000
AXPZ20 KNHC 202351
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI JUL 20 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2130 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM 09N84W TO A 1009 MB LOW 
PRES NEAR 08N102W TO A SECOND 1008 MB LOW PRES NEAR 13N117W TO 
08N130W THEN ITCZ TO BEYOND 05N140W. SCATTERED MODERATE TO 
ISOLATED STRONG FROM 08N TO 10N BETWEEN 87W AND 90W. SIMILAR 
CONVECTION IS WITHIN 240 NM N AND 60 NM S OF THE MONSOON TROUGH 
BETWEEN 100W AND 107W...AND WITHIN 180 NM N OF THE MONSOONS 
TROUGH/ITCZ BETWEEN 123W AND 135W.

...DISCUSSION...
A 1030 MB SUBTROPICAL HIGH CENTERED WELL N OF THE FORECAST AREA
AND THE HAWAIIAN ISLANDS NEAR 41N161W WITH RIDGE 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 A 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 INTERACTING WITH A SURFACE 
TROUGH EXTENDING FROM 15N110W TO THE 1009 MB LOW CENTER NEAR 
08N101W. THIS TROUGH WILL BE RE-ANALYZED AS A TROPICAL WAVE ON 
THE 0000 UTC ANALYSIS AS THE TROUGH APPEARS TO BE THE SOUTHERN 
PORTION OF A TROPICAL WAVE WHICH MOVED ACROSS CENTRAL AMERICA 
INTO THE BAY OF CAMPECHE ON THU. EASTERLY WAVE DIAGNOSTIC FIELDS
SUPPORT THE INTRODUCTION OF THIS AVE ON THE NEXT ANALYSIS. 
   
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS NOTED EITHER 
SIDE OF THE TROUGH AXIS FROM 08N TO 15N BETWEEN 100W AND 106W. 
TROPICAL CYCLONE FORMATION IS NOT EXPECTED IN ASSOCIATION WITH 
EITHER OF THESE LOWS DURING THE NEXT 48 HOURS. GLOBAL MODELS 
CONTINUE TO INDICATE A LOW PRESSURE CENTER 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 CONTINUES TO BE THE MOST AGGRESSIVE IN DEVELOPING THIS LOW. 

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

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. NARROW LINES OF LOW 
LEVEL CLOUDS ARE NOTED GENERALLY ORIENTED PARALLEL TO THE NE 
WIND FLOW.

FRESH GAP WINDS HAVE STARTED FUNNELING THROUGH INTO THE GULF OF 
TEHUANTEPEC LATE THIS AFTERNOON...LIKELY IN ASSOCIATION WITH A 
1020 MB HIGH PRES CENTERED BETWEEN TAMPICO AND TUXPAN IN MEXICO. 
VISIBLE SATELLITE IMAGERY SHOWS A LINE OF SHOWERS WITH EMBEDDED 
TSTMS MOVING AWAY FROM THE GULF OF TEHUANTEPEC...AN INDICATION 
THAT WINDS ARE STARTING TO BLOW ACROSS THE AREA. IN ADDITION... 
IXTEPEC IN THE STATE OF OAXACA IS REPORTING GUSTY NLY WINDS OF 
20 KT OVER THE PAST SEVERAL HOURS. THIS GAP WIND EVENT WILL 
CONTINUE THROUGH THE NEXT 48 HOURS. 

$$
COBB