Hurricane Isabel

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Matt-hurricanewatcher
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Hurricane Isabel

#1 Postby Matt-hurricanewatcher » Fri Jul 25, 2008 10:28 pm

I find it a little weird to have a 2003 archives without isabel thread.

ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM ISABEL SPECIAL DISCUSSION NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
9 AM EDT SAT SEP 06 2003

SATELLITE DATA INDICATE THAT THE TROPICAL WAVE IN THE FAR EASTERN
ATLANTIC HAS BECOME BETTER ORGANIZED AND IS NOW TROPICAL STORM
ISABEL. SINCE THE SHEAR IS LOW AHEAD OF THE TROPICAL CYCLONE A
GRADUAL STRENGTHENING IS INDICATED.

ISABEL IS MOVING WESTWARD AT 11 KNOTS. THIS GENERAL TRACK IS
EXPECTED TO CONTINUE DURING THE NEXT 2 TO 3 DAYS WITH A GRADUAL
TURN TO THE WEST-NORTHWEST AS THE WESTERN PORTION OF THE
SUBTROPICAL RIDGE WEAKENS.

A REGULAR ADVISORY WILL BE ISSUED AT 1500Z TODAY.

FORECASTER AVILA

FORECAST POSITIONS AND MAX WINDS

INITIAL 06/1300Z 14.0N 34.0W 35 KT
12HR VT 06/1800Z 14.0N 35.0W 40 KT
24HR VT 07/0600Z 14.0N 37.5W 45 KT
36HR VT 07/1800Z 14.5N 40.0W 55 KT
48HR VT 08/0600Z 15.0N 42.5W 65 KT
72HR VT 09/0600Z 15.5N 46.5W 65 KT
96HR VT 10/0600Z 16.5N 50.0W 65 KT
120HR VT 11/0600Z 17.5N 54.5W 65 KT


MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM ISABEL DISCUSSION NUMBER 2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT SAT SEP 06 2003

SATELLITE IMAGES SHOW THAT THE CLOUD PATTERN ASSOCIATED WITH ISABEL
IS GRADUALLY BECOMING BETTER ORGANIZED. IT APPEARS TO BE DEVELOPING
A CENTRAL DENSE OVERCAST AND HAS A WELL DEFINED CURVED BAND. THE
OUTFLOW IS FAIR IN ALL QUADRANTS BUT THE NORTHEAST. THE SHEAR IS
FORECAST TO REMAIN LOW OVER THE TROPICAL ATLANTIC AS INDICATED BY
GLOBAL AND SHIPS MODELS. IN ADDITION...SSTS ARE INCREASING ALONG
THE PATH OF ISABEL. THEREFORE...STRENGHTENING IS INDICATED AND
ISABEL MAY BECOME A HURRICANE IN THE NEXT 2 OR 3 DAYS.

MORE RECENT VISIBLE SATELLITE IMAGES INDICATE THAT THE CENTER
APPEARS TO BE A LITTLE TO THE SOUTH OF PREVIOUSLY INDICATED. BEST
ESTIMATE OF THE INITIAL MOTION IS 270 AT 12 KNOTS. BECAUSE THE
SUBTROPICAL RIDGE IS WELL ESTABLISHED TO THE NORTH OF ISABEL...A
WESTWARD MOTION IS EXPECTED TO CONTINUE. A GRADUAL TURN TO THE
WEST-NORTHWEST IS POSSIBLE IN ABOUT 4 TO 5 DAYS AS THE TROPICAL
CYCLONE APPROACHES A WEAKNESS OF THE RIDGE. THE OFFICIAL FORECAST
IS SIMILAR TO THE LATEST GFS.

FORECASTER AVILA

FORECAST POSITIONS AND MAX WINDS

INITIAL 06/1500Z 13.6N 34.5W 35 KT
12HR VT 07/0000Z 13.7N 36.4W 40 KT
24HR VT 07/1200Z 14.0N 39.0W 45 KT
36HR VT 08/0000Z 14.5N 41.5W 55 KT
48HR VT 08/1200Z 15.0N 44.0W 65 KT
72HR VT 09/1200Z 16.0N 48.0W 65 KT
96HR VT 10/1200Z 17.0N 51.9W 65 KT
120HR VT 11/1200Z 18.0N 56.5W 65 KT


ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM ISABEL DISCUSSION NUMBER 3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT SAT SEP 06 2003

SATELLITE IMAGES DURING THE DAY INDICATE THAT ISABEL HAS CONTINUED
TO BECOME BETTER ORGANIZED. THE TROPICAL STORM HAS A LARGE ENVELOPE
DEFINED BY LOW CLOUDS ON SATELLITE...CONVECTIVE CURVED BANDS AND AN
EXPANDING CENTRAL DENSE OVERCAST. THE OUTFLOW CONTINUES TO BE
FAIRLY GOOD IN ALL QUADRANTS BUT THE NORTHEAST. SATELLITE INTENSITY
ESTIMATES AND AN EARLIER ADEOS SCATTEROMETER SUPPORT INCREASING THE
WINDS TO 45 KNOTS. THE OCEAN IS PLENTY WARM AHEAD OF ISABEL AS
INDICATED BY BUOYS AND THE SHEAR IS FORECAST TO REMAIN LOW.
THEREFORE...ISABEL IS FORECAST TO BECOME A HURRICANE.

