDITIONS APPEAR
FAVORABLE FOR AT LEAST SOME SLIGHT ADDITIONAL STRENGTHENING OVER
THE NEXT COUPLE OF DAYS AS THE HURRICANE MOVES OVER WARMER WATER.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL 13/1500Z 22.2N 61.5W 130 KT
12HR VT 14/0000Z 22.6N 63.0W 135 KT
24HR VT 14/1200Z 23.0N 64.8W 135 KT
36HR VT 15/0000Z 23.7N 66.7W 130 KT
48HR VT 15/1200Z 24.5N 68.7W 130 KT
72HR VT 16/1200Z 26.0N 71.0W 125 KT
96HR VT 17/1200Z 28.5N 73.0W 120 KT
120HR VT 18/1200Z 31.5N 75.0W 110 KT



** Ok, since I am learning can someone please tell me about the forecast postions. It shows that today at 1200Z that she should be at 23.0N & 64.8 W but she is at 23.7 N & 66.3 W now.. They do not show here near where she is now until 15/000Z. Am I reading this wrong? I am a little confused on this so any help would be appreciated!! Thanks!!

[Derek Ortt]

yesterdays discussion

[Deenac813]

yesterdays discussion

Thank you!! I did not notice that & I just got that from the National Hurricane Website..

Deena

[GalvestonDuck]

It happens, sometimes the link takes you to the wrong place...sometimes they have the wrong time or date and you've gone to the right one, but you wouldn't know it from looking at the heading.



Glad you asked...somebody else might have seen that and been confused also.

[Deenac813]

Glad you asked...somebody else might have seen that and been confused also.

Thanks.. boy was I embarrassed.. I am trying really hard to learn & figure things out & that really confused me..

[vortex100]

I know that they are only human and make mistakes, but the people at the NHC should know many of us a waiting impatiently for their discussions and forecasts. I hope they correct this error soon. Has anyone contacted them?

[Deenac813]

I know that they are only human and make mistakes, but the people at the NHC should know many of us a waiting impatiently for their discussions and forecasts. I hope they correct this error soon. Has anyone contacted them?

I just want back & refreshed the page & now it is showing the 5 am again.. I guess someone caught it & they should be putting the new 11 am up any time..

[Stormsfury]

11 am EDT (as of 11:10 am) still not updated on the NHC site. Maybe they already realized it.

SF

[Stormsfury]

000
WTNT43 KNHC 141459
TCDAT3
HURRICANE ISABEL DISCUSSION NUMBER 34
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT SUN SEP 14 2003

SATELLITE IMAGERY SUGGESTS THAT ISABEL HAS WEAKENED DURING THE PAST
6 HOURS OR SO. EYEWALL CLOUD TOPS HAVE WARMED TO ABOVE -70C AND THE
THREE SATELLITE AGENCIES HAVE COME IN WITH A CONSENSUS INTENSITY
ESTIMATE OF T6.5...OR 127 KT. THE EYE REMAINS VERY DISTINCT AND
CIRCULAR...ALBEIT WITH AN UNUSUALLY LARGE 40 NMI DIAMETER. THE
INTENSITY HAS ONLY BEEN DECREASED SLIGHTLY DOWN TO 135 KT SINCE THE
EYE HAS BECOME EMBEDDED DIRECTLY IN THE CENTER OF THE CENTRAL DEEP
CONVECTION. SUCH PERFECT SYMMETRY OFTENTIMES INDICATES A CYCLONE
STRONGER THAN SATELLITE THE ESTIMATES...WHICH WAS THE CASE
YESTERDAY. RECON WILL IS SCHEDULED TO INVESTIGATE THE HURRICANE
THIS AFTERNOON.

