Tropical Storm FLOSSIE (CPAC): Discussions, Analysis and Ima

[clfenwi]

WTPA42 PHFO 122041
TCDCP2

HURRICANE FLOSSIE DISCUSSION NUMBER 17
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092007
1100 AM HST SUN AUG 12 2007

SATELLITE IMAGES OVER THE PAST 6 HOURS INDICATE A WEAKENING OF
HURRICANE FLOSSIE IN TERMS OF WARMER CLOUD TOP TEMPERATURES AND A
RESTRICTED UPPER LEVEL OUTFLOW IN THE SOUTHEASTERN SEMICIRCLE. A
1622 UTC MICROWAVE PASS ALSO SHOWED A BREAK IN THE EYEWALL TO THE
EAST. THE DVORAK T-NUMBER ESTIMATES FROM PHFO AND SAB HAVE COME
DOWN TO 102 KT BUT THE CURRENT INTENSITIES HAVE BEEN KEPT UP AT 127
KT AND 115 KT RESPECTIVELY. THE ADT INTENSITY ESTIMATE INDICATES
115 KT. GIVEN THE WEAKER PRESENTATION IN THE LATEST IMAGES THE
INITIAL INTENSITY WILL BE LOWERED A NOTCH TO 115 KT.

FLOSSIE IS MOVING IN A GENERAL WEST-NORTHWEST DIRECTION AT 12 KT TO
THE SOUTH OF A SUBTROPICAL RIDGE. THE LARGE-SCALE MODELS ALL
DEVELOP AN UPPER LEVEL TROUGH NEAR THE HAWAIIAN ISLANDS WITHIN THE
NEXT COUPLE OF DAYS. THE STRENGTH OF THE TROUGH AND THE EFFECTS OF
VERTICAL SHEAR FROM THE ASSOCIATED SOUTHERLY WINDS PLAY A KEY ROLE
IN DETERMINING THE FUTURE TRACK AND INTENSITY OF FLOSSIE. THE
LATEST OBJECTIVE AIDS ARE LESS TIGHTLY PACKED THAN 6 HOURS AGO WITH
THE HWRF SHIFTING CONSIDERABLY AND BECOMING ONE OF THE NORTHERN
OUTLIERS. NOGAPS IS ALSO A NORTHERN OUTLIER WHILE THE GFS AND UKMET
SOLUTIONS ARE ON THE SOUTH SIDE OF THE ENVELOPE. THE FORECAST
TRACK IS SLIGHTLY FASTER THAN THE PREVIOUS PACKAGE DUE TO A SMALL
SPEED INCREASE IN THE GUIDANCE BUT THE ALIGNMENT REMAINS UNCHANGED
AND IS NORTH OF THE VARIOUS CONSENSUS TRACKS.

IT APPEARS VERTICAL SHEAR IS STARTING TO AFFECT FLOSSIE AS INDICATED
BY RESTRICTED OUTFLOW IN SATELLITE IMAGERY AND A CIMSS ANALYSIS
SHOWING 10 TO 15 KT OF SHEAR FROM THE SOUTHEAST. SHEAR IS EXPECTED
TO INCREASE OVER THE NEXT SEVERAL DAYS AND SEA SURFACE TEMPERATURES
SHOULD SLOWLY DECREASE ALONG THE FORECAST TRACK UNTIL FLOSSIE
PASSES SOUTH OF THE BIG ISLAND. THE CURRENT INTENSITY FORECAST
FOLLOWS THE PREVIOUS FORECAST AND IS ROUGHLY IN LINE WITH THE GFDL
BUT HIGHER THAN HWRF AND SHIPS. THIS KEEPS FLOSSIE AT HURRICANE
STRENGTH AS IT PASSES SOUTH OF THE BIG ISLAND OF HAWAII ON TUESDAY.

THE CURRENT TRACK AND INTENSITY FORECAST MAY REQUIRE WATCHES FOR
PORTIONS OF THE HAWAIIAN ISLANDS EARLY ON MONDAY.

AIR FORCE RECONNAISSANCE IS ENROUTE AND IS SCHEDULED TO MAKE ITS
FIRST PASS THROUGH THE SYSTEM AT AROUND 13/0000 UTC.

