000
AXPZ20 KNHC 182209
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN APR 18 2010

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2115 UTC.

...ITCZ...
AXIS ALONG 06N77W TO 08N100W TO 06N117W TO 08N130W TO 05N140W.  
SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 45 NM OF 
AXIS FROM 84W-87W.  ISOLATED MODERATE CONVECTION WITHIN 180 NM 
OF AXIS FROM 105W-123W.

...DISCUSSION...
DEEP LAYER CYCLONIC VORTEX AT 29N129W ASSOCIATED WITH STRONG 
SHORT WAVE HAS 120 KT JET STREAM ROUNDING ITS BASE AND PROMPTING
DIFFLUENT FLOW ALOFT.  THIS IN TURN ENHANCES CONVECTION WITHIN 
180 NM NE QUADRANT OF VORTEX.  UPPER LEVEL TROUGH EXTEND FROM 
VORTEX TO 20N140W WITH VERY DRY AIR MASS DUE TO MODERATE TO 
STRONG SUBSIDENCE WITHIN 240 NM OF AXIS.  VORTEX IS WELL STACKED 
ABOVE SURFACE LOW PRES 1007 MB BRINGING COLD FRONT DEEP INTO E 
PAC WITH NEAR GALE SURFACE WINDS AND 12-14 FT NW SWELLS 
SPREADING AS FAR S AS 05N.  COLD FRONT EFFECTIVELY DIMINISHES NE 
TRADES BUT REESTABLISHES THEM AGAIN ONCE FRONT MOVES E BY END OF 
FORECAST PERIOD.

SE OF VORTEX...BROAD ANTICYCLONE AT 08N116W WITH HIGHLY 
AMPLIFIED RIDGE EXTEND ITS GRIP TO 95W BRINGING FAIRLY DRY AIR 
MASS S OF 22N E OF 110W.  RIDGE CONFINES SWATH OF ABUNDANT 
TROPICAL MOISTURE ADVECTED NE TOWARDS NORTHERN  BAJA CALIFORNIA 
PENINSULA BUT WITH LITTLE UPLIFT MECHANISM TO PROMPT RAINFALL 
EVENT.  DOWNSTREAM...SHARP UPPER LEVEL TROUGH BRINGS MINOR AREA 
OF MODERATE DIFFLUENT FLOW ENHANCING SCATTERED MODERATE ISOLATED 
STRONG CONVECTION ALONG ITCZ FROM 84W-87W.  

ELSEWHERE AT THE SURFACE...
WEAK SURFACE HIGH PRES 1015 MB AT 24N120W MAINTAIN LID OVER 
CLOUD VERTICAL DEVELOPMENT WITN ONLY ISOLATED CONVECTION ALONG 
ITCZ W OF 105W.  MODEL GUIDANCE SOLUTIONS MAINTAIN STRONGER HIGH 
PRES IN PLACE WITH MINOR OSCILLATIONS.  AS HIGH PRES 
STRENGTHENS...FRESH NW TO N WINDS MOVE ALONG NW COAST OF BAJA 
CALIFORNIA AND SPREAD S...EVENTUALLY ALSO MOVING INTO GULF OF 
CALIFORNIA BEYOND FORECAST PERIOD.  

$$
WALLY BARNES