000
AXPZ20 KNHC 300237
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT JUN 30 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 
0130 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM 08N77W TO 08N89W TO 09N92W. 
ITCZ AXIS EXTENDS FROM 05N100W TO 09N120W TO 06N130W TO 06N140W. 
ISOLATED MODERATE CONVECTION LIES WITHIN 150 NM EITHER SIDE OF 
THE AXIS BETWEEN 81W AND 91W. ISOLATED MODERATE CONVECTION IS 
WITHIN 240 NM N OF THE AXIS BETWEEN 123W AND 133W.
 
...DISCUSSION...

A TROPICAL WAVE LIES N OF THE MONSOON TROUGH THROUGH THE GULF OF 
FONSECA INTO CENTRAL HONDURAS. THE ASSOCIATED CONVECTION ALONG 
THE MONSOON TROUGH IS DESCRIBED IN THE SECTION ABOVE. THIS 
CONVECTION CUTS OFF N OF NICARAGUA WHERE 45 KT E-NE FLOW IS 
INHIBITING THE DEVELOPMENT OF DEEP CONVECTION. ENHANCED 
LOW-LEVEL EASTERLY FLOW ASSOCIATED WITH THE WAVE IS FUNNELING 
THROUGH THE GULF OF PAPAGAYO. THE 1808 UTC OSCAT PASS SHOWED 
WINDS TO 25 KT IN THE GULF WHILE SHIP 3FQS8 REPORTED 19 KT NE 
WINDS AND 8 FT SEAS NEAR 12N92W AT 2300 UTC. THE OSCAT PASS ALSO 
REVEALS A CLOSED LOW LEVEL CIRCULATION THAT HAS DEVELOPED SW OF 
PAPAGAYO. THIS LOW WAS ANALYZED NEAR 08N89W AT 1010 MB. NO 
SIGNIFICANT DEVELOPMENT OF THE LOW IS EXPECTED THROUGH THE END 
OF THE PERIOD SUN EVENING. FRESH WINDS ARE EXPECTED TO PERSIST 
DOWNWIND OF PAPAGAYO THROUGH SUN AFTERNOON. 

ISOLATED MODERATE CONVECTION CAN BE FOUND ALONG THE ITCZ BETWEEN 
123W AND 133W. THIS CONVECTION HAS WANED A BIT OVER THE LAST 12 
HOURS. THE 2126 UTC OSCAT PASS SHOWS A NARROW BAND OF FRESH 
TRADES JUST N OF THE ITCZ AND W OF THIS CONVECTION. THE 
SUBTROPICAL RIDGE TO THE N IS RELATIVELY WEAK...STEMMING FROM 
1035 MB HIGH PRES WELL NW OF THE AREA NEAR 36N166W. THE RIDGING 
OVER THE WESTERN PORTION OF THE FORECAST AREA WILL WEAKEN 
FURTHER AS A DISSIPATING COLD FRONT MOVES INTO NW WATERS 
OVERNIGHT TONIGHT. FRESH TRADES WILL SHIFT W OF THE AREA BY 
EARLY SAT MORNING AS A RESULT. NO SIGNIFICANT WEATHER OR SEAS 
OVER 8 FT ARE EXPECTED WITH THIS DISSIPATING FRONT. THE LOW PRES 
SYSTEM ANCHORING THIS FRONT WILL MOVE INTO NORTHERN CALIFORNIA 
OVERNIGHT SAT NIGHT...DECREASING SURFACE PRESSURES IN THE 
WESTERN U.S. WHILE HIGH PRES BUILDS ALONG 37N BEHIND THE FRONT. 
THIS WILL RESULT IN A TIGHTER PRES GRADIENT OFF BAJA CALIFORNIA. 
NW WINDS ARE EXPECTED TO BECOME A FRESH BREEZE BY SAT MORNING AS 
HIGH PRES E OF THE FRONT JOGS SLIGHTLY CLOSER TO SHORE BEFORE 
DISSIPATING. WINDS WILL THEN BECOME FRESH TO STRONG ON SUN AND 
EXPAND SOUTHWARD ALONG THE PENINSULA AS THE PRES GRADIENT 
STRENGTHENS BETWEEN THE NORTHWARD DISPLACED SUBTROPICAL RIDGE 
AND TROUGHING OVER THE WESTERN U.S. AND MEXICO.

AN UPPER LEVEL RIDGE STEMMING FROM AN ANTICYCLONE NEAR THE 
SOUTHERN TIP OF BAJA CALIFORNIA EXTENDS SE ALONG THE MEXICAN 
COAST. THE UPPER DIFFLUENCE ASSOCIATED WITH THIS RIDGE IS 
ENHANCING CONVECTION IN WESTERN MAINLAND MEXICO...WITH SCATTERED 
MODERATE TO STRONG CONVECTION FOUND WITHIN 90 NM OF MEXICAN 
COAST FROM 17N TO 21N INCLUDING OVER MANZANILLO.

$$
SCHAUER