000
AXPZ20 KNHC 191558
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1605 UTC TUE MAY 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1545 UTC.
 
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... 
A MONSOONAL CIRCULATION IS NOT PRESENTLY EVIDENT ACROSS THE 
REGION. THE ITCZ AXIS EXTENDS FROM 06N92W TO 07N101W TO 06N109W. 
IT RESUMES IN A FRACTURED STATE BEGINNING AT 05N114W TO 06N123W 
...THEN FROM 06N127W TO 06N132W...AND FROM 07N134W TO 04N140W. 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 240 NM N 
OF THE ITCZ BETWEEN 115W-120W...AND WITHIN 60 NM OF THE ITCZ W 
OF 131W.

...DISCUSSION...                                           
DEEP LAYERED TROUGHING PERSISTS ACROSS THE NE PACIFIC THIS 
MORNING N OF 28N AND E OF 140W AND INTO THE PACIFIC NW U.S. TO 
THE S OF THE TROUGH...AN UPPER LEVEL RIDGE PREVAILS N OF THE 
EQUATOR W OF 110W WITH THE CULPRIT ANTICYCLONE AT 10N140W. A MID 
LEVEL TROUGH SHIFTING EASTWARD CUTS THROUGH RIDGE ALONG 127W 
FROM 07N TO 21N. UPPER LEVEL DIFFLUENT FLOW ON EITHER SIDE OF 
THE ANTICYCLONE CONTINUES TO SUPPORT THE ACTIVE CONVECTION 
DESCRIBED ABOVE UNDER ITCZ/MONSOON TROUGH. A MID/UPPER LEVEL 
TROUGH EXTENDS FROM FROM THE FAR NW CARIBBEAN SOUTHWESTWARD 
ACROSS CENTRAL AMERICA AND INTO THE EPAC E OF 110W...WHERE AN 
UPPER LOW IS EVIDENT NEAR 08N96W. THE TROUGH CONTINUES TO S OF 
THE EQUATOR AT 94W. THE ATMOSPHERE REMAINS MOIST AND UNSTABLE E 
OF THE TROUGH WHERE CLUSTERS OF SCATTERED MODERATE CONVECTION 
ARE NOTED...INCLUDING ONE LARGE ONE FROM 13N TO 16N BETWEEN 94W-
96W. 
 
AT THE SURFACE...AN OLD COLD FRONT HAS WEAKENED TO A TROUGH FROM 
31N127W TO 24N140W. ISOLATED SHOWERS ARE POSSIBLE WITHIN 30-60 
NM OF THE TROUGH. PREVIOUS SCATTEROMETER DATA INDICATED WINDS OF 
15 KT OR LESS ON EITHER SIDE OF THE FRONT...AND SEAS TO THE NW 
OF THE FRONT REMAIN IN THE 5 TO 6 FT RANGE AND ARE EXPECTED TO 
SUBSIDE SLIGHTLY THROUGH WEDNESDAY. OTHERWISE...THE REMAINDER OF 
THE FORECAST WATERS N OF 12N REMAIN UNDER THE INFLUENCE OF A 
WEAK SURFACE RIDGE ANCHORED BY A 1022 MB HIGH CENTERED NEAR 
29N125W WITH AXIS EXTENDING SOUTHEASTWARD TO NEAR 20N112W WITH 
MODERATE TO FRESH NE TRADES OCCURRING TO THE S AND SW OF THE 
RIDGE BETWEEN ABOUT 10N AND 22N. SEAS ACROSS THIS AREA ARE IN 
THE RANGE OF 5-7 FT...EXCEPT TO 8 FT PRIMARILY IN NW SWELLS FROM 
12N TO 18N BETWEEN 121W AND 125W...AND ALSO WITHIN 60 NM OF A 
LINE FROM 16N125W TO 16N130W...WHERE 20 KT NE TRADES ARE MIXING 
WITH DECAYING NW SWELLS. TO THE E OF THE HIGH...THE PRES 
GRADIENT BETWEEN IT AND LOWER PRES ACROSS THE GULF OF CALIFORNIA 
AND NORTHWESTERN MEXICO IS GENERATING A MODERATE NORTHWESTERLY 
BREEZE ALONG MOST OF THE PACIFIC COASTAL WATERS OF THE BAJA 
CALIFORNIA PENINSULA. THIS PATTERN IS EXPECTED TO REMAIN 
GENERALLY UNCHANGED FOR THE NEXT 48 HOURS...AND ALLOW FOR 
DIURNAL HEATING ALONG THE BAJA PENINSULA TO ENHANCE THE NW WINDS 
OF MOSTLY 20 KT WITH SOME POCKETS OF 20-25 KT WITHIN 60 NM OF 
THAT COAST THIS AFTERNOON AND EARLY EVENING...AND AGAIN WED 
AFTERNOON AND EVENING WITH INDUCED SEAS BUILDING TO 7-8 FT. LOW 
PRES JUST N OF THE FAR NORTHERN GULF OF CALIFORNIA WILL INITIATE 
SW-W WINDS OF 20-25 KT N OF 30N BETWEEN 113W-115W BEGINNING LATE 
WED NIGHT INTO EARLY WED MORNING. 

IN THE DEEP TROPICS REGION...SEVERAL TROUGHS (EASTERLY TYPE WAVE 
FEATURES) ARE PROPAGATING WESTWARD THROUGH THE REGION W OF 
90W...WITH THE FIRST ONE ALONG 111W FROM 04N TO 10N...ANOTHER 
ONE ALONG 125W FROM 06N TO 11N...AND A THIRD ONE OF SMALL 
AMPLITUDE ALONG 132W/133W FROM 07N TO 10N. THE MOST ACTIVE 
CONVECTION ASSOCIATED WITH THESE FEATURES IS OCCURRING 
UNDERNEATH THE AFOREMENTIONED UPPER RIDGE. THESE TROUGHS WILL  
WILL CONTINUE TO MOVE WESTWARD 10-15 KT OVER THE NEXT FEW DAYS 
...WITH THE GRADIENT BETWEEN THEM AND TO THE RIDGE TO THE N 
ALLOWING FOR MODERATE TO FRESH NE TRADES TO FOLLOW THE WESTERN 
MOST TWO TROUGH AS THEY TRACK WESTWARD. 

GAP WINDS...                                             
OVERNIGHT NOCTURNAL DRAINAGE FLOW AGAIN ENHANCED THE NE TO E 
FLOW ACROSS THE GULF OF PAPAGAYO AND DOWNWIND TO 88W...WITH 
WINDS IN THE 20 TO 25 KT RANGE...AND SEAS NEAR 8 FT. THESE WINDS 
ARE FORECAST TO DIMINISH TO 15-20 KT BY LATE THIS AFTERNOON...OR 
EARLY THIS EVENING.

LOOKING AHEAD...ANOTHER STRONG SOUTHERN HEMISPHERIC SW SWELL 
WILL MOVE INTO THE REGIONAL WATERS LATE IN THE WEEK. SEAS WILL 
BUILD TO 8 FT AND GREATER ALONG THE EQUATORIAL WATERS BY THU 
MORNING. THIS PULSE OF LONG PERIOD SWELL (FORECAST PERIODS OF  
15-17 SEC) IS EXPECTED TO REACH THE COASTLINES OF CENTRAL 
AMERICA BY LATE FRI...AND WILL GENERATE LARGE AND DANGEROUS SURF 
ALONG THE PACIFIC COASTLINES THROUGH THE UPCOMING WEEKEND.
 
$$
AGUIRRE