000
AXPZ20 KNHC 210246
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT JUL 21 2012

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 
0230 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM 09N84W TO A 1009 MB LOW 
PRES NEAR 07N103W TO 10N112W TO A 1010 MB LOW PRES NEAR 13N118W 
TO 11N126W THEN ITCZ TO BEYOND 05N140W. SCATTERED MODERATE TO 
ISOLATED STRONG WITHIN 240 NM N AND 90 NM S OF THE MONSOON 
TROUGH BETWEEN 102W AND 108W...AND WITHIN 120 NM N OF THE 
MONSOON TROUGH/ITCZ BETWEEN 123W AND 135W.

...DISCUSSION...
A 1030 MB SUBTROPICAL HIGH CENTERED WELL N OF THE FORECAST AREA 
AND THE HAWAIIAN ISLANDS NEAR 41N158W WITH RIDGE AXIS EXTENDING 
SE THROUGH 30N128W TO NEAR 20N112W. THE PRESSURE GRADIENT 
BETWEEN THIS FEATURE AND LOWER PRES ALONG THE MONSOON TROUGH IS 
MAINTAINING FRESH 20 KT WINDS FROM 11N TO 15N BETWEEN 120W AND 
130W BASED ON AN EARLIER 1738 UTC ASCAT SCATTEROMETER PASS. THIS 
AREA OF TRADES WILL SHIFT WESTWARD OVER THE NEXT 48 HOURS. 
EXPECT SEAS OF 8 TO 10 FT GENERATED BY THESE WINDS.

THERE ARE TWO WEAK LOW PRES SYSTEMS EMBEDDED IN THE MONSOON 
TROUGH. NONE OF THEM ARE SHOWING SIGN OF ORGANIZATION. THE 
EASTERNMOST IS THE ACTIVE ONE AND IS SITUATED NEAR THE BASE OF 
A TROPICAL WAVE EXTENDING FROM 15N103W TO THE 1009 MB LOW CENTER 
NEAR 07N103W. THIS TROPICAL WAVE REPRESENTS THE FRACTURED 
SOUTHERN PORTION OF A TROPICAL WAVE WHICH MOVED ACROSS CENTRAL 
AMERICA INTO THE BAY OF CAMPECHE ON THU. EASTERLY WAVE 
DIAGNOSTIC FIELDS SUPPORT THE CONTINUATION OF THE TROPICAL WAVE 
INTO THE EAST PACIFIC.   
   
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS NOTED WITHIN 
120 NM EITHER SIDE OF THE TROPICAL WAVE AXIS FROM 08N TO 11N.
TROPICAL CYCLONE FORMATION IS NOT EXPECTED IN ASSOCIATION WITH 
EITHER OF THESE LOWS DURING THE NEXT 48 HOURS. GLOBAL MODELS 
CONTINUE TO INDICATE A BROAD AREA OF LOW PRESSURE FORMING WITHIN 
THE MONSOON TROUGH IN THE AREA BETWEEN 90W AND 95W BY LATE SUN 
AND MON. THIS LOW PRESSURE AREA COULD BE THE RESULT OF A 
TROPICAL WAVE...CURRENTLY OVER THE CENTRAL CARIBBEAN 
...INTERACTING WITH THE TOPOGRAPHY OF CENTRAL AMERICA AND THE 
MONSOON TROUGH. THE GFS HAS BACKED OFF ON THE DEVELOPMENT OF 
THIS FEATURE AND IS MORE IN LINE WITH THE OTHER GLOBAL MODELS.

CROSS EQUATORIAL LONG PERIOD SW SWELLS OF 21-22 SECONDS ARE NOW 
IMPACTING THE COAST OF MEXICO...CENTRAL AMERICA AND BAJA 
CALIFORNIA. THE POTENTIAL EXISTS FOR LARGE BREAKING WAVES AND 
DANGEROUS RIP CURRENTS ALONG THE COAST TONIGHT AND THROUGH THE 
WEEKEND AS THE SWELL TRAIN SLOWLY SUBSIDES. 

GAP WINDS OF 20 KT...WITH PULSES TO 25 KT ARE EXPECTED TO 
CONTINUE OVER THE GULF OF PAPAGAYO AS FRESH TRADE WIND FLOW IN 
THE SW CARIBBEAN FUNNELS THROUGH THE GAP. THE WINDS WILL BE 
GREATEST DURING THE OVERNIGHT AND EARLY MORNING HOURS WITH THE 
ASSISTANCE OF THE NOCTURNAL DRAINAGE FLOW. 

FRESH GAP WINDS HAVE STARTED FUNNELING THROUGH INTO THE GULF OF 
TEHUANTEPEC THIS EVENING...LIKELY IN ASSOCIATION WITH A 1020 
MB HIGH PRES CENTERED BETWEEN TAMPICO AND TUXPAN IN MEXICO. THIS 
GAP WIND EVENT WILL PEAK OVERNIGHT TONIGHT AND EARLY SAT WITH 
WINDS LOCALLY TO 30 KT. THE GAP WIND EVENT WILL GRADUALLY WIND 
DOWN THROUGH THE NEXT 48 HOURS. 

$$
COBB