000
AXPZ20 KNHC 202149
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT SEP 20 2008

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 
2100 UTC.

...SPECIAL FEATURES...

A BROAD AREA OF LOW PRESSURE IS LOCATED OFF THE MEXICAN COAST 
AND CENTERED IN THE VICINITY OF 13N97W. WINDS ARE 20 TO 25 KT 
WITHIN 180 NM S AND 90 NM N SEMICIRCLE OF THE LOW CENTER. THE 
LOW IS ATTACHED TO A TROPICAL WAVE ALONG 97W N OF 05N INTO 
MEXICO AND IS MOVING W ABOUT 10 KT. 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 NW.

...TROPICAL WAVES...

A TROPICAL WAVE ALONG 106W FROM 05N TO 16N IS MOVING W 5 TO 10 
KT. THIS WAVE IS LOCATED WITHIN THE WESTERN PERIPHERY OF THE LOW 
PRESSURE AREA NOTED ABOVE AND MOST OF THE STRONG CONVECTIVE 
ACTIVITY IS LOCATED E OF THE WAVE AXIS.

A TROPICAL WAVE IS REPOSITIONED TO ALONG 120W FROM 05N TO 16N 
AND MOVING W ABOUT 10 KT. A 1012 MB LOW IS ATTACHED TO THE WAVE 
AT 10N AND IS CLEARLY SEEN IN THE LATEST VISIBLE IMAGERY. 
CONVECTION ASSOCIATED WITH THE WAVE IS LOCATED S OF 12N AND TIED 
TO THE ITCZ.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 11N86W TO 14N99W TO 09N110W TO 
10N115W TO 10N140W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION IS LOCATED WITHIN 150 NM N AND 60 NM S OF THE AXIS 
BETWEEN 94W AND 101W. SCATTERED MODERATE CONVECTION IS LOCATED 
WITHIN 90 NM N AND 120 NM S OF THE AXIS BETWEEN 118W AND 126W.

...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 15 TO 20 KT FROM 05N TO 12N AND UP 
TO 25 KT S OF 05N TO THE EQUATOR. A SURFACE RIDGE IS LOCATED 
FROM A 1024 MB HIGH CENTERED NEAR 36N145W THROUGH 28N128W TO 
22N117W. 

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 15N100W. SATELLITE CLOUD DRIFT WINDS ALOFT ARE NE TO E AND 
MEASURE BETWEEN 30 TO 45 KT AND ARE STRONGEST S OF 08N TO THE 
EQUATOR.

$$
CAB