000
AXPZ20 KNHC 121559
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC MON AUG 12 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 FEATURE...

A 1008 MB LOW PRES SYSTEM IS NEAR 14N126W MOVING NW AT 10 KT. 
SCATTERED MODERATE TO STRONG CONVECTION IS DISPLAYED FROM THE 
CENTER WITHIN 120 NM OF IT IN THE SW QUADRANT. THIS LOW BECOME 
BETTER ORGANIZED OVERNIGHT...AND HAS A HIGH CHANCE OF 
INTENSIFYING INTO A TROPICAL CYCLONE OVER THE NEXT 48 HOURS AS 
IT TRACKS IN A GENERALLY WESTWARD MOTION. 

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...       
MONSOON TROUGH AXIS EXTENDS FROM THE SW CARIBBEAN SEA NEAR 
12N76W TO ACROSS NORTHERN COSTA RICA TO 11N93W TO 09.5N100W TO 
LOW PRES NEAR 09N110W 1008 MB AND TO 12N136W. THE TROUGH RESUMES 
AT 13N138W TO 12N140W. SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION IS WITHIN 120 NM N OF THE TROUGH W OF 138W...AND 
WITHIN 120 NM S OF THE TROUGH E OF 88W.

...DISCUSSION...

AN UPPER LEVEL ANTICYCLONE IS NOTED OVER FAR N CENTRAL MEXICO AT 
30N107W WITH A RIDGE STRETCHING SW TO 24N126W TO A COL REGION AT 
19N139W. BROAD UPPER LEVEL SW TO W FLOW PREVAILS TO THE N OF 
THE RIDGE...WITH SATELLITE WATER VAPOR IMAGERY SHOWING MODERATE 
TO STRONG SUBSIDENCE ALLOWING FOR DRY AND STABLE ATMOSPHERIC 
CONDITIONS THERE. E TO NE WINDS ALOFT GENERALLY PREVAIL ACROSS 
THE REMAINDER OF THE AREA S AND SE OF THE RIDGE...CONTINUING TO 
PRODUCE A GENERALLY LIGHTLY SHEARED ENVIRONMENT. THE SPECIAL 
FEATURE LOW IS OBSERVED TO THE SW OF THE AFOREMENTIONED RIDGE. 
AN INVERTED MID TO UPPER TROUGH IS ALONG 120W MOVING WESTWARD.
 
AN INVERTED MID TO UPPER LEVEL TROUGH IS IDENTIFIED ON WATER 
VAPOR IMAGERY...AND ALSO SEEN IN UPPER MODEL DATA TO BE ALONG 
126W...AND TO MOVE WESTWARD.  NE TO E WINDS AHEAD OF THIS TROUGH 
CONTINUE TO AFFECT THE SURFACE LOW NEAR 14N126W WITH VERTICAL 
SHEAR. ANOTHER INVERTED MID/UPPER TROUGH IS NOTED OVER THE FAR 
EASTERN PART OF THE AREA TO THE SSW OF THE ANTICYCLONE ROUGHLY 
ALONG 114W FROM 15N TO 25N. INSTABILITY ALOFT BEHIND THE TROUGH 
IN COMBINATION WITH VERY WARM OCEAN TEMPERATURES IS ALLOWING FOR 
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION TO 
FIRE UP WITHIN 330 NM E OF THE TROUGH FROM 15N TO 24N. THIS AREA 
OF WEATHER SHOULD CONTINUE TO TRANSLATE WESTWARD INTO THIS 
EVENING. 

AT THE SURFACE...A WEAK 1021 MB HIGH IS ANALYZED NEAR 31N136W 
WITH A RIDGE EXTENDING SE TO NEAR 23N118W. RELATIVELY WEAK HIGH 
PRES COVERS THE AREA TO THE N OF 19N AND W OF 121W. THE WEAK 
PRES GRADIENT BETWEEN THE HIGH AND PERSISTENT LOW PRES ALONG THE 
SIERRA MADRES OCCIDENTALES HAS BEEN PRODUCING NNW WINDS 15-20 KT 
ALONG AND OFFSHORE OF THE W COAST OF BAJA CALIFORNIA TO ABOUT 
117W...WHERE WAVE MODEL GUIDANCE AND A FEW SHIP OBSERVATIONS 
FROM THE PAST 24 HOURS INDICATED PEAK SEAS ARE 5-6 FT. THESE 
CONDITIONS ARE FORECAST TO GENERALLY PREVAIL OVER THE NEXT 24-48 
HOURS...WITH BRIEF PULSING OF WINDS TO AROUND 20 KT WITH HIGHER 
GUSTS AND SEAS BRIEFLY 6-7 FT EXPECTED EACH OF THE NEXT FEW 
EVENINGS. THE HIGH IS FORECAST TO WEAKEN SLIGHTLY AS IT SHIFTS 
SLOWLY E DURING THE NEXT 24-48 HOURS. 
 
THE PRES GRADIENT BETWEEN THE HIGH AND THE MONSOON TROUGH 
CONTINUES TO SUPPORT NE WINDS OF 20-25 KT WITH SEAS PRESENTLY TO 
9 FT TO THE NW AND N OF THE SPECIAL FEATURES LOW. THESE 
CONDITIONS ARE LIKELY IN INCREASE OVER THE NEXT 48 HOURS IF THE 
LOW DEVELOPS FURTHER INTO A TROPICAL CYCLONE. THE OTHER LOW 
EARLIER ANALYZED OVER THE FAR WESTERN PART OF THE AREA NEAR 138W 
HAS WEAKENED TO A TROUGH THIS MORNING JUST W OF THE AREA.

$$ 
AGUIRRE