A 24 TO 36 HOUR SATELLITE LOOP INDICATES THAT ISABEL HAS BEEN MOVING
SOUTH OF DUE WEST...OR PERHAPS IT WAS A REFORMATION UNDER THE
MID-LEVEL CIRCULATION. THE TROPICAL CYCLONE IS FORECAST TO MOVE
ABOUT 10 TO 12 KNOTS TOWARD THE WEST STEERED BY A RATHER STRONG
SUBTROPICAL RIDGE TO THE NORTH. HOWEVER...IN 3 TO 5 DAYS...THE
RIDGE IS EXPECTED TO ERODE AND ISABEL COULD BEGIN TO MOVE TO THE
WEST-NORTHWEST. THE OFFICIAL FORECAST IS SIMILAR TO THE GLOBAL
MODEL CONSENSUS...GUNA...BUT A LITTLE BIT BIASED TOWARD THE GFS.
THE LATTER IS THE ONLY MODEL THAT BRINGS THE TROPICAL CYCLONE VERY
CLOSE TO THE LEEWARD ISLANDS BEYOND 5 DAYS.

FORECASTER AVILA

FORECAST POSITIONS AND MAX WINDS

INITIAL 06/2100Z 13.4N 35.4W 45 KT
12HR VT 07/0600Z 13.4N 36.8W 50 KT
24HR VT 07/1800Z 13.5N 38.5W 60 KT
36HR VT 08/0600Z 14.5N 40.5W 65 KT
48HR VT 08/1800Z 15.5N 43.0W 70 KT
72HR VT 09/1800Z 17.0N 48.5W 75 KT
96HR VT 10/1800Z 18.0N 53.5W 75 KT
120HR VT 11/1800Z 18.5N 58.0W 75 KT


ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM ISABEL DISCUSSION NUMBER 4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT SAT SEP 06 2003

SATELLITE IMAGERY DURING THE EVENING SHOWS THAT ISABEL HAS A
WELL-DEFINED CURVED CONVECTIVE BAND WITH TOPS COLDER THAN -80C.
THE CIRRUS OUTFLOW IS EXCELLENT OVER THE SOUTH SEMICIRCLE AND FAIR
TO GOOD ELSEWHERE. SATELLITE INTENSITY ESTIMATES ARE 55 KT FROM
TAFB AND SAB...AND 45 KT FROM AFWA. THE INITIAL INTENSITY IS
RAISED TO 50 KT FOR THIS ADVISORY.

THE INITIAL MOTION IS 270/09. WATER VAPOR IMAGERY INDICATES THAT
ISABEL IS SOUTH OF A MID/UPPER-LEVEL RIDGE...WITH AN UPPER-LEVEL
LOW CENTERED NEAR 26N46W. LARGE-SCALE MODELS SUGGEST THAT THIS LOW
WILL CREATE ENOUGH WEAKNESS IN THE RIDGE TO ALLOW ISABEL TO
GRADUALLY TURN TO A WEST-NORTHWESTWARD COURSE DURING THE NEXT 24-48
HR...AND CONTINUE THAT GENERAL MOTION THROUGH DAY 5. NHC TRACK
GUIDANCE AGREES WITH THIS SCENARIO. SINCE SOME MODELS SHOWED
SOMEWHAT OF A NORTHWARD BIAS WHEN FABIAN WAS IN THIS AREA...THE
OFFICIAL FORECAST WILL LEAN TOWARD THE SOUTH SIDE OF THE GUIDANCE.
IT IS ALSO NUDGED JUST A LITTLE SOUTH OF THE PREVIOUS TRACK.

ISABEL SEEMS TO HAVE ALL THE INGREDIENTS TO STRENGTHEN
SIGNIFICANTLY...A LARGE CYCLONIC ENVELOPE...GOOD CONVECTIVE
STRUCTURE...COLD CLOUD TOPS...AND FAVORABLE OUTFLOW AND VERTICAL
SHEAR. THE SHIPS MODEL TAKES THE STORM TO 80 KT IN 60 HR AND THEN
STOPS INTENSIFICATION FOR REASONS NOT READILY APPARENT. THE GFDL
MAKES ISABEL A 90 KT HURRICANE IN 120 HR. THE INTENSITY FORECAST
WILL SHOW THE INTENSITY LEVELING OFF AT 80 KT IN AGREEMENT WITH THE
SHIPS MODEL. HOWEVER...IT WOULD NOT BE A SURPRISE TO SEE ISABEL
STRENGTHEN FASTER AND MORE THAN CURRENTLY FORECAST.

