000
AXPZ20 KNHC 131547
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
1605 UTC SAT JUL 13 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1430 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...   
     
THE MONSOON TROUGH EXTENDS FROM COASTAL COLOMBIA NEAR 10N76W TO 
07.5N81W TO 11.5N91W TO 10.5N110W TO 13N114W TO 11N122W...WHERE 
IT TRANSITIONS TO ITCZ...CONTINUING ON TO BEYOND 09N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 240 
NM S OF TROUGH AXIS BETWEEN 78W AND 84W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION NOTED WITHIN 180 NM N AND 240 NM S OF 
TROUGH AXIS W OF 97W. SCATTERED MODERATE TO STRONG CONVECTION 
NOTED WITHIN 150 NM N AND 180 NM S OF ITCZ BETWEEN 122W AND 134W.
 
...DISCUSSION... 

AN ELONGATED AND WEAKENING UPPER CYCLONE IS N OF THE AREA AT  
35N137W WITH A NEGATIVELY-TILTED TROUGH EXTENDING SE TO 
27.5N119W...WHERE IT HAS BECOME WEAKLY CONNECTED TO A WWD 
SHIFTING MIDDLE/UPPER CYCLONE CENTERED NEAR 19N110W. A NARROW 90 
NM WIDE LINE OF MODERATE CONVECTION WAS OCCURRING ON THE ERN 
PERIPHERY OF THIS CYCLONE...FROM MANZANILLO MEXICO S TO NEAR 
17N106W. S AND SE OF THESE FEATURES...NARROW UPPER LEVEL RIDGING 
GENERALLY PREVAILS...SNAKING FROM A WEAK ANTICYCLONE NEAR 17N96W 
SW TO 11N105W THEN NW TO NEAR 17N124W. A BROADER AND SUBTLE 
MIDDLE LEVEL RIDGE CAN BE DETECTED IN WATER VAPOR IMAGERY TO THE 
NW OF THIS UPPER RIDGING...CENTERED NEAR 21.5N141W...WITH WLYS 
ALOFT TO THE N AND ELYS TO THE S. A MIDDLE LEVEL TUTT AXIS CAN 
ALSO BE SEEN IN WATER VAPOR IMAGERY OCCURRING ALONG THE SE AND 
S SIDE OF THIS MIDDLE LEVEL RIDGE...WITH SEVERAL SMALL TUTT 
CELLS SHIFTING WWD...BETWEEN 123W AND 153W.  MODERATE TO STRONG 
SUBSIDENCE PREVAILS WITHIN THIS MIDDLE LEVEL RIDGING...GENERALLY 
N OF 19N AND W OF 120W. 

AN ELONGATED UPPER TROUGH PREVAILS ACROSS THE DEEP TROPICS S OF 
08N AND BETWEEN 126W AND 150W. THE TROUGH CONTINUES TO WEAKEN 
WITH TIME. HOWEVER...THE UPPER FLOW PATTERN REMAINS SLIGHTLY 
 BETWEEN THE NARROW UPPER RIDGE TO THE NE AND THIS 
TROUGH...AND IS AIDING IN SUSTAINING CONVECTION DESCRIBED ABOVE 
ALONG THE ITCZ.  

BROAD UPPER LEVEL NE FLOW DOMINATES THE DEEP TROPICS E OF 
100W...INFLUENCED BY A LARGE S HEMI ANTICYCLONE CENTERED OVER 
PERU. THIS FLOW IS GENERALLY CONFLUENT YIELDING MODESTLY STABLE 
CONDITIONS ALOFT.

AT LOW LEVELS...A 1029 MB HIGH PRES CENTER WAS ANALYZED WELL N 
OF THE DISCUSSION AREA NEAR 42N146W AND EXTENDS A RIDGE SE TO 
NEAR 28N120W. THE PRES GRADIENT BETWEEN THE HIGH AND THE ITCZ 
REMAINS MODEST TODAY...AND IS YIELDING NE TRADES OF MAINLY 15 KT 
WITH A FEW SMALL AREAS OF 20 KT...W OF 130W BETWEEN THE ITCZ AND 
18N. SEAS THERE ARE RUNNING 6-7 FT IN MIXED NE AND S SWELL. 
EXPECT THESE CONDITIONS TO PERSIST INTO MON AS THE HIGH 
STRENGTHENS SLIGHTLY.

BOTH MARINE AND ATMOSPHERIC CONDITIONS ACROSS THE REGION ARE 
EXPECTED TO REMAIN GENERALLY TRANQUIL FOR THE NEXT FEW DAYS WITH 
NO SIGNIFICANT CHANGES TO THE CURRENT PATTERN. SEVERAL PULSES OF 
MODERATE SIZED LONG PERIOD SW SWELL WILL MOVE THROUGH THE AREA 
WATERS OVER THE NEXT FEW DAYS AND REACH THE PACIFIC COASTS OF 
CENTRAL AMERICA AND MEXICO. WINDS ARE EXPECTED TO GENERALLY 
REMAIN AT 20 KT OR LESS AND SEAS LESS THAN 8 FT REGION WIDE 
THROUGH MONDAY.
 
$$ 
STRIPLING