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Eastern Pacific Tropical Weather Discussion (Text)



000
AXPZ20 KNHC 040245
TWDEP 

TROPICAL WEATHER DISCUSSION                                 
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
0405 UTC MON MAY 04 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 
0200 UTC. 

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

THE MONSOON TROUGH EXTENDS FROM 08N76.5W TO 04N95W TO 09N111W TO 
LOW PRES 1008 MB NEAR 08N116.5W TO 08.5N122W...WHERE IT 
TERMINATES. ITCZ EXTENDS FROM 06N128W TO BEYOND 06.5N140W. 
SCATTERED MODERATE TO STRONG CONVECTION NOTED N OF 02.5N E OF 
83.5W. SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 150 
NM N AND 360 NM S OF TROUGH BETWEEN 84W AND 100W. SCATTERED 
MODERATE TO STRONG CONVECTION NOTED WITHIN 180 NM SE AND 330 NM 
NW QUADRANT OF LOW PRES NEAR 08N116.5W. 

...DISCUSSION...    

AN UPPER LEVEL BLOCKING PATTERN HAS DEVELOPED ACROSS THE BROAD 
REGION...WITH A BROAD UPPER RIDGE ACROSS THE TROPICAL NE PACIFIC 
S OF 30N AND CENTERED ALONG ABOUT 110-111W...WITH A BROAD UPPER 
TROUGH ACROSS THE GULF OF MEXICO AND INTO THE NW CARIBBEAN ALONG 
83-85W...AND A DOWNSTREAM BROAD UPPER RIDGE ACROSS THE TROPICAL 
ATLANTIC ALONG 50W. A MIDDLE TO UPPER LEVEL TROUGH AXIS PREVAILS 
ACROSS NW PORTIONS OF THE DISCUSSION AREA...WITH SEVERAL SMALL 
EMBEDDED CYCLONES ALONG THE AXIS...AND PASSES THROUGH 30N127W TO 
25N131W...WHILE AN UPSTREAM SHORTWAVE TROUGH IS ALONG 144W AND N 
OF 25N AND IS PROGRESSING EASTWARD. THESE TWO TROUGHS ARE 
FORECAST TO SHIFT ENE OVER THE RIDGE AND INTO THE WESTERN U.S. 
THROUGH THU...AND WILL ACT TO FLATTEN THE UPPER RIDGE. UPPER 
LEVEL CONDITIONS ASSOCIATED WITH THE RIDGE ARE EXPECTED TO 
MAINTAIN CONDITIONS FAVORABLE FOR CONTINUED ACTIVE CONVECTION 
ACROSS THE TROPICS E OF 100W...AND IN THE VICINITY OF 120W... 
THROUGH MON MORNING BEFORE CONVECTION DIMINISHES.

AT THE SURFACE...A WEAKENING HIGH PRESSURE RIDGE CONTINUES 
ACROSS W PORTIONS...ANCHORED ON A 1026 MB HIGH NEAR 35N146W AND 
EXTENDS SE TO NEAR 21N110W. THE PRESSURE GRADIENT BETWEEN THE 
HIGH AND THE ITCZ TO THE S IS SUFFICIENT TO PROMOTE MODERATE TO 
FRESH NE TRADEWINDS S OF 26N AND W OF 132W. THE HIGH IS EXPECTED 
TO REMAIN GENERALLY STATIONARY AND STRENGTHEN SLIGHTLY THROUGH 
WED BEFORE SHIFTING SE AND WEAKENING AHEAD OF AN APPROACHING 
COLD FRONT. NW WINDS ACROSS THE W COASTAL WATERS OF BAJA 
CALIFORNIA ARE EXPECTED TO INCREASE TO 15-20 KT MON NIGHT 
THROUGH MID WEEK AS THIS HIGH PRES BUILDS TO THE COAST. 
ELSEWHERE...WINDS REMAIN LIGHT TO MODERATE ACROSS THE REMAINDER 
OF THE AREA.

LARGE SW SOUTHERN HEMISPHERIC SWELL CONTINUES TO MOVE N AND NE 
ACROSS MUCH OF THE AREA THIS EVENING...AND HAS PEAKED IN SIZE 
TODAY. SUNDAY MORNING AND AFTERNOON ALTIMETER PASSES MEASURED 
WAVE HEIGHTS OF 10 TO 14 FT ACROSS THE WATERS E OF 
100W...DOMINATED BY THIS LONG PERIOD SW SWELL. LARGE AND 
DANGEROUS SURF ALONG THE PACIFIC COASTLINES FROM PERU TO 
COLOMBIA TO MEXICO WILL GRADUALLY BEGIN TO SUBSIDE TONIGHT AND 
THEN MORE QUICKLY ON MONDAY BEFORE THIS CURRENT SWELL EVENT ENDS 
LATE MON NIGHT. SIGNIFICANT SWELL IS ALSO ENTERING THE SOUTHERN 
SECTIONS OF THE GULF OF CALIFORNIA...WERE SEAS ARE EXPECTED TO 
BUILD TO 7 TO 10 FEET OVERNIGHT. 

$$
STRIPLING

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Page last modified: Monday, 04-May-2015 02:45:56 UTC