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Eastern Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 302138
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC MON MAR 30 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 
2130 UTC. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

A WEAK TROUGH EXTENDS FROM 08N90W TO 05N95W...THEN TRANSITIONS 
TO ITCZ...CONTINUING FROM 05N95W TO 07N115W TO 05N125W TO BEYOND 
06N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED 
 WITHIN 150 NM S OF AXIS BETWEEN 118W AND 125W...AND WITHIN 210 
NM N OF AXIS BETWEEN 118W AND 131W. A DIFFLUENT PATTERN ALOFT IS 
HELPING TO INDUCE THIS CONVECTIVE ACTIVITY. 

DURING THE PERIOD FROM LATE FEBRUARY TO EARLY APRIL...THE 
MONSOONAL CIRCULATION OVER THE TROPICAL NE PACIFIC IS NOT 
PRESENT...AND OCCASIONALLY BREAKS DOWN WITH CONVERGENCE
NOTED ON EACH SIDE OF THE EQUATOR IN WHAT IS REFERRED TO AS A 
DOUBLE ITCZ STRUCTURE. CURRENTLY A SURFACE TROUGH CONTINUES TO 
BE ANALYZED S OF THE EQUATOR FROM 06S85W TO 01S97W. SCATTERED 
MODERATE CONVECTION IS NOTED FROM 04S TO 06S BETWEEN 86W AND 
89W. COMPUTER MODEL GUIDANCE SUGGESTS THE PRESENCE OF AN ACTIVE 
SOUTHERN ITCZ OVER THE NEXT 24-48 HOURS. 

...DISCUSSION...                                                

A RIDGE COVERS THE NORTHERN WATERS MAINLY N OF 17N W OF 120W. 
SOUTH OF THE RIDGE...THE PRES GRADIENT BETWEEN THE HIGH AND 
LOWER PRES ALONG THE ITCZ IS RESULTING IN FRESH NE TRADEWINDS 
FROM 14N TO 18N W OF 135W...WHERE SEAS ARE 8-9 FT. A WEAKENING 
COLD FRONT IS CLIPPING THE FAR NW CORNER OF THE AREA THROUGH 
TONIGHT WHILE DISSIPATING. A STRONGER HIGH PRES IN THE WAKE OF 
THE FRONT WILL THEN DOMINATE THE NORTHERN FORECAST WATERS ON 
TUE. THIS WILL BRING AN INCREASE IN NORTHERLY WINDS AND SEAS BY 
TUE EVENING AS PRES GRADIENT TIGHTENS BETWEEN THE HIGH AND LOWER 
PRES ACROSS SOUTHWESTERN UNITED STATES AND NW MEXICO. UNDER THE 
INFLUENCE OF THIS WEATHER PATTERN...EXPECT FRESH TO STRONG 
NORTHERLY WINDS MAINLY N OF 27N BETWEEN 119W AND 127W WITH SEAS 
BUILDING TO 12 FT PRIMARILY IN NW SWELL TUE EVENING INTO WED 
MORNING. MARINE GUIDANCE SUGGESTS THAT FRESH NE-E WINDS WILL 
BLOW ACROSS MOST OF THE WATERS N OF 20N W OF 120W BY WED NIGHT. 
ADDITIONAL PULSES OF NW SWELL ARE REACHING THE FAR NW PART OF 
THE FORECAST REGION AND WILL MIX WITH THE SOUTHERLY SWELL 
ALREADY IN PLACE TO BUILD SEAS TO 9 FT N OF LINE FROM 30N118W TO 
26N120W TO 26N130W TO 19N140W BY TUE MORNING.

A TROUGH IS ANALYZED ON THE 1800 UTC SURFACE MAP FROM 14N113W TO 
09N115W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS SEEN 
ON SATELLITE IMAGERY ON EITHER SIDE OF THE TROUGH AXIS... 
ESPECIALLY FROM 10N TO 12N BETWEEN 110W AND 117W.

WITH THE EXCEPTION OF THE GAP WIND REGIONS...MAINLY LIGHT TO 
GENTLE WINDS PREVAIL ACROSS MOST OF THE AREA E OF 110W. LONG 
PERIOD SOUTHERLY SWELL CONTINUES TO FADE ACROSS MUCH OF THIS 
REGION WITH SEAS GENERALLY UNDER 6-7 FT. 

GAP WINDS...

GULF OF TEHUANTEPEC...FRESH NORTHERLY WINDS ARE EXPECTED TO 
PERSIST ACROSS THE GULF OF TEHUANTEPEC AND DOWNWIND FOR ABOUT 
180 NM THROUGH LATE TUE MORNING...WITH NOCTURNAL DRAINAGE FLOW 
ENHANCING THE WINDS TO NEAR 30 KT SHORTLY AFTER SUNRISE. THE 
WINDS ARE EXPECTED TO DROP BELOW 20 KT BY LATER TUE AFTERNOON. 

GULF OF PAPAGAYO...PULSING OF NOCTURNAL WINDS ARE EXPECTED 
ACROSS THE GULF OF PAPAGAYO THROUGH WED MORNING...REACHING 20-25 
KT FROM 0600 TO 1200 UTC...WITH SEAS OF 7-8 FT THROUGH AND 
DOWNWIND OF THE GULF.

$$
COBB

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Page last modified: Monday, 30-Mar-2015 21:38:15 UTC