HURRICANE KEITH DISCUSSION NUMBER 11
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT SUN OCT 01 2000
KEITH HAS A SPECTACULAR APPEARANCE ON SATELLITE IMAGERY...WITH A
WELL-DEFINED 15-20 N MI DIAMETER EYE. AIR FORCE RECON FOUND A
MINIMUM CENTRAL PRESSURE OF 942 MB AND...FROM A GPS DROPWINDSONDE...
A MEAN WIND OF 140 KNOTS OVER THE LOWEST 150 METERS IN THE SOUTHERN
PORTION OF THE EYEWALL. THIS REDUCES TO A SURFACE WIND SPEED NEAR
115 KNOTS. KEITH IS NOW A CATEGORY FOUR HURRICANE AND A LITTLE MORE
STRENGTHENING COULD OCCUR TODAY IF THE INNER CORE REMAINS OVER
WATER. HOWEVER SOME FLUCTUATIONS IN INTENSITY CAN BE EXPECTED...DUE
TO EYEWALL REPLACEMENT CYCLES WHICH ARE COMMON IN INTENSE
HURRICANES. WEAKENING WILL OCCUR WHEN THE CENTER MOVES OVER
YUCATAN. ASSUMING THE CENTER REACHES THE GULF OF MEXICO...
RESTRENGTHENING MAY BE LIMITED BY INCREASED SHEAR AND/OR DRIER AIR.
RECON FIXES SHOW A SLOW ERRATIC MOTION...SO KEITH REMAINS IN A WEAK
STEERING CURRENT AT THIS TIME. THE NCEP GLOBAL MODEL SHOWS THE
SYSTEM IN A MID-TROPOSPHERIC COL BETWEEN A WEAK RIDGE OVER THE
NORTHWEST GULF REGION AND A RIDGE TO THE EAST-NORTHEAST. THE GLOBAL
MODELS SUGGEST THAT THE EASTERN RIDGE WILL BE THE SLIGHTLY MORE
DOMINANT ONE IN A FEW DAYS TIME...AND PRODUCE A NORTH-NORTHWEST
MOTION WHICH WOULD MOVE KEITH OVER EASTERN YUCATAN AND EVENTUALLY
INTO THE GULF OF MEXICO. THE TRACK GUIDANCE MODELS ARE MOSTLY
SPREAD FROM A NORTHWARD TO A NORTHWESTWARD MOTION DURING THE PERIOD.
THE OFFICIAL TRACK FORECAST IS SIMILAR TO THE PREVIOUS ONE...SHOWING
A SLOW NORTHWARD MOTION BEGINNING IN ABOUT 24 HOURS AND BRINGING
KEITH INTO THE SOUTH-CENTRAL GULF BY THE END OF THE PERIOD. THIS IS
ALSO SIMILAR TO THE TRACK SHOWN BY THE EXPERIMENTAL FLORIDA STATE
UNIVERSITY SUPERENSEMBLE MODEL.
ONE SHOULD RECALL THAT 48- AND 72-HR FORECAST POSITIONS ARE SUBJECT
TO ERRORS OF A COUPLE OF HUNDRED MILES.
FORECASTER PASCH
<font size=3 face="courier, courier new">
Tropical Depression FIFTEEN
ADV LAT LON TIME WIND PR STAT
1 16.10 -82.90 09/28/21Z 25 1004 TROPICAL DEPRESSION
2 16.20 -83.20 09/29/03Z 25 1004 TROPICAL DEPRESSION
3 16.20 -83.20 09/29/09Z 30 1004 TROPICAL DEPRESSION
4 17.20 -84.30 09/29/15Z 30 1004 TROPICAL DEPRESSION
+12 17.50 -84.50 09/30/00Z 35 - TROPICAL STORM
+24 18.00 -84.70 09/30/12Z 40 - TROPICAL STORM
+36 18.50 -85.00 10/01/00Z 45 - TROPICAL STORM
+48 19.50 -85.00 10/01/12Z 50 - TROPICAL STORM
+72 20.50 -85.00 09/02/12Z 65 - HURRICANE-1
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[This message has been edited by Marty (edited 10-01-2000).]