000
AXPZ20 KNHC 191611
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON AUG 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.
                                    
...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...     
MONSOON TROUGH EXTENDS FROM 10N74W TO 11.5N88W TO DEVELOPING LOW 
PRES NEAR 12.5N106.5W 1008 MB TO LOW PRES NEAR 14N117.5W 1008 MB 
TO 12N127W TO BEYOND 13N140W. SCATTERED MODERATE TO STRONG 
CONVECTION NOTED FROM 04N TO 08N BETWEEN 77.5W AND 80W. 
SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 180 NM N OF 
TROUGH BETWEEN 93W AND 105W...AND 150 NM EITHER SIDE BETWEEN 
105W AND 109W. SCATTERED MODERATE TO STRONG CONVECTION NOTED 
FROM 10N TO 16N BETWEEN 116W AND 123W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION NOTED WITHIN 120 NM S AND 60 NM N OF 
TROUGH W OF 125W. 

...DISCUSSION...                                            
UPPER LEVEL ANTICYCLONE CENTERED AT 22N137W DRIFTING NW...AND 
HAS EXPANDED NORTHWARD PAST 24 HOURS IN RESPONSE TO UPPER 
TROUGHS AT HIGHER LATITUDES TO THE NW AND NW. DEEP LAYERED UPPER 
CYCLONE OFF COAST OF S CALIFORNIA NEAR 34N124W WITH MEAN TROUGH 
EXTENDING S TO NEAR 21N123W. UPPER CONVERGENCE OCCURRING BETWEEN 
FLOW ON BACK SIDE OF TROUGH AND SE PERIPHERY OF UPPER RIDGE 
PRODUCING ZONE OF STRONG SUBSIDENCE JUST N OF MONSOON 
TROUGH...FROM 20N TO 15N BETWEEN 125W AND 136W. A NARROW UPPER 
RIDGE REMAINS ALONG ABOUT 110W...CENTERED ON A WEAKENING  
ANTICYCLONE NEAR 22N111W...BEING NUDGED SLOWLY W BY WWD SHIFTING 
UPPER CYCLONE OVER S TEXAS AND N MEXICO. ELY FLOW ALOFT PERSISTS 
S OF 15N AND W OF 108W...MAINTAINING A LIGHTLY SHEARED 
ENVIRONMENT...AND CONTINUES TO ALLOW FOR CLUSTERS OF DEEP 
CONVECTION NEAR THE MONSOON TROUGH. UPPER PATTERN TO SHIFT N OF 
15N TO SHIFT SLIGHTLY WWD NEXT FEW DAYS...AND WILL PLAY KEY ROLE 
IN FORECAST FOR POTENTIAL TROPICAL DEVELOPMENT OF LOW OR LOWS 
DEVELOPING WITHIN AN ELONGATED LOW TO MIDDLE LEVEL CYCLONIC 
CIRCULATION FORECAST TO DEVELOP ABOUT THE MONSOON TROUGH BETWEEN 
100W AND 130W OVER THE NEXT SEVERAL DAYS.

AT LOWER LEVELS...EPAC RIDGE REMAINS MODEST...CENTERED ON A 1026 
MB HIGH NEAR 38N140W...EXTENDING SE TO NEAR 22N118W. WEAK PRES 
GRADIENT LIMITING NNW FLOW ALONG AND OFFSHORE OF BAJA CALIFORNIA 
TO GENERALLY 15 KT OR LESS OVERNIGHT AND THIS MORNING...BUT 
EXPECTED TO INCREASE SLIGHTLY TONIGHT THROUGH WED TO 15-20 KT. 

VERY ACTIVE CONVECTION DESCRIBED ABOVE CONTINUES ALONG THE 
MONSOON TROUGH BETWEEN 97W AND 124W...BEING FORCED BY A SERIES 
OF MODEST EASTERLY WAVES PROPAGATING WWD THROUGH THE TROPICS. 
MID LEVEL CYCLONIC TURNING IS SUGGESTED BY SATELLITE IMAGERY 
ALONG 107W AND 117W THIS MORNING...WHERE SOME OF THE MOST ACTIVE 
CONVECTION IS OCCURRING. GLOBAL MODELS CONTINUE TO BE ADAMANT 
THAT A LOW PRES CENTER WILL DEVELOP ALONG THE E END OF THIS 
REGION DURING THE NEXT 48-72 HOURS...BETWEEN 103W AND 110W...AND 
MOVE NORTHWESTWARD IN THE GENERAL DIRECTION TOWARDS 20N110W. 
CONDITIONS ARE VERY FAVORABLE FOR THIS TO OCCUR...AND THERE IS A 
HIGH PROBABILITY OF A TROPICAL CYCLONE DEVELOPING WITHIN THIS 
AREA DURING THE NEXT 5 DAYS. THE STEERING CURRENTS ARE NOT 
EXPECTED TO CHANGE MUCH DURING THIS TIME...AND WOULD TAKE SUCH A 
SYSTEM NW TO NNW AND TOWARDS THE OFFSHORE WATERS OF SOUTHERN 
BAJA CALIFORNIA. INTERESTS ACROSS THIS AREA SHOULD FOLLOW THE 
EXPECTED EVOLUTION OF THIS AREA OF WEATHER THROUGHOUT THE WEEK.
 
$$
STRIPLING