000
AXPZ20 KNHC 131525
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON OCT 12 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500UTC.

...SPECIAL FEATURE... 

AT 1500 UTC TROPICAL STORM PATRICIA WAS LOCATED NEAR 21.4N 
109.0W OR ABOUT 105 NM S-SE OF THE SOUTHERN TIP OF BAJA 
CALIFORNIA MOVING N-NE OR 015 DEG AT 6 KNOTS. MAXIMUM SUSTAINED 
WIND SPEED WAS 50 KT GUSTS TO 60 KT. ESTIMATED MINIMUM CENTRAL 
PRESSURE WAS 997 MB. UPPER OUTFLOW APPEARS TO BE GOOD IN THE 
NORTHEAST AND SOUTHWEST QUADRANTS AND THE CIRCULATION APPEARS 
ELONGATED IN THE NORTHEAST TO SOUTHWEST ORIENTATION. DEEP 
CONVECTION SURROUNDING PATRICIA HAD DIMINISHED DURING THE LAST 
24 HOURS BUT HAS REMAINED UNCHANGED DURING THE LAST SEVERAL 
HOURS. SCATTERED STRONG CONVECTION IS WITHIN 75 NM OVER THE 
NORTH SEMICIRCLE AND WITHIN 120 NM OVER THE SOUTH SEMICIRCLE.
PATRICIA IS EXPECTED TO REMAIN OVER WARM WATERS AND IN A LOW 
SHEAR ENVIRONMENT FOR THE NEXT 48 HOURS...AS IT MAKES A TURN 
NORTHWEST...AND THEN WESTWARD. THIS WILL BRING THE STORM OVER 
COOLER WATERS AND IN A DRIER MORE STABLE LOW LEVEL ENVIRONMENT 
AND LIKELY LEAD TO A QUICK DEMISE TO THIS SYSTEM. SEE LATEST NHC 
FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC 
FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE WAS ANALYZED ALONG LINE FROM 13N88W TO LOW NEAR 
07N88W 1009 MB CONTINUE TO 04N87W. THE TROPICAL WAVE IS MOVING W 
AROUND 12 KT. SATELLITE IMAGERY INDICATED WIDELY SCATTERED 
MODERATE CONVECTION WITHIN 150 NM OF THE CENTER OF THE LOW AND 
ORGANIZED BY THE LOW LEVEL CIRCULATION HOWEVER THE CONVECTION 
DOES NOT SEEM TO BE CONSOLIDATING NEAR THE LOW CENTER. GLOBAL 
MODELS FORECAST THE LOW TO MOVE SLOWLY WEST AND DEVELOP INTO A 
TROPICAL CYCLONE IN ABOUT 3 TO 4 DAYS. 

ANOTHER TROPICAL WAVE WAS ANALYZED ALONG 104W/105W FROM 03N TO 
12N MOVING WEST 12 KT. ONLY ISOLATED MODERATE CONVECTION NEAR 
THE WAVE AXIS AT 10N IS NOTED.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS CENTERED ALONG AXIS FROM 
09N78W TO 06N95W TO 10N105W TO 11N115W TO 10N140W. SCATTERED 
MODERATE TO STRONG CONVECTION IS WITHIN 75 NM OF THE POINT 
06N98W. SCATTERED MODERATE WITHIN 30 NM EITHER SIDE OF THE ITCZ 
WEST OF 115W.

A TROUGH IN THE ITCZ WAS ALONG THE LINE FROM 17N135W TO 09N138W. 
AN AREA OF CONVECTION IS LOCATED EAST OF THE TROUGH WITH 
SCATTERED MODERATE TO STRONG CONVECTION WITHIN 90 NM OF THE 
POINT 12.5N132W. THERE APPEARS TO BE GOOD UPPER OUTFLOW 
SUPPORTING THE CONVECTION AND ALSO THERE APPEARS TO BE SOME 
CYCLONIC TURNING OF THE CONVECTION. THE GFS FORECAST MODEL KEEPS 
A WEAK LOW IN THIS AREA AND DRIFTS THE SYSTEM WEST.

...DISCUSSION...

DEEP LAYER TROUGH IS NORTH OF A LINE FROM 30N105W TO 20N114W TO 
17N140W. THE PORTION OF THIS AREA SOUTH OF 25N AND THE PART FROM 
25N TO 30N W OF 125W IS DRY AND CLOUD FREE IN THE MIDDLE AND 
UPPER LEVELS WITH BROKEN STRATOCUMULUS IN THE LOWER LEVELS. 
NORTH OF 30N AND WEST OF BAJA CALIFORNIA TO 125W THE MIDDLE AND 
UPPER LEVELS ARE MOIST WITH SOME MULTI 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 AREA.

AN UPPER TROUGH IS OVER NORTHERN CENTRAL AMERICA AND IS MOVING 
WEST. SCATTERED MODERATE CONVECTION WITHIN 75 NM OF THE POINT 
11.5N91W IS ASSOCIATED WITH THE TROUGH. ALSO A BAND OF SCATTERED 
MODERATE TO STRONG CONVECTION IS WITHIN 60 NM EITHER SIDE OF 
100W FROM 08N TO 13N IS ASSOCIATED WITH THE WESTERN FRINGES OF 
THE TROUGH CIRCULATION. 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 125W. WEAK SURFACE 
HIGH IS CENTERED NEAR 22.5N120.5W 1014 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