000
AXPZ20 KNHC 022129
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC THU AUG 02 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.

...TROPICAL WAVES...
THE SOUTHERN END OF A TROPICAL WAVE OVER CENTRAL AMERICA IS 
MOVING OFF THE PACIFIC COAST OF COSTA RICA. THIS WAVE CURRENTLY 
LIES ALONG 84W N OF 08N AND IS MOVING W AROUND 15 KT. SCATTERED 
MODERATE WITH ISOLATED STRONG CONVECTION CAN BE FOUND FROM 04N 
TO 10N BETWEEN 80W AND 87W...INCLUDING OVER INLAND PORTION OF 
PANAMA AND COSTA RICA. SHOWERS AND THUNDERSTORMS WILL CONTINUE 
WITH THIS WAVE AS IT MOVES W INTO THE PACIFIC. WINDS ARE 
CURRENTLY A MODERATE BREEZE OR LESS NEAR THE WAVE. THOSE WIND 
CONDITIONS ARE EXPECTED TO CONTINUE THROUGH SAT.

A TROPICAL WAVE LIES ALONG 101W FROM 10N TO 15N. THE WAVE IS 
MOVING W AROUND 5-10 KT. SCATTERED MODERATE CONVECTION WAS NEAR 
THE WAVE FROM 07N TO 11N BETWEEN 97W AND 103W...IN THE REGION 
WHERE THE WAVE IS CLOSEST TO THE MONSOON TROUGH. THE WAVE 
CONTINUES TO BE IN AN AREA OF SUBSIDENCE ON THE EAST SIDE OF AN 
UPPER ANTICYCLONE CENTERED NEAR 16N110W AND LOWER PRECIPITABLE 
WATER VALUES THAN THE OTHER TROPICAL WAVES IN THE PACIFIC. WINDS 
ARE ONLY AS STRONG AS A MODERATE BREEZE WITH THIS WAVE.

A TROPICAL WAVE STRETCHES FROM 17N116W TO 11N119W AND IS MOVING 
W AROUND 10-15 KT. SCATTERED MODERATE CONVECTION WAS FOUND NEAR 
THE WAVE FROM 13N TO 16N BETWEEN 115W AND 120W. THE CONVECTION 
WITH THE WAVE HAS FLARED OVER THE LAST 6 HOURS IN THE REGION 
WHERE THE WAVE CROSSES THE RIDGE AXIS ALOFT AND UPPER DIFFLUENCE 
IS PRESENT. PRECIPITABLE WATER IMAGERY STILL SHOWS PLENTIFUL LOW 
LEVEL MOSITURE NEAR THE WAVE. THE MOST RECENT ASCAT PASSES SHOW 
WINDS ARE GENERALLY A MODERATE BREEZE NEAR THE WAVE...WITH A 
FRESH BREEZE FOUND NEAR THE CONVECTION.  

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE MONSOON TROUGH AXIS WAS ANALYZED 09N83W TO 08N88W TO 10N100W 
TO 09N106W. ITCZ AXIS WAS ANALYZED FROM 09N106W TO 09N110W TO 
11N115W THEN CONTINUES FROM 10N122W TO 09N130W TO 10N140W. 
SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WAS WITHIN 
180 NM N AND 120 NM S OF THE AXIS W OF 125W AND ELSEWHERE FROM 
05N TO 09N BETWEEN 123W AND 128W. 

...DISCUSSION...
THE 1031 MB SUBTROPICAL HIGH NEAR 40N140W IS FORECAST TO 
CONTINUE MOVING NW OVER THE NEXT TWO DAYS...WEAKENING THE 
RIDGING OVER THE FORECAST AREA. THE BELT OF FRESH TO STRONG 
TRADE WINDS CURRENTLY FOUND N OF THE ITCZ AND W OF 130W WILL 
SHRINK WESTWARD BEGINNING LATE FRI AS THE SUBTROPICAL HIGH 
MIGRATES. A STRONG SOUTH PACIFIC SUBTROPICAL RIDGE IS CURRENTLY 
IN PLACE AND IS FORCING A FRESH TO STRONG SE BREEZE PRIMARILY S 
OF 06N BETWEEN 120W AND 130W. THE 1812 UTC ASCAT PASS CONFIRMED 
THESE WIND CONDITIONS. THE SUBTROPICAL HIGH IN THE SOUTH PACIFIC 
SHOULD WEAKEN OVERNIGHT AND WINDS WILL DIMINISH. 

CROSS-EQUATORIAL SOUTHERLY SWELL CONTINUES TO MOVE AS FAR N AS 
04N BETWEEN 100W AND 128W. THE LEADING EDGE OF THIS SWELL HAS 
PERIODS IN EXCESS OF 20 SECONDS. IT WILL PASS THE GALAPAGOS 
LATER TODAY AND REACH THE COASTLINE FROM PANAMA THROUGH SOUTHERN 
MEXICO ON FRI BEFORE MOVING NORTHWARD INTO THE SOUTHEASTERN GULF 
OF CALIFORNIA AND THE PACIFIC COAST OF BAJA CALIFORNIA SUR ON 
SAT. INTERESTS ALONG THE COAST SHOULD BE AWARE OF THE POTENTIAL 
FOR HIGH SURF AND POSSIBLY SOME COMPLICATIONS ENTERING HARBORS 
AND INLETS. SWELL HEIGHTS TO 10 FT CAN BE EXPECTED AS FAR N AS 
09N THROUGH SAT EVENING. 

AN UPPER TROUGH LIES OVER N WATERS FROM 31N131W TO 25N123W TO 
15N140W. THE SOUTHERN END OF THE TROUGH IS BECOMING MORE ZONAL 
AS THE UPPER ENERGY IN THE NORTHERN PORTION OF THE TROUGH LIFTS 
OUT TO THE NE. DIFFLUENT SW FLOW ALOFT BETWEEN THE TROUGH AND AN 
UPPER RIDGE THAT EXTENDS FROM THE AN ANTICYCLONE NEAR 16N110W TO 
15N122W TO 11N140W IS VENTING LARGE AREAS OF CONVECTION ALONG 
THE ITCZ. THIS CONVECTION COINCIDES WITH THE REGION OF HIGHEST 
PRECIPITABLE WATER IN THE FORECAST AREA AND AN AREA OF MODERATE 
UPPER DIFFLUENCE. THESE CONDITIONS ARE EXPECTED TO CONTINUE 
THROUGH SAT. THIS CONVECTION IS DESCRIBED IN THE SECTION ABOVE.

THE SURFACE PRESSURE GRADIENT WILL INCREASE IN THE EVENING HOURS 
ALONG THE CENTRAL COAST OF BAJA CALIFORNIA OVER THE NEXT FEW 
DAYS AS DIURNALLY LOWER PRESSURE OVER MAINLAND MEXICO BUTTS UP 
AGAINST THE SUBTROPICAL RIDGE. THIS WILL BRIEFLY INCREASE THE 
WINDS TO A FRESH BREEZE IN THE REGION EACH EVENING.

$$
SCHAUER