000
AXPZ20 KNHC 190311
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SUN JUN 19 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0330 UTC.

...SPECIAL FEATURE...
BROAD 1006 MB LOW PRES IS CENTERED NEAR 13N98W ALONG THE MONSOON 
TROUGH AXIS...APPROXIMATELY 300 NM SE OF ACAPULCO MEXICO. AN 
ASCAT PASS FROM 1630Z SHOWED THE LOW LEVEL CENTER WITH WINDS 20 
TO 30 KT IN THE NORTHERN QUADRANT OF THE LOW. THE ASCAT ALSO 
DEPICTED THE A LARGE AREA OF SW WINDS TO 20 KT S OF THE LOW. AN 
ELONGATED SURFACE TROUGH EXTENDS NE FROM THE LOW THROUGH THE 
GULF OF TEHUANTEPEC. CLUSTERS OF MODERATE TO STRONG CONVECTION 
PERSIST MAINLY IN THE NW QUADRANT OF THE LOW PRES. THE LOW PRES 
REMAINS SITUATED TO THE SOUTH OF A LARGE UPPER RIDGE CENTERED 
OVER CENTRAL MEXICO. CONVECTION AROUND THE LOW IS STRUGGLING TO 
COALESCE AMID STRONG E SHEAR ON THE SOUTH SIDE OF THE UPPER 
RIDGE. THE RIDGE WILL WEAKEN THROUGH LATE SUN AS A DEEP LAYER 
TROUGH DIGS INTO THE WESTERN UNITED STATES. THIS WILL ALLOW THE 
SHEAR TO LESSEN AND THE CONVECTION AROUND THE LOW TO 
INCREASE...RESULTING IN THE LOW DEEPENING INTO EARLY NEXT WEEK 
AS GRADUALLY MOVES WNW PARALLEL TO THE COAST OF MEXICO. HEAVY 
RAINFALL ALONG THE COAST OF MEXICO BY LATE SUN INTO MON. IN 
ADDITION...AS SW FLOW INCREASES S OF THE LOW...FRESH SW SWELL UP 
TO 15 FT WITH PERIODS TO 10 SECONDS WILL DEVELOP AND PUSH INTO 
COASTAL AREAS IN SOUTHERN MEXICO FROM CHIAPAS TO GUERRERO SUN 
AND MON.    
 
...ITCZ/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 09N84W TO LOW PRES NEAR 13N98W 1006 
MB TO 08N130W. THE ITCZ EXTENDS FROM 08N130W TO 05N140W. 
SCATTERED MODERATE WITHIN 120 NM S OF MONSOON TROUGH BETWEEN 
105W AND 110W.

...DISCUSSION...

W OF 110W...1031 MB SURFACE HIGH PRES IS CENTERED NEAR 37N143W 
DRIFTING SW. A WINDSAT PASS FROM 15Z SHOWED AN AREA OF 20 KT 
STILL PRESENT ON THE SE PERIPHERY OF THE HIGH PRES...N OF 25N W 
OF 135W. AN ALTIMETER PASS FROM AROUND 16Z SHOWED SEAS OF 6 OT 
8 FT IN RESIDUAL N SWELL. THE NE FLOW WILL DIMINISH THROUGH LATE 
SUN AS THE SURFACE HIGH WEAKENS AND REORGANIZES TO THE 
WEST...AHEAD OF A DEEP LAYER TROUGH DIGGING INTO THE NE PACIFIC. 
FURTHER EAST...A SHIP OBSERVATION FROM OFF THE COAST OF CENTRAL 
BAJA CONFIRMED THE PRESCIENCE OF FRESH NORTHERLY FLOW IN THAT 
AREA...BETWEEN THE HIGH PRES TO THE WEST...AND A DEVELOPING 
TROUGH OVER THE SW UNITED STATES AND NW MEXICO. 

E OF 110W...THE MAIN FORECAST ISSUE WILL CONTINUE TO BE THE 
DEVELOPMENT AND MOVEMENT OF THE LOW NEAR 13N98W...AS WELL AS THE 
INCREASE IN SW WINDS OVER A LARGE AREA TO THE S OF THE LOW WITH 
A RELATED INCREASE IN FRESH SW SWELL MOVING TOWARD THE MEXICAN 
COAST. SOUTHERLY CROSS-EQUATORIAL SWELL WILL ALSO BE A FACTOR 
MAINLY S OF 05N BETWEEN 90W AND 110W. LOOKING AHEAD...SOUTHERLY 
SWELL AROUND 8 TO 10 FT WILL PUSH AS FAR N AS 08N BY TUE. AS THE 
UPPER ANTICYCLONE OVER N CENTRAL MEXICO REORGANIZES TO 
SOUTH...NE SHEAR WILL INCREASE ALOFT BETWEEN FURTHER EAST IT 
WILL CAP CONVECTION BETWEEN 90W AND 110W. FURTHER E...SW FLOW 
WILL CONTINUE TO CONVERGE WITH NE TO E TRADES OVER THE SW 
CARIBBEAN TO PRODUCE CLUSTERS OF SHOWERS AND THUNDERSTORMS E OF 
90W THROUGH EARLY NEXT WEEK.  

$$
CHRISTENSEN