Caribbean-On-Line's Caribbean Hurricane Blog



Tropical Storm Josephine

Hanna, Ike and Josephine: Triple Storm Threat

Published on September 4, 2008 5:35 PM | Comments

This isn't that old, but the NHC seems to think that Hanna will not become a hurricane again. Also - Ike will probably weaken a bit, and they describe it here as a "monster" storm when in fact at this point the footprint of Ike is rather small for a category 4 storm. Sort of distressing that they have to hype the news like this and can't just report the facts. And no mention in this report of the number of dead in Haiti - just the phrase "wreaked havoc":




TROPICAL STORM JOSEPHINE DISCUSSION NUMBER 3

Published on September 2, 2008 6:14 PM | Comments

TROPICAL STORM JOSEPHINE DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL102008 500 PM EDT TUE SEP 02 2008

JOSEPHINE CONTINUES TO EXHIBIT A RATHER IMPRESSIVE APPEARANCE IN VISIBLE IMAGERY...ALTHOUGH THE INFRARED CLOUD TOPS ARE STILL NOT ALL THAT COLD...WITH SOLID AND FAIRLY SYMMETRIC CONVECTIVE BANDING AND WELL-DEFINED UPPER-LEVEL OUTFLOW IN ALL DIRECTIONS. LACKING ACTUAL WIND DATA ANYWHERE NEAR THE CENTER OF THE CYCLONE...THE INITIAL INTENSITY ESTIMATE IS AN UNCERTAIN 45 KT. SOME DVORAK ESTIMATES AND AN EARLIER AMSU INTENSITY ESTIMATE SUGGEST THE STORM COULD BE A LITTLE STRONGER...BUT WE CAN WAIT UNTIL THE VARIOUS ESTIMATES PERHAPS COME INTO BETTER AGREEMENT. NEVER MIND THE DETAILS...JOSEPHINE APPEARS POISED TO STRENGTHEN SOME MORE. THE STORM IS CURRENTLY LOCATED OVER RATHER WARM SEA-SURFACE TEMPERATURES OF ABOUT 28 CELSIUS...AND THE WATERS WILL REMAIN THAT WARM FOR ABOUT THE NEXT 24 HOURS. COMBINE THAT WITH THE COMPLETE ABSENCE OF WIND SHEAR...AND STRENGTHENING APPEARS LIKELY IN THE SHORT TERM. ALL OF THE OBJECTIVE GUIDANCE MODELS EXCEPT FOR THE HWRF FORECAST A HURRICANE...AND THE INTENSITY CONSENSUS IS AT 65 KT AT 24 HOURS. THIS IS ALSO SHOWN IN THE NEW OFFICIAL FORECAST... WHICH IS AN UPWARD ADJUSTMENT FROM THE PREVIOUS ADVISORY. ALL OF THE INTENSITY GUIDANCE CONTINUES TO FORECAST A WEAKENING TREND AT DAYS 3-5...HOWEVER...IN RESPONSE TO JOSEPHINE PASSING OVER COOLER SSTS IN A COUPLE OF DAYS...AND DUE TO INCREASING SOUTHERLY WIND SHEAR ON THE EASTERN FLANK OF AN UPPER-LEVEL LOW. GIVEN THIS GUIDANCE...THE OFFICIAL FORECAST SHOWS A WEAKER CYCLONE AT FIVE DAYS...AND EVEN 55 KT IS ABOVE NEARLY ALL OF THE MODEL PREDICTIONS.

A SUBTROPICAL RIDGE CENTERED NORTHWEST OF JOSEPHINE IS USHERING THE TROPICAL CYCLONE WEST-NORTHWESTWARD AT ABOUT 290/12. MODELS ARE CLUSTERED FAIRLY TIGHTLY AROUND THIS SAME HEADING AND SPEED FOR THE NEXT 48 HOURS. AFTER THAT...THE GFDL AND HWRF FORECAST A FASTER MOTION THAT EVENTUALLY BECOMES NORTHWESTWARD INTO A WEAKNESS IN THE RIDGE ASSOCIATED WITH THE DEEP-LAYER LOW THAT WILL CROSS THE NORTH-CENTRAL ATLANTIC. THE GLOBAL MODELS ARE EITHER SLOWER OR FARTHER SOUTH. SINCE THE GFDL AND HWRF SEEM TO HAVE THE BEST HANDLE ON THE INITIAL MOTION...THOSE SOLUTIONS ARE SLIGHTLY FAVORED...AND THE OFFICIAL TRACK FORECAST IS A LITTLE RIGHT OF THE CONSENSUS AND IS VERY SIMILAR TO THE PREVIOUS ADVISORY.



