000
AXPZ20 KNHC 132128
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON OCT 12 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... 

AT 2100 UTC TROPICAL STORM PATRICIA WAS LOCATED NEAR 22.1N 
108.9W OR ABOUT 75 NM SE OF THE SOUTHERN TIP OF BAJA CALIFORNIA 
MOVING NE OR 010 DEG AT 6 KNOTS. MAXIMUM SUSTAINED WIND SPEED 
WAS 45 KT GUSTS TO 55 KT. ESTIMATED MINIMUM CENTRAL PRESSURE WAS 
1000 MB. UPPER OUTFLOW APPEARS TO BE GOOD IN THE NORTHEAST AND 
SOUTHWEST QUADRANTS BUT THE CIRCULATION HAS BECOME ELONGATED IN 
THE NORTHEAST TO SOUTHWEST ORIENTATION ALSO DEEP CONVECTION 
SURROUNDING PATRICIA HAD DIMINISHED DURING THE LAST SEVERAL 
HOURS. LITTLE DEEP CONVECTION IS NOW ASSOCIATED WITH THE STORM. 
PATRICIA IS EXPECTED CONTINUE TO WEAKEN AND BECOME A DEPRESSION 
WEDNESDAY NIGHT. PATRICIA IS FORECAST TO TURN NORTHWEST...AND 
THEN WESTWARD. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO 
HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE WAS ANALYZED ALONG 92W FROM 04N TO 12N AND IS  
MOVING WEST 15 KT. A LOW PREVIOUSLY ALONG THE WAVE IS NOW 
LOCATED NEAR 07N86W WITH A CENTRAL PRESSURE OF 1010 MB AND THE 
LOW IS MOVING SLOWLY WEST. SATELLITE IMAGERY INDICATED A NARROW 
BAND OF SCATTERED MODERATE CONVECTION WITHIN 40 NM EITHER SIDE 
OF A LINE FROM 08.5N86.5W TO 05.5N90.5W. THE CONVECTION DOES NOT 
APPEAR TO BE ORGANIZED BY EITHER THE LOW OR THE WAVE. GLOBAL 
MODELS FORECAST THE LOW TO MOVE SLOWLY WEST AND DEVELOP INTO A 
TROPICAL CYCLONE IN ABOUT 3 TO 4 DAYS. 

TROPICAL WAVE PREVIOUSLY ANALYZED ALONG 104W/105W FROM 03N TO 
12N HAS DISSIPATED AND IS NO LONGER A FEATURE.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE 09N78W TO 
06N95W TO 10.5N115W TO 09.5N140W. SCATTERED MODERATE WITH 
ISOLATED STRONG CONVECTION IS WITHIN 60 NM EITHER SIDE OF A LINE 
FROM 05N99W TO 10N103W. SCATTERED MODERATE CONVECTION IS WITHIN 
30 NM EITHER SIDE OF THE ITCZ WEST OF 115W.

A TROUGH IN THE ITCZ IS ALONG THE LINE FROM 19N135W TO 
12.5N137W. AN AREA OF CONVECTION THAT WAS LOCATED EAST OF THE 
TROUGH HAS DIMINISHED WITH SCATTERED MODERATE CONVECTION WITHIN 
60 NM OF THE POINT 11.5N134W. THE GFS FORECAST MODEL KEEPS A 
WEAK LOW IN THIS AREA AND DOES NOT DEVELOP THE LOW.

...DISCUSSION...

DEEP LAYER TROUGH IS NORTH OF A LINE FROM 30N104W TO 12N118W TO 
15N125W TO 20N130W TO 20N140W. THE PORTION OF THIS AREA SOUTH OF 
25N AND THE PART FROM 25N TO 30N W OF 123W IS DRY AND CLOUD FREE 
IN THE MIDDLE AND UPPER LEVELS WITH SCATTERED TO BROKEN 
STRATOCUMULUS IN THE LOWER LEVELS. NORTH OF 30N AND WEST OF BAJA 
CALIFORNIA TO 123W THE MIDDLE AND UPPER LEVELS ARE MOIST WITH 
SOME MIDDLE LEVEL CLOUDS OVER THE AREA MOSTLY NORTH OF 30N. THE 
TROUGH AND ASSOCIATED WESTERLY FLOW IS FORECAST TO MOVE NORTH AS 
THE RIDGE TO THE SOUTH BUILDS OVER THE NORTHEAST PART OF THE 
PACIFIC AREA.

AN UPPER TROUGH IS OVER AND JUST OFFSHORE NORTHERN CENTRAL 
AMERICA AND IS MOVING WEST. SCATTERED MODERATE CONVECTION  
WITHIN 60 NM OF THE POINT 11N93.5W IS ASSOCIATED WITH THE 
TROUGH. ELSEWHERE BROAD ANTICYCLONIC FLOW IS OBSERVED IN THE 
MIDDLE AND UPPER LEVELS. 
 
WEST TO SOUTHWEST SURFACE WINDS ASSOCIATED WITH A LOW WELL 
NORTH OF THE AREA ARE NORTH OF 28N WEST OF 123W. WEAK SURFACE 
HIGH IS CENTERED NEAR 22.5N120W 1016 MB. ELSEWHERE EXCEPT FOR 
THE TROPICAL STORM MENTIONED ABOVE A BROAD TROUGH COVERS THE 
AREA.

FRESH TO STRONG TRADE WIND FLOW ACROSS THE SW CARIBBEAN WILL 
CONTINUE TO FILTER THROUGH COSTA RICA AND INTO THE GULF OF 
PAPAGAYO. FURTHER SOUTH...INCREASED SW FLOW S OF THE ITCZ 
POSSIBLY IN RELATION TO THE TROPICAL WAVE NOW ALONG 87W.

$$
LL