000
AXPZ20 KNHC 302141
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN SEP 30 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 
2030 UTC.

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

MONSOON TROUGH EXTENDS FROM W CARIBBEAN NEAR 14.5N82.5W ACROSS 
NICARAGUA TO DEVELOPING LOW PRES NEAR 11N93W 1010 MB TO 08N108W  
WHERE IT REMAINS FRACTURED...THEN RESUMES FROM LOW PRES NEAR 
14.5N115.5W 1012 MB TO 13N124W WHERE IT TRANSITIONS TO 
ITCZ...CONTINUING ON TO BEYOND 10N140W. SCATTERED MODERATE TO 
STRONG CONVECTION NOTED FROM 04.5N TO 10N E OF 86W. SCATTERED 
MODERATE TO STRONG CONVECTION NOTED WITHIN 90 NM N AND 180 NM S 
OF TROUGH BETWEEN 83W AND 101W.

...DISCUSSION...

BROAD UPPER RIDGE ACROSS THE AREA CENTERED ON ANTICYCLONE NEAR 
21.5N114W EXTENDS W TO 124W AND E INTO CENTRAL MEXICO...AND 
SEPARATES UPPER LEVEL TROUGH TO THE NE ALONG 98W AND TO THE NW 
ALONG 133W-134W. S/W TROUGH DROPPING INTO BACKSIDE OF CENTRAL 
U.S. TROUGH IS ALLOWING UPPER RIDGE TO SLOWLY BEGIN TO BUILD NWD 
OF 30N. PATTERN FORECAST TO AMPLIFY NEXT FEW DAYS AS CENTRAL 
U.S. TROUGH DIGS S AND S INTO NW GULF OF MEXICO. VIGOROUS TUTT 
LOW OVER NW CARIBBEAN EXTENDS VERY NARROW TUTT AXIS SW ACROSS 
CENTRAL AMERICA THEN WSW TO NEAR 08N103W. UPPER LEVEL 
DEFORMATION ZONE HAS DEVELOPED BETWEEN TUTT LOW AND W END OF 
TUTT YIELDING GOOD UPPER DIVERGENCE ACROSS MONSOON TROUGH 
BETWEEN 87W AND 100W...SUPPORTING CONVECTION DESCRIBED ABOVE. 
TUTT TO GRADUALLY WEAKEN MON AND PRODUCE STABILIZING CONDITIONS 
ALOFT BETWEEN 90W AND 100W BY LATE AFTERNOON AND EVENING.  

A STRONG NE-SW ORIENTED HIGH PRES RIDGE N OF THE DISCUSSION AREA 
EXTENDS FROM WELL OFFSHORE OF OREGON NEAR 43.5N133W TO 25N144W. 
A WEAK RIDGE PREVAILS OVER THE TROPICAL EAST PACIFIC N OF 15N W 
OF 12W. LOW PRES REMNANT OF MIRIAM CAN CLEARLY BE SEEN IN 
SATELLITE IMAGERY DRIFTING SSW...AND BARELY HANGING ON AS  
NOTEWORTHY SURFACE FEATURE NEAR 19N114.5W...WITH RECENT 
SCATTEROMETER WINDS SHOWING 10-15 KT WINDS ACROSS THE W 
SEMICIRCLE. MARINE CONDITIONS ARE FAIRLY BENIGN OVER REST OF THE 
DISCUSSION AREA AS TRADEWINDS ARE LIGHT TO MODERATE DUE TO WEAK 
HIGH PRES...AND THE MONSOONAL SWLY WINDS ARE GENERALLY 15 KT AND 
LESS. SEAS E OF 120W THEREFORE CONTINUE TO SUBSIDE AND ARE 
GENERALLY AROUND 6-7 FT OVER MOST OF THE DISCUSSION AREA... 
EXCEPT FROM 06N TO 11N BETWEEN 92W AND 103W WHERE SW SWELL 
DOMINATES...AND ACROSS NW PORTIONS WHERE FRESH NE WINDS N OF THE 
AREA AND LINGERING LONG PERIOD NW SWELL ARE PRODUCING SEA 
HEIGHTS 8 TO 10 FT NW OF A LINE FROM 28N122W TO 15N140W.

A COLD FRONT IS MOVING ACROSS THE NW GULF OF MEXICO THIS EVENING 
AND IS EXPECTED TO SWEEP ACROSS THE GULF OF MEXICO EARLY THIS 
WEEK. HIGH PRES BUILDING BEHIND THE FRONT OVER SOUTHERN MEXICO 
WILL BE A FAVORABLE SET UP FOR A MINOR GULF OF TEHUANTEPEC GAP 
WIND EVENT...EXPECTED TO COMMENCE TUE. NLY WINDS AROUND 20 KT 
WILL BEGIN TO SPILL OUT OF THE GULF OF MEXICO...ACROSS THE 
CHIVELAS PASS AND THROUGH THE GULF OF TEHUANTEPEC TUE MORNING... 
THEN INCREASE TO 20-25 KT LATER ON TUE. THIS GAP WIND FLOW IS 
THEN EXPECTED TO PULSE TO 20-30 KT IN THE EARLY MORNINGS HOURS 
ON EACH SUCCESSIVE DAY THROUGH AT LEAST THU....BUILDING 
DOWNSTREAM SEAS TO 8-10 FT BY EARLY THU.

$$
STRIPLING