000
AXPZ20 KNHC 190256
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
0405 UTC SAT SEP 19 2015

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0200 UTC.               

...SPECIAL FEATURES...

AN ELONGATED AREA OF LOW PRES EXTENDS FROM A FEW HUNDRED MILES S 
OFF THE SOUTHERN TIP OF CALIFORNIA...SOUTHWESTWARD INTO THE 
TROPICS...WITH A PAIR OF LOW PRESSURE CENTERS EMBEDDED NEAR EACH 
END...LOCATED NEAR 17.5N112W AND 15.5N119.5W. SATELLITE IMAGERY 
IS SHOWING PERSISTENT ACTIVE CONVECTION IN ASSOCIATION WITH THIS 
MONSOONAL LIKE CIRCULATION...WITH SCATTERED MODERATE TO STRONG 
CONVECTION WITHIN 240 NM ACROSS THE W SEMICIRCLE OF THE EASTERN-
MOST LOW...AND SCATTERED MODERATE TO STRONG CONVECTION WITHIN 
150 NM ACROSS THE NW QUADRANT OF THE WESTERN-MOST LOW. AFTERNOON 
SCATTEROMETER DATA SHOWED WINDS GENERALLY 15-20 KT SURROUNDING 
THIS ELONGATED CIRCULATION. 

GLOBAL MODELS CONTINUE TO INDICATE THAT THIS ELONGATED AREA OF 
LOW PRES WILL ROTATE COUNTER CLOCKWISE...AND BECOME MORE NE TO 
SW ALIGNED TONIGHT THROUGH FRIDAY...AND CONTINUE TO ADVECT 
ABUNDANT TROPICAL MOISTURE TOWARDS CENTRAL AND SOUTHERN BAJA 
CALIFORNIA AS WELL AS THE ADJACENT GULF AND MEXICAN STATES TO 
THE E. THE MOISTURE SHOULD THEN SPREAD FARTHER NW-N ACROSS 
NORTHERN BAJA CALIFORNIA SAT AND SAT NIGHT AS THE ELONGATED LOW 
PRES AREA BEGINS TO SHIFT N-NW. INCREASING RAIN CHANCES SHOULD 
BE EXPECTED ACROSS THESE AREAS...EXTENDING INLAND ACROSS 
MAINLAND MEXICO TO THE W SLOPES OF THE SIERRA MADRES 
OCCIDENTALES...WITH THE POTENTIAL FOR HEAVY RAINS...FLASH 
FLOODING AND LANDSLIDES THROUGH THE WEEKEND. THERE IS SOME 
POTENTIAL FOR THE EASTERN MOST LOW TO IMPROVE IN ORGANIZATION 
DURING THE NEXT 48 HOURS...AND THIS SYSTEM HAS A MEDIUM CHANCE 
FOR DEVELOPMENT INTO A TROPICAL CYCLONE AS IT MOVES NW TO N-NW.

...TROPICAL WAVES... 

A TROPICAL WAVE IS INVOF 85W-86W AND EXTENDS ACROSS CENTRAL 
AMERICA AND ACROSS THE GULF OF HONDURAS...MOVING W 10-15 KT. 
SCATTERED SHOWERS AND TSTMS ARE NOTED BEHIND THE WAVE AXIS 
EXTENDING FROM CARIBBEAN COASTAL AREAS OF HONDURAS AND NICARAGUA 
SE INTO THE SW CARIBBEAN...WHILE ACTIVITY AHEAD OF THE WAVE IS 
INCREASING ACROSS PACIFIC COASTAL AREAS OF HONDURAS AND NW 
NICARAGUA.
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...            

THE MONSOON TROUGH AXIS EXTENDS FROM COLOMBIA NEAR 09N73W TO 
10N88W TO LOW PRES 1007 MB NEAR 06N101.5W...WHERE IT HAS 
FRACTURED...THEN RESUMES FROM 22N110W TO LOW PRES1005 MB NEAR 
17.5N112W TO LOW PRES 1007 MB NEAR 15.5N119.5W TO 11N131W TO 
BEYOND 11N140W. SCATTERED MODERATE TO STRONG CONVECTION NOTED 
FROM 07N TO 10N E OF 83W. ISOLATED TO SCATTERED MODERATE TO 
STRONG CONVECTION NOTED WITHIN 90 NM N AND 240 NM S OF TROUGH 
BETWEEN 122W AND 138W.
 
...DISCUSSION...

WELL TO THE NW OF THE ELONGATED AREA OF LOW PRES...A 1023 MB 
HIGH PRES CENTER IS ANALYZED N OF THE HAWAIIAN ISLANDS NEAR 
35N149W WITH A RIDGE EXTENDING E THEN SE TO NEAR 22N115W. THE 
PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES IN THE TROPICS IS 
RESULTING IN FRESH TO STRONG NE TRADE WINDS WITHIN 150 NM NW OF 
A LINE FROM 19N140W TO 20N131W...WHERE SEAS ARE IN THE RANGE OF 
7-9 FT. THIS AREA OF FRESH TO STRONG NE TRADE WINDS IS FORECAST 
TO SHRINK IN COVERAGE AS IT SHIFTS W THROUGH SUN. ELSEWHERE... 
MODERATE TO FRESH NE TRADES ARE FOUND FROM ABOUT 16N TO 22N W OF 
124W...PER AFTERNOON SCATTEROMETER DATA...WHERE SEAS ARE IN THE 
5-7 FT RANGE. THE RIDGE WILL SHIFT SLIGHTLY EWD DURING THE NEXT 
48 HOURS...WHILE THE ELONGATED LOW PRES REALIGNS NE TO 
SW...WHICH WILL ACT TO DIMINISH THESE TRADES SLIGHTLY.
 
TO THE E OF THE RIDGE...NWLY WINDS OF 10-15 KT WERE DEPICTED BY 
AFTERNOON SCATTEROMETER DATA...WHERE SEAS ARE GENERALLY 
GENERALLY 4-5 FT IN MIXED SW AND NW SWELL. THE EASTERN PORTION 
OF THE RIDGE WILL WEAKEN SLIGHTLY OVER THE NEXT FEW DAYS...AS 
THE N PORTION OF THE ELONGATED LOW PRES AREA LIFTS N OF 
20N...PRODUCING WEAKENING WINDS ALONG THE WATERS W OF BAJA 
CALIFORNIA. HOWEVER...INCREASING WINDS ACROSS THE OFFSHORE 
WATERS OF CALIFORNIA WILL GENERATE A NEW PULSE OF N-NW SWELL 
THAT WILL MOVE INTO NE PORTIONS OF THE DISCUSSION AREA OVER THE 
WEEKEND AND RAISE SEA HEIGHTS TO 6-8 FT...MAINLY W OF 118W. 
OTHERWISE...SEAS WILL CONTINUE TO BE DOMINATED BY PULSES OF 
MODERATE SW SOUTHERN HEMISPHERIC SWELL.
  
$$
STRIPLING