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Eastern Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 301526
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
1605 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC. 

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

A WEAK TROUGH EXTENDS FROM 06N89W TO 04N94W...THEN TRANSITIONS 
TO ITCZ...CONTINUING FROM 04N94W TO 06N110W TO 07N118W TO BEYOND 
06N140W. NUMEROUS MODERATE TO ISOLATED STRONG CONVECTION IS 
NOTED WITHIN 150 NM S OF ITCZ AXIS BETWEEN 119W AND 125W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS WITHIN 210 NM N 
OF AXIS BETWEEN 118W AND 130W. A DIFFLUENT PATTERN ALOFT IS 
HELPING TO INDUCE THIS CONVECTIVE ACTIVITY. 

DURING LATE WINTER TO EARLY SPRING SEASONS...FROM LATE FEBRUARY 
TO EARLY APRIL...A MONSOONAL CIRCULATION IS TYPICALLY NOT 
PRESENT ACROSS THE TROPICAL NE PACIFIC...AND CAN BE BRIEFLY 
REPLACED BY A DOUBLE ITCZ STRUCTURE...ONE ON EACH SIDE OF THE 
EQUATOR. THIS MORNING...A TROUGH CONTINUES TO BE ANALYZED S OF 
THE EQUATOR...CURRENTLY FROM 04S84W TO 03S93W. SCATTERED 
MODERATE CONVECTION IS NOTED FROM 04S TO 06S BETWEEN 84W AND 
87W...NEAR 04S91W AND NEAR 03S93W. COMPUTER MODEL GUIDANCE 
SUGGESTS THE PRESENCE OF AN ACTIVE SOUTHERN ITCZ OVER THE NEXT 
24-48 HOURS. 

...DISCUSSION...                                                

A RIDGE COVERS THE N WATERS MAINLY N OF 15N W OF 125W. SOUTH OF 
THE RIDGE...THE PRES GRADIENT BETWEEN THE HIGH AND LOWER PRES 
ALONG THE ITCZ IS RESULTING IN FRESH TO STRONG NE TRADEWINDS 
FROM 14N TO 19N W OF 135W...WHERE SEAS ARE 8-9 FT. A WEAKENING 
COLD FRONT IS APPROACHING THE FAR NW CORNER OF THE AREA AND WILL 
CLIP THE REGION LATER TODAY AND 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 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 128W WITH BUILDING SEAS TO 12 FT PRIMARILY IN 
NW SWELL TUE EVENING INTO WED MORNING. MARINE GUIDANCE SUGGESTS 
THAT FRESH TO STRONG 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 1200 UTC SURFACE MAP FROM 14N113W TO 
09N114W. 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 TO STRONG NORTHERLY WINDS ARE 
EXPECTED TO PERSIST ACROSS THE GULF OF TEHUANTEPEC AND DOWNWIND 
FOR ABOUT 200 NM THROUGH WED MORNING...WITH NOCTURNAL DRAINAGE 
FLOW ENHANCING THE WINDS TO NEAR 30 KT EACH NIGHT. SEAS ARE 
EXPECTED TO BUILD TO 9-10 FT WITH THE STRONGEST WINDS.

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.

$$
GR


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Page last modified: Monday, 30-Mar-2015 15:26:30 UTC