000
AXPZ20 KNHC 182120
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
2205 UTC TUE JUN 18 2013

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...            
MONSOON TROUGH AXIS EXTENDS FROM 09N84W TO 08N95W TO 11N102W TO  
1008 MB LOW PRES NEAR 09N107W 08N110W TO 11N120W. ITCZ AXIS 
CONTINUES FROM 11N120W TO 11N130W TO 08N140W. SCATTERED MODERATE 
TO STRONG FROM 06N TO 10N BETWEEN 78W AND 88W. SCATTERED 
MODERATE ISOLATED STRONG FROM 07N TO 10N BETWEEN 102W AND 110W 
AND FROM 10N TO 13N BETWEEN 105W AND 110W. SIMILAR CONVECTION IS 
WITHIN ABOUT 90NM OF A LINE FROM 09N11W TO 11N115W TO 12N120W.

...DISCUSSION...                                                
ALOFT...MAINLY WESTERLY FLOW DOMINATES THE FORECAST REGION N OF 
25N. TO THE SOUTH OF THESE WINDS...BROAD ANTICYCLONE CENTERED 
NOW NEAR 17N135W COVERS MOST OF THE AREA FROM 10N TO 25N W OF 
110W. A RIDGE EXTENDS FROM THE ANTICYCLONE NEWD TO SOUTHERN BAJA 
CALIFORNIA INTO NORTHERN MEXICO. MODERATE TO STRONG SUBSIDENCE 
PREVAILS N OF 18N W OF 110W LEADING TO RATHER DRY AND STABLE 
ATMOSPHERIC CONDITIONS. A WEAK UPPER LOW IS SEEN NEAR 14N99W. A 
TROUGH EXTENDS FROM THE LOW NNE TO NEAR TAMPICO MEXICO. A 
SLIGHTLY UPPER DIFFLUENT FLOW PATTERN BETWEEN THE LOW AND THE 
RIDGE IS HELPING TO INDUCE THE CONVECTION NEAR THE SURFACE LOW 
PRES EMBEDDED WITHIN THE MONSOON TROUGH NEAR 09N107W. ELY FLOW 
ALOFT ON THE SOUTHERN PERIPHERY OF AN UPPER ANTICYCLONE OVER THE 
CARIBBEAN SEA IS ADVECTING MID TO UPPER LEVEL MOISTURE ACROSS 
THE FAR EASTERN PORTION OF THE AREA N OF 05N AND E OF ABOUT 90W. 

ELSEWHERE AT THE SURFACE...A 1029 MB HIGH PRES ANALYZED NW OF 
THE DISCUSSION AT 33N145W EXTENDS A RIDGE SEWD TO NEAR 20N115W. 
THIS SYSTEM IS FORECAST TO MOVE EWD TOWARDS 33N140W IN 24 HOURS. 
THE PRES GRADIENT TO ITS E IN COMBINATION WITH LOWER PRES OVER 
THE WRN U.S. W COAST WILL SUPPORT FRESH TO STRONG WINDS NEAR THE 
COAST OF CENTRAL AND SRN CALIFORNIA THROUGH THE NEXT 48 HRS. NW 
TO N SWELLS GENERATED BY THESE WINDS ARE FILTERING S INTO THE NE 
PORTION OF THE AREA TO N OF 28N E OF 122W WHERE NW-N WINDS OF 20-
25 KT AND SEAS OF 8-10 FT ARE EXPECTED THROUGH THU.

ADDITIONAL PULSES OF CROSS EQUATORIAL SW SWELLS WITH LEADING 
EDGE PERIOD OF 19-20 SECONDS ARE PROPAGATING THROUGH THE SOUTH-
CENTRAL WATERS...RAISING SEAS TO 8 FT S OF 03N BETWEEN 126W AND 
137W. THESE SWELLS ARE FORECAST BY WAVEWATCH GUIDANCES TO REACH 
THE COASTLINES OF CENTRAL AMERICA AND MEXICO LATER TONIGHT INTO 
WED THEN WILL BE REINFORCED BY YET ANOTHER BATCH OF LONG PERIOD 
SW SWELLS WITH PERIODS OF 16-18 SECONDS. THESE SWELLS COULD LEAD 
TO ROUGH SURF NEAR AND ALONG THE ABOVE COASTLINES. 

$$ 
GR