000
AXPZ20 KNHC 300308
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SUN OCT 30 2011

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 
0100 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS IS ANALYZED FROM 10N85W TO 11N92W TO 
07N101W TO 10N115W TO 10N123W. INTERTROPICAL CONVERGENCE ZONE 
AXIS IS ANALYZED FROM 10N123W TO 11N132W TO 09N140W. SCATTERED 
MODERATE WITH ISOLATED STRONG CONVECTION LIES E OF 89W S OF AXIS 
TO 04N.

...DISCUSSION...

A RAPIDLY WEAKENING UPPER LOW OVER THE NW PORTION OF THE AREA 
SHOULD FINALLY BE DRAWN NORTHEASTWARD INTO A TROUGH AMPLIFYING 
OVER THE WESTERN U.S. BEGINNING SUN NIGHT. WATER VAPOR IMAGERY 
CURRENTLY SHOW MOISTURE BEING ADVECTED FROM THE TROPICS TOWARD 
THIS LOW. WIDESPREAD CIRRUS AND ALTO-STRATUS IS FOUND PRIMARILY 
FROM 22N TO 31N BETWEEN 120W AND 127W AS WELL AS OVER BAJA 
CALIFORNIA SUR AND THE SOUTHERN GULF OF CALIFORNIA. AS THE LOW 
WEAKENS AND MOVES NE...THE CLOUDINESS HERE WILL WANE. THIS LOW 
IS PART OF A WEAKENING MEAN TROUGH THAT EXTENDS W TO THE 
HAWAIIAN ISLANDS. ANOTHER UPPER LOW WITHIN THE TROUGH LIES JUST 
W OF THE AREA AND E OF THE BIG ISLAND OF HAWAII. THIS LOW IS 
EXPECTED TO DRIFT E...WITH SOME UPPER LEVEL CLOUDS MOVING INTO W 
WATERS PRIMARILY N OF 15N THROUGH MON. 

THE 1026 MB SUBTROPICAL HIGH LIES NEAR 36N134W AND EXTENDS A 
RIDGE AXIS SE TO 20N115W. THE PRES GRADIENT BETWEEN THE SW SIDE 
OF THE RIDGE AND THE ITCZ/MONSOON TROUGH IS STRONG ENOUGH TO 
YIELD FRESH TRADE WINDS OVER WATERS W OF 125W BETWEEN 13N AND 
21N ACCORDING TO THE 1858 UTC ASCAT PASS. THESE TRADES WILL VARY 
LITTLE THROUGH THE WEEKEND AS THE SUBTROPICAL HIGH POSITION AND 
STRENGTH REMAINS MOSTLY UNCHANGED. ON MON...THE HIGH IS EXPECTED 
TO MERGE WITH A STRONGER HIGH TO ITS NW. THIS WILL SHIFT THE 
AREA OF FRESH TRADE WINDS SLIGHTLY FARTHER W.

THE 1540 UTC ASCAT PASS SHOWED FRESH SW FLOW S OF THE MONSOON 
TROUGH OVER THE FAR SE PORTION OF THE AREA S OF PANAMA. SHIP 
A8SF8 REPORTED 23 KT SW WINDS NEAR 03N80W...E OF THE ASCAT 
SWATH...AT 0000 UTC. THESE WINDS ARE EXPECTED TO CONTINUE 
FOR THE NEXT DAY OR TWO AS THE PRES GRADIENT REMAINS TIGHT 
BETWEEN TROUGHING OVER THE WESTERN CARIBBEAN AND RIDGING S OF 
THE EQUATOR IN THE EASTERN PACIFIC. THE STRENGTH OF THE WINDS 
HERE WILL LARGELY BE TIED TO THE STRENGTH OF THE TROUGHING IN 
THE CARIBBEAN. SCATTERED MODERATE WITH ISOLATED STRONG 
CONVECTION FOUND OVER MUCH OF THE AREA OFFSHORE OF 
COLOMBIA...PANAMA...AND COSTA RICA IS DESCRIBED IN THE SECTION 
ABOVE. SCATTERED MODERATE CONVECTION EXTENDS INLAND OVER MUCH OF 
PANAMA...COSTA RICA...AND NICARAGUA WHILE STRONG CONVECTION IS 
FOUND FARTHER N NEAR THE GULF OF FONSECA AND NW NICARAGUA. THIS 
AREA LIES UNDER UPPER LEVEL DIFFLUENCE ASSOCIATED WITH A RIDGE 
AXIS THAT EXTENDS TO AN ANTICYCLONE OVER EASTERN CUBA AND WITHIN 
THE REGION OF HIGHEST PRECIPITABLE WATER VALUES IN THE FORECAST 
AREA. WIDESPREAD PRECIPITATION SHOULD CONTINUE IN THIS AREA 
THROUGH MON.

GAP WINDS...THE 1538 UTC ASCAT PASS FAILED TO SHOW WINDS TO GALE 
FORCE IN THE GULF OF TEHUANTEPEC. HOWEVER...ENHANCEMENT OF THE 
WINDS EXPECTED HERE WITH NIGHTTIME DRAINAGE FLOW FROM THE 
MOUNTAINS AND A SURGE OF COLDER AND MUCH DRIER AIR CURRENTLY 
MAKING ITS WAY S THROUGH THE WESTERN GULF OF MEXICO AND EXPECTED 
TO REACH CHIVELA PASS SUN WILL HELP KEEP WINDS HOVERING NEAR 
GALE FORCE THROUGH MON. THE GALE WARNING WILL CONTINUE TO BE IN 
EFFECT THROUGH THE END OF THE FORECAST PERIOD MON EVENING.

$$
SCHAUER