000
AXPZ20 KNHC 181455
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1605 UTC FRI SEP 18 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.               

...TROPICAL WAVES... 

A TROPICAL WAVE IS NOW ENTERING THE BASIN ALONG 87W AND EXTENDS 
ACROSS HONDURAS AND EXTREME WESTERN NICARAGUA MOVING W NEAR 15 
KT. SCATTERED SHOWERS AND TSTMS ARE NOTED ALONG THE WAVE AXIS 
EXTENDING INTO THE GULF OF HONDURAS AND THE CARIBBEAN SEA W OF 
80W. THE WAVE IS FORECAST TO REACH NEAR 89W TONIGHT...AND TO 
NEAR 93W BY FRI NIGHT.  
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...            

MONSOON TROUGH AXIS EXTENDS FROM 09N83W TO 10N92W TO 08N104W. 
SCATTERED MODERATE ISOLATED STRONG WITHIN 60 NM OF TROUGH 
BETWEEN 87W AND 90W
 
...DISCUSSION...

THE ELONGATED AREA OF LOW PRES CENTERED SEVERAL HUNDRED MILES S 
OFF THE SOUTHERN TIP OF CALIFORNIA REMAINS THE DOMINANT WEATHER 
FEATURE ACROSS THE AREA. THIS BROAD AREA OF LOW PRES CONSISTS OF 
A 1006 MB LOW CONSOLIDATING NEAR 18N110W...AND A 1007 MB LOW 
NEAR 16N120W. ENERGY FROM A PREVIOUS TROPICAL WAVE ADDED TO THE 
FORMATION OF THIS AREA OF LOW PRES. LATEST INFRARED SATELLITE 
IMAGERY IS SHOWING CONVECTION INCREASING IN ASSOCIATION WITH THE 
CONSOLIDATING LOW PRES NEAR 18N110W WITH SCATTERED STRONG 
CONVECTION NOTED WITHIN 240 NM IN THE W AND NW QUADRANTS OF THE 
LOW...AND  SCATTERED MODERATE ISOLATED STRONG CONVECTION 
ELSEWHERE FROM 12N TO 18N BETWEEN 112W AND 120W. 

AN EARLIER 0508 UTC ASCAT PASS REVEALED GENERALLY LIGHT TO 
MODERATE WINDS AROUND THE AREA OF LOW PRES. MODERATE SW WINDS 
ALOFT AHEAD OF A SERIES OF UPPER LEVEL TROUGHS LOCATED N OF 17N 
BETWEEN 120W-130W ARE TRANSPORTING UPPER MOISTURE FROM THIS 
CONVECTION NNE TOWARDS CENTRAL BAJA CALIFORNIA...AND THE SW U.S. 
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. PRESENTLY... 

WELL TO THE NW OF THE AFOREMENTIONED AREA OF LOW PRES...A 1020 
MB HIGH PRES CENTER IS ANALYZED N OF THE HAWAIIAN ISLANDS NEAR 
35N151W WITH A RIDGE EXTENDING SE TO NEAR 22N114W. THE PRES 
GRADIENT BETWEEN THE RIDGE AND LOWER PRES IN THE TROPICS IS 
RESULTING IN FRESH TO STRONG NE TRADE WINDS WITHIN 180 NM NW OF 
A LINE FROM 19N130W TO 17N140W...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 THROUGH SUN.
 
THE 0732 UTC RAPIDSCAT PASS SHOWED NW TO N WINDS OF 10-15 KT E 
OF THE RIDGE TO THE COAST OF BAJA CALIFORNIA WHERE SEAS ARE 
GENERALLY GENERALLY 4-5 FT IN MIXED SW AND NW SWELL AS SEEN IN 
RECENT ALTIMETER PASSES. THE RIDGE WILL CHANGE LITTLE THROUGH 
FRI BEFORE WEAKENING SAT AS THE N PORTION OF THE ELONGATED LOW 
PRES AREA LIFTS N OF 20N. HOWEVER...INCREASING WINDS ACROSS THE 
OFFSHORE WATERS OF CALIFORNIA WILL GENERATE A NEW PULSE OF NNW 
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.
  
$$
COBB