FORECAST POSITIONS AND MAX WINDS

INITIAL 12/2100Z 13.9N 145.8W 115 KT
12HR VT 13/0600Z 14.4N 147.5W 110 KT
24HR VT 13/1800Z 15.3N 149.8W 100 KT
36HR VT 14/0600Z 16.2N 151.8W 95 KT
48HR VT 14/1800Z 17.0N 154.0W 90 KT
72HR VT 15/1800Z 18.5N 157.8W 70 KT
96HR VT 16/1800Z 20.0N 161.5W 55 KT
120HR VT 17/1800Z 21.3N 165.7W 50 KT

$$
FORECASTER KODAMA/BIRCHARD

[clfenwi]

BULLETIN
HURRICANE FLOSSIE ADVISORY NUMBER 17
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092007
1100 AM HST SUN AUG 12 2007

...DANGEROUS HURRICANE FLOSSIE CONTINUES TO MOVE TOWARD THE
HAWAIIAN ISLANDS...

AT 1100 AM HST...2100Z...THE CENTER OF HURRICANE FLOSSIE WAS
LOCATED NEAR LATITUDE 13.9 NORTH...LONGITUDE 145.8 WEST OR ABOUT
735 MILES EAST-SOUTHEAST OF HILO HAWAII AND ABOUT 945 MILES
EAST-SOUTHEAST OF HONOLULU HAWAII.

FLOSSIE IS MOVING TOWARD THE WEST-NORTHWEST NEAR 14 MPH AND THIS
MOTION IS EXPECTED TO CONTINUE OVER THE NEXT 24 HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 135 MPH...WITH HIGHER GUSTS. SOME
WEAKENING IS FORECAST DURING THE NEXT 24 HOURS.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 40 MILES FROM THE
CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 90
MILES.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 949 MB...28.02 INCHES.

EVERYONE IN THE HAWAIIAN ISLANDS IS URGED TO CONTINUE MONITORING
THE PROGRESS OF HURRICANE FLOSSIE. THE CURRENT FORECAST BRINGS
TROPICAL STORM FORCE WINDS TO THE SOUTHERN BIG ISLAND LATE TUESDAY.
HOWEVER...A NORTHWARD SHIFT IN THE TRACK COULD POTENTIALLY BRING
HURRICANE CONDITIONS TO THE BIG ISLAND.

REPEATING THE 1100 AM HST POSITION...13.9 N...145.8 W. MOVEMENT
TOWARD...WEST-NORTHWEST NEAR 14 MPH. MAXIMUM SUSTAINED WINDS...
135 MPH. MINIMUM CENTRAL PRESSURE...949 MB.

THE NEXT ADVISORY WILL BE ISSUED BY THE CENTRAL PACIFIC HURRICANE
CENTER AT 500 PM HST.

$$
FORECASTER KODAMA/BIRCHARD

[hurricanefloyd5]

windsdown to 130mph

[HurricaneRobert]

This is still a beautiful storm and the eye looks very solid, despite the loss of convection in the SE (due to shear?). Is that an indication that it is annular? It looks like Daniel from last year.

[miamicanes177]

It looks better now than it did a couple of hours ago. Maybe it's trying to maintain itself and resist rapid decay.

[Derek Ortt]

convection is coming back... likely just a minor fluctuation.

This is close to its MPI

[HurricaneRobert]

Hawaii is finally coming into view on the floater. Also hwrf and gfdl have flipped their predicted tracks. GFDL is taking it south of the big island and HWRF is taking it north. Do these models have as many problems predicting intensity when a hurricane is annular as they do for rapid intensification?

[Derek Ortt]

yes... the models are beyond brutal for annular hurricanes, ESPECIALLY SHIPS

[HurricaneBill]

Has an annular cyclone ever happened in the southern hemisphere?

[Chacor]

Has an annular cyclone ever happened in the southern hemisphere?

Earlier this year, Meteo France noted one of the cyclones looked annular. I'll have to check which one it was.

[Derek Ortt]

not sure, but I'd check the Brazilian hurricane as it formed over water temps that favor annular hurricanes

[Chacor]

Has an annular cyclone ever happened in the southern hemisphere?

