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Eastern Pacific Tropical Weather Discussion



000
AXPZ20 KNHC 052154
TWDEP 

TROPICAL WEATHER DISCUSSION                                     
NWS NATIONAL HURRICANE CENTER MIAMI FL                         
2205 UTC TUE MAY 05 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 2145 UTC. 

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

SCATTEROMETER WINDS INDICATE THAT THE MONSOON TROUGH FORMS NEAR 
06N90W AND EXTEND S SW TO AN EMBEDDED 1010 MB LOW PRESSURE AT 
05N98W...AND THEN CONTINUES W TO 05N107W WHERE SCATTEROMETER 
WINDS INDICATE A TRANSITION TO AN ITCZ. THE ITCZ EXTENDS NW TO 
AN EMBEDDED TROUGH AT 10N121W...THEN TURNS SW TO BEYOND 
04.5N140W. THE ITCZ EMBEDDED TROUGH IS ANALYZED FROM 07N121W TO 
13N120W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED 
NEAR THE EASTERN PORTION OF THE MONSOON TROUGH...WITHIN 240 NM 
OF 04N89W. SIMILAR CONVECTION IS OBSERVED S OF THE EMBEDDED LOW 
PRESSURE...WITHIN 120 NM EITHER SIDE OF A LINE FROM 01N95W TO 
05N108W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS 
FLARING N OF THE ITCZ AND EXTENDS SW ALONG THE EMBEDDED TROUGH 
WITHIN 90 NM EITHER SIDE OF A LINE FROM 11N111W TO 11N119W TO 
07N125W. ISOLATED CELLS OF MODERATE CONVECTION ARE NOTED 
ELSEWHERE FROM 02S-10N BETWEEN 84-137W. 

A 1009 MB LOW PRESSURE CENTER IS ANALYZED ALONG THE CARIBBEAN 
COAST OF COLOMBIA NEAR 11N75.5W WITH A TROUGH EXTENDING SW 
ACROSS THE COLOMBIA/PANAMA BORDER TO A BASE OVER THE TROPICAL 
PACIFIC NEAR 06N79W. SCATTERED MODERATE CONVECTION OCCASIONALLY 
FLARES WITHIN 45 NM EITHER SIDE OF THIS TROUGH.  

...DISCUSSION... 

AN UPPER CYCLONE IS OBSERVED AT 35N124W WITH AN UPPER TROUGH 
EXTENDING SSW TO BASE AT 23N127W. AN UPPER ANTICYCLONE IS 
CENTERED NEAR 11N114W WITH AN UPPER RIDGE EXTENDING W ACROSS THE 
TROPICAL PACIFIC TO BEYOND 08N140W. AN UPPER RIDGE ALSO EXTENDS 
E FROM THE ANTICYCLONE TO A FAIRLY SHARP CREST OVER COASTAL 
NORTHERN COSTA RICA. SOME UPPER MOISTURE IS ROTATING 
CYCLONICALLY AROUND THE UPPER CYCLONE AND WILL PASS NE ACROSS 
SOUTHERN CALIFORNIA TONIGHT. OTHERWISE VERY DRY UPPER AIR IS 
INDICATED OVER THE NORTHERN PORTION OF THE DISCUSSION AREA 
INCLUDING NORTHERN MEXICO...ROUGHLY N OF A LINE FROM 28N110W TO 
21N140W. UPPER DIFFLUENCE ALONG THE PREVIOUSLY DESCRIBED WESTERN 
TROPICAL RIDGE IS ENHANCING CONVECTION ALONG THE ITCZ AND ITS 
EMBEDDED TROUGH ALSO PREVIOUSLY DESCRIBED. THE RESULTANT DEBRIS 
MOISTURE IS ADVECTED N FROM THE ITCZ BETWEEN 110W AND 120W. THIS 
MOISTURE MERGES AT 20N110W WITH A TROPICAL PLUME ORIGINATING IN 
THE CENTRAL PACIFIC THAT STREAMS ENE ACROSS THE DISCUSSION AREA 
WITHIN 150 NM EITHER SIDE OF A LINE FROM 17N140W TO ACROSS 
SOUTHERN BAJA AND CENTRAL MEXICO. UPPER DIFFLUENCE ALONG THE 
EASTERN TROPICAL RIDGE IS ENHANCING CONVECTION OVER AND TO THE S 
OF THE MONSOON TROUGH AS PREVIOUSLY DESCRIBED...WITH THE UPPER 
DEBRIS MOISTURE ADVECTED S ACROSS THE EQUATOR BETWEEN 85-118W. 

ELSEWHERE AT THE LOW LEVELS A SURFACE RIDGE EXTENDS FROM 32N137W 
TO 16N104W. A SURFACE TROUGH EMBEDDED IN THE ITCZ FROM 07N121W 
TO 13N120W IS FORECAST TO SHIFT W FROM 05N131W TO 14N126W ON WED 
AND FROM 04N134W TO 13N129W ON THU. THE GRADIENT IS EXPECTED TO 
TIGHTEN SW OF THE RIDGE AXIS OVER THE NEXT FEW DAYS INCREASING 
THE NE TRADES TO 20-25 KT BETWEEN THE TROUGH AND THE RIDGE WITH 
SEAS BUILDING 7-10 FT IN THE NE WINDS WAVES THAT WILL MIX WITH  
LONG PERIOD SW AND NW SWELL. ALTHOUGH THE TROUGH WILL MOVE W OF 
140W ON FRI...EXPECT THE FRESH NE TRADES TO CONTINUE THROUGH THE 
UPCOMING WEEKEND ACROSS THE TROPICAL WATERS BETWEEN 08-19W WITH 
EMBEDDED PATCHES OF STRONG TRADES. FRESH NW-N WINDS ARE EXPECTED 
ACROSS THE SUBTROPICAL WATERS NE OF THE RIDGE INTO THE UPCOMING 
WEEKEND. LONG PERIOD NW SWELL WILL PROPAGATE S INTO THE 
DISCUSSION AREA AND MIX WITH LONG PERIOD SOUTHERLY SWELL DRIVING 
THE COMBINED SEAS TO 7-10 FT ACROSS THE WATERS N OF 28N BETWEEN 
116-128W THROUGH THU NIGHT...THEN GRADUALLY SUBSIDING THEREAFTER.

ANOTHER BATCH OF LONG PERIOD SW SWELL WILL CROSS THE EQUATOR 
BETWEEN 92-120W ON SUN NIGHT REACHING ALONG 03N ON MON.  

GULF OF CALIFORNIA...A SURFACE LOW WILL MOVE E OVER THE FAR 
NORTHERN GULF OF CALIFORNIA TONIGHT WHERE IT WILL MEANDER 
THROUGH FRI. THE GRADIENT WILL SUPPORT S-SW 20-25 KT PULSES 
WITHIN ABOUT 90 NM S OF THE CENTER. AS THE LOW MOVES E ON THU 
NIGHT THE GRADIENT MAY BRIEFLY SUPPORT NW-N 20-25 KT WINDS OVER 
THE NW QUADRANT AS WELL. THE BRIEF STRONG PULSES WITH LIMITED 
FETCH SHOULD ONLY ALLOW SEAS TO BUILD TO 7 FT.

$$ 
NELSON


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Page last modified: Tuesday, 05-May-2015 21:54:19 UTC