000
AXPZ20 KNHC 210949
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED AUG 21 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.
                                    
...SPECIAL FEATURES...
LOW PRES EMBEDDED IN MONSOON TROUGH AT 14N110W IS DEVELOPING ITS
OWN ANTICYCLONE OVERHEAD TO ENHANCE ITS OUTFLOW...SIGN OF
IMPROVING TROPICAL ORGANIZATION...WHILE REMAINING EMBEDDED IN
WARM MOIST AIR MASS ALONG MONSOON TROUGH.  UPPER LEVEL WIND SHEAR
HAS DIMINISHED AND SEA SURFACE TEMPERATURES REMAIN QUITE WARM...
ALL INGREDIENTS FOR FURTHER INTENSIFICATION AND POSSIBILITY OF
BECOMING A TROPICAL CYCLONE WITHIN NEXT 24-48 HOURS INCREASES. 
WHILE MOST MODELS FOCUS ON ITS FORMATION...INTENSITY...TRACK AND
TIMING REMAINS HIGHLY UNCERTAIN DUE TO THEIR DIVERGENT SOLUTIONS.

WHILE MOST MODELS KEEP A SECOND LOW PRES CENTER 1009 MB AT 
15N118W SEPARATED FROM MAIN FEATURE THROUGH FORECAST PERIOD...
GFS BRINGS THEM TOGETHER...SPINS THEM LIKE DUMBBELLS THEN MERGES
BOTH INTO ONE.  UNCERTAINTY RULES WITH EITHER SOLUTION.

REGARDLESS OF FINAL OUTCOME...REGION AROUND BOTH CENTERS LIKELY
TO BECOME VERY WINDY...NEAR TROPICAL STORM FORCE...WITH LONG
FETCH OF SW WINDS DRAWN TOWARDS THE CENTERS BUILDING SEAS TO
ABOVE 12 FT.  SCATTERED MODERATE TO STRONG CONVECTION LIKELY TO 
CONTRIBUTE TO HIGHER WINDS AND SEAS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...          
MONSOON TROUGH EXTENDS FROM 10N86W TO 09N95W TO 14N107W TO LOW 
PRES 1008 MB AT 14N110W TO LOW PRES AT 15N118W TO 10N136W TO
BEYOND 10N140W.  SCATTERED MODERATE TO STRONG CONVECTION S OF
AXIS TO 06N E OF 108W.  SCATTERED MODERATE ISOLATED STRONG 
CONVECTION WITHIN 240 NM S OF AXIS FROM 110W TO 121W.  

...DISCUSSION...
BROAD UPPER LEVEL ANTICYCLONIC CIRCULATION OVER NW PORTION OF
BASIN CENTERED AT 21N138W DRIFTS W.  VERY DRY AND STABLE AIR
MASS N OF 14N W OF 127W AND N OF 20N E OF 127W.  UPPER LEVEL 
TROUGH EXTENDS FROM DEEP LAYER WELL DEFINED CYCLONE AT 35N125W
TO 32N125W TO 15N128W. TROUGH CONTRIBUTES TO NORTHWARD ADVECTION
OF CONVECTIVE DEBRIS FROM MONSOON TROUGH TOWARD BAJA CALIFORNIA.
UPPER TROUGH ALSO BRINGING STRONG SW SHEAR OVER SURFACE LOW PRES
1009 MB AT 15N118W EMBEDDED IN MONSOON TROUGH.  CYCLONE SHIFTS
NE THU AND WEAKENS TROUGH WHICH MAY IN TURN ALLOW THIS LOW PRES
CENTER SOME INTENSIFICATION AND INTERACTION WITH MAIN FEATURE
LOW PRES.  AGAIN...LARGE DISAGREEMENT IN MODEL SOLUTIONS ADDS
UNCERTAINTY TO FORECAST.

SURFACE HIGH PRES CENTER 1022 MB WELL N OF AREA AT 46N130W WITH
RIDGE AXIS EXTENDING SE TO 22N117W.  LAX PRES GRADIENT EXTENDS 
ACROSS MOST WATERS WITH LIGHT TO MODERATE WINDS AND SEAS UNDER 8
FT...EXCEPT FOR MODERATE TO FRESH SW FLOW S OF MONSOON TROUGH.
 
$$
WALLY BARNES