Earlier this year, Meteo France noted one of the cyclones looked annular. I'll have to check which one it was.

Intense TC Dora was said by MF to be annular. And Derek Catarina had rainbands definitely (it was also partially attached to a front if I remember correctly).

[TexasSam]

I had to go look up what a Annular hurrican is:

Annular hurricane
From Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Annular_hurricane

[Derek Ortt]

I'll have to recheck the microwave for catarina whenever NRL ever gets up and running (there hasn't been GFDN... so I dont think its just an NRL website issue)

[HURAKAN]

TROPICAL CYCLONE GUIDANCE MESSAGE
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI
0041 UTC MON AUG 13 2007

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO CPHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

CENTRAL PACIFIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE FLOSSIE (EP092007) 20070813 0000 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
070813 0000 070813 1200 070814 0000 070814 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 13.8N 146.4W 14.7N 149.1W 15.8N 151.7W 16.9N 153.9W
BAMD 13.8N 146.4W 14.8N 149.1W 16.1N 151.8W 17.6N 153.9W
BAMM 13.8N 146.4W 14.4N 149.0W 15.4N 151.7W 16.5N 153.9W
LBAR 13.8N 146.4W 14.2N 148.6W 15.2N 150.9W 16.2N 152.8W
SHIP 115KTS 97KTS 81KTS 65KTS
DSHP 115KTS 97KTS 81KTS 65KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
070815 0000 070816 0000 070817 0000 070818 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 17.8N 156.0W 19.0N 159.8W 19.5N 164.2W 20.1N 169.6W
BAMD 19.1N 155.3W 22.4N 155.3W 25.7N 151.5W 28.6N 146.2W
BAMM 17.4N 155.6W 18.8N 158.0W 19.5N 160.0W 20.1N 163.0W
LBAR 17.5N 154.2W 19.8N 155.4W 22.2N 154.6W 26.0N 153.3W
SHIP 55KTS 40KTS 28KTS 16KTS
DSHP 55KTS 40KTS 28KTS 16KTS

...INITIAL CONDITIONS...
LATCUR = 13.8N LONCUR = 146.4W DIRCUR = 275DEG SPDCUR = 11KT
LATM12 = 13.5N LONM12 = 144.0W DIRM12 = 278DEG SPDM12 = 11KT
LATM24 = 13.2N LONM24 = 141.7W
WNDCUR = 115KT RMAXWD = 15NM WNDM12 = 120KT
CENPRS = 959MB OUTPRS = 1011MB OUTRAD = 180NM SDEPTH = D
RD34NE = 90NM RD34SE = 70NM RD34SW = 70NM RD34NW = 90NM

$$
NNNN

[Cyclenall]

It looks like it's back to 120 knots now IMO, better looking and the convection is a bit deeper then this afternoon. The eye just has to clear out again.

[Chacor]

It looks like it's back to 120 knots now IMO, better looking and the convection is a bit deeper then this afternoon. The eye just has to clear out again.

Given what recon found only a short time ago (121 kt flight level) I don't think they'll raise it back to 120.

[CrazyC83]

I'd nudge it down to 110 kt with a 955 pressure right now...thinking the 956 lowest found in Recon did not sample the whole thing. Still I see no evidence of it still being Cat 4.

[Cyclenall]

It looks like it's back to 120 knots now IMO, better looking and the convection is a bit deeper then this afternoon. The eye just has to clear out again.

Given what recon found only a short time ago (121 kt flight level) I don't think they'll raise it back to 120.

I actually forgot they put recon through Flossie, it took a while. It looks like 120 knots, but recon only found 110 knots? Oops .

