000
WTPZ45 KNHC 202032
TCDEP5
TROPICAL STORM RICK DISCUSSION NUMBER  22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP202009
200 PM PDT TUE OCT 20 2009
 
AN AIR FORCE RECONNAISSANCE AIRCRAFT INVESTIGATING RICK THIS
AFTERNOON FOUND MAXIMUM FLIGHT LEVEL WINDS OF 70 KT IN THE
NORTHEAST QUADRANT AND AN ESTIMATED MINIMUM PRESSURE OF 990 MB.  IN
ADDITION...THE PEAK SURFACE WIND ESTIMATED FROM THE SFMR WAS 55 KT
WEST OF THE CENTER.  BASED ON THESE DATA...THE INITIAL INTENSITY IS
AGAIN HELD AT 55 KT. RICK IS CURRENTLY IN AN ENVIRONMENT OF ABOUT
20 KT OF SOUTHWESTERLY VERTICAL WIND SHEAR. THE SHIPS MODEL NO
LONGER SHOWS MUCH DECREASE IN THE SHEAR DURING THE NEXT 12 HOURS
BEFORE IT INCREASES SIGNIFICANTLY. THEREFORE...THIS INTENSITY
FORECAST SHOWS SLIGHT WEAKENING PRIOR TO LANDFALL AS A COMPROMISE
BETWEEN REGIONAL HURRICANE MODELS AND STATISTICAL GUIDANCE.   AFTER
LANDFALL...MORE RAPID WEAKENING SHOULD COMMENCE AS THE LOW-LEVEL
CIRCULATION BECOMES DISRUPTED BY THE RUGGED TERRAIN OF MAINLAND
MEXICO.
 
AIRCRAFT FIXES AND EARLIER MICROWAVE DATA CONFIRMED PREVIOUS
ESTIMATES OF THE INITIAL MOTION OF 045/7.  WATER VAPOR IMAGES SHOW
A MID- TO UPPER-LEVEL TROUGH AMPLIFYING OVER THE SOUTHWESTERN
UNITED STATES. THIS TROUGH IS EXPECTED TO CONTINUE TO STEER RICK
NORTHEASTWARD WITH AN INCREASE IN FORWARD SPEED THROUGH LANDFALL.
THIS TRACK FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS ONE AND
IS VERY NEAR THE MODEL CONSENSUS.  ON THIS TRACK...THE CENTER OF
RICK IS EXPECTED TO PASS SOUTH OF THE SOUTHERN TIP OF BAJA
CALIFORNIA TONIGHT AND APPROACH THE COAST OF MAINLAND MEXICO IN
ABOUT 24 HOURS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/2100Z 20.4N 110.1W    55 KT
 12HR VT     21/0600Z 21.5N 108.7W    55 KT
 24HR VT     21/1800Z 23.2N 106.5W    50 KT
 36HR VT     22/0600Z 25.2N 103.9W    25 KT...INLAND
 48HR VT     22/1800Z...DISSIPATED
 
$$
FORECASTER CANGIALOSI/AVILA