000
AXPZ20 KNHC 241559
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC WED OCT 24 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

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

MONSOON TROUGH EXTENDS FROM 12.5N86W TO LOW PRES NEAR 11N96.5W 
1008 MB TO 13.5N108W TO 08N124W...WHERE IT TRANSITIONS TO ITCZ 
CONTINUING ON THROUGH 08N138W TO BEYOND 08N140W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 240 NM S OF 
TROUGH E OF 112W AND WITHIN 90 NM N AND 150 NM S OF TROUGH 
BETWEEN 111W AND 118W. SCATTERED MODERATE TO STRONG CONVECTION 
WAS NOTED WITHIN 240 NM SW AND 300 NM NW QUADRANTS OF LOW PRES 
NEAR 11N96.5W.

...DISCUSSION...

AN UPPER LEVEL BLOCKING PATTERN PREVAILS THIS MORNING FROM THE 
TROPICS TO ABOUT 35N BETWEEN THE EASTERN PACIFIC ALONG 130W TO 
THE EASTERN ATLANTIC. FROM WEST TO EAST...A 
RIDGE-TROUGH-RIDGE-TROUGH-RIDGE PATTERN EXISTS. THIS IS CAUSING 
PROGRESSIVE UPPER LEVEL FLOW ACROSS THE CENTRAL PACIFIC TO LIFT 
OVER AND ACROSS A BROAD UPPER RIDGE DOMINATING MUCH OF THE 
DISCUSSION AREA...CENTERED ON AN UPPER ANTICYCLONE NEAR 21N108W. 
A LARGE POOL OF ABUNDANT TROPICAL MOISTURE PREVAILS ACROSS THE 
TROPICS FROM 06N TO 13N E OF 120W...WITH CONVECTION DESCRIBED 
ABOVE BEING INITIATED BY MODERATE TO FRESH MONSOONAL FLOW S OF 
THE TROUGH. UPPER LEVEL ELY WINDS S OF THE UPPER RIDGE CONTINUE 
TO DIVERT AROUND THE DEEPER CONVECTION S OF THE MONSOON TROUGH. 
THIS UPPER PATTERN WILL CHANGE LITTLE IN THE NEXT 24 HOURS BUT 
WILL BEGIN TO BROADEN AND FLATTEN BY FRI AS UPPER TROUGHING DIGS 
SW ACROSS CENTRAL AMERICA NEAR 90W.

AN AREA OF BUILDING HIGH PRES OVER THE NORTH-CENTRAL WATERS 
CENTERED NEAR 31N133W WILL SHIFT E ALONG 31N THROUGH THU. THE 
PRESENCE OF A LOW PRES TROUGH OVER NW MEXICO AND BAJA CALIFORNIA 
WILL TIGHTEN THE PRES GRADIENT OVER THE NE PORTION...BRINGING 
FRESH TO STRONG N-NW WINDS ACROSS THE NEAR AND OFFSHORE WATERS W 
OF THE BAJA PENINSULA. EXPECT 20-25 KT WINDS TO GRADUALLY EXPAND 
SWD TO NEAR 23N BY THU BETWEEN 115W AND 122W...WITH SEAS 
BUILDING TO 10 FT. GLOBAL MODELS ARE HINTING AT THE POSSIBILITY 
OF WINDS INCREASING TO 30 KT N OF 29N ACROSS THE REGION THU... 
RAISING SEAS TO 11 FT. THIS ENHANCED PRES GRADIENT WILL ALSO 
INDUCE NNW WINDS 20-25 KT THROUGH THE NORTHERN TWO-THIRDS OF THE 
GULF OF CALIFORNIA BY THU EVENING CONTINUING THROUGH FRI...WITH 
SEAS BUILDING TO 8 FT BY FRI MORNING.

THE LARGE CYCLONIC CIRCULATION ASSOCIATED WITH HURRICANE SANDY 
IN THE W CENTRAL CARIBBEAN IS STRENGTHENING W-SW WIND FLOW S OF 
THE MONSOON TROUGH EXTENDING INTO THE COASTAL WATERS OF 
NICARAGUA....COSTA RICA...AND PANAMA...WHERE SEAS ARE REACHING 
AT OR NEAR 8 FT. MOIST CONVERGENT MONSOONAL FLOW WILL PRODUCE 
WIDESPREAD AREAS OF RAIN WITH OCCASIONAL MODERATE TO HEAVY 
SQUALLS ACROSS PANAMA AND COSTA RICA...GRADUALLY SHIFTING N INTO 
NICARAGUA THROUGH THU...WITH STRONG GUSTY WINDS POSSIBLE IN 
HEAVIER DOWNPOURS.

SCATTEROMETER DATA OVERNIGHT SHOWED FRESHENING N WINDS 20-25 KT 
WITH A SMALL AREA TO 30 KT THROUGH THE GULF OF TEHUANTEPEC. 
CYCLONIC FLOW AROUND T.S. SANDY IN COMBINATION WITH A WEAK RIDGE 
THAT NOSES SOUTHWEST ACROSS THE SE GULF OF MEXICO IS SUPPORTING 
ENHANCED WINDS THROUGH THE ISTHMUS OF TEHUANTEPEC...WHICH ARE 
EXPECTED TO PULSE BETWEEN 15-30 KT THROUGH EARLY THU...THEN 
PULSE 15-25 KT THROUGH FRI.

GLOBAL MODEL GUIDANCE INDICATES MULTIPLE WEAK TO MODERATE 
CYCLONIC CIRCULATIONS EMBEDDED WITHIN THE MONSOON TROUGH 
DEVELOPING E OF 120W OVER THE NEXT 2-3 DAYS WITH LITTLE 
SIGNIFICANT INTENSIFICATION EXPECTED. THIS WILL HELP KEEP A 
CONVERGENCE ZONE OF FAIRLY ACTIVE CONVECTION E OF 125W THROUGH 
FRI.

$$
STRIPLING