000
AXPZ20 KNHC 021551
TWDEP 

TROPICAL WEATHER DISCUSSION                                      
NWS NATIONAL HURRICANE CENTER MIAMI FL                           
1605 UTC TUE JUL 02 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 
1545 UTC.

...SPECIAL FEATURES...

TROPICAL STORM DALILA AT 17.7N 106.9W 994 MB AT 1500 UTC JUL 02 
MOVING W OR 270 DEGREES AT 02 KT. MAXIMUM SUSTAINED WINDS ARE 55 
KT WITH GUSTS TO 65 KT. DALILA CONTINUES TO EXPERIENCE 
SOUTHEASTERLY WIND SHEAR WHILE ALSO ENTRAINING DRY UPPER AIR 
INTO THE CIRCULATION OVER ITS SOUTHERN SEMICIRCLE. CURRENTLY 
NUMEROUS STRONG CONVECTION IS OBSERVED WITHIN 150 NM OVER THE NW 
SEMICIRCLE...BUT ONLY OBSERVED WITHIN ABOUT 30 NM OVER THE SE 
SEMICIRCLE. THE SYSTEM IS UNDER AN UPPER RIDGE RESULTING IN VERY 
LITTLE MOVEMENT. THE SYSTEM IS FORECAST TO REMAIN A TROPICAL 
STORM FOR ABOUT 3 DAYS. SEE THE LATEST FORECAST/ADVISORY UNDER 
AWIPS/WMO HEADERS MIATCMEP4/WTNT24 KNHC FOR MORE DETAILS.

A LOW PRESSURE SYSTEM HAS FORMED ALONG A TROPICAL WAVE MOVING
THROUGH THE MONSOON TROUGH NEAR 12.5N94W AND IS ESTIMATED AT
1009 MB. SCATTERED MODERATE TO STRONG CONVECTION IS CURRENTLY
OBSERVED WITHIN 240 NM OVER THE NW SEMICIRCLE AND ABOUT 60 NM
ELSEWHERE S OF THE CENTER. THIS SYSTEM IS EXPECTED TO MOVE NW 
AND GRADUALLY STRENGTHEN OVER THE NEXT FEW DAYS WITH THE
POSSIBILITY OF TROPICAL CYCLONE FORMATION. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...   
     
THE MONSOON TROUGH AXIS EXTENDS W FROM COLOMBIA AT 10N75W 
TO ACROSS OVER NORTHERN COSTA RICA TO THE COAST AT 10N86W...
THEN TURNS NW TO THE EMBEDDED LOW PRESSURE PREVIOUSLY DESCRIBED
NEAR 12.5N94W. THE MONSOON TROUGH RESUMES WELL SW OF TROPICAL
CYCLONE DALILA NEAR 16N119W AND CONTINUES WSW TO 11N133W 
WHERE SCATTEROMETER WINDS INDICATE A TRANSITION TO AN 
INTERTROPICAL CONVERGENCE ZONE WHICH IN TURNS CONTINUES W TO
BEYOND 11N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION
IS OBSERVED FROM 03N-09N TO THE E OF 81W...WITHIN 90 NM OF
THE COAST OF CENTRAL AMERICA FROM 81W-87W...WITHIN 30 NM 
EITHER SIDE OF A LINE FROM 07N91W TO 10N98W...WITHIN 60 NM 
EITHER SIDE OF A LINE FROM 09.5N119W TO 15N126W...WITHIN 
150 NM OF 08.5N133W AND ALONG THE ITCZ WITHIN 60 NM OF
10N139W.    

...DISCUSSION... 

A DEEP LAYERED CYCLONE IS VERTICALLY STACKED AT 31N140W WITH
AN UPPER TROUGH EXTENDING SE TO 22N133W. THE ASSOCIATED SURFACE
LOW IS ANALYZED AT 1008 MB WITH ITS COLD FRONT EXTENDING S FROM
32N136W TO 22N140W. A REINFORCING NW SURGE WILL TIGHTEN THE
GRADIENT LATER TODAY...INCREASING THE SOUTHERLY FLOW TO 15-20 KT
WITHIN ABOUT 240 NM E OF THE SURFACE FRONT...WITH SEAS BUILDING 
TO 8 FT BRIEFLY NEAR 30N135W TONIGHT.

AN UPPER ANTICYCLONE IS N OF OF THE TROPICAL CYCLONE DALILA
NEAR 26N108W WITH A RIDGE EXTENDING N TO THE BORDER OF MEXICO
AND ARIZONA WHERE IT NEARLY MERGES WITH A RIDGE EXTENDING SE
ALONG THE CALIFORNIA/ARIZONA BORDER. DEBRIS MOISTURE IS 
ADVECTED N UNDER THE RIDGE TO AS FAR N AS SE ARIZONA.  

AN UPPER TROUGH EXTENDS S ACROSS THE GULF OF MEXICO TO A BASE
OVER THE ISTHMUS OF TEHUANTEPEC. ANOTHER UPPER ANTICYCLONE
IS NOTED E OF THE TROPICAL CYCLONE NEAR 17N103W WITH A RIDGE 
EXTENDING SE TO 12N92W. THIS PATTERN SETS UP AN AREA OF UPPER
DIFFLUENCE OVER THE EASTERN SEGMENT OF THE MONSOON TROUGH AND
IS ENHANCING THE CONVECTION NEAR THE DEVELOPING SURFACE LOW 
AT 12.5N94W.       
 
$$ 
NELSON