TROPICAL STORM JOSEPHINE DISCUSSION NUMBER 2

Published on September 2, 2008 12:33 PM | Comments

So Josephine is pretty organized and could intensify rapidly to a point - and then the various computer models tend to disagree as to what happens. We need to keep and eye on this one.

TROPICAL STORM JOSEPHINE DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL102008 1100 AM EDT TUE SEP 02 2008

VISIBLE IMAGERY REVEALS AN INCREASE IN THE CYCLONE'S ORGANIZATION...WITH VERY WELL-DEFINED CONVECTIVE BANDS AND EVEN A DECEPTIVE CENTRAL FEATURE DISGUISED AS AN EYE. THE CONVECTIVE TOPS ARE NOT EXCEPTIONALLY COLD IN THE INFRARED...BUT DVORAK INTENSITY ESTIMATES ARE A CONSENSUS 35 KT...SO THE DEPRESSION IS UPGRADED TO A TROPICAL STORM...THE TENTH OF THE 2008 ATLANTIC SEASON. JOSEPHINE IS CURRENTLY OVER SEA-SURFACE TEMPERATURES OF ABOUT 28 CELSIUS...AND THE WATERS ALONG THE FORECAST TRACK WILL REMAIN AT LEAST THAT WARM FOR ABOUT THE NEXT 24 HOURS. WIND SHEAR IS ESSENTIALLY NON-EXISTENT OVER THE CYCLONE...SO STEADY STRENGTHENING SEEMS LIKELY IN THE SHORT TERM...AND COULD BE RAPID GIVEN THE INCREASED ORGANIZATION AND THAT THE SHIPS-BASED RI INDEX GIVES A 50% CHANCE OF AN INTENSITY INCREASE OF 30 KT OR MORE IN THE NEXT 24 HOURS. BEYOND 24 HOURS...JOSEPHINE WILL TRAVERSE SLIGHTLY COOLER WATERS...AND DUE TO AN UPPER-LEVEL LOW FORECAST BY THE MODELS TO MOVE IN TANDEM WITH THE TROPICAL CYCLONE...WIND SHEAR WILL PROBABLY INCREASE IN A COUPLE OF DAYS. EVEN THOUGH ALL OF THE OBJECTIVE GUIDANCE CALLS FOR A WEAKENING TREND TO START BY 72 HOURS...TO MAINTAIN SOME CONTINUITY THE NEW OFFICIAL INTENSITY FORECAST SIMPLY SHOWS AN INTENSITY PLATEAU AT 60 KT IN THE LONGER TERM.

THE INITIAL MOTION REMAINS BRISK ALONG A HEADING JUST NORTH OF DUE WEST...OR 280/13...BUT THE INITIAL POSITION HAS BEEN ADJUSTED SLIGHTLY NORTH OF THE PREVIOUS TRACK BASED ON VISIBLE IMAGERY AND AN EARLIER QUIKSCAT PASS. A MID-LEVEL HIGH CENTERED OVER THE EAST-CENTRAL SUBTROPICAL ATLANTIC IS CURRENTLY THE PRIMARY STEERING MECHANISM...BUT THIS FEATURE IS FORECAST BY THE MODELS TO PROCEED WESTWARD AND SHIFT TO THE WESTERN ATLANTIC IN A FEW DAYS. MEANWHILE...THE DEEP-LAYER LOW JUST OFF THE NORTHEASTERN UNITED STATES WILL PROPAGATE EASTWARD AND ERODE THE RIDGE NORTH OF JOSEPHINE...WHICH WILL PROBABLY JUST CAUSE A SLIGHT BEND TO THE RIGHT AND A SLOWER FORWARD MOTION AT DAYS 3-5. MODELS ARE IN VERY GOOD AGREEMENT THROUGH 48 HOURS BUT THEN DIVERGE MARKEDLY...WITH THE GFS TURNING THE CYCLONE WESTWARD AND THE GFDL AND HWRF TAKING IT NORTHWESTWARD. THE OFFICIAL TRACK FORECAST SPLITS THE DIFFERENCE AND FOLLOWS THE CONSENSUS...WHICH IS JUST A LITTLE NORTH OF THE PREVIOUS ADVISORY.



