000
AXPZ20 KNHC 090910
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON MAY 09 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 
0830 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ALONG 06N77W TO 
09N100W TO 06N120W TO 08N140W. SCATTERED MODERATE AND ISOLATED 
STRONG CONVECTION N OF 04N E OF 85W. SCATTERED MODERATE 
CONVECTION WITHIN 90 NM N OF AXIS AND 30 S OF AXIS BETWEEN 95W 
AND 100W. SCATTERED MODERATE AND ISOLATED STRONG WITHIN 90 NM N 
OF AXIS BETWEEN 110W AND 130W.

...DISCUSSION...

A TIGHT GRADIENT BETWEEN A 1032 MB SURFACE HIGH PRES AREA 
CENTERED NEAR 36N150W AND TROUGHING OVER NW MEXICO IS 
MAINTAINING NW 30 KT WINDS ALONG THE COAST OF BAJA CALIFORNIA. 
THIS WILL PERSIST THROUGH LATE TUE WHEN NW SWELL OF 8 TO 9 FT 
WILL MOVE AS FAR S AS 28N E OF 120W OFF THE NORTHERN COAST OF 
BAJA. SMALL AREAS OF FRESH TRADE WINDS S OF THE SURFACE RIDGE 
FROM 10N TO 20N W OF 125W WILL SHRINK IN AREA AND INTENSITY INTO 
WED AS THE HIGH PRES N OF THE AREA WEAKENS. 

GOES HIGH DENSITY WINDS AND ANIMATED WATER VAPOR IMAGERY 
INDICATE A BROAD UPPER LEVEL DEFORMATION AREA PERSISTS OVER THE 
ITCZ W OF 90W...TO THE SOUTH OF COSTA RICA AND PANAMA. A 0240Z 
ASCAT PASS SHOWED ONLY LIGHT WINDS ALONG THE ITCZ...SUGGESTING 
THAT THE UPPER DYNAMICS WERE LIKELY THE MAIN IMPETUS FOR 
CLUSTERS OF MODERATE TO STRONG CONVECTION THAT ERUPTED YESTERDAY 
EVENING BETWEEN THE ITCZ AND THE COAST. SATELLITE IMAGERY ALSO 
HINTED OF A BROAD LOW PRES CENTER S OF WESTERN PANAMA NEAR 
06N81W WITH AN ESTIMATED PRES OF 1008 MB. THIS IS LIKELY AN 
ARTIFACT OF THE CONVECTION IN THE AREA...AND WILL PROBABLY 
DISSIPATE LATER TODAY. IN THE MEANTIME...THE LOW PRES IS 
ENHANCING LOW LEVEL GRADIENT FLOW ON ITS NORTH SIDE TO SUPPORT 
20 TO 25 KT WINDS FUNNELING INTO THE GULF OF PAPAGAYO AS NOTED 
BY THE 0240Z ASCAT PASS. THIS WAS WELL INITIALIZED BY THE ECMWF 
AND UKMET...AND TO A LESSER EXTENT BY THE GFS. DRAINAGE EFFECTS 
ARE LIKELY SECONDARY GIVEN THE WARM AND MOIST ATMOSPHERE AND 
EVENING TIMING OF THE PAPAGAYO WINDS. ALL MODELS SHOW THE 
GRADIENT FLOW DIMINISHING LATER TODAY.

AN UPPER TROUGH ALONG 105W BETWEEN 03N AND 11N IS SUPPORTING A 
WEAK SURFACE TROUGH ALONG 100W ALONG WITH SCATTERED MODERATE TO 
STRONG CONVECTION N OF THE TROUGH ALONG THE ITCZ. 

A 06Z ASCAT PASS SHOWED A SURGE OF CROSS-EQUATORIAL FLOW TO 20 
KT...HELPING ENHANCE CONVECTION ALONG THE ITCZ BETWEEN 120W AND 
130W. SEAS TO 8 FT WERE NOTED IN EARLIER ALTIMETER PASS NEAR 
THIS AREA AS WELL...LIKELY IN SE WIND WAVES AND SW SWELL. 

GULF OF CALIFORNIA...ALTHOUGH NO DATA ARE AVAILABLE FROM THE 
NORTHERN GULF...STRONG SW WINDS IN THE COLORADO VALLEY BETWEEN 
CALIFORNIA AND ARIZONA HINT THAT GFS INITIALIZATIONS OF FRESH SW 
WINDS MAY BE ON TARGET...AND WINDS WILL PERSIST THROUGH MIDDAY.

$$
CHRISTENSEN