000
AXPZ20 KNHC 210916
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED OCT 21 2009

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...SPECIAL FEATURE... 

TROPICAL STORM RICK AT 21.8N 108.2W AT 0900 UTC OCT 21 OR ABOUT 
115 NM SOUTHEAST OF CABO SAN LUCAS MEXICO AND ABOUT 130 NM 
SOUTHWEST OF MAZATLAN MEXICO. RICK IS MOVING NE OR 050 DEG AT 12 
KT. ESTIMATED MINIMUM CENTRAL PRES 990 MB. MAXIMUM SUSTAINED 
WINDS ARE 55 KT WITH GUSTS TO 65 KT. NUMEROUS MODERATE TO STRONG 
CONVECTION IS WITHIN 100 NM OF THE POINT 23.5N108W. THE LOW 
LEVEL CENTER IS IN THE SOUTHERN PART OF THE CONVECTION. THE 
SYSTEM IS BEING SHEARED BY STRONG SOUTHWEST WINDS AS A RESULT 
MOST OF THE CONVECTION IS TO THE NORTH AND NORTHEAST OF THE LOW 
LEVEL CENTER. THERE IS POTENTIAL FOR THE HEAVY RAINFALL 
ASSOCIATED WITH RICK TO PRODUCE LIFE THREATENING FLASH FLOODS 
AND MUD SLIDES. RICK IS EXPECTED TO WEAKEN SLIGHTLY BEFORE 
MOVING INLAND TODAY. SEE LATEST NHC FORECAST/ ADVISORY 
UNDER AWIPS/WMO HEADERS MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

NONE.

...ITCZ...

INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...07N77W TO 
07N90W TO 13N110W TO 08N120W TO 11N140W. SCATTERED MODERATE 
CONVECTION IS WITHIN 45 NM EITHER SIDE OF THE ITCZ FROM 84W TO 
100W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF THE 
POINTS 07N104W AND 09N107W. SCATTERED MODERATE TO STRONG 
CONVECTION IS WITHIN 75 NM EITHER SIDE OF THE ITCZ FROM 121W TO 
128W.

OTHER CONVECTION...
SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION IS WITHIN 75 
NM OF THE COAST OF CENTRAL AMERICA FROM WESTERN PANAMA TO 
NORTHERN COSTA RICA.

...DISCUSSION...

TWO TROUGHS ARE OVER THE AREA. ONE IS OVER NORTHERN MEXICO AND 
THE ADJACENT PACIFIC OCEAN. THIS TROUGH INCLUDES THE TROPICAL 
STORM RICK. DEEP LAYER MOISTURE EMANATING FROM RICK IS SPREADING 
OVER CENTRAL AND NORTHEASTERN MEXICO WITH MULTI LEVEL CLOUDS AND 
SOME EMBEDDED RAIN. A SHARP DEEP LAYER SHORTWAVE MOVING THROUGH 
THE TROUGH IS OVER THE ARIZONA/NEW MEXICO BORDER AND IS 
PRODUCING DRY CONDITIONS OVER NORTHWEST MEXICO AND THE NORTH 
HALF OF THE BAJA PENINSULA. ALSO ASSOCIATED WITH THE OVERALL 
TROUGH IS A MAINLY UPPER TROUGH THAT EXTENDS ALONG THE LINE FROM 
NEAR 20N105W TO 10N125W THEN WEAKLY TO 11N140W. THE AREA NORTH 
OF THIS LINE IS DRY AND CLOUD FREE IN THE MIDDLE AND UPPER 
LEVELS. OVERCAST STRATOCUMULUS IN THE LOWER LEVELS IS BETWEEN 
17N AND 27N WITH BROKEN STRATOCUMULUS NORTH OF 27N.

THE OTHER TROUGH IS OVER NORTHERN COSTA RICA AND EXTENDS OUT 
ABOUT 360 NM. THIS AREA IS DIFFLUENT ALOFT WITH MULTI LEVEL 
CLOUDS AND EMBEDDED AREAS OF CONVECTION. 

THE REMAINDER OF THE MIDDLE AND UPPER LEVELS IS UNDER BROAD 
ANTICYCLONIC FLOW.

MODERATE SURFACE RIDGE IS NORTH OF 15N WEST OF 115W. ELSEWHERE 
EXCEPT FOR THE TROPICAL CYCLONE RICK A BROAD TROUGH IS ANALYZED 
AT THE SURFACE.

GAP WINDS IN THE GULF OF TEHUANTEPEC HAVE DIMINISHED TO 20 KNOTS 
AND WILL FALL TO LESS THAN 20 KT BY THIS EVENING.

$$
LL