ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM TROPICAL STORM KEVIN DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP142009 200 PM PDT SAT AUG 29 2009 THE CYCLONE HAS DEVELOPED A CURVED BAND THAT WRAPS AROUND TO THE WEST AND SOUTH OF THE ESTIMATED CENTER...RESULTING IN DVORAK CI-NUMBERS OF 3.0 FROM TAFB AND 2.5 FROM SAB AND 1800 UTC. BASED ON THIS...THE CYCLONE IS UPGRADED TO KEVIN WITH AN INITIAL INTENSITY OF 40 KT. KEVIN IS THE SEVENTH NAMED STORM TO FORM THIS MONTH IN THE EAST PACIFIC BASIN...THE MOST IN AUGUST SINCE 1968 AND THE MOST IN ANY MONTH SINCE 1985. RECENT SATELLITE DATA SUGGESTS THAT THE CENTER OF KEVIN IS LOCATED FARTHER SOUTHWEST THAN PREVIOUSLY THOUGHT. THE CYCLONE IS CURRENTLY LOCATED SOUTH OF A WEAKNESS IN THE SUBTROPICAL RIDGE...RESULTING IN LIGHT STEERING CURRENT. AS A RESULT...THE CYCLONE HAS BEEN MOVING VERY LITTLE OVER THE PAST SEVERAL HOURS. A LONGER-TERM INITIAL MOTION ESTIMATE OF 285/08 WAS USED TO INITIALIZE THE GUIDANCE...AND THE ADVISORY MOTION IS 290/04. THE TRACK MODEL GUIDANCE SHOWS A VERY WIDE SPREAD THROUGH THE PERIOD. THE GFDL...HWRF...AND ALL OF THE GLOBAL MODELS EXCEPT THE CANADIAN NOW SHOW AT LEAST SOME EASTWARD COMPONENT OF MOTION. THIS SEEMS TO BE DUE TO INTERACTION OF KEVIN WITH HURRICANE JIMENA AND THE STEERING INFLUENCE OF A MID- TO UPPER-LEVEL TROUGH THAT IS CURRENTLY DIGGING SOUTHWEST FROM BAJA CALIFORNIA. THE AMOUNT OF EASTWARD MOTION VARIES DRAMATICALLY...WITH THE UKMET...GFDL... GFS...NOGAPS...AND ECMWF SHOWING AN EASTWARD COMPONENT OF MOTION THROUGH DAY 5. HOWEVER...THE HWRF...GFS ENSEMBLE MEAN AND CANADIAN SHOW A TURN TO THE WEST LATE IN THE PERIOD...IT IS DIFFICULT TO SORT OUT THESE DIFFERENCES SINCE THE GLOBAL MODEL ANALYSES OF BOTH JIMENA AND KEVIN SEEM TO BE TOO WEAK. ALSO...THE HWRF RUN FOR KEVIN HAS AN UNREALISTICALLY WEAK REPRESENTATION OF JIMENA...WHICH IS THE MUCH STRONGER CYCLONE AT THIS TIME. ALL THIS BEING SAID...THE OFFICIAL FORECAST TRACK HAS BEEN MODIFIED CONSIDERABLY FROM THE PREVIOUS PACKAGE. INITIALLY...THE TRACK IS FARTHER SOUTHWEST OF THE PREVIOUS PACKAGE DUE TO THE INITIAL POSITION AND MOTION. LATER IN THE PERIOD...THE OFFICIAL FORECAST TRENDS TOWARD THE MODELS THAT SHOW THE EASTWARD TURN. AFTER AN INITIAL NORTHWEST MOTION...THE FORECAST TURNS KEVIN NORTHWARD BY 24 HOURS FOLLOWED BY A GRADUAL NORTHEASTWARD TURN AT SLOW SPEED THROUGH DAY 4. BY DAY 5...A VERY SLOW NORTHWARD MOTION IS INDICATED...DUE TO THE LARGE SPREAD IN THE GUIDANCE. NEEDLESS TO SAY...THERE IS VERY LOW CONFIDENCE IN THIS TRACK FORECAST. THE SHIPS AND LGEM CONTINUE TO SHOW MORE STRENGTHENING THAN THE DYNAMICAL INTENSITY AIDS. GIVEN RECENT ORGANIZATIONAL TRENDS...THE OFFICIAL FORECAST FOLLOWS THE STATISTICAL MODELS THROUGH 36 HOURS...SHOWING A PEAK AT 50 KT FOLLOWED BY A SLOW DECREASE LATER IN THE PERIOD AS THE CYCLONE REACHES COOLER WATERS AND SHEAR BEGINS TO INCREASE. FORECAST POSITIONS AND MAX WINDS INITIAL 29/2100Z 12.8N 122.2W 40 KT 12HR VT 30/0600Z 13.2N 122.9W 45 KT 24HR VT 30/1800Z 14.2N 122.9W 50 KT 36HR VT 31/0600Z 15.1N 122.7W 50 KT 48HR VT 31/1800Z 16.1N 122.2W 45 KT 72HR VT 01/1800Z 17.5N 121.5W 40 KT 96HR VT 02/1800Z 18.5N 120.5W 35 KT 120HR VT 03/1800Z 19.5N 120.5W 30 KT $$ FORECASTER BRENNAN NNNN
Alternate Formats
About Alternates -
E-Mail Advisories -
RSS Feeds
Cyclone Forecasts
Latest Advisory -
Past Advisories -
About Advisories
Marine Forecasts
Latest Products -
About Marine Products
Tools & Data
Satellite Imagery -
US Weather Radar -
Aircraft Recon -
Local Data Archive -
Forecast Verification -
Deadliest/Costliest/Most Intense
Learn About Hurricanes
Storm Names
Wind Scale -
Prepare -
Climatology -
NHC Glossary -
NHC Acronyms -
Frequently Asked Questions -
AOML Hurricane-Research Division
About Us
About NHC -
Mission/Vision -
Other NCEP Centers -
NHC Staff -
Visitor Information -
NHC Library
NOAA/
National Weather Service
National Centers for Environmental Prediction
National Hurricane Center
11691 SW 17th Street
Miami, Florida, 33165-2149 USA
nhcwebmaster@noaa.gov
Disclaimer
Privacy Policy
Credits
About Us
Glossary
Career Opportunities
Page last modified: Thursday, 31-Dec-2009 12:09:25 UTC