FORECASTER BEVEN

FORECAST POSITIONS AND MAX WINDS

INITIAL 07/0300Z 13.4N 36.1W 50 KT
12HR VT 07/1200Z 13.4N 37.4W 60 KT
24HR VT 08/0000Z 13.8N 39.4W 65 KT
36HR VT 08/1200Z 14.7N 41.8W 70 KT
48HR VT 09/0000Z 15.6N 44.4W 75 KT
72HR VT 10/0000Z 17.0N 49.4W 80 KT
96HR VT 11/0000Z 18.0N 54.5W 80 KT
120HR VT 12/0000Z 18.5N 59.0W 80 KT


NNNN

ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM ISABEL DISCUSSION NUMBER 5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT SUN SEP 07 2003

OVERNIGHT SATELLITE IMAGERY SHOWS THAT ISABEL CONTINUES TO EXHIBIT A
WELL-DEFINED CURVED CONVECTIVE BAND...AND THE LAST FEW IMAGES
SUGGEST THAT THE CONVECTION HAS BEGUN TO WRAP CLOSER TO THE CENTER.
SATELLITE INTENSITY ESTIMATES ARE A CONSENSUS 55 KT FROM
TAFB...SAB...AND AFWA. THEREFORE...THE INITIAL INTENSITY IS RAISED
TO 55 KT FOR THIS ADVISORY. GLOBAL MODELS SUGGEST THAT A MID/UPPER
LEVEL RIDGE WILL REMAIN NORTH OF THE CYCLONE THROUGH THE FORECAST
PERIOD...PROVIDING FAVORABLE CONDITIONS FOR STRENGTHENING. THE
SHIPS MODEL TAKES ISABEL TO 85 KT IN 72 HOURS...AND THE GFDL BRINGS
THE INTENSITY UP TO 95 KT IN 48 HOURS. THE INTENSITY FORECAST WILL
BE RATHER CONSERVATIVE AND INDICATE GRADUAL STRENGTHENING OVER THE
NEXT 2-3 DAYS...WITH THE INTENSITY LEVELING OFF AT 85 KT BY 72
HOURS WHICH IS IN GENERAL AGREEMENT WITH SHIPS.

THE INITIAL MOTION IS 275/09...SLIGHTLY NORTH OF THE PREVIOUS
ADVISORY. THE SYNOPTIC PATTERN REMAINS BASICALLY UNCHANGED FROM
THE PREVIOUS FORECAST...WITH ISABEL BEING STEERED BY A MID/UPPER
LEVEL RIDGE TO THE NORTH. WATER VAPOR IMAGERY INDICATES AN
UPPER-LEVEL TROUGH ABOUT 900 NM NORTHWEST OF THE TROPICAL CYCLONE.
LARGE-SCALE GLOBAL MODELS SUGGEST THAT THIS TROUGH WILL CREATE JUST
ENOUGH OF A WEAKNESS IN THE RIDGE TO ALLOW FOR A MORE
WEST-NORTHWEST MOTION BEYOND 12 HOURS...AND CONTINUE THAT MOTION
THROUGH DAY 5. NHC TRACK GUIDANCE BASICALLY FOLLOWS THIS
SCENARIO...WITH THE FORECAST TRACK ADJUSTED A TAD TO THE NORTH OF
THE PREVIOUS TRACK AND REMAINING ON THE SOUTH SIDE OF THE GUIDANCE.

FORECASTER MOLLEDA/LAWRENCE

FORECAST POSITIONS AND MAX WINDS

INITIAL 07/0900Z 13.7N 37.1W 55 KT
12HR VT 07/1800Z 13.8N 38.5W 60 KT
24HR VT 08/0600Z 14.8N 40.9W 65 KT
36HR VT 08/1800Z 15.6N 43.2W 70 KT
48HR VT 09/0600Z 16.5N 45.3W 75 KT
72HR VT 10/0600Z 18.0N 50.0W 85 KT
96HR VT 11/0600Z 18.5N 55.5W 85 KT
120HR VT 12/0600Z 19.0N 60.0W 85 KT

ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
HURRICANE ISABEL DISCUSSION NUMBER 6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT SUN SEP 07 2003

SATELLITE IMAGERY THIS MORNING INDICATES THAT ISABEL HAS DEVELOPED A
VERY LARGE RAGGED EYE. SATELLITE INTENSITY ESTIMATES ARE 65 KT FROM
TAFB AND SAB...AND 77 KT FROM AFWA...SO THE INITIAL INTENSITY IS
SET AT 65 KT. THE UPPER-LEVEL OUTFLOW PATTERN IS NEARLY CIRCULAR
AND APPEARS TO BE UNRESTRICTED AND EXPANDING.

