000
AXPZ20 KNHC 170235
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
0405 UTC WED JUL 17 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0215 UTC.

...TROPICAL WAVES...                                     
TROPICAL WAVE EXTENDS FROM 16N105.5W TO 10N106W. A CLUSTER OF 
MODERATE TO STRONG CONVECTION HAS DEVELOPED E OF THE WAVE AXIS 
AND COVERS THE AREA FROM 13N TO 15N BETWEEN 101W AND 105W. 
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS NOTED 
ELSEWHERE FROM 10N TO 16N BETWEEN 104W AND 108W. THE WAVE 
COINCIDES WITH A SURGE OF MOISTURE PRESENT IN TOTAL PRECIPITABLE 
WATER IMAGERY. AN EARLIER ASCAT PASS SHOWED NE WINDS OF 10-15 KT 
AHEAD OF THE WAVE AXIS. THIS SYSTEM IS FORECAST TO GRADUALLY 
BECOME DIFFUSE AS IT TRACKS WESTWARD THROUGH THURSDAY. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...           
THE MONSOON TROUGH AXIS EXTENDS FROM 09N84W TO 12N106W TO 
11N120W. THE INTERTROPICAL CONVERGENCE ZONE AXIS CONTINUES FROM 
11N120W TO 12N127W THEN RESUMES AT 11N132W TO 09N140W. SCATTERED 
MODERATE TO ISOLATED STRONG CONVECTION IS NOTED WITHIN 180 NM S 
OF TROUGH BETWEEN 88W AND 92W. SIMILAR CONVECTION IS FROM 08N TO 
10N BETWEEN 105W AND 111W. ISOLATED MODERATE CONVECTION CAN BE 
FOUND FROM 07N TO 10N W OF 127W.

...DISCUSSION...                                               
ALOFT...AN ANTICYCLONE LOCATED WEST OF AREA NEAR 12N145W EXTENDS 
A RIDGE NE ACROSS THE NW WATERS TO ABOUT 28N126W. MODERATE TO 
STRONG SUBSIDENCE AND IMPLIED DRY AIR MASS IS NOTED UNDER THE 
INFLUENCE OF THIS RIDGE...PARTICULARLY N OF 15N W OF 125W. TO 
THE EAST OF THE RIDGE...AN UPPER LEVEL LOW IS SPINNING NEAR 
22N122W WITH A TROUGH EXTENDING SOUTH TO NEAR 13N122W. ANOTHER 
UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER NW MEXICO HAS 
A RIDGE EXTENDING SOUTH ALONG THE COAST OF MEXICO TO NEAR PUERTO 
ANGEL. MODERATE TO STRONG SE WINDS ARE NOTED BETWEEN THE UPPER 
LOW AND THE ANTICYCLONE. A SMALL AREA OF UPPER DIFFLUENCE 
ASSOCIATED WITH THIS RIDGE SUPPORTS THE CONVECTION RELATED TO 
THE TROPICAL WAVE. AN INVERTED TROUGH IS ALSO NOTED ALONG THE 
SOUTHERN PERIPHERY OF THIS ANTICYCLONE...STRETCHING FROM 18N112W 
TO 13N110W. A THIRD ANTICYCLONIC CIRCULATION IS LOCATED OVER 
NORTHERN CENTRAL AMERICA. 

MOST OF THE ACTIVE WEATHER ACROSS THE FORECAST REGION IS RELATED 
TO THE MONSOON TROUGH...THE ITCZ AND THE TROPICAL WAVE ALONG 
105W/106W. TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE 
NEXT 48 HOURS. 

AT THE SURFACE...A STRONG HIGH PRES LOCATED WELL NW OF THE 
FORECAST REGION EXTENDS A RIDGE SE ACROSS THE N WATERS TO NEAR 
22N116W. MODERATE TO FRESH TRADE WINDS ARE NOTED PER THE MOST 
RECENT ASCAT PASSES BETWEEN THE SOUTHERN PERIPHERY OF THE RIDGE 
AND THE ITCZ W OF 130W. SEAS OVER THIS AREA RANGE FROM 4 TO 5 FT 
IN THE NW CORNER AND MAXIMIZE IN THE 6 TO 7 FT RANGE FROM 10N TO 
20N WEST OF 128W ACCORDING TO AN ALTIMETER PASS. THESE OVERALL 
CONDITIONS WILL CHANGE LITTLE OVER THE NEXT 48 HOURS. GENTLE TO 
MODERATE NW WINDS CURRENTLY ALONG THE WESTERN SHORE OF THE BAJA 
CALIFORNIA PENINSULA ARE EXPECTED TO INCREASE TO 20 KT N OF 27N 
W OF THE BAJA PENINSULA TO ALONG 120W LATER ON THU...WITH 
ASSOCIATED SEAS TO NEAR 8 FT.

A WEAK SURFACE TROUGH IS ANALYZED FROM 15N127W TO 10N131W ON THE 
0000 UTC SURFACE MAP. ISOLATED TO SCATTERED MODERATE CONVECTION 
IS NOTED ON EITHER SIDE OF THE TROUGH AXIS...MORE CONCENTRATED 
NEAR THE NORTHERN END. NE WINDS OF 15-20 KT ARE EXPECTED AHEAD 
OF THE TROUGH...FORECAST TO MOVE WWD OVER THE NEXT COUPLE OF 
DAYS...REACHING 140W LATER ON THU.
   
GAP WINDS OF 15-20 KT WILL PERSIST ACROSS THE GULF OF PAPAGAYO 
THROUGH FRIDAY MORNING AS FRESH TO STRONG TRADE WIND FLOW IN THE 
SW CARIBBEAN FUNNELS TROUGH THE GAP. THE WINDS ARE GREATEST 
DURING THE OVERNIGHT AND EARLY MORNING HOURS WITH THE ASSISTANCE 
OF THE NOCTURNAL DRAINAGE FLOW.

LONG PERIOD CROSS EQUATORIAL SOUTHWESTERLY SWELLS RESULTING IN 
COMBINED SEAS TO 9 FT DOMINATE THE FORECAST WATERS S OF A LINE 
FROM 00N102W TO 06N115W TO 06N124W 00N126W. THIS SWELL EVENT 
WILL CONTINUE TO PROPAGATE NORTHWARD DURING THE NEXT 24-48 HOURS 
WITH ANOTHER SET OF LONG PERIOD SW SWELLS...WAVE PERIOD OF 19 TO 
21 SECONDS...REACHING PARTS OF THE COAST OF MEXICO BY WED...AND 
PARTS OF THE COAST OF CENTRAL AMERICA BY THU. 
 
$$ 
GR