000
AXPZ20 KNHC 201549
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN NOV 20 2011

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1415 UTC.

...SPECIAL FEATURE...

TROPICAL DEPRESSION THIRTEEN-E NEAR 10.6N 104.7W AT 20/1500 UTC 
MOVING W AT 11 KT. A GENERAL WESTWARD OR WEST-NORTHWESTWARD 
MOTION IS EXPECTED DURING THE NEXT COUPLE OF DAYS. ESTIMATED 
MINIMUM PRESSURE IS 1005 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 
KT WITH GUSTS TO 40 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER 
AWIPS/WMO HEADERS MIATCMEP3/WTPZ33 FOR MORE DETAILS. CONVECTION 
HAS CONTINUED TO DEEPEN MAINLY NE OF THE CENTER AND THE 
DEPRESSION IS EXPECTED TO BECOME A TROPICAL STORM LATER TODAY. 
NUMEROUS MODERATE TO SCATTERED STRONG CONVECTION IS NOTED FROM 
FROM 10N TO 14N BETWEEN 101W AND 104W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS FROM 12N TO 14N BETWEEN 104W AND 
107W. ISOLATED MODERATE CONVECTION IS FROM 09N TO 12N BETWEEN 
104W AND 107W. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM NORTHERN COSTA RICA TO 08N90W TO 
09N95W WHERE IT ENDS. THE INTERTROPICAL CONVERGENCE ZONE BEGINS 
AT 08N108W AND CONTINUES TO 09N120W TO 10N129W TO 09N140W. 
SCATTERED MODERATE CONVECTION IS WITHIN 60 NM EITHER SIDE OF 
ITCZ AXIS BETWEEN 108W AND 110W. SIMILAR CONVECTION IS WITHIN 60 
NM N AND 120 NM S OF ITCZ AXIS BETWEEN 127W AND 129W. 

...DISCUSSION...

AN UPPER-LEVEL TROUGH ENTERS THE FORECAST REGION THROUGH 30N125W 
THEN EXTENDS SW AND W TO BEYOND 25N140W. SW FLOW AHEAD OF THIS 
TROUGH IS ADVECTING ABUNDANT MID TO UPPER LEVEL MOISTURE ACROSS 
THE N WATERS INTO BAJA CALIFORNIA AND NW MEXICO. THE ASSOCIATED 
COLD FRONT IS JUST MOVING INTO THE FAR N WATERS AND STRETCHES 
FROM 30N128W TO 29N135W. NW WINDS OF 20 KT ARE NOTED IN THE WAKE 
OF THE FRONT WITH BUILDING SEAS TO 13 FT IN NW SWELL. THESE 
SWELLS WILL CONTINUE TO PROPAGATE ACROSS THE REGIONAL WATERS 
COVERING MAINLY THE AREA N OF 15N AND W OF 110W. THE FRONT WILL 
MOVE SE REACHING FROM 29N115W TO 27N117W IN ABOUT 24 HOURS AND 
WILL DISSIPATE OVER THE NE CORNER BY TUE MORNING. 

AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR THE VICINITY OF THE 
GULF OF TEHUANTEPEC WITH A RIDGE AXIS EXTENDING FROM IT TO NEAR 
13N121W. UPPER LEVEL DIFFLUENCE ALONG THE RIDGE IS ENHANCING 
CONVECTION ALONG THE ITCZ AS IS DESCRIBED IN THE SECTION ABOVE. 
IN ADDITION...THE RIDGE IS HELPING TO SUSTAIN THE DEVELOPING 
TREND OF CONVECTION ASSOCIATED WITH TROPICAL DEPRESSION 
THIRTEEN-E. 

ELSEWHERE AT THE SURFACE...HIGH PRES CENTERED WELL W-NW OF THE 
REGION NEAR 32N152W EXTENDS A RIDGE MAINLY EWD TO NEAR 27N115W.  
AN AREA OF TRADES IS NOTED ON THE SOUTHERN PERIPHERY OF THE 
RIDGE FROM 10N TO 20N W OF 129W. THE TRADES WILL EXPAND EASTWARD 
REACHING NEAR 117W OVER THE NEXT 48 HRS AS THE TROPICAL STORM 
THIRTEEN-E MOVES FURTHER WESTWARD.

A SURFACE TROUGH IS ANALYZED ALONG THE ITCZ EXTENDING FROM 
12N129W TO 08N131W AND WILL MOVE WWD.

GAP WINDS...
N-NE WINDS OF 20 KT ARE FORECAST TO FILTER INTO THE GULF OF 
TEHUANTEPEC IN ABOUT 24 HOURS...BUT DIMINISH MON EVENING.

GULF OF PAPAGAYO NE-E 20 KT WINDS ARE EXPECTED TO PULSATE ON AND 
OFF THROUGH TUE.  

$$
GR