000
AXPZ20 KNHC 192123
TWDEP 

TROPICAL WEATHER DISCUSSION                                    
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
2205 UTC FRI JUL 19 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.

...TROPICAL WAVES...                                            
A TROPICAL WAVE EXTENDS FROM 19N110W TO 13N113W MOVING W ABOUT 
10 KT. CONVECTION HAS DIMINISHED IN ASSOCIATION WITH THE WAVE 
SINCE YESTERDAY. CURRENTLY...ONLY SCATTERED SHOWERS AND ISOLATED 
TSTMS ARE NOTED WITHIN 90 NM AHEAD OF THE WAVE AXIS. THIS 
FEATURE COINCIDES WITH A BULGE OF MOISTURE PRESENT IN TOTAL 
PRECIPITABLE WATER IMAGERY. GLOBAL MODELS CONTINUE TO SUGGEST 
THAT THE WAVE WILL GRADUALLY LOSE ITS SURFACE IDENTITY AS IT 
TRACKS WESTWARD THROUGH THE NEXT COUPLE OF DAYS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...        
MONSOON TROUGH EXTENDS FROM 09N84W TO 11N95W TO 06N105W TO 
12N110W. ITCZ AXIS EXTENDS FROM 13N114W TO 11N130W TO 08N140W. 
SCATTERED MODERATE TO STRONG CONVECTION IS N OF 10N BETWEEN 95W 
AND 99W...AND FROM 11N TO 13N BETWEEN 94W AND 95W. SCATTERED 
MODERATE CONVECTION CAN BE FOUND FROM 10N TO 13N BETWEEN 127W 
AND 138W AND FROM 13N TO 16N W OF 138W.

...DISCUSSION...                                          
ALOFT...AN ANTICYCLONE LOCATED WEST OF AREA NEAR 15N145W EXTENDS 
A RIDGE EWD ACROSS THE WEST-CENTRAL WATERS TO NEAR 15N130W. THE 
WEAK UPPER LOW HAS WEAKENED AND NOW A TROUGH EXTENDS FROM 
28N132W TO 21N129W TO 16N129W. UPPER LEVEL SW FLOW DOMINATES THE 
NW CORNER OF THE AREA AHEAD OF A BROAD UPPER TROUGH LOCATED NW 
OF THE DISCUSSION REGION. SATELLITE WATER VAPOR IMAGERY SHOWS 
MODERATE TO STRONG SUBSIDENCE INDUCING A DRY AND VERY STABLE 
ATMOSPHERIC ENVIRONMENT N OF 18N BETWEEN 125W AND 133W. AN 
ANTICYCLONE CENTERED NEAR 23N106W EXTENDS A RIDGE OVER MUCH OF 
NORTH-CENTRAL MEXICO WITH THE EXCEPTION OF THE NW PART WHERE A 
WELL DEFINED DEEP LAYER LOW SITUATED NEAR 29N111W CONTINUES TO 
GENERATE SOME SHOWER AND TSTM ACTIVITY THERE. ANOTHER RIDGE 
EXTENDING FROM THE FOUR CORNER REGION IN U.S. COVERS THE NE PART 
OF THE FORECAST AREA BETWEEN THE AFOREMENTIONED UPPER LOW OVER 
NW MEXICO AND THE TROUGH TO THE WEST. ELY WINDS ALOFT ARE NOTED 
ACROSS MUCH OF THE AREA N OF 05N AND E OF ABOUT 110W. THESE 
WINDS ARE TRANSPORTING DEBRIS CLOUDINESS FROM CONVECTION ALONG 
AND NEAR THE MONSOON TROUGH. 

AT THE SURFACE...A RIDGE DOMINATES THE FORECAST WATERS N OF 17N 
W OF 120W ANCHORED BY A 1029 MN HIGH LOCATED NEAR 37N136W. NW 
WINDS OF 10-15 KT ARE JUST WEST OF BAJA CALIFORNIA BETWEEN THIS 
RIDGE AND LOWER PRES OVER WESTERN MEXICO. A SMALL AREA OF 20 KT 
NE WINDS AND SEAS TO 8 FT IS NOTED FROM 14N TO 18N W OF 135W. 
THESE WINDS ARE BLOWING BEHIND THE TROUGH THAT WAS AFFECTING THE 
WEST-CENTRAL WATERS DURING THE PREVIOUS DAYS. THIS TROUGH IS NOW 
WEST OF AREA. 

A TIGHT PRES GRADIENT BETWEEN THE COAST OF NORTHERN CALIFORNIA 
AND 130W WILL INCREASE WINDS TO 20-30 KT THERE. SEAS ASSOCIATED 
WITH THESE WINDS ARE EXPECTED TO PROPAGATE SOUTH AS NORTHERLY 
SWELLS REACHING THE FAR NORTH WATERS BY SAT. THIS SWELL EVENT 
WILL PERSIST ON SUN AFFECTING MAINLY THE WATERS N OF 28N BETWEEN 
122W AND 128W WITH SEAS TO NEAR 9 FT. 

LONG PERIOD CROSS EQUATORIAL SOUTHWESTERLY SWELLS DOMINATE MUCH 
OF THE FORECAST WATERS.   

$$ 
GR