000
AXPZ20 KNHC 220954
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
1005 UTC SAT JUN 22 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 
0945 UTC.

...SPECIAL FEATURES...
A SURFACE LOW HAS DEVELOPED NEAR 12N102W ALONG A TROPICAL WAVE 
MOVING THROUGH THE MONSOON CIRCULATION...AND IS ACCOMPANIED BY 
SCATTERED MODERATE AND ISOLATED STRONG CONVECTION WITHIN 60 NM 
EITHER SIDE OF A LINE FROM 07N95W TO 12N100W OVER THE SE 
QUADRANT...AND OVER THE SW SEMICIRCLE WITHIN 120 NM OF A LINE 
FROM 08N104W TO 11N108W TO 15N108W. A SECOND SURFACE LOW IS ALSO 
EMBEDDED ALONG THE MONSOON TROUGH NEAR 14.5N115W...WITH ONLY 
SCATTERED MODERATE CONVECTION CURRENTLY OBSERVED WITHIN 30 NM N 
OF THE CENTER. MODEL CONSENSUS AGREE WITH THE CONTINUED 
DEVELOPMENT...POSSIBLY TROPICAL CYCLONE DEVELOPMENT...OF THE 
EASTERNMOST LOW PRES WITH THE GFS MODEL THE MOST AGGRESSIVE. THE 
WESTERNMOST LOW IS EXPECTED TO PERSIST THROUGH ABOUT 48 
HOURS...WITH POSSIBLE TROPICAL CYCLONE FORMATION DURING THAT 
WINDOW...THEN SHOULD LOSE IDENTITY IN THE BROADER CIRCULATION 
AROUND THE LOW FURTHER E. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...            
THE MONSOON TROUGH AXIS EXTENDS W ACROSS THE PACIFIC COAST OF 
THE PANAMA AND COSTA RICA BORDER TO 09N86W...THEN NW TO 
13N99W... THEN SW INTO A 1008 MB EMBEDDED LOW PRESSURE NEAR 
12N102W. THE MONSOON TROUGH RESUMES NEAR ANOTHER 1008 MB LOW 
PRESSURE AT 14.5N115W...AND CONTINUES SW TO 09N128W WHERE 
SCATTEROMETER WINDS INDICATE A TRANSITION TO AN INTERTROPICAL 
CONVERGENCE ZONE WHICH CONTINUES W TO BEYOND 08N140W. EXCEPT AS 
PREVIOUSLY MENTIONED AROUND THE TWO SURFACE LOWS...SCATTERED 
MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 60 NM EITHER 
SIDE OF A LINE FROM 12.5N120W TO 10N127W...AND WITHIN 60 NM 
EITHER SIDE OF A LINE FROM 08N132W TO 08N140W. SCATTERED 
MODERATE TO STRONG CONVECTION IS ALSO OBSERVED WITHIN 120 NM OF 
COAST OF CENTRAL AMERICA FROM 77W-85W AND FROM 87W-103W.

...DISCUSSION...
A SMALL UPPER LEVEL CYCLONE IS OBSERVED AT 21N107W WITH AN UPPER 
TROUGH EXTENDING W-SW TO 19N120W...THEN SW INTO ANOTHER UPPER  
CYCLONE OVER THE TROPICS AT 12N136W. THIS UPPER TROUGH SEPARATES 
THE FLOW ASSOCIATED WITH TWO LARGE UPPER ANTICYCLONES. AN 
ANTICYCLONE TO THE N OF THE TROUGH IS CENTERED AT 24N119W... 
WITH AN UPPER RIDGE EXTENDING E TO A SHARP CREST OVER MEXICO AT 
25N107W...AND AN UPPER RIDGE EXTENDS W TO A CREST AT 21N135W. A 
BAND OF THIN UPPER MOISTURE...ORIGINATING FROM ITCZ CONVECTION W 
OF 150W...CONTINUES TO STREAM NE ACROSS THE DISCUSSION AREA 
ALONG THE N PERIPHERY OF THE RIDGE...ROUGHLY WITHIN 150 NM OF A 
LINE FROM 25N140W TO 32N125W TO BEYOND 33N110W. OTHERWISE...THE 
UPPER LEVELS APPEAR VERY DRY N OF 20N W OF 106W. 

AN UPPER ANTICYCLONE IS CENTERED NEAR 15N107W...WITH A RIDGE 
EXTENDING SE TO 05N99W...AND A RIDGE EXTENDING W TO A CREST AT 
16N125W. THE ASSOCIATED UPPER DIFFLUENCE IS ENHANCING THE 
CONVECTION PREVIOUSLY DESCRIBED ALONG THE MONSOON TROUGH AND 
NEAR THE TWO EMBEDDED SURFACE LOWS. THE RESULTANT DEBRIS 
MOISTURE FANS OUT WITHIN 300 NM EITHER SIDE OF A LINE FROM 
12N102W TO 15N113W TO 13N127W. DENSE UPPER MOISTURE IS ALSO 
OBSERVED ACROSS THE TROPICS S OF 19N BETWEEN 77W-102W. A BROAD 
UPPER TROUGH IS NOTED S OF 07N BETWEEN 115W-130W...AND IS 
ACCOMPANIED BY DRY AIR ALOFT SUPPRESSING CONVECTION IN THAT AREA.

A 1029 MB SURFACE HIGH IS CENTERED NEAR 33N138W WITH A RIDGE 
EXTENDING SE TO 18N112W. NORTHERLY WINDS AT 15-20 KT ARE 
OCCURRING E OF THE RIDGE...GENERALLY N OF 30N BETWEEN 118W-
125W...WITH SEAS 7-9 FT IN N SWELL. THE GRADIENT WILL CONTINUE 
TO SUPPORT THESE CONDITIONS THROUGH THE WEEKEND. NE TRADES AREA 
ARE AT 15-20 KT SW OF THE RIDGE ACROSS THE WATERS W OF 130W WITH 
SEAS 6-8 FT IN THE NE SWELL. THESE CONDITIONS ARE EXPECTED TO 
SHIFT W OF 140W ON SUN.  
  
SE AND SW SWELL RESULTING IN COMBINED SEAS TO 9 FT WILL CROSS 
THE EQUATOR BETWEEN 125W TONIGHT...AND PROPAGATE NE TO ALONG 10N 
BETWEEN 100W-130W ON SUN NIGHT...BY THEN MERGING WITH MIXED 
SWELL DEVELOPING NEAR THE PREVIOUSLY DESCRIBED SURFACE LOWS. THE 
SOUTHERLY SWELL COMPONENT SHOULD REACH THE COAST OF CENTRAL 
AMERICA BETWEEN 97W-105W LATE MON...AND REACH THE SOUTHERN GULF 
OF CALIFORNIA TUE NIGHT. 
 
$$ 
NELSON