000
AXPZ20 KNHC 122158
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT OCT 12 2013

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...SPECIAL FEATURES...
LOW PRES CENTER 1006 MB EMBEDDED IN MONSOON TROUGH AT 15N109W
REMAINS STRONG DESPITE AN UNFAVORABLE UPPER LEVEL ENVIRONMENT...
MAINLY DUE TO THE ABUNDANT WARM TROPICAL MOISTURE AVAILABLE AND
29 DEGREES SEA SURFACE TEMPERATURES.  MECHANICAL UPLIFT PROMPTS
NUMEROUS MODERATE AND SCATTERED STRONG CONVECTION MAINLY IN NW
SEMICIRCLE OF CENTER.  SHEARING ACTION OF SW WINDS IS TAKING ITS
TOLL IN THE SYSTEM AND ALTHOUGH IT IS EXPECTED TO SLOWLY
STRENGTHEN WITHIN 24 HOURS...IT IS LIKELY TO BE SHORT-LIVED 
BEFORE IT TURNS NE...WEAKENS AND MOVE MAINLAND MEXICO IN THE
BAJA CALIFORNIA PENINSULA.  SYSTEM HAS HIGH PROBABILITY OF
REACHING TROPICAL CYCLONE STRENGTH DURING NEXT 48 HOURS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...           
MONSOON TROUGH EXTENDS FROM 09N84W TO 15N106W TO LOW PRES 1006 MB
AT 15N109W TO LOW PRES 1008 MB AT 12N117W TO 10N126W TO 10N130W
...THEN RESUMES FROM LOW PRES 1012 MB AT 14N134W TO BEYOND 
09N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION S OF AXIS
TO 05N.  NUMEROUS MODERATE SCATTERED STRONG CONVECTION WITHIN
300 NM N OF AXIS FROM 97W TO 118W. 

...DISCUSSION...
LARGE AMPLITUDE UPPER LEVEL TROUGH REMAINS IN PLACE FROM 
SOUTHERN CALIFORNIA 32N120W TO 09N126W...MAKING LITTLE PROGRESS
EASTWARD AS HEALTHY UPPER LEVEL ANTICYCLONE SITS STUBBORNLY WELL
ANCHORED OVER CENTRAL MEXICO.  SQUEEZED SOUTHERLY AIR FLOW
BETWEEN SYSTEMS INCREASES...SPECIALLY OVER AFOREMENTIONED SURFACE
LOW PRES...SHEARING CONVECTION NORTHWARD AND ADVECTING MOIST
CONVECTIVE DEBRIS OVER MAINLAND MEXICO.  

UPPER LEVEL TROUGH MAINTAINS VERY DRY AND STABLE SUBSIDING AIR
MASS OVER BASIN W OF AXIS.  WHILE ANTICYCLONE ALLOWS ABUNDANT
TROPICAL MOISTURE TO MOVE ACROSS E PAC BETWEEN 05N AND MONSOON
TROUGH.  SECOND LOW PRES CENTER AT 12N117W REMAINS UNDER AN
ENVIRONMENT FAVORABLE FOR STRENGTHENING BUT IS QUICKLY
APPROACHING EDGE OF DRY AIR MASS WHICH WOULD SPELL ITS DOOM.  

...ELSEWHERE AT THE LOWER LEVELS...
MODERATE TO FRESH NW WINDS ALONG COAST OF BAJA CALIFORNIA...
BETWEEN HIGH PRES CENTER 1027 MB AND WEAK TROUGH OVER GULF OF 
CALIFORNIA AND THE SIERRA MADRE. 

FARTHER W...LOW PRES CENTER 1012 MB ...REMNANT OF NARDA WHICH
REFUSES TO DIE ALTHOUGH DEVOID OF ANY SIGNIFICANT CONVECTION...
IS AT 14N134W.  STILL ASSOCIATED WITH FRESH TO STRONG NE WINDS
AND SEAS TO 10 FT WITHIN 180 NM IN ITS NW QUADRANT.  SYSTEM IS
EXPECTED TO DRIFT SW AND OPEN INTO A TROUGH BY 24-48 HOURS.

GULF OF TEHUANTEPEC...TROPICAL WAVE COUPLED WITH UPPER LEVEL 
TROUGH MOVE THROUGH CENTRAL AMERICA SUN AND MON BRINGING STRONG
N WINDS ACROSS CHIVELAS PASS INTO GULF OF TEHUANTEPEC LATE SUN.
EVENT EXPECTED TO BE WEAK AND SHORT-LIVED. 
 
$$
WALLY BARNES