000
AXPZ20 KNHC 192135
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON OCT 19 2009

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...SPECIAL FEATURE... 
HURRICANE RICK AT 18.5N 111.7W AT 19/2100 UTC OR ABOUT 305 NM 
S-SW OF SOUTHERN TIP OF BAJA CALIFORNIA MOVING N-NW AT 6 KT.  
ESTIMATED MINIMUM CENTRAL PRES 976 MB.  MAXIMUM SUSTAINED WINDS 
HAVE DECREASED TO 85 KT WITH GUSTS TO 105 KT.  RICK NOW A 
CATEGORY TWO HURRICANE AND IS FORECAST TO WEAKEN FURTHER AS 
UPPER LEVEL SHEAR INCREASE.  NEVERTHELESS RICK REMAINS A SERIOUS 
THREAT WITH DAMAGING WINDS AND POTENTIAL FOR HEAVY RAINFALL.  
SEE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...
TROPICAL WAVE ALONG 88W N OF 02N HAS MODERATE EASTERLY SHEAR 
ALOFT PREVENTING IT FROM ANY SIGNIFICANT STRENGTHENING.  THESE 
CONDITIONS BECOME LESS ADVERSE AS WAVE MOVES W BUT ANY 
INTENSIFICATION SHOULD BE BEYOND FORECAST PERIOD. SCATTERED 
MODERATE CONVECTION REMAINS E OF WAVE AXIS FROM 07N-09N. 

WEAK TROPICAL WAVE ALONG 126W FROM 06N TO 16N MOVING W AT 15 KT.
ALTHOUGH CONDITIONS ALOFT REMAIN SLIGHTLY FAVORABLE FOR 
INTENSIFICATION...WAVE ASSOCIATED CONVECTION REMAINS MINIMAL AND 
LITTLE CHANGE IS EXPECTED. 

...ITCZ...
AXIS ALONG 10N85W TO 08N95W TO 14N105W TO 14N114W TO 08N124W TO 
13N140W. SCATTERED MODERATE TO STRONG CONVECTION WITHIN 120 NM S 
OF AXIS E OF 90W.  SCATTERED MODERATE CONVECTION WITHIN 120 NM S 
OF AXIS 111W-120W.

...DISCUSSION...
MOSTLY QUASI-ZONAL W FLOW N OF 20N AS WEAK UPPER LEVEL TROUGH 
LIES FROM 32N118W TO 24N140W.  WELL DEFINED ANTICYCLONE NEAR 
09N116W PREVENTS TROUGH FROM DIGGING MUCH FURTHER S.  SECOND 
ANTICYCLONE OVER MAINLAND MEXICO HELPS IN STEERING HURRICANE 
RICK INTO WEAKNESS BETWEEN BOTH ANTICYCLONIC CENTERS.   

AT THE SURFACE...
HIGH PRES CENTER 1024 MB WITH RIDGE ALONG 30N MAINTAINS GOOD 
HOLD OVER MOST OF E PAC N OF 20N WITH FRESH N TO NE BREEZE AS 
HURRICANE RICK TURNS NE INTO MEXICO.  HIGH PRES WEAKENS SLIGHTLY 
AS IT MOVES E FORCED BY APPROACHING COLD FRONT.  MODERATE BREEZE 
ALONG SOUTHERN PERIPHERY OF RIDGE MAKES NE TRADES FROM 15N-23N W 
OF 126W.  MODERATE NW SWELL AFFECT EXTREME NW CORNER OF BASIN. 

HEALTHY COLD FRONT SKIRTS NORTHERN BORDER OF BASIN WITH FRESH  
BREEZE.  WINDS QUICKLY DIMINISH AS FRONT LIFTS NORTHEASTWARD BUT 
LEAVING LARGE LONG PERIOD NW SWELLS IN ITS WAKE AFFECTING E PAC 
BY LATE MON.   

GALE FORCE N TO NE WIND S AND SW OF GULF OF TEHUANTEPEC DIMINISH 
BELOW GALE FORCE WITHIN 18 HOURS BUT STRONG NE BREEZE STILL 
REMAIN OVER AREA FOR OVER 48 HOURS.

$$
WALLY BARNES