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TROPICAL STORM LANE DISCUSSION NUMBER 13
NATIONAL WEATHER SERVICE MIAMI FL
8 AM PDT FRI SEP 08 2000
LANE CONTINUES TO SHOW A COLD BUT BROAD CURVED CONVECTIVE BAND.
SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB ARE 55 KT.
HOWEVER...CONVECTION ATTEMPTING TO WRAP AROUND THE NORTH SIDE OF THE
CENTER HAS WARMED DURING THE PAST FEW HOURS...SO THE MAXIMUM WINDS
ARE INCREASED ONLY TO 40 KT FOR THIS PACKAGE. THIS MAY BE A BIT ON
THE CONSERVATIVE SIDE.
THE BEST ESTIMATE OF THE INITIAL MOTION IS 330/5. WATER VAPOR
IMAGERY SHOWS A LARGE MID/UPPER LEVEL RIDGE OVER NORTHWEST MEXICO...
AND LARGE-SCALE GUIDANCE INDICATES THIS FEATURE WILL PERSIST THROUGH
THE FORECAST PERIOD. THE BIGGEST QUESTION IS HOW MUCH RIDGING WILL
BUILD WESTWARD NORTH OF LANE AND POSSIBLY FORCE LANE MORE WESTWARD.
THE NOGAPS AND THE AVN BUILD MORE RIDGING...WHILE THE UKMET KEEPS A
WEAKNESS IN THE RIDGE DUE TO A DEVELOPING UPPER LEVEL TROUGH WEST OF
CALIFORNIA. NHC TRACK GUIDANCE REFLECTS THIS DIVERGENCE IN
OPINION...WITH THE UKMET FOLLOWING A MORE NORTHWEST TRACK AND THE
AVN-BASED GUIDANCE CALLING FOR MORE OF A TURN TO THE WEST. GIVEN
THE UNCERTAINLY...THE OFFICIAL FORECAST WILL BE ADJUSTED ONLY
SLIGHTLY WEST OF THE PREVIOUS TRACK...IN BEST AGREEMENT WITH THE
UKMET.
VERTICAL SHEAR SEEMS TO HAVE DECREASED...AND WITH THE CURRENT COLD
CONVECTION THERE IS NO OBVIOUS REASON LANE SHOULD NOT STRENGTHEN.
HOWEVER...INTERNAL DISORGANIZATION MAY BE SLOWING THE PROCESS DOWN.
THE INTENSITY FORECAST CALLS FOR LANE TO STRENGTHEN INTO A HURRICANE
BY 48 HR...FOLLOWED BY NO CHANGE AS IT MOVES INTO COOLER WATER. IF
LANE EVER GETS ITS ACT TOGETHER...IT COULD STRENGTHEN FASTER THAN
CURRENTLY FORECAST.
FORECASTER BEVEN
FORECAST POSITIONS AND MAX WINDS
INITIAL 08/1500Z 16.3N 108.7W 40 KTS
12HR VT 09/0000Z 17.0N 109.0W 45 KTS
24HR VT 09/1200Z 17.9N 109.6W 50 KTS
36HR VT 10/0000Z 18.9N 110.4W 55 KTS
48HR VT 10/1200Z 20.0N 111.5W 65 KTS
72HR VT 11/1200Z 22.0N 113.5W 65 KTS
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