000
AXPZ20 KNHC 040308
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU OCT 04 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 
0300 UTC.

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

THE MONSOON TROUGH EXTENDS WSW ACROSS EASTERN PANAMA AND THE 
GULF OF PANAMA AND SOUTHERN COSTA RICA TO 09N83W...THEN TURNS NW 
TO 12N92W...W TO 12N100W...THEN NW TO 14N106W...THEN SW 
09N118W...WNW TO 11N126W THEN FINALLY SW TO 07N136W WHERE LOW 
LEVEL WINDS INDICATE A TRANSITION TO AN ITCZ WHICH CONTINUES SW 
TO BEYOND 06N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION 
WITH FREQUENT LIGHTNING IS NOTED WITHIN 60 NM EITHER SIDE OF A 
LINE FROM 07N82W TO 06N88W...WITHIN 30 NM OF THE CENTRAL 
AMERICAN COAST FROM 81W TO 93W AND WITHIN 180 NM EITHER SIDE OF 
A LINE FROM 14N95W TO 14N101W TO 08N110W. ISOLATED MODERATE TO 
STRONG CONVECTIVE CLUSTERS ARE OBSERVED WITHIN 30 NM EITHER SIDE 
OF A LINE FROM 11N116W TO 08N125W TO 09N130W.

...DISCUSSION...

AN UPPER LEVEL CYCLONE IS CENTERED NEAR 33N135W WITH AN UPPER 
LEVEL TROUGH AXIS EXTENDING S THROUGH ANOTHER SMALL CYCLONE AT 
19N134W TO A BASE OVER THE DEEP TROPICS NEAR 12.5N133.5W. AN 
UPPER LEVEL ANTICYCLONE IS POSITIONED NEAR 25N116W WITH A RIDGE 
EXTENDING N BEYOND 32N117W. A SECOND UPPER LEVEL RIDGE EXTENDS 
SW TO A BROAD CREST ALONG 130W FROM 16N TO 24N. ANOTHER UPPER 
CYCLONE IS NOTED NEAR 03N130W. WEAK UPPER DIFFLUENCE IS NOTED 
OVER THE DEEP TROPICS ALONG THE SOUTHERN PERIPHERY OF THE 
ANTICYCLONE SUPPORTING THE CONVECTION ALONG THE MONSOON TROUGH 
AS PREVIOUSLY DESCRIBED. SOME OF THE DEBRIS MOISTURE IS ADVECTED 
NE AS A NARROW AND GRADUALLY THINNING TROPICAL PLUME ALONG THE W 
PERIPHERY OF THE UPPER RIDGE...ROUGHLY THROUGH POINTS 19N128W TO 
25N126W TO 33N118W. THE REST OF THE DEBRIS MOISTURE SEEMS TO 
EVAPORATE NEAR THE DECAYING CLUSTERS AS THE UPPER LEVELS ARE 
VERY DRY AIR OVER THE REMAINDER OF THE DISCUSSION AREA W OF 
110W. 

AN UPPER LEVEL CYCLONE OVER NE ARKANSAS TRAILS AN UPPER TROUGH 
AXIS SW OVER THE NW GULF OF MEXICO REACHING ACROSS CENTRAL 
MEXICO TO OVER THE PACIFIC AT 17N105W...THEN CONTINUING S ACROSS 
THE DEEP TROPICS TO TO A BASE AT 04N109W EFFECTIVELY SEPARATING 
THE UPPER FLOW OVER THE DEEP TROPICAL PACIFIC. TO THE E OF THIS 
TROUGH IS AN UPPER LEVEL RIDGE EXTENDING NW FROM SOUTH 
AMERICA...AND IS ADVECTING UPPER MOISTURE S ACROSS THE 
DISCUSSION AREA E OF 100W. THE DEBRIS MOISTURE FROM THE 
PREVIOUSLY MENTIONED CONVECTION...IN THE AREA 10N TO 15N BETWEEN 
91W AND 105W...IS SPREADING NE ACROSS CENTRAL AMERICA BETWEEN 
88W AND 100W...MERGING WITH A PERSISTENT TROPICAL PLUME OVER THE 
SE GULF OF MEXICO.

ELSEWHERE AT THE LOW LEVELS...A BROAD SURFACE RIDGE COVERS THE 
AREA N OF 20N W OF 110W. SOUTHWESTERLY LOW LEVEL WINDS AT 15 TO 
20 KT ALONG WITH CROSS EQUATORIAL SW SWELL CONTINUES TO RESULT 
IN SEAS TO 8 FT IN THE AREA FROM 06N TO 10N BETWEEN 105W AND 
119W. THE WINDS ARE EXPECTED TO DIMINISH TO 15 KT THU AFTERNOON 
AS THE SW SWELL DECAYS TO LESS THAN 8 FT.

GAP WINDS...GALE FORCE WINDS HAVE DIMINISHED TO 30 KT IN AND 
JUST DOWNSTREAM OF THE GULF OF TEHUANTEPEC AND EXPECTED TO 
FURTHER DIMINISH TO 25 KT AFTER THE NORMAL SUNRISE SURGE ON 
THU...BUT EXPECT ANOTHER NEAR SUNRISE SURGE TO 25 KT ON FRI. THE 
INITIAL DRAINAGE SURGE AT 20 TO 25 KT HAS PROPAGATED W ACROSS 
THE AREA FROM 12N TO 15N BETWEEN 96W AND 103W...WITH SEAS OF 8 
TO 12 FT. THIS AREA WILL SHRINK IN SIZE AS IT SHIFTS W THU AND 
FRI. 

IN AND DOWNSTREAM OF THE GULF OF PAPAGAYO...NE TO E WINDS ARE 
FORECAST TO INCREASE TO 20 TO 25 KT LATE TONIGHT AND PERSIST 
THROUGH LATE THU NIGHT BEFORE DIMINISHING.

$$
NELSON