000
AXPZ20 KNHC 052115
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN AUG 05 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 
2000 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE EXTENDS FROM 1011 MB LOW PRES NEAR 12N105W TO 
17N104W. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 150 
NM EITHER SIDE OF THE WAVE AND NEAR THE MONSOON TROUGH AXIS S OF 
THE WAVE FROM 08N TO 12N BETWEEN 102W AND 110W. FURTHER 
DEVELOPMENT OF THE LOW PRES SYSTEM IS POSSIBLE AS IT CONTINUES 
W-NW AROUND 10 KT. THE LOW MAY BECOME A TROPICAL CYCLONE 
WITHIN THE NEXT 48 HOURS.

A TROPICAL WAVE EXTENDS FROM 11N124W TO 16N128W. THIS WAVE IS 
MOVING W AT 10 KT. CONVECTION HAS DISSIPATED NEAR THE WAVE TODAY 
AS UPPER LEVEL CONFLUENCE AND 20-30 KT NORTHERLY WINDS ALOFT 
HAVE MOVED OVER THE WAVE. WHILE CONVECTION HAS WANED...THE PRES 
GRADIENT BETWEEN THE SURFACE TROUGHING ASSOCIATED WITH THE WAVE 
AND THE SUBTROPICAL RIDGE SHOULD BE STRONG ENOUGH FOR FRESH TO 
STRONG WINDS TO BUILD NEAR THE WAVE OVER THE NEXT FEW DAYS. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH AXIS WAS ANALYZED 08N78W TO 10N84W TO 08N93W 
TO 11N101W TO 10N106W TO 11N113W TO 09N126W. THE ITCZ AXIS WAS 
ANALYZED FROM 09N126W TO 08N140W. SCATTERED MODERATE WITH 
ISOLATED STRONG CONVECTION WAS FROM 05N TO 11N BETWEEN 80W AND 
96W AS WELL AS WITHIN 120 NM N OF THE AXIS BETWEEN 114W AND 121W 
AND WITHIN 120 NM S OF THE AXIS BETWEEN 115W AND 126W. SCATTERED 
MODERATE CONVECTION WAS WITHIN 120 NM S OF THE AXIS BETWEEN 132W 
AND 137W AS WELL AS WITHIN 90 NM EITHER SIDE OF THE AXIS W OF 
138W.

...DISCUSSION...
A WEAK SUBTROPICAL RIDGE EXTENDS OVER N WATERS WITH 1021 MB HIGH 
PRES CENTERED NEAR 30N130W. THE RIDGE WILL SLOWLY BUILD 
BEGINNING MON AS THE SUBTROPICAL HIGH CONSOLIDATES NW OF THE 
FORECAST AREA. LIGHT TO MODERATE WINDS ARE CURRENTLY UNDERNEATH 
THIS RIDGE ACROSS THE WATERS N OF THE MONSOON TROUGH/ITCZ 
AXIS...WITH MODERATE TO FRESH WINDS FOUND NEAR THE 
AFOREMENTIONED TROPICAL WAVES. THE PRES GRADIENT BETWEEN THE 
MONSOON TROUGH/ITCZ AND THE SE PACIFIC SUBTROPICAL HIGH IS 
SUPPORTING MODERATE TO FRESH SOUTHERLY FLOW W OF 95W AS OBSERVED 
BY THE MOST RECENT ASCAT PASSES.

SWELL PERIODS REMAIN ABOVE 20 SECONDS IN THE SOUTHERN GULF OF 
CALIFORNIA AND ALONG THE COAST OF BAJA CALIFORNIA NORTE. THIS  
CROSS-EQUATORIAL SOUTHERLY SWELL TRAIN HAS IMPACTED THE ENTIRE 
COASTLINE WITHIN THE FORECAST AREA OVER THE PAST FEW DAYS. THIS 
SWELL IS BEGINNING TO SUBSIDE...BUT WILL CONTINUE TO PRIMARILY 
IMPACT THE COASTLINE OF MEXICO OVERNIGHT TONIGHT PRODUCING 
DANGEROUS SURF AND RIP CURRENTS AT THE BEACHES. HIGHEST 
ASSOCIATED SIGNIFICANT WAVE HEIGHTS ARE ACROSS THE S CENTRAL 
WATERS WITH SEAS TO 8-9 FT. THE SWELL WILL GRADUALLY DECAY MON 
AND TUE WITH SEAS SUBSIDING TO LESS THAN 8 FT BY MON AFTERNOON.

GAP WINDS...NORTHERLY WINDS ARE EXPECTED TO BRIEFLY INCREASE TO 
20 TO 25 KT IN THE GULF OF TEHUANTEPEC BY MON MORNING AND ARE 
FORECAST TO PERSIST THROUGH TUE. THIS GAP WIND EVENT WILL BE 
INDUCED BY RELATIVELY HIGHER SURFACE PRESSURES OVER THE SW GULF 
OF MEXICO AHEAD OF ATLANTIC TROPICAL STORM ERNESTO AND LOWER 
PRES ASSOCIATED WITH THE MONSOON TROUGH WHICH WILL BE DRIFTING 
NORTHWARD AS ERNESTO APPROACHES CENTRAL AMERICA AND THE YUCATAN.

$$
SCHAUER