000
AXPZ20 KNHC 252135
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT SEP 25 2010

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2130 UTC.

...SPECIAL FEATURE...

MOST RECENT VISIBLE SATELLITE IMAGERY INDICATED THAT THE AREA OF 
LOW PRESSURE NEAR 15.5N108W CONTINUES TO SHOW SOME SIGNS OF 
ORGANIZATION WITH A VERY WELL DEFINED LOW LEVEL CIRCULATION
EXPOSED JUST TO THE EAST OF SCATTERED TO NUMEROUS STRONG 
CONVECTION. THIS CONVECTION EXTENDED OUT 150 NM TO THE W OF THE 
CENTER OF THE LOW AND REMAINED DISPLACED TO THE WEST OF THE LOW 
LEVEL CENTER AS A RESULT OF CONTINUED EASTERLY SHEAR. THE SHEAR 
APPEARS TO BE SLOWLY LESSENING WITH TIME. A 1632 UTC HIGH 
RESOLUTION ASCAT PASS INDICATED WINDS OF 20 TO 25 KT WITHIN 
120-150 NM OF THE LOW. THERE IS A MODERATE PROBABILITY OF 
TROPICAL CYCLONE FORMATION WITH THIS SYSTEM OVER THE NEXT 48 
HOURS AS IT TRACKS TO THE WEST.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 08N83W TO 08N120W TO 12N130W TO 
13N132W. SCATTERED MODERATE WITHIN 60 NM OF AXIS BETWEEN 88W AND 
101W.

...DISCUSSION...

EXPANSIVE RIDGE DOMINATES MOST OF THE DISCUSSION AREA AND IS 
ANCHORED TO AN ANTICYCLONE CENTERED NEAR 30N120W. THE RIDGE 
ITSELF EXTENDS FROM NW MEXICO ALONG 27N THROUGH THE ANTICYCLONE 
THEN WESTWARD THROUGH 29N130W TO 25N140W. WATER VAPOR IMAGERY 
INDICATED THAT THE RIDGE WAS SHIFTING NORTHWARD AND GAINING 
AMPLITUDE AS A TROUGH IN THE CENTRAL PACIFIC DEEPENS ALONG 153W. 
A BROAD SWATH OF MODERATE TO STRONG EASTERLY WINDS WERE NOTED S 
OF THE RIDGE AXIS. THESE WINDS WERE ADVECTING TROPICAL MOISTURE 
WESTWARD TO ALONG 125W.   

SURFACE OBSERVATIONS FROM SALINA CRUZ MEXICO LOCATED ON THE 
SOUTH END OF THE ISTHMUS OF TEHUANTEPEC INDICATED NORTHERLY 
WINDS OF 20 KT OVER THE PAST SEVERAL HOURS AHEAD OF TROPICAL 
DEPRESSION MATTHEW CURRENTLY MOVING OVER NORTHERN GUATEMALA
TOWARD SOUTHERN MEXICO. THE INCREASED NORTHERLY FLOW IN THE GULF 
OF TEHUANTEPEC HAS INDUCED THE DEVELOPMENT OF A WEAK LOW PRES 
NEAR 14N94W. AN AREA OF SCATTERED MODERATE CONVECTION WAS NOTED 
WITHIN 90 NM TO THE SW OF THE LOW. IN ADDITION...1454 AND 1634
UTC ASCAT PASSES SHOWED SW WINDS OF 15 TO 20 KT WELL 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 12N135W. 
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