THE INITIAL MOTION IS 295/09...BASED ON ABOUT A 9 HOUR MOTION
BETWEEN SUCCESSIVE MICROWAVE POSITIONS. THE EYE FEATURE IS RAGGED
AND NOT REALLY A TRUE EMBEDDED EYE. CONVENTIONAL WATER VAPOR AND
SSMI VAPOR SATELLITE IMAGERY INDICATE DRY AIR HAS BEEN WRAPPING
INTO THE CENTER FROM THE SOUTHEAST THROUGH NORTHEAST...WHICH HAS
ACTUALLY ERODED THE CONVECTION ON THE NORTH SIDE. FOR THIS REASON
...THE INITIAL POSITION WAS PLACED NEAR THE SOUTHERN EDGE OF THE
'EYE' AND CLOSER TO THE DEEPEST CONVECTION. EVEN WITH THAT...THE
INITIAL POSITION IS STILL MORE THAN 40 NMI NORTH OF THE PREVIOUS
ADVISORY POSITION. THE GLOBAL MODELS ARE IN FAIRLY GOOD AGREEMENT
AND THERE IS GOOD CONVERGENCE ON A WEST-NORTHWESTWARD TRACK THROUGH
48-72 HOURS...WITH A MORE WESTWARD MOTION AFTER THAT. THIS IS
CONSISTENT WITH THE DEVELOPING SYNOPTIC PATTERN...WHICH INDICATES
THAT THE SUBTROPICAL RIDGE ALONG 32N LATITUDE SHOULD GRADUALLY
SHIFT WESTWARD AND PERHAPS EVEN CLOSE OFF A 500 MB HEIGHT CENTER A
COUPLE HUNDRED MILES SOUTHEAST OF BERMUDA. THE OFFICIAL TRACK IS
SIMILAR TO BUT TO THE RIGHT OF THE PREVIOUS TRACK...MAINLY DUE TO
THE MORE NORTHERLY INITIAL POSITION.

AT LEAST STEADY STRENGTHENING SHOULD OCCUR SINCE ISABEL NOW HAS AN
EYE FEATURE...IS OVER 82F WATER WITH WARMER SSTS AHEAD...AND HAS AN
IMPRESSIVE OUTFLOW PATTERN. BOTH THE SHIPS AND GFDL INTENSITY
MODELS BRING ISABEL UP TO 96 KT IN 42-60 HOURS...SO THIS TREND WAS
CLOSELY FOLLOWED. THE INTENSITY WAS LEVELED OFF AFTER 48 HOURS
SINCE ISABEL IS FORECAST TO BEGIN CROSSING A POSSIBLE COLD WAKE
LEFT BEHIND BY HURRICANE FABIAN LAST WEEK.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL 07/1500Z 14.5N 37.7W 65 KT
12HR VT 08/0000Z 15.1N 39.2W 75 KT
24HR VT 08/1200Z 15.8N 41.3W 85 KT
36HR VT 09/0000Z 16.6N 43.8W 95 KT
48HR VT 09/1200Z 17.3N 46.3W 100 KT
72HR VT 10/1200Z 18.5N 51.0W 100 KT
96HR VT 11/1200Z 19.0N 55.5W 100 KT
120HR VT 12/1200Z 19.5N 60.0W 100 KT


Becomes a hurricane.


ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
HURRICANE ISABEL DISCUSSION NUMBER 7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT SUN SEP 07 2003

THE ALLEGED EYE OF ISABEL PASSED OVER BUOY 13008 LOCATED AT 15N 38W
BETWEEN 14-15Z. THE BUOY REPORTED 37 KT AND 24 KT NORTHEAST WINDS
...TO THE SOUTH OF ALL THE SATELLITE CENTER POSITIONS. THESE WIND
REPORTS SUGGEST THAT THE ACTUAL CENTER IS FARTHER SOUTH NEAR THE
SOUTHERN PORTION OF THE EYE FEATURE...AS MENTIONED IN THE PREVIOUS
DISCUSSION. DURING THE PAST 6 HOURS...THE EYE FEATURE...OVERALL
CONVECTIVE PATTERN...AND OUTFLOW PATTERN HAVE CONTINUED TO IMPROVE.
THE INITIAL INTENSITY OF 70 KT IS BASED ON SATELLITE INTENSITY
ESTIMATES OF 65 KT FROM TAFB AND SAB...AND 77 KT FROM AFWA.

THE INITIAL MOTION ESTIMATE IS 295/13. THE INITIAL POSITION REMAINS
ABOUT 24 NMI SOUTH OF THE SATELLITE POSITIONS. THE 12Z GLOBAL
MODELS ARE IN EVEN BETTER AGREEMENT NOW ON KEEPING AT LEAST A
MODERATE SUBTROPICAL RIDGE NORTH OF ISABEL ALONG 32N LATITUDE
THROUGHOUT THE FORECAST PERIOD...AND EVEN BUILD IT WESTWARD ACROSS
THE BAHAMAS AND FLORIDA. THIS SHOULD KEEP ISABEL MOVING
WEST-NORTHWESTWARD THROUGH 48-72 HOURS...WITH A GRADUAL WESTWARD
MOTION DEVELOPING AFTER THAT. THE PREVIOUS FORECAST TRACK WAS ONLY
SHIFTED SLIGHTLY NORTHWARD AND SLOWED A LITTLE AFTER 72 HOURS...
WHICH IS CONSISTENT WITH THE GLOBAL MODEL CONSENSUS.