Tropical Storm Josephine Open Thread

Published on September 2, 2008 12:26 PM | Comments

Use this post to ask questions or post comments about Tropical Storm Josephine.



Tropical Storm Josephine 5 Day Cone

Published on September 2, 2008 12:07 PM | Comments



TD 10

Published on September 2, 2008 8:35 AM | Comments

If TD 10 does (and it is forecast to) become a named storm it will be "Josephine".



TROPICAL DEPRESSION TEN DISCUSSION NUMBER 1

Published on September 2, 2008 5:29 AM | Comments

TROPICAL DEPRESSION TEN DISCUSSION NUMBER 1 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL102008 500 AM EDT TUE SEP 02 2008

SATELLITE IMAGERY INDICATES THE LARGE TROPICAL DISTURBANCE JUST SOUTH OF THE CAPE VERDE ISLANDS HAS DEVELOPED ENOUGH CONVECTIVE CURVED BAND FEATURES TO BE CLASSIFIED AS TROPICAL DEPRESSION TEN. SATELLITE INTENSITY ESTIMATES ARE T2.0/30 KT AND T2.5/35 KT FROM TAFB AND SAB...RESPECTIVELY.

THE INITIAL MOTION ESTIMATE IS 275/14. THE DEPRESSION IS EXPECTED TO MOVE IN A WEST TO WEST-NORTHWESTWARD MOTION FOR THE NEXT 24 HOURS OR SO...AND THEN TURN MORE WEST-NORTHWESTWARD AND SLOW A LITTLE BIT AS THE CYCLONE MOVES INTO A WEAKNESS IN THE SUBTROPICAL RIDGE TO THE NORTH. THE MID/UPPER-LEVEL TROUGH THAT IS EXPECTED TO WEAKEN THE RIDGE BETWEEN 30N-40 LONGITUDE IS FORECAST BY MOST OF THE GLOBAL MODELS TO WEAKEN AND LIFT OUT TO THE NORTHEAST BY 72-96 HOURS...WHICH WILL ALLOW THE RIDGE TO SLOWLY BUILD BACK IN AND TURN THE CYCLONE MORE WESTWARD BY DAYS 4 AND 5. THE OFFICIAL FORECAST IS SIMILAR TO BUT TO THE SOUTH OF THE NHC MODEL CONSENSUS TO ACCOUNT FOR WHAT APPEARS TO BE A POLEWARD BIAS BY THE GFDL AND HWRF MODELS.

THE CYCLONE IS EXPECTED TO STEADILY INTENSIFY FOR THE NEXT 24 HOURS OR SO DUE TO A VERY FAVORABLE UPPER-LEVEL FLOW REGIME. HOWEVER...BY 36-48 HOURS...ALL OF THE MODELS SUGGEST THAT SOUTHERLY VERTICAL SHEAR OF 20-30 KT WILL DEVELOP...WHICH COULD DISRUPT OR EVEN HALT THE STRENGTHENING PROCESS. SOME OF THE MODELS LIKE THE GFS COMPLETELY DISSIPATE THE CYCLONE...WHICH SEEMS UNREASONABLE AT THIS TIME GIVEN THE LARGE CIRCULATION ENVELOPE NOTED IN SATELLITE IMAGERY. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE SHIPS MODEL THROUGH 48 HOURS...AND THEN HIGHER AT 96 AND 120 HOURS DUE TO THE CYCLONE FORECAST TO REMAIN SOUTH OF 20N LATITUDE OVER WARMER WATER AND UNDER LESS SHEAR THAN THE SHIPS MODEL IS DEPICTING.