000
AXPZ20 KNHC 181001
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1005 UTC SAT APR 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0945 UTC. 
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...              

ITCZ AXIS EXTENDS FROM 03N110W TO 02N122W TO 04N133W. SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION EXISTS FROM 05N-11N W OF 
132W. 

A TROUGH EXTENDS FROM 08N90W TO 07N97W TO 04N105W. SCATTERED 
MODERATE CONVECTION IS WITHIN 180 NM S OF THE TROUGH BETWEEN 
90W-92W...AND WITHIN 60 NM OF TROUGH BETWEEN 97W-105W.

...DISCUSSION... 

A MID TO UPPER LEVEL TROUGH IS MOVING EASTWARD ACROSS WESTERN 
MEXICO. A LARGE MID LEVEL ANTICYCLONE IS CENTERED NEAR 09N122W 
WITH ITS ASSOCIATED ANTICYCLONIC FLOW COVERING THE AREA W OF 
100W. DIFFLUENCE ALOFT ALONG THE WESTERN PERIPHERY OF THE 
ANTICYCLONE IS ENHANCING THE CONVECTIVE ACTIVITY DESCRIBED 
ABOVE. DEBRIS MOISTURE...IN THE FORM OF BROKEN TO OVERCAST MID 
AND UPPER LEVEL CLOUDS...FROM THIS ACTIVITY CONTINUES TO BE 
ADVECTED NEWD IN STRONG SW FLOW WITHIN 350 NM OF A LINE FROM 
11N138W TO 19N135W TO 22.5N126W WHERE IT THINS OUT AS IT 
APPROACHES DRIER PRESENT BEHIND THE MID TO UPPER LEVEL TROUGH. A 
SMALL ANTICYCLONE IS SEEN OVER THE FAR EASTERN PART OF THE AREA 
AT 08N92W. DIFFLUENCE ALOFT BETWEEN IT AND THE LARGE ANTICYCLONE 
IS HELPING TO SUPPORT CONVECTION AS DESCRIBED WITH TROUGH UNDER 
ITCZ/MONSOON TROUGH. 
 
AT THE SURFACE...NEARLY STATIONARY STRONG HIGH PRES OF 1033 MB 
LOCATED N OF THE AREA AT 39N138W EXTENDS A RIDGE SEWD TO 32N135W 
TO 26N127W TO NEAR 20N114W. HIGH PRES COVERS THE AREA N OF 16N W 
OF 113W. A TROUGH MOVING SLOWLY WESTWARD IS ANALYZED ALONG 140W 
FROM 02N TO 13N. THE PRES GRADIENT BETWEEN THE TROUGH AND THE 
HIGH PRES IS RESULTING IN A SWATH OF FRESH NE-E TRADE WINDS OVER 
THE FAR WESTERN PORTION FROM 10N-19N W OF 131W AS NOTED IN THE 
LATEST ASCAT PASS. SEAS THERE ARE IN THE 9-10 FT RANGE. THE 1033 
MB HIGH CENTER IS FORECAST TO BEGIN TO SHIFT SW AND WEAKEN SUN 
AND MON IN RESPONSE TO A WEAKENING COLD FRONT THAT NEARS THE FAR 
NW CORNER OF THE AREA. WITH THE PRES GRADIENT CURRENTLY IN PLACE 
EXPECTED TO REMAIN FAIRLY CONSTANT OVER THE NEXT COUPLE OF 
DAYS...THE ONGOING NE-E FRESH TRADE WINDS ARE FORECAST TO CHANGE 
LITTLE WITH SEAS AT ABOUT 8-9 FT. GENTLE TO MODERATE WINDS WILL 
CONTINUE ELSEWHERE ACROSS THE AREA.

$$
AGUIRRE