000
AXPZ20 KNHC 251547
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT SEP 25 2010

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1545 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 09N89W TO 08N115W TO 12N130W TO 
09N140W. NO SIGNIFICANT CONVECTION.

...DISCUSSION...

EXPANSIVE RIDGE DOMINATES MOST OF THE DISCUSSION AREA AND IS 
ANCHORED TO AN ANTICYCLONE CENTERED NEAR 29N118W. THE RIDGE 
ITSELF EXTENDS FROM NORTHERN MEXICO ALONG 28N THROUGH THE 
ANTICYCLONE THEN WWD THROUGH 28N130W TO 25N140W. WATER VAPOR 
IMAGERY INDICATED THAT THE RIDGE WAS SHIFTING NORTHWARD AND 
GAINING AMPLITUDE AS A TROUGH IN THE CENTRAL PACIFIC DEEPENS 
ALONG 152W. A BROAD SWATH OF MODERATE TO STRONG EASTERLY WINDS 
WERE NOTED S OF THE RIDGE AXIS. THESE WINDS WERE ADVECTING 
TROPICAL MOISTURE WWD TO ALONG 125W.   

FIRST VISIBLE IMAGES OF THE DAY INDICATED THAT THE AREA OF LOW 
PRESSURE NEAR 16N107W HAD A VERY WELL DEFINED CIRCULATION WITH 
SCATTERED TO NUMEROUS STRONG CONVECTION DISPLACED TO THE WEST 
OF THE LOW LEVEL CENTER AS A RESULT OF CONTINUED EASTERLY SHEAR.
THE SHEAR APPEARS TO BE WANING WITH TIME AND THERE IS NOW A 
MODERATE PROBABILITY OF TROPICAL CYCLONE FORMATION WITH THIS 
SYSTEM OVER THE NEXT 48 HOURS. 

LAND BASED WEATHER OBSERVATIONS AT SALINA CRUZ MEXICO ON THE 
SOUTH END OF THE ISTHMUS OF TEHUANTEPEC IS NOW REPORTING 
NORTHERLY WINDS OF 15 KT AHEAD OF TROPICAL STORM MATTHEW 
CURRENTLY MOVING ALONG THE N COAST OF HONDURAS TOWARD SOUTHERN 
MEXICO. THE INCREASED NORTHERLY FLOW HAS INDUCED THE DEVELOPMENT 
OF A WEAK LOW PRES IN THE GULF OF TEHUANTEPEC NEAR 14N95W. 
A BURST OF STRONG CONVECTION WAS NOTED WITHIN 75 NM OF THE LOW
AND WAS ALSO DISPLACED TO THE W OF THE CENTER. IN 
ADDITION...ASCAT DATA SHOW MODERATE SW FLOW TO THE SOUTH. THIS 
FLOW WILL INCREASE TO 20 TO 25 KT ON SUN AS THE REMNANT LOW OF 
MATTHEW MOVES FURTHER INTO CENTRAL AMERICA.  

FURTHER WEST...WEAK LOW PRES 1010 MB IS CENTERED NEAR 12N131W. 
AN EARLIER 0540Z ASCAT PASS SHOWED PERSISTENT 20 KT WINDS AROUND 
THIS LOW. THIS LOW WILL MEANDER A LITTLE FURTHER TO THE 
NORTHEAST ALONG THE ITCZ OVER THE NEXT COUPLE OF DAYS WITH 
LITTLE DEVELOPMENT. 

THE WAVEWATCH III MODEL INDICATES LONG PERIOD NW SWELLS DRIVING 
COMBINED SEA HEIGHTS TO 13 FT MOVING INTO THE FAR NW WATERS ON 
SUN. THE SWELLS SHOULD DAMPEN WITH TIME BUT ARE EXPECTED TO 
REACH THE NORTHERN BAJA PENINSULA TUE...JUST AS A NEW SWELL 
TRAIN ARRIVES IN THE NW CORNER OF THE AREA. 

$$
COBB