000
AXPZ20 KNHC 211607
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI OCT 21 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...ITCZ/MONSOON TROUGH...
MONSOON TROUGH FROM BROAD CYCLONIC CIRCULATION ACROSS SW 
CARIBBEAN TO NW COAST OF COSTA RICA NEAR 10.5N88W TO 16N106W TO 
07N125W THEN TRANSITIONS TO ITCZ CONTINUING TO 08.5N140W.  
SCATTERED MODERATE CONVECTION NOTED WITHIN 150 NM S OF AXIS 
BETWEEN 80W AND 88W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION NOTED WITHIN 180 NM N OF AXIS BETWEEN 103W AND 110W. 

...DISCUSSION...

ALOFT...A ZONAL UPPER FLOW PATTERN PREVAILS ACROSS N PORTIONS OF 
THE AREA FROM 20N TO 30N. AN UPPER RIDGE EXTENDS W-SW TO E-NE 
ACROSS THE AREA FROM AN UPPER ANTICYCLONE NEAR 14N150W TO 
23N115W...WHILE ANOTHER UPPER ANTICYCLONE WAS CENTERED ALONG 
THEW COAST OF MEXICO NEAR 20N103.5W AND SHIFTING W. THIS RIDGE 
WAS PRODUCING UPPER LEVEL EASTERLIES GENERALLY S OF 13-15N 
EXTENDING FROM THE FAR W CARIBBEAN AND CENTRAL AMERICA TO BEYOND 
140W.

AT LOWER LEVELS...A PAIR OF 1026 MB HIGH PRES CENTERS WERE 
LOCATED JUST NW OF THE AREA...WITH A MEAN CENTERPOINT NEAR 
32N138W...AND RIDGE EXTENDING SE TO NEAR 20N112W. A SUFFICIENTLY 
TIGHT PRES GRADIENT ALONG THE CALIFORNIA AND BAJA CALIFORNIA 
COASTS WAS PRODUCING NW TO N WINDS OF 20 KT ACROSS THE OFFSHORE 
CALIFORNIA WATERS EXTENDING S TO 28N BETWEEN 117W AND 124W. 
FARTHER E...COLD AIR SPILLING FROM THE GULF OF MEXICO CROSSING 
THE CHIVELAS PASS INTO THE GULF OF TEHUANTEPEC HAS DIMINISHED 
BELOW GALE FORCE...BUT CONTINUES AS STRONG BREEZE WITH N TO NE 
WINDS 20 TO 30 KT. RECENT MODEL GUIDANCE SUGGESTS WINDS TO 
GENERALLY REMAIN IN THE 20 TO 30 KT RANGE FOR THE NEXT FEW 
DAYS... POSSIBLY INCREASING TO MINIMAL GALE FORCE DURING THE 
LATE NIGHT AND EARLY MORNING HOURS...ENHANCED BY TYPICAL 
DRAINAGE FLOW. A DEVELOPING LOW PRESSURE SYSTEM IN THE SW 
CARIBBEAN IS SHOWING SIGNS OF BETTER ORGANIZATION THIS MORNING 
AND COULD INTENSIFY DURING THE NEXT FEW DAYS. THIS TOO WOULD 
INCREASE THE PRESSURE GRADIENT ACROSS THE REGION AND ALLOW FOR 
GALES INTO THE GULF OF TEHUANTEPEC. 

MODERATE NE TRADES WILL INCREASE TO 20 KT WITHIN 24 HOURS S OF 
THE RIDGE FROM 13N TO 20N W OF 135W AND CONTINUE FOR THE NEXT 
FEW DAYS. 

OTHERWISE...THE MONSOON TROUGH AND ASSOCIATED MONSOONAL FLOW 
DOMINATE THE REMAINDER OF THE AREA S OF 20N AND E OF 110W.
LONG PERIOD SW SWELL FROM THE SRN HEMISPHERE CONTINUES ACROSS 
THIS AREA...WITH OFFSHORE SEAS GENERALLY IN THE 4 TO 6 FT RANGE 
AND WILL INCREASE THROUGH THE WEEKEND AS A NEW PULSE OF SW SWELL 
ARRIVES SAT.
 
$$
STRIPLING