000
AXPZ20 KNHC 172216
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC THU SEP 17 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2115 UTC.               

...TROPICAL WAVES... 

A TROPICAL WAVE INVOF 110W-111W IS BECOMING INCREASINGLY 
DIFFICULT TO IDENTIFY...AS IT HAS BEGUN TO MOVE INTO AN ELONGATED 
E TO W CYCLONIC CIRCULATION ASSOCIATED WITH THE MONSOON TROUGH. 
ISOLATED TO SCATTERED MODERATE TO STRONG CONVECTION IS OCCURRING 
MAINLY AROUND THE PERIPHERY OF THIS CYCLONIC CIRCULATION...FROM 
10.5N TO 20N BETWEEN 104W AND 120W. ADDITIONAL TROPICAL MOISTURE 
FROM THE WAVE CAN BE SEEN MOVING N-NW AND INTO THE SOUTHERN 
PORTIONS OF THE GULF OF CALIFORNIA...AND THE COASTAL ZONES OF 
SINALOA MEXICO. GLOBAL MODELS CONTINUE TO INDICATE THAT THIS 
ELONGATED AREA OF LOW PRESSURE WILL ROTATE COUNTER CLOCKWISE AND 
BECOME MORE NE TO SW ALIGNED TONIGHT THROUGH FRIDAY...AND 
CONTINUE TO ADVECT ABUNDANT TROPICAL MOISTURE NORTH AND 
NORTHWESTWARD ACROSS SOUTHERN BAJA CALIFORNIA AND THE ADJACENT 
GULF AND MEXICAN STATES TO THE E...THEN SHIFT FARTHER N-NW INTO 
NORTHERN BAJA SAT AND SAT NIGHT AS THE ELONGATED LOW PRESSURE 
AREA BEGINS TO SHIFT N-NE. INCREASING RAIN CHANCES SHOULD BE 
EXPECTED ACROSS THESE AREAS...SPREADING INLAND ACROSS MAINLAND 
MEXICO TO THE W SLOPES OF THE SIERRA MADRES OCCIDENTALES...WITH 
THE POTENTIAL FOR HEAVY RAINS...FLASH FLOODING AND LANDSLIDES.
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...            

THE MONSOON TROUGH EXTENDS W FROM COLOMBIA NEAR 11N74.5W TO 
09N86W TO 09.5N92W TO 07N98W TO 10N103W...WHERE IT BECOMES ILL 
DEFINED... THEN RESUMES FROM LOW PRES 1009 MB NEAR 17N108.5W TO 
LOW PRES 1009 MB NEAR 16N117W TO 09.5N130W TO LOW PRES 1009 MB 
NEAR 11N139W TO BEYOND 11N140W. SCATTERED MODERATE TO STRONG 
CONVECTION NOTED WITHIN 150 NM N AND 270 NM S OF TROUGH E OF 
102W...AND WITHIN 60 NM N AND 270 NM S OF TROUGH BETWEEN 120W 
AND 131W.  
 
...DISCUSSION...

THE ELONGATED MONSOONAL CIRCULATION IS BECOMING THE DOMINANT 
WEATHER FEATURE ACROSS THE AREA. TO THE NW...1027 MB HIGH 
PRESSURE IS CENTERED N OF THE HAWAIIAN ISLANDS NEAR 35N153W WITH 
A RIDGE EXTENDING SE TO NEAR 22N113W. THE PRESSURE GRADIENT 
BETWEEN THE RIDGE AND LOWER PRESSURE INVOF OF THE MONSOON TROUGH 
IS PROMOTING FRESH TO STRONG NE TRADEWINDS TO THE W AND NW OF A 
TROUGH FROM 15N134W TO 19N131W TO 21N126W...WHERE SEAS ARE 
RUNNING 7-9 FT. THE FRESH NE TRADES EXTEND WWD BEYOND 140W AND 
GENERALLY S OF 23N. TO THE E OF THE RIDGE...AFTERNOON 
SCATTEROMETER DATA INDICATED N-NW WINDS AROUND 15 KT ACROSS THE 
NEAR AND OFFSHORE PACIFIC WATERS OF BAJA CALIFORNIA SOUTHWARD TO 
CABO SAN LAZARO...WHERE SEAS WERE GENERALLY 4-5 FT IN MIXED SW 
AND NW SWELL. THE RIDGE WILL GENERALLY REMAIN INTACT THROUGH 
FRIDAY BEFORE WEAKENING SAT AS THE ELONGATED LOW PRESSURE AREA 
LIFTS N OF 20N. HOWEVER...INCREASING WINDS ACROSS THE OFFSHORE 
WATERS OF CALIFORNIA WILL GENERATE A NEW PULSE OF N-NW SWELL 
THAT WILL MOVE INTO NE PORTIONS OVER THE WEEKEND AND RAISE SEA 
HEIGHTS TO 6-8 FT...MAINLY W OF 118W. OTHERWISE...REGIONAL SEAS 
WILL CONTINUE TO BE DOMINATED BY PULSES OF MODERATE SW SOUTHERN 
HEMISPHERIC SWELL.
  
$$
STRIPLING