000
AXPZ20 KNHC 081531
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI JUN 08 2012

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...
THE MONSOON TROUGH EXTENDS FROM 06N78W TO 07N89W...THEN 
CONTINUES FROM LOW PRES 1010 MB NEAR 10N102W TO 06N123W. ITCZ 
EXTENDS FROM 06N123W TO LOW PRES 1011 MB NEAR 08N131W TO 
05N140W. NUMEROUS MODERATE TO ISOLATED STRONG CONVECTION NOTED 
FROM 04N TO 06N E OF 81W. SCATTERED MODERATE CONVECTION FROM 06N 
TO 08N BETWEEN 100W TO 103W. SCATTERED MODERATE CONVECTION 
WITHIN 90 NM EITHER SIDE OF ITCZ AXIS BETWEEN 110W AND 120W.

...DISCUSSION...
AN UPPER TROUGH EXTENDS FROM 30N155W TO 10N130W. SUBSIDENCE IN 
THE NW FLOW ON THE W SIDE OF THE UPPER TROUGH AXIS IS 
SUPPRESSING DEEP LAYER MOISTURE AND CONVECTION W OF 130W ALONG 
THE ITCZ. CONVECTION HAS DIMINISHED NEAR A 1011 MB LOW PRES AREA 
NEAR 08N131W THAT CONTINUES TO DRIFT W ALONG THE ITCZ INTO THE 
MORE UNFAVORABLE AREA ON THE WEST SIDE OF THE UPPER TROUGH. 
GLOBAL MODELS SHOW THE SURFACE LOW WEAKENING AND OPENING INTO A 
TROUGH AS IT CROSSES 140W BY LATE SAT INTO EARLY SUN. 

DIVERGENT SW FLOW BETWEEN THE UPPER TROUGH AND AN UPPER RIDGE 
CENTERED NEAR 10N105W IS PROVIDING UPPER EXHAUST FOR OUTFLOW 
FROM AREAS OF CONVECTION ALONG THE ITCZ BETWEEN 110W AND 
120W. FURTHER NORTH...PERSISTENT SURFACE 1030 MB HIGH PRES NEAR 
35N145W IS MAINTAINING A LARGE AREA OF MODERATE TO FRESH TRADE 
WINDS FROM 10N TO 25N W OF 125W...AS WELL AS FRESH NW TO N WINDS 
N OF 25N BETWEEN 118W AND 125W. 

A 1010 MB SURFACE LOW IS CENTERED ALONG THE MONSOON TROUGH NEAR 
10N102W. THE LOW FORMED IN THE LAST 12 HOURS BENEATH A BROAD 
UPPER ANTICYCLONE CENTERED NEAR 10N105W. SCATTERED MODERATE 
CONVECTION IS ONGOING TO THE SE OF THE CIRCULATION FROM 06N TO 
08N BETWEEN 100W TO 103W. LOOSE CONSENSUS OF THE 
GFS...UKMET...AND ECMWF SHOWS THE LOW DRIFTING WNW TO 11N105W 
AROUND 1006 MB BY 48 HOURS...AND TO 12N109W AROUND 1007 MB BY 72 
HOURS. MODEL GUIDANCE DIVERGE AFTERWORDS WITH THE GFS SHOWING IT 
CONTINUING WESTWARD ALONG THE MONSOON TROUGH/ITCZ...AND THE 
ECMWF AND UKMET BASICALLY DISSIPATING SLIGHTLY TO THE N OF THE 
FAVORABLE CONVERGENCE OF THE MONSOON TROUGH BY LATE IN THE WEEK.

FURTHER EAST...A VIGOROUS UPPER LOW IS CENTERED NEAR 10N79W AND 
IS MOVING WEST ACROSS PANAMA. DRY MID AND UPPER LEVELS 
ASSOCIATED WITH SUBSIDENT N TO NE FLOW ALOFT ON THE W SIDE OF 
THE UPPER LOW IS IMPEDING WIDESPREAD CONVECTION ACROSS COSTA 
RICA AND NICARAGUA...WITH ONLY A FEW SMALL CLUSTER OF CONVECTION 
NOTED OFF THE COASTS THIS MORNING. HOWEVER...A COMBINATION OF 
UPPER DIVERGENCE ON THE S AND E SIDES OF THE LOW...ALONG WITH 
SOME ASSISTANCE OF LIGHT SW FLOW TO THE S OF THE MONSOON TROUGH 
IN THE AREA...AS WELL AS THE TYPICAL NOCTURNAL EFFECTS HAVE 
TOGETHER CREATED A LARGE AREA OF NUMEROUS SHOWERS AND SCATTERED 
TSTMS ALONG THE COAST OF COLOMBIA AND THE BAY OF PANAMA. THE 
GFS...ECMWF...AND TO A LESSER EXTENT THE UKMET SHOW THE UPPER 
RIDGE NEAR 10N105W WILL SHIFT N AS THE UPPER LOW DRIFTS W AND 
OPENS INTO A MID TO UPPER TROUGH ALONG 90W BY LATE SUN. THE 
MODEL CONSENSUS GOES ON TO SHOW AN ASSOCIATED SURFACE LOW 
FORMING IN FAVORABLE SW SURFACE FLOW AND DEEPENING NEAR 10N95W 
BY LATE MON. MODELS DIVERGE ON POSITION AND INTENSITY OF THE LOW 
THROUGH MID WEEK WITH THE GFS BEING THE MOST AGGRESSIVE.

$$
CHRISTENSEN