[Coredesat]

They didn't raise it, but they didn't lower it either:

WTPA42 PHFO 130251
TCDCP2

HURRICANE FLOSSIE DISCUSSION NUMBER 18
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP092007
500 PM HST SUN AUG 12 2007

FLOSSIE CONTINUES TO MAINTAIN AN IMPRESSIVE SATELLITE SIGNATURE THIS
AFTERNOON...ALTHOUGH EYE WALL CONVECTION IS NOT AS WIDE AS IT WAS AT
THIS TIME YESTERDAY. CURRENT SATELLITE DVORAK INTENSITIES RANGE FROM
6.0 TO 6.5...AND AIR FORCE RECONNAISSANCE AIRCRAFT REPORTED MAXIMUM
FLIGHT LEVEL WINDS OF 121 KT IN THE NORTHEAST QUADRANT THIS
AFTERNOON. WITH THIS CONGRUENT DATA IN MIND...THE ADVISORY INTENSITY
WILL REMAIN 115 KT. AIRCRAFT DATA ALSO CONFIRMED THAT FLOSSIE IS A
TIGHTLY-WOUND SYSTEM...WITH TROPICAL STORM FORCE WINDS OBSERVED IN A
RADIUS SIMILAR TO THOSE CONTAINED IN PREVIOUS ADVISORIES.

FORECAST REASONING HAS CHANGED LITTLE FROM THE PREVIOUS ADVISORY...
SO THE NEW FORECAST TRACK OFFERS FEW CHANGES. FLOSSIE IS TRACKING
TOWARD THE WEST-NORTHWEST UNDER THE INFLUENCE OF A MID AND UPPER
RIDGE TO ITS NORTH...AND THIS SYNOPTIC SCENARIO IS NOT EXPECTED TO
CHANGE MUCH THROUGH TOMORROW...EXPOSING THE SYSTEM TO MODERATE SHEAR
FROM THE SOUTH AND SOUTHEAST. AFTERWARD...FLOSSIE WILL BE ENTERING
AN ENVIRONMENT OF INCREASING SOUTHERLY SHEAR...DUE TO THE PRESENCE
OF A PERSISTENT UPPER TROUGH NORTHWEST OF THE MAIN HAWAIIAN ISLANDS.
THE STRENGTH OF THE TROUGH...AND THE EFFECTS OF VERTICAL SHEAR FROM
THE ASSOCIATED SOUTHERLY WINDS...WILL PLAY A KEY ROLE IN DETERMINING
THE FUTURE TRACK AND INTENSITY OF FLOSSIE. LATEST OBJECTIVE AIDS ARE
FAIRLY TIGHTLY PACKED...WITH THE NOGAPS AND CONSENSUS MODELS
SHIFTING SOUTHWARD FROM EARLIER RUNS. THE TRACK FORECAST LIES ON THE
NORTHERN SIDE OF THE ENVELOPE...IN DEFERENCE TO THE CYCLONE/S
POSITION IN RELATION TO THE ISLANDS.

THE INTENSITY FORECAST CALLS FOR A WEAKENING TREND THROUGH THE
PERIOD AS THE CYCLONE MOVES OVER AREAS OF LOWER OCEANIC HEAT
CONTENT...AND INCREASED SOUTHERLY SHEAR. INITIALLY THE WEAKENING
TREND WILL BE GRADUAL DUE TO MODERATE SOUTHERLY SHEAR...WITH
INCREASING SHEAR VALUES LATER IN THE PERIOD LEADING TO A MORE
ROBUST WEAKENING TREND. THE FORECAST CLOSELY FOLLOWS THE PREVIOUS
FORECAST AS WELL AS THE GFDL AND HWRF GUIDANCE...AND KEEPS FLOSSIE
AT HURRICANE STRENGTH AS IT PASSES SOUTH OF THE BIG ISLAND OF HAWAII
LATE TUESDAY.

THE CURRENT TRACK AND INTENSITY FORECAST MAY REQUIRE WATCHES FOR
PORTIONS OF THE HAWAIIAN ISLANDS EARLY ON MONDAY.

FORECAST POSITIONS AND MAX WINDS

INITIAL 13/0300Z 14.0N 147.0W 115 KT
12HR VT 13/1200Z 14.6N 148.8W 110 KT
24HR VT 14/0000Z 15.6N 151.0W 105 KT
36HR VT 14/1200Z 16.5N 153.3W 100 KT
48HR VT 15/0000Z 17.2N 155.2W 90 KT
72HR VT 16/0000Z 18.7N 158.9W 70 KT
96HR VT 17/0000Z 20.3N 162.6W 55 KT
120HR VT 18/0000Z 21.1N 167.0W 50 KT

$$

FORECASTER BIRCHARD/KODAMA