000
AXPZ20 KNHC 270950
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE APR 27 2010

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0915 UTC.

...ITCZ...
AXIS ALONG 07N78W TO 08N90W TO 05N102W TO 07N116W TO 05N140W.  
SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 180 NM OF 
AXIS FROM 84W TO 95W.  SCATTERED MODERATE CONVECTION WITHIN 120 
NM OF AXIS W OF 113W. 

...DISCUSSION...
SHARP UPPER LEVEL TROUGH FROM 32N112W TO 23N140W USHERS IN DRY 
AIR MASS WITHIN 300 NM OF NW AXIS AND MARKS NORTHERNMOST 
BOUNDARY OF LARGE PLUME OF TROPICAL MOISTURE ADVECTED NE BY 140 
KT JETSTREAM PARALLEL AND SE OF AXIS.  BROAD DOWNSTREAM MID/ 
UPPER LEVEL ANTICYCLONIC GYRE CENTERED AT 14N100W EXPANDS E TO 
MERGE WITH RIDGE OVER SOUTH AMERICA.  WEAK UPPER LEVEL TROUGH 
BEING SQUEEZED OUT OF PICTURE STILL REMAINS FROM COSTA RICA TO 
06N90W.  TROUGH STILL PRODUCES AREA OF DIFFLUENT FLOW ALOFT OVER 
WEAK SURFACE TROUGH FROM 12N88W TO 06N90W ENHANCING DEEP 
CONVECTION IN SURGES.  SEVERAL SURFACE CYCLONIC SWIRLS WERE 
NOTED EARLIER WITH VISIBLE IMAGERY BUT UNABLE TO IDENTIFY THEM 
UNDER IR.  ALTHOUGH NO ORGANIZATION OF SYSTEM IS EXPECTED...AREA 
WILL LIKELY REMAIN WITH SCATTERED TO NUMEROUS DEEP CONVECTION AS 
TROUGH MOVES OUT BY THU.  PLENTY OF MID TO UPPER MOISTURE 
AVAILABLE FOR ITCZ CONVECTION AROUND SOUTHERN PERIPHERY OF 
ANTICYCLONIC GYRE.

ELSEWHERE AT THE SURFACE...
COLD FRONT NEAR 30N138W MOVES INTO E PAC AS PREVIOUS HIGH PRES 
RIDGE DISSIPATES THROUGH TODAY.  FRONT SKIRTS NORTHERN LATITUDES 
OF BASIN AND EXITS ACROSS BAJA CALIFORNIA WITH SLIGHT INCREASE 
OF WINDS TO FRESH BREEZE ALONG BOTH COAST OF THE PENINSULA THU.  
HIGH PRES CENTER 1030 MB BUILDS IN WAKE OF FRONT JUST NW OF 
BASIN AND TIGHTENS PRES GRADIENT THU CAUSING INCREASE IN TRADES 
W OF 130W.

LARGE LONG PERIOD NW SWELLS PROPAGATE THROUGH BASIN AND MERGE 
WITH CROSS-EQUATORIAL SW SWELL ACROSS TROPICS THROUGH THU.

$$
WALLY BARNES