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Eastern Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 310310
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
0405 UTC TUE MAR 31 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0230 UTC. 

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

THE ITCZ EXTENDS FROM 06N95W TO 05N105W TO 07N122W TO BEYOND 
05N140W. SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED 
WITHIN 180 NM S OF AXIS BETWEEN 118W AND 122W...AND WITHIN 120 
NM S AND 240 NM N OF AXIS BETWEEN 124W AND 132W. A DIFFLUENT 
PATTERN ALOFT IS HELPING TO INDUCE THE CONVECTIVE ACTIVITY
BETWEEN 124W AND 132W. 

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 03S90W TO 01S100W. 
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 DISSIPATING 
COLD FRONT IS CLIPPING THE FAR NW CORNER OF THE AREA TONIGHT AND 
TUE. STRONGER HIGH PRES IN THE WAKE OF THE FRONT WILL THEN 
DOMINATE THE NORTHERN FORECAST WATERS TUE AND WED. 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. NWP 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 30N117W TO 24N125W TO 20N135W BY LATE 
TUE. 

A STATIONARY TROUGH IS ANALYZED ON THE 0000 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 109W AND 116W.

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 5-7 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: Tuesday, 31-Mar-2015 03:10:50 UTC