000
AXPZ20 KNHC 231451
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE OCT 23 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 
1445 UTC.

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

MONSOON TROUGH FROM 12N87W TO 11N110W TO 07N126W TO 10N135W.   
SCATTERED MODERATE TO STRONG WITHIN 150 NM N AND 90 NM S OF THE 
TROUGH BETWEEN 95W AND 101W. SCATTERED MODERATE ISOLATED STRONG 
WITHIN 120 NM EITHER SIDE OF TROUGH BETWEEN 105W AND 118W. 


...DISCUSSION...

A WEAK COLD FRONT ENTERS THE FAR NORTHERN PORTION OF THE 
AREA FROM 31N120W TO 28N128W WHERE IT BECOMES A SHEAR LINE. 
THIS FRONT IS EXPECTED TO DISSIPATE TONIGHT AND WED WEST OF 
NORTHERN BAJA CALIFORNIA. STRONG HIGH PRES BUILDING BEHIND THE 
NEAR 31N140W TONIGHT WILL SHIFT EASTWARD ALONG 31N THROUGH WED 
NIGHT...WHICH TIGHTENS THE PRES GRADIENT ACROSS THE NE 
PORTION OF THE AREA AND INCREASE N-NW WINDS ALONG THE WEST COAST 
OF THE BAJA PENINSULA. EXPECT NW TO N WINDS OF 20 TO 25 KT N OF 
25N E OF 120W WED MORNING THROUGH EARLY FRI. BUILDING HIGH PRES 
ALONG 30N WILL ALSO STRENGTHEN NE TRADE WINDS N OF THE MONSOON 
TROUGH W OF 125W THROUGH THE END OF THE WEEK. 

INTENSIFYING CIRCULATION ASSOCIATED WITH LARGE TROPICAL STORM 
SANDY IN THE SW CARIBBEAN IS ACTING TO STRENGTHEN W-SW WIND FLOW 
S OF THE MONSOON TROUGH WHICH EXTENDS ACROSS NICARAGUA INTO THE 
CARIBBEAN. EXPECT MOIST CONVERGENT MONSOONAL FLOW TO PRODUCE 
WIDESPREAD RAIN AND OCCASIONAL MODERATE TO HEAVY SHOWERS ACROSS 
PANAMA AND COSTA RICA...GRADUALLY SHIFTING NORTHWARD INTO 
NICARAGUA THROUGH THU...WITH STRONG GUSTY WINDS POSSIBLE IN 
HEAVIER DOWNPOURS.  

SCATTEROMETER DATA SHOWS LIGHT TO MODERATE WINDS ACROSS MOST OF 
THE DISCUSSION AREA EXCEPT FOR MODERATE TO FRESH W-SW WINDS JUST 
S OF THE MONSOON TROUGH E OF 110W. NORTHEASTERLY WINDS IN THE 
BAY OF CAMPECHE ENHANCED BY THE CIRCULATION OF SANDY ARE 
FILTERING INTO THE GULF OF TEHUANTEPEC PRODUCING 20-25 KT WINDS 
PER A 0550 UTC ASCAT PASS. AS SANDY TRACKS TO THE N AND WINDS IN 
THE AREA BACK TO THE NORTH...FUNNELING WINDS INTO THE GULF OF 
TEHUANTEPEC MAY INCREASE TO 30 KT EARLY WED BEFORE DROPPING OFF 
ON THU AS SANDY MOVES INTO THE ATLANTIC. THE DOWNSTREAM EFFECTS 
OF THIS ONGOING WIND EVENT MAY INDUCE A CYCLONIC CIRCULATION TO 
DEVELOP S OF TEHUANTEPEC. GFS STILL INSISTS ON VIGOROUS 
DEVELOPMENT OF THIS SYSTEM IN THE FRI TO SUN TIME FRAME ALONG 
105W...WHILE THE OTHER NWP MODELS KEEP A WEAK SYSTEM MOVING 
ALONG TO THE W. SINCE THE TEHUANTEPEC GAP WINDS DROP OFF 
BEGINNING THU THE OTHER NWP MODEL SOLUTIONS ARE PREFERRED AS THE 
GFS MAY BE OVERFORECASTING THE INTERACTION OF THE TEHUANTEPEC 
WINDS WITH THE INCIPIENT LOW PRES AREA. 

$$
COBB