000
AXPZ20 KNHC 201528
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT SEP 20 2008

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 
1500 UTC.

...SPECIAL FEATURES...

A BROAD AREA OF LOW PRESSURE IS LOCATED OFF THE MEXICAN COAST 
AND CENTERED IN THE VICINITY OF 12N103W. A LARGE AREA OF LAYERED 
CLOUDS WITH SHOWERS AND TSTMS...SOME STRONG...ARE LOCATED WITHIN 
125 NM EITHER SIDE OF A LINE FROM 17N105.5W TO 13N96W AND 
ASSOCIATED WITH THE ITCZ. MAIN EFFECTS OF THIS SYSTEM IS THE 
POTENTIAL FOR HEAVY RAINS ALONG THE MEXICAN COAST FROM THE GULF 
OF TEHUANTEPEC WESTWARD TO 103W. GRADUAL DEVELOPMENT INTO A 
TROPICAL CYCLONE IS POSSIBLE OVER THE NEXT 48 HOURS AS THE 
SYSTEM MOVES SLOWLY WNW.

...TROPICAL WAVES...

A TROPICAL WAVE ALONG 96W N OF 08N INTO MEXICO IS MOVING W 10 
KT. THE WAVE IS EMBEDDED WITHIN THE BROAD LOW PRESSURE AREA 
MENTIONED ABOVE AND MAY ENHANCE THE HEAVY RAINFALL OVER THE NEXT 
DAY OR TWO.

A TROPICAL WAVE ALONG 106W FROM 07N TO 16N IS MOVING W ABOUT 10 
KT. THIS WAVE IS LOCATED WITHIN THE WESTERN PERIPHERY OF THE LOW 
PRESSURE AREA AND MOST OF THE STRONG CONVECTIVE ACTIVITY IS 
LOCATED E OF THE WAVE AXIS.

A TROPICAL WAVE ALONG 122W FROM 07N TO 16N IS MOVING W ABOUT 10 
KT. CONVECTION ASSOCIATED WITH THE WAVE IS LOCATED S OF 10N AND 
TIED TO THE ITCZ.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 07N77W TO 14N96W TO 09N113W TO 
09N126W TO 08N131W TO 11N140W. SCATTERED MODERATE ISOLATED 
STRONG CONVECTION IS LOCATED FROM 02N TO 07N E OF 84W. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION IS LOCATED FROM 06N TO 11N 
BETWEEN 120W AND 125W. SCATTERED MODERATE CONVECTION IS LOCATED 
WITHIN 120 NM OF AXIS W OF 128W.

...DISCUSSION...

W OF 105W...
WATER VAPOR IMAGERY INDICATES SUBSIDENCE N OF A LINE FROM 
20N105W TO 14N125W TO 16N140W AND IS STRONGEST N OF 25N E OF 
135W. THE MAIN FEATURE ALOFT IS A BROAD RIDGE WITH THE AXIS  
CENTERED ALONG 16N/17N BETWEEN 105W AND 140W WITH SOUTHWESTERLY 
WINDS LOCATED N OF THE AXIS W OF 130W BECOMING WESTERLY E OF 
130W ACROSS BAJA CALIFORNIA. WINDS AT THE UPPER LEVELS ARE 
NORTHEASTERLY TO EASTERLY S OF ABOUT 12N WITH SATELLITE CLOUD 
DRIFT WINDS INDICATING SPEEDS UP TO 30 KT. AT THE SURFACE A 
TROUGH IS LOCATED FROM 14N137W TO 08N141W. A SURFACE RIDGE IS 
LOCATED FROM A 1023 MB HIGH CENTERED NEAR 36N146W THROUGH 
28N135W TO 18N110W. 

E OF 105W...
A RIDGE ALOFT THAT CUTS ACROSS THE GULF OF MEXICO FROM NE 
FLORIDA TO THE BAY OF CAMPECHE CONTINUES SW INTO THE PACIFIC TO 
NEAR 15N105W. SATELLITE CLOUD DRIFT WINDS ALOFT ARE NE TO E AND 
MEASURE BETWEEN 30 TO 45 KT AND ARE STRONGEST S OF 05N TO THE 
EQUATOR.

$$
CAB