000
AXPZ20 KNHC 150942
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU SEP 15 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0845 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM COSTA RICA AT 11N86W TO 08N98W 
TO 11N108W TO A 1011 MB LOW PRESSURE CENTER AT 10N112W TO 1012 
MB LOW PRES AT 14N125W TO 12N129W. THE ITCZ AXIS EXTENDS FROM 
12N129W TO BEYOND 10N140W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION EXISTS N OF 03N E OF 82W...AND WITHIN 120 NM S OF 
TROUGH BETWEEN 95W AND 102W.  SCATTERED MODERATE CONVECTION 
EXISTS WITHIN 120 NM S OF TROUGH BETWEEN 106W AND 114W AND 
WITHIN 180 NM S OF ITCZ AXIS W OF 133W.

..TROPICAL WAVE...

A TROPICAL WAVE EXTENDS FROM 11N TO 16N ALONG 99W WITH A 1009 MB 
LOW EMBEDDED ON THE WAVE AXIS NEAR 12N99W.  SCATTERED MODERATE 
ISOLATED STRONG CONVECTION EXISTS WITHIN 120 NM OF THE WAVE AXIS 
AND N OF 16N BETWEEN 100W AND 105W.

AT THE SURFACE...THE NE TROPICAL PACIFIC IS RELATIVELY QUIET 
THIS EVENING.  THERE IS ONLY ONE SMALL PATCH OF OCEAN WITH WINDS 
OF ABOUT 20 KT OR HIGHER WITH 20 KT NE TRADEWINDS NEAR 10N W OF 
128W...AND EVEN THIS MIGHT BE BELOW 20 KT AS SUGGESTED BY THE 
0316Z WINDSAT PASS.  THE LACK OF MODERATE OR STRONG WINDS IS DUE 
TO A WEAK PRESSURE GRADIENT ASSOCIATED WITH A MODEST 1027 MB 
SURFACE HIGH AT 33N146W.  ACROSS THE REGION AS WELL...NO 
TROPICAL CYCLONES ARE CURRENTLY OCCURRING.  TWO CONVECTION-LESS 
SWIRLS ARE OBSERVED NEAR 10N112W AND 14N125W...THOUGH NEITHER 
WOULD APPEAR TO HAVE MUCH CHANCE OF DEVELOPING INTO A TROPICAL 
CYCLONE DURING THE NEXT COUPLE OF DAYS.  A THIRD VORTEX...THE 
AFOREMENTIONED LOW EMBEDDED ON THE TROPICAL WAVE NEAR 99W...HAS 
HAD SOME DEEP CONVECTION...BUT NOT CONSISTENTLY ENOUGH TO 
INITIATE DVORAK CLASSIFICATIONS.  THE GLOBAL MODELS MAINTAIN OR 
PERHAPS SLIGHTLY SPINUP THIS VORTEX DURING THE NEXT FEW DAYS.  
THE SYSTEM HAS A LOW CHANCE TO DEVELOP INTO A TROPICAL CYCLONE 
DURING THE NEXT TWO DAYS BECAUSE OF MODERATE EASTERLY VERTICAL 
SHEAR.  SW MONSOONAL FLOW ON THE SOUTH SIDE OF THE LOW IS 
ANTICIPATED TO REACH ABOUT 20 KT WITHIN TWO DAYS...AS A SOLUTION 
BASED UPON A BLEND OF THE 00Z GFS AND ECMWF MODELS.  NO 
SIGNIFICANT SWELL EVENTS ARE EXPECTED TO REACH INTO OUR AREA OF 
RESPONSIBILITY FROM THE NORTH DURING THE NEXT FEW DAYS.

IN THE UPPER LEVELS...RIDGING PREVAILS FROM THE MEXICO COAST 
NEAR 20N WEST-SOUTHWESTWARD TO 12N140W.  SOUTH OF THE RIDGE 
AXIS...EASTERLY WINDS ARE ADVECTING THE UPPER LEVEL MOISTURE AND 
CLOUDINESS ORIGINATING IN THE MONSOON TROUGH TOWARD THE WEST.  
NORTH OF THE RIDGE AXIS...A SHORT WAVE TROUGH EXTENDS FROM SO 
CALIFORNIA SOUTHWARD ALONG 120W INTO OUR WATERS WITH NO 
SIGNIFICANT WEATHER ASSOCIATED WITH IT AT THIS TIME.

$$
LANDSEA