000
AXPZ20 KNHC 240926 RRA
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
1005 UTC FRI MAY 24 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...SPECIAL FEATURE...

A 1010 MB LOW IS EMBEDDED WITHIN THE MONSOON TROUGH NEAR 09N104W 
MOVING WNW 10 KT. THIS AREA OF DISTURBED WEATHER CONTINUES TO 
PRODUCE DISORGANIZED SHOWERS AND THUNDERSTORMS. LATEST SATELLITE 
IMAGERY INDICATES THAT CONVECTION HAS DIMINISHED TO THE E AND SE 
OF THE LOW CENTER. SCATTERED MODERATE TO ISOLATED STRONG 
CONVECTION IS NOTED WITHIN 120 NM E SEMICIRCLE. THE LOW IS 
UNDERNEATH UPPER LEVEL RIDGING...AND OVER RATHER WARM SEA 
SURFACE TEMPERATURE. THESE INGREDIENTS MAY ALLOW THE LOW TO 
GRADUALLY INTENSIFY OVER THE NEXT 48 HOURS...WITH A MEDIUM 
PROBABILITY OF TROPICAL CYCLONE FORMATION.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...           
MONSOON TROUGH AXIS EXTENDS FROM 11N86W TO 13N90W TO LOW PRES 
NEAR 09N104W 1011 MB TO 10N115W. ITCZ BEGINS AT 09N119W TO 
10N135W. SCATTERED MODERATE ISOLATED STRONG FROM 05N TO 08N 
BETWEEN 84W AND 88W...FROM 08N TO 11N BETWEEN 97W AND 99W AND 
WITHIN 150 NM S OF THE ITCZ AXIS BETWEEN 125W AND 130W. 
SCATTERED MODERATE WITHIN 90 NM EITHER SIDE OF ITCZ FROM 130W TO 
134W. 

...DISCUSSION...

A GENERALLY RIDGE-TROUGH-RIDGE UPPER LEVEL PATTERN IS ANALYZED 
ACROSS THE DISCUSSION AREA. THE FIRST RIDGE EXTENDS N-NW FROM AN 
ANTICYCLONE LOCATED NEAR 12N127W AND IS COVERING THE WATERS W OF 
110W. THE TROUGH IS ALONG 30N120W 20N114W 11N116W. THE SECOND 
RIDGE IS BROAD IN NATURE...AND COVERS THE AREA E OF THE TROUGH. 
UPPER DIFFLUENCE ASSOCIATED WITH THIS RIDGE IS HELPING TO INDUCE 
SOME CLUSTERS OF MODERATE TO STRONG CONVECTION VERY CLOSE TO THE 
PACIFIC COAST OF NICARAGUA...EL SALVADOR AND OVER THE EASTERN 
PART OF THE GULF OF TEHUANTEPEC...PARTICULARLY N OF 14N BETWEEN 
93W AND 95W. THE UPPER TROUGH WILL MOVE EWD TODAY REACHING THE 
NW PART OF MEXICO AS ANOTHER AND STRONGER UPPER LEVEL TROUGH 
REACHES THE FAR NW PORTION OF THE FORECAST AREA TONIGHT. 

AT THE SURFACE...A 1032 MB HIGH CENTERED NEAR 38N142W EXTENDS A 
RIDGE SEWD TO NEAR 20N118W. THE TIGHT PRES GRADIENT BETWEEN THE 
RIDGE AND LOW PRES OVER THE WRN U.S. CONTINUES TO RESULT IN 
STRONG NW-N WINDS JUST N OF THE FORECAST WATERS. THE 0536 UTC 
ASCAT PASS PROVIDED OBSERVATIONS OF THESE WINDS. UNDER THE 
INFLUENCE OF THIS RIDGE...MAINLY NE WINDS OF 15-20 KT ARE NOTED 
N OF THE ITCZ AND W OF 120W.  

THE REMNANTS OF ALVIN ARE STILL SEEN USING NIGHT CHANNEL VISIBLE 
IMAGES 11N136W. A TROUGH IS ANALYZED ACROSS THE AREA AND GOES 
FROM 12N35W TO BEYOND 9N140W. A MODEST REGION OF FRESH NE WINDS 
AROUND 20 KT CONTINUE N OF THIS TROUGH AND ARE PRODUCING SEAS 8-
9 FT. THIS TROUGH WILL CONTINUE W AND EXIT THE AREA LATER TODAY. 

STRENGTHENING HIGH PRES ACROSS THE GULF OF MEXICO WILL PRODUCE A 
BRIEF GAP WIND EVENT ACROSS THE GULF OF TEHUANTEPEC THIS 
UPCOMING WEEKEND. THE FORECAST CALL FOR WINDS REACHING 25 KT 
WITH SEAS TO 8 FT. WINDS ARE ALSO EXPECTED TO BRIEFLY INCREASE 
TO 25 KT ACROSS THE GULF OF PAPAGAYO PROBABLY IN ASSOCIATION 
WITH A DEVELOPING LOW PRES ALONG THE MONSOON TROUGH S OF 10N. 
 
LONG PERIOD CROSS EQUATORIAL SW SWELL AT 17-19 SECONDS DOMINATES 
MOST OF THE FORECAST WATERS E OF 115W. LONG PERIOD NW SWELL ARE 
INVADING THE NW WATERS. 

$$
GR