000
AXPZ20 KNHC 260913
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE APR 26 2011

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 FROM 03N80W TO 04N117W TO 00N121W  SCATTERED MODERATE 
ISOLATED STRONG CONVECTION WITHIN 60 NM EITHER SIDE OF AXIS 
BETWEEN 90W TO 95W.  SCATTERED MODERATE TO STRONG CONVECTION 
WITHIN 60 NM S OF AXIS BETWEEN 100W  TO 105W.

...DISCUSSION...
W OF 110W...THE NE PORTION OF AN UPPER TROUGH THAT HAD EXTENDED 
FROM N CENTRAL MEXICO TO 17N140W HAS LIFTED OUT...LEAVING A CUT 
OFF UPPER CYCLONE NEAR 17N134W. AN UPPER ANTICYCLONE IS CENTERED 
TO THE NORTH NEAR 26N127W...CREATING A REX BLOCK PATTERN ALONG 
WITH THE UPPER CYCLONE. THIS WILL BE SHORTLIVED AS THE UPPER 
ANTICYCLONE SHIFTS E AND DEAMPLIFIES THROUGH TODAY AND THE CUT 
OFF CYCLONE SHIFTS NW BEFORE BECOMING ABSORBED IN AN APPROACHING 
UPPER TROUGH. AT THE SURFACE...A 1028 MB HIGH CENTERED NEAR 
31N134W WILL SHIFT E AND WEAKEN AS THE SUPPORTING UPPER 
ANTICYCLONE DEAMPLFIES. THIS WILL ALLOW MODERATE TO FRESH TRADES 
S OF THE HIGH...FROM ROUGHLY 06N TO 20N W OF 120W...TO DIMINISH 
THROUGH WED. FRESH TO STRONG NW TO N WINDS N OF 25N E OF 125W TO 
THE NORTHERN BAJA COAST WILL PERSIST BETWEEN THE HIGH PRES AND 
LOW PRES OVER THE GULF OF CALIFORNIA. NW SWELL TO 11 FT WILL 
ALSO PUSH SOUTHWARD INTO THIS AREA OFF NORTHERN BAJA. A COLD 
FRONT WILL ACCOMPANY THE APPROACHING UPPER TROUGH FROM THE 
WEST...ALTHOUGH THIS WILL STALL AND DISSIPATE N OF 30N THROUGH 
WED NIGHT. 

E OF 110W...SHIP ZCDF4 REPORTED FRESH SOUTHERLY FLOW NEAR THE 
GULF OF TEHUANTEPEC OVER THE PAST FEW HOURS. WHILE WIND SPEEDS 
MAY BE A LITTLE OVERDONE COMPARED WITH  CONTEMPORARY ASCAT DATA 
AND LAND BASED OBSERVATIONS...IT DOES INDICATE A ANOMALOUS BUT 
MODEST SOUTHERLY GAP EVENT IS UNDERWAY...BETWEEN RIDGING THROUGH 
THE GULF OF MEXICO...AND TROUGHING OVER TEXAS AND N CENTRAL 
MEXICO. WHILE THE GFS AND UKMET DO NOT INITIALIZE THIS...THE 
ECMWF DOES AND HINTS IT WILL PERSIST INTO WED BEFORE 
DIMINISHING. FURTHER SOUTH...AN UPPER ANTICYCLONE THAT HAD BEEN 
CENTERED NEAR 13N100W HAS WEAKENED AND SHIFTED E. ASSOCIATED 
DIVERGENCE ALOFT ON THE SOUTHERN EDGE OF THIS ANTICYCLONE HAS 
ABATED...ALLOWING PERSISTENT CONVECTION THAT HAD BE FLARING 
ALONG THE ITCZ NEAR 115W TO DIMINISH. 

$$
CHRISTENSEN