ISABEL CURRENTLY HAS A VERY IMPRESSIVE OUTFLOW PATTERN AND...
UNFORTUNATELY...THE GLOBAL MODELS ARE FORECASTING IT TO BECOME EVEN
BETTER. BY 36-48 HOURS... ALL OF THE GLOBAL MODELS EXCEPT THE UKMET
ARE FORECASTING MORE THAN 50 KT OF OUTFLOW ON THE WEST SIDE OF
ISABEL BEING DRAWN INTO AN UPPER-LEVEL LOW LOCATED JUST NORTHEAST
OF THE LEEWARD ISLANDS. A PATTERN LIKE THAT CAN OFTENTIMES LEAD TO
RAPID OR EXPLOSIVE DEEPENING. THE SHIPS INTENSITY MODEL BRINGS
ISABEL UP TO 97 KT IN 60 HOURS...BUT THE OFFICIAL FORECAST IS A
LITTLE HIGHER SINCE SHIPS WAS LOW/SLOW WITH THE INTENSIFICATION OF
FABIAN. THE INTENSITY WAS LEVELED OFF AFTER 48 HOURS SINCE ISABEL
MAY CROSS A POSSIBLE COLD WAKE LEFT BEHIND BY HURRICANE FABIAN.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL 07/2100Z 15.2N 39.1W 70 KT
12HR VT 08/0600Z 15.8N 40.5W 75 KT
24HR VT 08/1800Z 16.5N 42.8W 85 KT
36HR VT 09/0600Z 17.2N 45.2W 95 KT
48HR VT 09/1800Z 18.0N 47.7W 100 KT
72HR VT 10/1800Z 19.0N 52.0W 100 KT
96HR VT 11/1800Z 19.5N 55.5W 100 KT
120HR VT 12/1800Z 19.5N 60.0W 100 KT




ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
HURRICANE ISABEL DISCUSSION NUMBER 8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT SUN SEP 07 2003

ISABEL CONTINUES TO GET BETTER ORGANIZED AND HAS IMPRESSIVE COLD
CLOUD TOPS SURROUNDING THE 35 NMI DIAMETER EYE. THE INITIAL
INTENSITY OF 80 KT IS BASED ON SATELLITE INTENSITY ESTIMATES OF 77
KT FROM TAFB AND SAB...AND 90 KT FROM AFWA.

THE INITIAL MOTION ESTIMATE IS 285/13. ISABEL IS MOVING IN THIS
DIRECTION IN RESPONSE TO A SUBTROPICAL RIDGE TO THE NORTH. THE
GLOBAL MODELS ARE ALL IN AGREEMENT THAT THE RIDGE WILL REMAIN
THROUGHOUT THE FORECAST PERIOD AND ISABEL SHOULD CONTINUE TO MOVE
IN A WEST-NORTHWEST TO WEST MOTION FOR THE NEXT FIVE DAYS WITH THE
SYSTEM ENDING UP JUST TO THE NORTHEAST OF THE LEEWARD ISLANDS ON
DAY FIVE. THE OFFICIAL FORECAST REFLECTS THIS AND IS ESSENTIALLY AN
UPDATE OF THE PREVIOUS FORECAST.

THE SHIPS MODEL SEEMS TO BE HANDLING THE INTENSIFICATION OF ISABEL
VERY WELL SO THE INTENSITY FORECAST BASICALLY FOLLOWS THE SHIPS
GUIDANCE.

FORECASTER JARVINEN

FORECAST POSITIONS AND MAX WINDS

INITIAL 08/0300Z 16.1N 40.2W 80 KT
12HR VT 08/1200Z 16.8N 42.0W 85 KT
24HR VT 09/0000Z 17.7N 44.4W 90 KT
36HR VT 09/1200Z 18.5N 46.9W 95 KT
48HR VT 10/0000Z 19.2N 49.3W 100 KT
72HR VT 11/0000Z 19.7N 53.2W 100 KT
96HR VT 12/0000Z 20.2N 56.7W 100 KT
120HR VT 13/0000Z 20.5N 60.0W 100 KT


NNNN


ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
HURRICANE ISABEL DISCUSSION NUMBER 9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT MON SEP 08 2003

ISABEL CONTINUES TO GET BETTER ORGANIZED AND HAS IMPRESSIVE COLD
CLOUD TOPS SURROUNDING THE EYE WHICH HAS DECREASED IN DIAMETER SINCE
THE LAST ADVISORY. THE INITIAL INTENSITY IS NOW 90 KT AND IS BASED
ON SATELLITE INTENSITY ESTIMATES OF 102 KTS FROM TAFB AND 90 KTS
FROM SAB AND AIR FORCE GLOBAL. IN FACT...ISABEL MAY BE STRONGER BUT
I WANT TO SEE IF IT CAN MAINTAIN THESE SATELLITES ESTIMATES FOR AT
LEAST ANOTHER CYCLE BEFORE I GO ABOVE 90 KTS

