000
AXPZ20 KNHC 130235
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SAT OCT 13 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 
0215 UTC.

...SPECIAL FEATURES...

A BROAD AREA OF LOW PRESSURE EMBEDDED IN THE MONSOON TROUGH IS 
LOCATED NEAR 15N108W OR ABOUT 370 MILES SOUTHWEST OF MANZANILLO 
MEXICO. THIS SYSTEM CONTINUES TO PRODUCE DISORGANIZED SHOWERS 
AND THUNDERSTORMS...AND MOST OF THE CONVECTIVE ACTIVITY IS 
CONCENTRATED TO THE NW OF THE CENTER. NUMEROUS MODERATE TO 
STRONG CONVECTION IS SEEN WITHIN 180 NM NW QUADRANT. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION IS NOTED ELSEWHERE FROM 13N 
TO 15N BETWEEN 110W AND 115W. UPPER-LEVEL WINDS ARE EXPECTED TO 
BECOME CONDUCIVE FOR DEVELOPMENT DURING THE NEXT COUPLE OF DAYS. 
THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE 
DURING THE NEXT 48 HOURS AS IT MOVES GENERALLY WESTWARD AT 10 TO 
15 MPH TOWARD AN AREA OF REDUCE SHEAR ALOFT. FOR NOW...EXPECT 
WINDS OF 20 TO 25 KT MAINLY TO THE NW AND SW QUADRANTS OF LOW 
CENTER WITH BUILDING SEAS TO AROUND 10 FT BY SUN.

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

MONSOON TROUGH EXTENDS FROM 09N84W TO LOW PRES 1007 MB NEAR 
15N108W TO 11N132W. THE ITCZ CONTINUES FROM 11N132W TO BEYOND 
10N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED 
FROM 11N TO 14N BETWEEN 101W AND 106W. A CLUSTER OF MODERATE TO 
STRONG CONVECTION IS WITHIN 35 NM OF 07N90W. SCATTERED MODERATE 
CONVECTION IS NEAR 10.5N121.5W AND NEAR 10.5N130W.

...DISCUSSION...

AN UPPER-LEVEL TROUGH IS MOVING ACROSS THE NW CORNER OF THE AREA 
PRODUCING W TO SW FLOW ACROSS MUCH OF THE WATERS N OF 20N. THE 
SWLY FLOW INCREASES OVER NW MEXICO AND THE SW CONUS AROUND A 
BROADER CUT-OFF UPPER LOW SPINNING OVER THE UTAH. THIS TROUGH 
SUPPORTS A STATIONARY FRONT THAT EXTENDS FROM 30N132W TO 
27N140W. THE FRONT IS EXPECTED TO WEAKEN LATE TODAY. AN 
ANTICYCLONIC CIRCULATION REMAINS CENTERED OVER CENTRAL MEXICO 
NEAR 20N100W AND IS PRODUCING MODERATE TO STRONG SE WINDS ALOFT 
OVER THE LOW PRES SYSTEM LOCATED NEAR 15N108W. FARTHER WEST... 
ANOTHER ANTICYCLONE IS LOCATED NEAR 16.5N120W EXTENDING A RIDGE 
WSW TO BEYOND 140W.

A 1022 MB HIGH PRES SITUATED NEAR 28.5N127W EXTENDS A RIDGE SE 
TO NEAR 21N112W. SCATTEROMETER PASSES SHOW AN AREA OF TRADE 
WINDS IN THE 20 TO 25 KT RANGE JUST TO THE S OF THIS HIGH PRES 
COVERING THE REGION FROM 14N TO 18N BETWEEN 125W AND 135W. NW 
SWELL TO 9 FT CONTINUES TO PROPAGATE INTO THE SAME GENERALLY 
AREA...BUT SEAS LESS THAN 8 FT CAN BE EXPECTED OUTSIDE THE MAIN 
TRADE WIND BELT AS THE SWELL DECAYS OVER THE NEXT COUPLE OF 
DAYS. THE HIGH PRES IS FORECAST TO SLIGHTLY STRENGTH DURING THE 
WEEKEND RESULTING IN NLY WINDS OF 20 KT JUST WEST OF THE WEST 
COAST OF BAJA CALIFORNIA PENINSULA. 

PERSISTENT STRONG HIGH PRES OVER THE GULF OF MEXICO CONTINUES TO 
ALLOW FRESH TO STRONG GAP WIND FLOW TO PULSE THROUGH THE GULF OF 
TEHUANTEPEC...PRIMARILY DURING OVERNIGHT AND EARLY MORNING HOURS.

HIGH PRES BUILDING ACROSS THE GREAT BASIN AND INTERMOUNTAIN WEST 
WILL ENHANCE WINDS SLIGHTLY IN THE GULF OF CALIFORNIA THIS 
WEEKEND...ALLOWING PERIODS OF 20 TO 25 KT NW FLOW BETWEEN 24N 
AND 27N TODAY. THE AERIAL EXTENT OF THESE WINDS WILL INCREASE 
TONIGHT FROM 24N TO 29N. 

$$
GR