THE INITIAL MOTION ESTIMATE IS 290/10. THERE IS NO SIGNIFICANT
CHANGE TO PREVIOUS FORECAST TRACK OR REASONING. SATELLITE FIX
POSITIONS HAVE BEEN COMING IN ON TOP OF THE PREVIOUS FORECAST TRACK
AND THE LATEST 06Z NHC MODEL GUIDANCE IS ALSO NOW STRONGLY
CONVERGENT ABOUT THE PREVIOUS FORECAST TRACK. THERE WAS A SLIGHT
WESTWARD SHIFT TO THE MODEL CONSENSUS...BUT THERE IS NOW MUCH LESS
DIVERGENCE AMONG THE GLOBAL AND REGIONAL MODELS THROUGHOUT THE
FORECAST PERIOD. UNFORTUNATELY...THE MODELS ARE NOW IN EXCELLENT
AGREEMENT WITH ISABEL MAKING LANDFALL ALONG THE CENTRAL U.S. EAST
COAST IN ABOUT 4 DAYS. THERE IS STILL UNCERTAINTY ON WHERE THE
EXACT LANDFALL COULD OCCUR SINCE THE DEVELOPING CENTRAL U.S. TROUGH
COULD DEEPEN AND DIG SOUTHWARD MORE THAN IS FORECAST BY THE GLOBAL
MODELS...WHICH COULD LEAD A MORE NORTHWARD MOTION AND LANDFALL
FARTHER UP THE EAST COAST THAN WHAT IS CURRENTLY FORECAST.
UNFORTUNATELY...ALL OF THE MODEL GUIDANCE AGREE ON A LARGE AND
STRONG NORTH-SOUTH ORIENTED RIDGE REMAINING EAST OF ISABEL...WHICH
SHOULD PREVENT THE POWERFUL HURRICANE FROM RECURVING OUT TO SEA.
LANDFALL ALONG THE U.S MID-ATLANTIC COAST SOMEWHERE BETWEEN NORTH
CAROLINA AND NEW JERSEY BETWEEN 4 OR 5 DAYS IS APPEARING MORE AND
MORE LIKELY.

ONLY MINOR FLUCTUATIONS IN INTENSITY ARE EXPECTED FOR THE NEXT 3
DAYS AS ISABEL IS FORECAST TO MOVE OVER SIGHTLY WARMER WATER AND
REMAIN IN A FAVORABLE DOUBLE-OUTFLOW PATTERN. HOWEVER...BY 96
HOURS...ISABEL IS EXPECTED TO BE ACCELERATING NORTH-NORTHWESTWARD
UNDER INCREASING SOUTHERLY UPPER-LEVEL FLOW. HOWEVER...ALL OF THE
MODELS ARE IN GOOD AGREEMENT ON THE CENTRAL CORE OF ISABEL
REMAINING EAST OF THE STRONG JETSTREAM AND UNDER 20-25 KT 200 MB
WIND. THIS WOULD TEND TO KEEP ISABEL STRONGER THAN WHAT THE SHIPS
INTENSITY MODEL IS INDICATING...ESPECIALLY SINCE ISABEL WILL BE
MOVING OVER THE WARM GULFSTREAM SOUTH OF THE NORTH CAROLINA OUTER
BANKS AT THAT TIME. THEREFORE...LITTLE OR NO SIGNIFICANT WEAKENING
IS EXPECTED TO OCCUR UNTIL AFTER LANDFALL OCCURS.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL 14/1500Z 23.7N 66.3W 135 KT
12HR VT 15/0000Z 24.2N 67.9W 135 KT
24HR VT 15/1200Z 25.2N 69.6W 135 KT
36HR VT 16/0000Z 26.1N 70.6W 130 KT
48HR VT 16/1200Z 27.2N 71.6W 125 KT
72HR VT 17/1200Z 30.0N 73.2W 120 KT
96HR VT 18/1200Z 34.5N 75.5W 110 KT...NEAR NORTH CAROLINA
120HR VT 19/1200Z 41.0N 77.5W 70 KT...INLAND

[JetMaxx]

I've noticed over the past three years that the NHC site is sometimes among the last places on the internet to update their own forecast discussions.

The Plymouth State university and HWN sites always seem to update it first

You can find more than half-dozen links to all the TPC/NHC forecast products on each hurricane in progress....at the following web address
http://www.atwc.org

It's the website I utilize to get the advisories and discussions quicker.

[charleston_hugo_veteran]

Thanks!