THE INITIAL MOTION ESTIMATE IS 300/14. ISABEL IS MOVING IN THIS
DIRECTION IN RESPONSE TO A SUBTROPICAL RIDGE TO THE NORTH. BUT...
WATER VAPOR IMAGERY ALSO SHOWS AN UPPER COLD LOW THAT IS DEVELOPING
TO THE WEST OF ISABEL. THE SOUTHERLY AND SOUTHWESTERLY FLOW ON THE
EAST SIDE OF THIS COLD LOW MAY BE ADDING A NORTHERLY COMPONENT TO
THE MOTION. HOWEVER...THE GLOBAL MODELS EVENTUALLY MOVE THIS
SYSTEM TOWARD THE WEST AND WEAKEN IT. THE GLOBAL MODELS ARE ALL IN
AGREEMENT THAT THE RIDGE WILL REMAIN THROUGHOUT THE FORECAST PERIOD
AND ISABEL SHOULD CONTINUE TO MOVE IN A WEST-NORTHWEST TO WEST
MOTION FOR THE NEXT FIVE DAYS WITH THE SYSTEM ENDING UP JUST TO THE
NORTHEAST OF THE LEEWARD ISLANDS ON DAY FIVE. THE OFFICIAL FORECAST
REFLECTS THIS AND IS ESSENTIALLY AN UPDATE OF THE PREVIOUS
FORECAST.

THE SHIPS MODEL INTENSIFIES ISABEL TO 115 KTS IN 48 HOURS AND THE
OFFICIAL INTENSITY FORECAST REFLECTS THIS. HOWEVER...THE SYSTEM
MAY BE IN A RAPID DEEPENING MODE AND MAY GET STRONGER SOONER.

FORECASTER JARVINEN

FORECAST POSITIONS AND MAX WINDS

INITIAL 08/0900Z 16.9N 41.4W 90 KT
12HR VT 08/1800Z 17.9N 43.3W 100 KT
24HR VT 09/0600Z 18.8N 45.7W 105 KT
36HR VT 09/1800Z 19.4N 48.0W 110 KT
48HR VT 10/0600Z 19.8N 50.3W 115 KT
72HR VT 11/0600Z 19.9N 54.4W 115 KT
96HR VT 12/0600Z 20.2N 58.0W 115 KT
120HR VT 13/0600Z 20.6N 60.7W 115 KT


NNNN

MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
HURRICANE ISABEL DISCUSSION NUMBER 10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT MON SEP 08 2003

ISABEL HAS CONTINUED TO RAPIDLY INTENSIFY. THE INITIAL INTENSITY IS
INCREASED TO 100 KT BASED ON SATELLITE INTENSITY ESTIMATES OF 115
KT FROM TAFB AND AFWA...102 KT FROM SAB...AND 102 KT/T5.5 3-HOUR
OBJECTIVE DVORAK INTENSITY ESTIMATES. THE 100 KT INITIAL INTENSITY
IS ALSO CONSISTENT WITH THE LATEST AMSU INTENSITY ESTIMATES OF 100
KT AND 960 MB. OUTFLOW REMAINS QUITE IMPRESSIVE AND CONTINUES TO
IMPROVE AND THE EYE DIAMETER HAS DECREASED DOWN TO 25 NMI.

THE INITIAL MOTION ESTIMATE IS 290/12. IS APPEARS THAT ISABEL MAY BE
MAKING THE MORE WESTWARD TURN THAT THE GLOBAL MODELS HAVE BEEN
INDICATING. THE NHC MODEL GUIDANCE IS EVEN MORE TIGHTLY PACKED AND
IN GOOD AGREEMENT ON ISABEL MOVING WEST-NORTHWESTWARD FOR THE NEXT
36 HOURS...AND THEN TURNING MORE WESTWARD AFTER THAT. THIS IS QUITE
REASONABLE GIVEN THE STRENGTH AND EAST-WEST ORIENTATION OF THE
SUBTROPICAL RIDGE LOCATED ALONG 32N LATITUDE. A DISCONCERTING PART
OF THE MODEL GUIDANCE IS THE GFS AND NOGAPS MODELS CONTINUING TO
INSIST THAT ISABEL WILL MAKE A DIP SOUTH-OF-WEST AFTER 72 HOURS.
THEY BRING ISABEL DANGEROUSLY CLOSE TO THE NORTHERN LEEWARD ISLANDS
BY 120 HOURS. THE GFS AND NOGAPS HAD A LEFT OF TRACK BIAS WITH
FABIAN LAST WEEK...SO I PREFER TO WAIT ANOTHER 24 HOURS OR SO TO
SEE IF THIS SAME BIAS DEVELOPS. HOWEVER...THIS SCENARIO CAN NOT BE
COMPLETELY RULED OUT GIVEN THE DEEP MID-/UPPER-LEVEL TROUGH
NORTHWEST OF AFRICA THAT HAS BEEN DIGGING SOUTHWESTWARD. THAT COULD
CREATE ENOUGH LOW-LEVEL RIDGING FROM THE NORTHEAST TO NUDGE ISABEL
A LITTLE SOUTH OF DUE WEST...SIMILAR TO THE GFS-NOGAPS SCENARIO.

