000
AXPZ20 KNHC 122130
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI OCT 12 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 
2100 UTC.

...SPECIAL FEATURES...

A BROAD AREA OF LOW PRESSURE EMBEDDED IN THE MONSOON TROUGH IS 
LOCATED NEAR 14N107W. THIS SYSTEM CONTINUES TO PRODUCE 
DISORGANIZED SHOWERS AND THUNDERSTORMS...AND MOST OF THE 
CONVECTIVE ACTIVITY IS CONCENTRATED TO THE W OF THE CENTER FROM 
14N TO 17N BETWEEN 107W AND 112W. 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 1008 MB NEAR 
14N107W TO 11N132W. THE ITCZ CONTINUES FROM 11N132W TO BEYOND 
10N140W. SCATTERED MODERATE CONVECTION IS NEAR 11N127W AND 
WITHIN 75 NM N OF ITCZ AXIS W OF 135W. 

...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 MIGRATING THROUGH SOUTHERN CALIFORNIA 
INTO NEVADA. THIS TROUGH SUPPORTS A FRONTAL BOUNDARY THAT 
EXTENDS FROM 30N134W TO 27N140W. THE FRONT IS EXPECTED TO STALL 
AND WEAKEN BY LATE SAT. AN ANTICYCLONIC CIRCULATION REMAINS 
CENTERED OVER CENTRAL MEXICO NEAR 20N100W AND IS PRODUCING 
MODERATE TO STRONG E TO SE WINDS ALOFT OVER THE LOW PRES SYSTEM 
LOCATED NEAR 14N107W. FARTHER WEST...ANOTHER ANTICYCLONE IS 
LOCATED NEAR 15.5N122W EXTENDING A RIDGE WWD TO NEAR 140W.

AN EAST TO WEST ORIENTED SURFACE RIDGING IS ASSOCIATED WITH A 
1022 MB HIGH PRES AREA NEAR 27N127W. 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.
ACTIVE CONVECTION HAS BEEN FLARING OFF SOUTHERN MEXICO WHERE 
SOMEWHAT ENHANCED SW FLOW INTO THE MONSOON TROUGH ON THE SE SIDE 
OF THE DEVELOPING LOW IS CONVERGING WITH THE NE TO E GAP WINDS.

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.

$$
GR