000
WTPZ45 KNHC 210859
TCDEP5
TROPICAL STORM RICK DISCUSSION NUMBER  24
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP202009
200 AM PDT WED OCT 21 2009
 
INFRARED SATELLITE IMAGERY INDICATES THAT THE CLOUD PATTERN
ASSOCIATED WITH RICK HAS CHANGED LITTLE DURING THE LAST FEW HOURS.
THE CYCLONE CONTINUES TO CONSIST OF A SHIELD OF PULSATING DEEP
CONVECTION ORGANIZED IN A BANDING FEATURE OVER THE NORTHWEST
SEMICIRCLE...WITH A DISTINCT MID-LEVEL CIRCULATION CENTER EVIDENT
TO ITS SOUTHEAST. DVORAK T-NUMBERS AT 0600 UTC WERE 3.0 AND 3.5
FROM SAB AND TAFB...RESPECTIVELY...AND AGREE FAIRLY WELL WITH A
0148 UTC QUIKSCAT PASS THAT SUGGESTED A MAX INTENSITY OF AT LEAST
55 KT. ON THIS BASIS...THE INITIAL INTENSITY IS HELD AT 55 KT.
UW-CIMSS ANALYSES CURRENTLY INDICATE NEARLY 25 KT OF SOUTHWESTERLY
SHEAR OVER RICK...AND THE SHIPS MODEL OUTPUT SUGGESTS A FURTHER
INCREASE IN THE SHEAR DURING THE NEXT 12-24 HOURS. THE
PROHIBITIVELY HIGH VALUES OF SHEAR SHOULD RESULT IN WEAKENING PRIOR
TO LANDFALL IN SPITE OF SSTS WARMING ALONG THE FORECAST TRACK.
DISSIPATION IS LIKELY IN 24-36 HOURS ONCE THE CENTER QUICKLY MOVES
WELL INLAND OVER THE RUGGED TERRAIN OF THE SIERRA MADRE MOUNTAINS.
 
THE CENTER REMAINS EXCEEDINGLY DIFFICULT TO FIND...EVEN WITH
MICROWAVE AND SCATTEROMETER PASSES...BUT THE FORWARD MOTION APPEARS
TO HAVE INCREASED AND IS ESTIMATED AT 050/12. AN AMPLIFIED MID- TO
UPPER-LEVEL TROUGH PROGRESSING THROUGH THE SOUTHERN ROCKIES AND
NORTHERN MEXICO DURING THE NEXT 24 HOURS SHOULD STEER RICK ON A
CONTINUED NORTHEASTWARD COURSE WITH INCREASING FORWARD SPEED...AT
LEAST UNTIL LANDFALL...WHEN SOME OF THE GUIDANCE INDICATES THAT
RICK WILL SHEAR APART.   
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/0900Z 21.8N 108.2W    55 KT
 12HR VT     21/1800Z 23.1N 106.7W    50 KT
 24HR VT     22/0600Z 24.3N 104.7W    20 KT...REMNANT LOW INLAND
 36HR VT     22/1800Z...DISSIPATED
 
$$
FORECASTER KIMBERLAIN/FRANKLIN