HOME	ARCHIVES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

ZCZC MIATCDEP3 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM COSME DISCUSSION NUMBER   4
NATIONAL WEATHER SERVICE MIAMI FL
8 PM PDT FRI JUL 13 2001

COSME SHOWED SIGNS OF EASTERLY SHEAR DURING THE AFTERNOON...WITH
THE LOW LEVEL CENTER TRYING TO POP OUT FROM UNDERNEATH THE
CONVECTION.  HOWEVER...A NEW BURST OF CONVECTION HAS SINCE APPEARED
OVER THE CENTER.  THE INITIAL INTENSITY IS INCREASED TO 45 KT ON
THE BASIS OF SATELLITE INTENSITY ESTIMATES OF 55 KT...45 KT...AND
35 KT FROM AFWA...TAFB...AND SAB RESPECTIVELY.

THE STORM SEEMS TO HAVE SLOWED DURING THE AFTERNOON.  THE INITIAL
MOTION IS NOW 295/12...AND THE 6 HOUR MOTION MAY BE LESS THAN 10
KT.  COSME IS ON THE SOUTH SIDE OF THE SUBTROPICAL RIDGE...WHICH
LARGE-SCALE MODELS SUGGEST WILL WEAKEN AS A LARGE DEEP LAYER TROUGH
DEVELOPS OFF THE U.S. WEST COAST.  THIS SUGGESTS THAT COSME SHOULD
MOVE WEST-NORTHWESTWARD TO WESTWARD WITH SOME DECREASE IN FORWARD
SPEED.  NHC HURRICANE GUIDANCE GENERALLY AGREES WITH THIS
SCENARIO...ALTHOUGH THERE IS A CONSIDERABLE DIFFERENCE IN SPEED
BETWEEN THE MUCH FASTER BAM MODELS AND NHC91 AND THE MUCH SLOWER
GFDL...GFDN...AND UKMET.  THE OFFICIAL FORECAST WILL GO WITH THE
SLOWER MODELS...SLOWING COSME TO 4 KT AFTER 48 HR.  ONE NOTABLE
OUTLIER IS LBAR...WHICH CALLS FOR A TURN TO THE NORTHWEST.  WHILE
THIS IS POSSIBLE IF THE TROUGH TO THE NORTH DIGS MORE THAN CURRENTLY
FORECAST...THE STORM WOULD THEN QUICKLY DIE OVER COLD WATER.
 
WHILE COSME IS CURRENTLY PARTLY SHEARED...LARGE-SCALE MODELS
SUGGEST THE SHEAR SHOULD DECREASE...WHICH SHOULD ALLOW COSME TO
STRENGTHEN AS LONG AS IT CONTINUES OVER WARM WATER.  THE CURRENT
FORECAST TRACK TAKES COSME OVER COOLER WATER IN 24-36 HR...THUS
THE INTENSITY FORECAST CALLS FOR STRENGTHENING UP TO THAT TIME
AND SLOW WEAKENING THEREAFTER.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     14/0300Z 16.7N 112.7W    45 KTS
12HR VT     14/1200Z 17.2N 114.1W    50 KTS
24HR VT     15/0000Z 17.8N 115.6W    60 KTS
36HR VT     15/1200Z 18.3N 117.0W    60 KTS
48HR VT     16/0000Z 18.7N 118.5W    55 KTS
72HR VT     17/0000Z 19.0N 120.0W    50 KTS
 
 
NNNN