ISABEL IS ABOUT 18-24 HOURS INTO A RAPID INTENSIFICATION CYCLE...SO
THIS TREND IS FORECAST TO CONTINUE FOR ANOTHER 12 HOURS OR SO.
AFTER REACHING CATEGORY 4 INTENSITY...INNER-CORE CONVECTION AND
EYEWALL DYNAMICS WILL DICTATE ANY INTENSITY CHANGES. HOWEVER...THE
INTENSITY FORECAST COULD EASILY BE TOO LOW GIVEN THE CURRENT AND
FORECAST OUTFLOW PATTERN THAT WILL EVOLVE OVER THE NEXT 48 HOURS.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL 08/1500Z 17.2N 42.6W 100 KT
12HR VT 09/0000Z 17.9N 44.4W 115 KT
24HR VT 09/1200Z 18.6N 46.8W 120 KT
36HR VT 10/0000Z 19.2N 49.1W 120 KT
48HR VT 10/1200Z 19.4N 51.1W 120 KT
72HR VT 11/1200Z 19.5N 55.0W 120 KT
96HR VT 12/1200Z 19.5N 58.5W 120 KT
120HR VT 13/1200Z 20.0N 62.5W 120 KT


NNNN


ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
HURRICANE ISABEL DISCUSSION NUMBER 11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT MON SEP 08 2003

ISABEL HAS CONTINUED ITS RAPID INTENSIFICATION TREND. THE INITIAL
INTENSITY IS INCREASED TO 110 KT BASED ON SATELLITE INTENSITY
ESTIMATES OF 115 KT FROM TAFB AND AFWA...102 KT FROM SAB...AND 113
KT/T5.9 3-HOUR OBJECTIVE DVORAK INTENSITY ESTIMATES. THE OUTFLOW
REMAINS VERY IMPRESSIVE AND THE OVERALL CONVECTIVE PATTERN HAS ALSO
CONTINUED TO IMPROVE.

THE INITIAL MOTION ESTIMATE IS 295/12. THERE HAS BEEN SOME WOBBLING
ALONG THE TRACK THE PAST 6 HOURS...WHICH IS TYPICAL OF INTENSE
HURRICANES. THE NHC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON
ISABEL MOVING WEST-NORTHWESTWARD FOR THE NEXT 36 HOURS OR SO...AND
THEN TURNING MORE WESTWARD AFTER THAT. HOWEVER...THE GFS AND NOGAPS
MODELS MAINTAIN A WEST-SOUTHWESTWARD MOTION AFTER 48-72 HOURS. THE
REASON FOR THIS MORE SOUTHERLY TRACK IS NOT APPARENT IN THE MODEL
FIELDS...SO I AM CONTINUING TO PLACE LESS WEIGHT ON THAT SCENARIO
AT THIS TIME BASED ON THOSE MODELS HAVING A PREVIOUS LEFT-BIAS WITH
FABIAN. THE OFFICIAL FORECAST TRACK IS NUDGED SLIGHTLY NORTH OF THE
PREVIOUS TRACK THROUGH 36 HOURS...AND THEN COMES BACK ON TRACK
AFTER THAT. THIS IS CONSISTENT WITH THE GLOBAL MODEL CONSENSUS.

ISABEL IS 24 HOURS INTO A RAPID INTENSIFICATION CYCLE...BUT RARELY
DUE SUCH TRENDS OCCUR FOR MORE THAN 30-36 HOURS. THEREFORE...THE
CURRENT INTENSIFICATION TREND IS LEVELED OFF AFTER ABOUT 12 HOURS
OR SO. HOWEVER...UPPER-LEVEL CONDITIONS ARE FORECAST TO REMAIN
QUITE FAVORABLE THROUGHOUT THE FORECAST PERIOD...SO ISABEL COULD
STILL REACH CATEGORY 4 INTENSITY DURING THE NEXT 12 HOURS OR SO.
AFTER THAT...INNER-CORE CONVECTION AND EYEWALL DYNAMICS WILL
DICTATE ANY FURTHER INTENSITY CHANGES. HOWEVER...THE INTENSITY
FORECAST COULD EASILY BE TOO LOW GIVEN THAT THE OUTFLOW PATTERN IS
EXPECTED TO CONTINUE TO IMPROVE...THE VERTICAL SHEAR IS FORECAST TO
REMAIN LESS THAN 10 KT...AND ISABEL WILL BE MOVING OVER 28C AND
WARMER SSTS.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL 08/2100Z 17.9N 43.7W 110 KT
12HR VT 09/0600Z 18.6N 45.6W 120 KT
24HR VT 09/1800Z 19.2N 47.9W 125 KT
36HR VT 10/0600Z 19.5N 50.0W 125 KT
48HR VT 10/1800Z 19.5N 52.0W 125 KT
72HR VT 11/1800Z 19.5N 55.5W 125 KT
96HR VT 12/1800Z 19.5N 59.0W 125 KT
120HR VT 13/1800Z 20.0N 63.0W 125 KT

ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
HURRICANE ISABEL DISCUSSION NUMBER 12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT MON SEP 08 2003

DVORAK INTENSITY CLASSIFICATIONS FROM TAFB AND SAB WERE T6.0 OR 115
KT...AND THAT WILL BE THE ADVISORY INTENSITY. ISABEL HAS AN
IMPRESSIVE OUTFLOW PATTERN ALTHOUGH IT IS BEING SQUEEZED A LITTLE
BIT IN THE SOUTHWEST QUADRANT BY THE UPPER-LEVEL LOW TO ITS WEST.

THE INITIAL MOTION ESTIMATE IS 300/11. THERE IS A SPLIT IN THE
MODEL GUIDANCE THAT HAS SOME BEARING ON THE POTENTIAL THREAT TO THE
NORTHERN LEEWARD ISLANDS. WHILE THE CANADIAN AND UKMET MODELS BEND
THE TRACK ONLY SLIGHTLY TO THE LEFT FROM 24-72 HOURS...THE GFS AND
NOGAPS TURN THE TRACK HARDER...TO THE WEST-SOUTHWEST OR EVEN
SOUTHWEST...WHICH BRINGS THE CENTER UNCOMFORTABLY CLOSE TO THESE
ISLANDS. ONE DIFFERENCE IN THESE MODEL SOLUTIONS IS HOW STRONGLY
ISABEL INTERACTS WITH THE MID TO UPPER-LEVEL LOW CURRENTLY
APPROACHING THE HURRICANE FROM THE NORTHEAST...AS WELL AS THE
MID-LEVEL VORTEX ASSOCIATED WITH TROPICAL DEPRESSION FOURTEEN. IN
THE UKMET AND CANADIAN MODELS THERE IS NO APPRECIABLE
INTERACTION...WHILE IN THE GFS AND NOGAPS THE LOW IS CLOSE ENOUGH
TO DRAG ISABEL SOUTHWARD. IN PART BECAUSE OF THE IMPRESSIVE
ANTICYCLONIC OUTFLOW IN THE NORTHEAST QUADRANT OF ISABEL...AND THE
CURRENT DISARRAY OF TD FOURTEEN...MY FEELING IS THAT THE
INTERACTION IS BEING OVERDONE BY THE GFS AND NOGAPS. THE OFFICIAL
FORECAST IS VERY CLOSE TO THE GLOBAL MODEL CONSENSUS AND GFDL
SOLUTIONS...AND SLIGHTLY TO THE RIGHT OF THE PREVIOUS FORECAST.

I HAVE BACKED OFF A BIT FROM THE INTENSITY FORECAST OF THE PREVIOUS
ADVISORY. SST ANALYSES SHOW THAT ISABEL WILL BE PASSING OVER THE
COOL WAKE OF FABIAN IN ABOUT 36 HOURS...AND THERE COULD BE SOME
RESTRICTION OF THE OUTFLOW BY THE UPPER LOW APPROACHING FROM THE
NORTHEAST...EVEN IF THAT LOW DOES NOT COME CLOSE ENOUGH TO
APPRECIABLY AFFECT THE TRACK. IT IS ALSO QUITE RARE FOR STORMS TO
MAINTAIN MAJOR HURRICANE STATUS FOR FIVE DAYS. EVEN WITH THIS
ADJUSTMENT...THE OFFICIAL FORECAST REMAINS ABOVE THE GFDL AND SHIPS
INTENSITY GUIDANCE.

FORECASTER FRANKLIN

FORECAST POSITIONS AND MAX WINDS

INITIAL 09/0300Z 18.5N 44.5W 115 KT
12HR VT 09/1200Z 19.2N 46.2W 120 KT
24HR VT 10/0000Z 19.9N 48.5W 125 KT
36HR VT 10/1200Z 20.0N 50.6W 120 KT
48HR VT 11/0000Z 20.0N 52.5W 115 KT
72HR VT 12/0000Z 20.0N 56.0W 110 KT
96HR VT 13/0000Z 20.0N 59.5W 110 KT
120HR VT 14/0000Z 21.0N 63.0W 110 KT
Last edited by Matt-hurricanewatcher on Fri Jul 25, 2008 10:52 pm, edited 2 times in total.
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Re: Hurricane Isabel

#2 Postby Matt-hurricanewatcher » Fri Jul 25, 2008 10:30 pm

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Track of hurricane Isabel. Cat5!
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