000
AXPZ20 KNHC 050943
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU MAY 05 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 
0845 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS IS CENTERED ALONG 09N84W 
TO 07N90W TO 10N108W TO 06N140W. SCATTERED MODERATE TO STRONG 
CONVECTION NOTED WITHIN 210 NM N OF AXIS AND 60 NM S OF AXIS 
BETWEEN 100W AND 108W.

...DISCUSSION...

THE MAIN FORECAST CONCERN CONTINUES TO BE GAP WINDS. A 04Z ASCAT 
PASS CONFIRMED 35 TO 40 KT WINDS THROUGH THE GULF OF 
TEHUANTEPEC. AN EARLIER ALTIMETER PASS INDICATED SEAS AS HIGH AS 
16 FT S OF THE GULF...LIKELY DUE TO STRONG TO NEAR GALE FORCE 
WINDS AND N SWELL. THE GALES IN THIS AREA ARE DUE TO ANOMALOUSLY 
STRONG HIGH PRES N OF THE AREA OVER THE WESTERN GULF OF 
MEXICO...AND WILL DIMINISH BELOW GALE FORCE BY AFTERNOON AS THE 
HIGH PRES SHIFTS EAST. WINDS 20 KT OR GREATER AND RESIDUAL SWELL 
TO 8 FT WILL LINGER INTO FRI. 

FURTHER SOUTH...ALL MAJOR GLOBAL MODELS SHOW 20 TO 25 KT WINDS 
THROUGH THE GULF OF PAPAGAYO THIS MORNING...LIKELY DUE TO 
OVERNIGHT DRAINAGE EFFECTS AND THE TIGHTENED PRES GRADIENT 
BETWEEN THE HIGH PRES TO THE NORTH AND TROUGHING NEAR PANAMA. 
THIS DIMINISHES BY MIDDAY...WITH ONLY SHORT LIVED PULSES TO 20 
KT OVER THE NEXT COUPLE OF MORNINGS THROUGH THE GULF OF PAPAGAYO 
DUE TO OVERNIGHT DRAINAGE EFFECTS.

AN UPPER TROUGH SHOWS UP IN THE WESTERLY FLOW FROM 18N120W TO 
07N113W VIA WATER VAPOR IMAGERY AND THE GOES HIGH DENSITY WIND 
PRODUCT. DIVERGENT FLOW ALOFT PERSISTS IN A LARGE DEFORMATION 
ZONE BETWEEN THE UPPER TROUGH AND A BLOCKING COMPLEX MADE UP OF 
AN UPPER RIDGE OVER NORTHERN CENTRAL AMERICA AND AN UPPER 
CYCLONE OVER 03N85W. THE DIVERGENT FLOW ALOFT IS ENHANCING A 
LARGE CLUSTER OF CONVECTION ALONG THE ITCZ BETWEEN 100W AND 110W.

A 06Z ASCAT PASS SHOWS A BROAD SWATH OF FRESH TRADES...MAINLY W 
OF 130W N OF THE ITCZ...TO THE SE OF A 1035 MB SURFACE HIGH PRES 
NEAR 35N1145W. THESE TRADES WILL PERSIST THROUGH THE REMAINDER 
OF THE WEEK...AIDED BY THE APPROACH OF A WEAK WESTERLY MOVING 
SURFACE TROUGH ALONG THE ITCZ THROUGH FRI. A 00Z ALTIMETER PASS 
SHOWED LARGELY BETWEEN 6 TO 8 FT IN THE AREA OF TRADES...CLOSE 
TO WAVEWATCH INITIALIZATION.

$$
CHRISTENSEN