000
AXPZ20 KNHC 172129
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
2205 UTC FRI MAY 17 2013

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 
2100 UTC.

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

THE MONSOON TROUGH AXIS EXTENDS FROM 08N78W TO 08N90W TO 06N100W 
TO 08N108W...THEN RESUMES FROM 10N115W TO 1009 MB LOW PRES NEAR 
07N125W TO 07N129W. THE ITCZ AXIS EXTENDS FROM 07N129W TO 
05N140W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N OF THE 
ITCZ BETWEEN 81W AND 92W...WITHIN 90 NM EITHER SIDE OF THE 
MONSOON TROUGH BETWEEN 97W AND 102W...WITHIN 120 NM S OF THE 
MONSOON TROUGH BETWEEN 10N115W TO 128W...FROM 09N TO 11.5N 
BETWEEN 120W AND 125W...AND ALSO WITHIN 60 NM EITHER SIDE OF 
THE ITCZ BETWEEN 129W AND 134W.

...DISCUSSION...

ALOFT...AN UPPER ANTICYCLONE IS CENTERED OVER 28N136W. AN UPPER 
TROUGH STRETCHES FROM FAR NORTHERN BAJA CALIFORNIA THROUGH 
23N120W TO 20N136W. WATER VAPOR SATELLITE IMAGERY INDICATES MID 
TO UPPER LEVEL MOISTURE PRESENT ACROSS THE WATERS BEHIND THE 
TROUGH AXIS AND UNDER THE UPPER ANTICYCLONE. A JET STREAM BRANCH 
WITH SPEEDS OF 55 TO 75 KNOTS IS ALONG 14N W OF 120W...THEN 
TURNS NE TO ACROSS NORTHERN MEXICO. DEEP TROPICAL MOISTURE IS 
BEING ADVECTED FROM ALONG THE ITCZ AND MONSOON TROUGH TO THE NE 
ACROSS CENTRAL MEXICO WITHIN 600 NM AHEAD OF THE UPPER TROUGH. 
ELSEWHERE ALOFT...EASTERLY WINDS ARE PRESENT OVER THE SE PORTION 
OF THE AREA WITH ADDITIONAL TROPICAL MOISTURE PRESENT AS IS 
DESCRIBED IN THE SECTION ABOVE.

AT THE SURFACE...1026 MB HIGH PRES IS JUST W OF THE DISCUSSION 
WATERS NEAR 32N145W WITH A RIDGE EXTENDING SE THROUGH 30N140W TO 
23N112W. ANTICYCLONIC FLOW COVERS THE WATERS N OF 15N W OF 118W 
WITH GENTLE TO MODERATE NE-E WINDS AND 5-7 FT SEAS...EXCEPT IN 
THE W CENTRAL WATERS W OF A LINE FROM 21N140W TO 15N134W TO 
06N139W WHERE FRESH TRADES ARE PRESENT ALONG WITH 8-9 FT SEAS 
COMMINGLING IN NE WIND WAVES AND LONG PERIOD SW SWELL. THESE 
WINDS AND SEAS WILL DIMINISH AND SUBSIDE BY LATE SAT NIGHT AS 
THE PRES GRADIENT RELAXES OVER THE AREA.

THE 1008 MB REMNANTS OF ALVIN ARE CENTERED NEAR 11.5N113W. 
NUMEROUS MODERATE AND SCATTERED STRONG CONVECTION IS FROM 07N TO 
19N BETWEEN 108W AND 114W...AND VISIBLE SATELLITE IMAGERY SHOWS 
AN EXPOSED CENTER AS THE REGION REMAINS UNDER UPPER LEVEL 
WESTERLY SHEAR. FRESH TO STRONG WINDS ARE WITHIN 210 NM IN THE 
NE SEMICIRCLE OF THE REMNANT CENTER...ALONG WITH 8 TO 12 FT SEAS 
IN A BROAD MIX OF SWELL. THE REMNANT CENTER IS FORECAST TO MOVE 
TO 12N115W SAT AFTERNOON...THEN TO 12N119W SUN AFTERNOON. 
  
LONG PERIOD CROSS-EQUATORIAL MAINLY SW SWELLS WILL CONTINUE TO 
PROPAGATE WELL INTO THE CENTRAL PORTION OF THE AREA THROUGH SUN 
AFTERNOON...MIXING WITH SHORTER PERIOD SEAS GENERATED BY THE 
CIRCULATION OF ALVIN.

FRESH TO NEAR GALE FORCE NORTHERLY WINDS WILL SET UP ALONG THE 
CALIFORNIA COAST THIS WEEKEND AS HIGH PRES BUILDS W OF THE 
REGION WITH TROUGHING OVER INTERIOR CALIFORNIA. THESE WINDS WILL 
GENERATE NW SWELL WHICH WILL COVER THE WATERS N OF 29N BETWEEN 
118W AND 124W BY SUN AFTERNOON.

$$
LEWITSKY