000
AXPZ20 KNHC 292120
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI JUN 29 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 
1945 UTC.

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

THE MONSOON TROUGH AXIS EXTENDS FROM 08N78W TO 08N93W. THE ITCZ 
AXIS EXTENDS FROM 08N93W TO 05N105W TO 09N117W TO 06N140W. 
ISOLATED MODERATE CONVECTION LIES N OF THE AXIS E OF 83W 
INCLUDING OVER PORTIONS OF PANAMA AND COSTA RICA. SCATTERED 
MODERATE CONVECTION CAN BE FOUND WITHIN 210 NM S OF THE AXIS 
BETWEEN 81W AND 87W AND WITHIN 60 NM N OF THE AXIS BETWEEN 84W 
AND 86W. SCATTERED MODERATE CONVECTION ALSO LIES WITHIN 180 NM N 
AND 45 NM S OF THE AXIS BETWEEN 121W AND 134W.
 
...DISCUSSION...

A QUIET PATTERN REMAINS IN PLACE ACROSS THE ENTIRE FORECAST AREA.
A TROPICAL WAVE PASSING THROUGH CENTRAL AMERICA WILL MOVE OFF 
THE COAST OF COSTA RICA AND NICARAGUA INTO THE PACIFIC TONIGHT. 
THE ASSOCIATED CONVECTION ALONG THE EASTERN PORTION OF THE 
MONSOON TROUGH IS DESCRIBED IN THE SECTION ABOVE. THIS 
CONVECTION CUTS OFF N OF HONDURAS WHERE 45 KT E-NE FLOW IS 
INHIBITING THE DEVELOPMENT OF DEEP CONVECTION. ENHANCED 
LOW-LEVEL E WIND FLOW ASSOCIATED WITH THE WAVE IS FUNNELING 
THROUGH THE GULF OF PAPAGAYO...WITH FRESH WINDS EXPECTED TO 
PERSIST DOWNWIND OF PAPAGAYO THROUGH SUN. SOME OF THE NUMERICAL 
GUIDANCE SUGGEST A SURFACE LOW WILL SPIN UP ALONG THE WAVE SW OF 
PAPAGAYO TOMORROW...BUT NO SIGNIFICANT DEVELOPMENT OF THE LOW IS 
EXPECTED THROUGH THE END OF THE PERIOD SUN AFTERNOON.

SCATTERED MODERATE CONVECTION CAN BE FOUND ALONG THE ITCZ 
BETWEEN 121W AND 134W WHERE LIGHT...BROADLY DIFFUSE UPPER LEVEL 
WINDS ARE ENCOURAGING LIFT OF THE LOW-LEVEL TO MID-LEVEL 
MOSITURE POOLED ALONG THE ITCZ. THE 1814 UTC ASCAT 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 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 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.

$$
SCHAUER