000
AXPZ20 KNHC 190347
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE MAY 19 2009

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0315 UTC.

...ITCZ...

THE ITCZ AXIS EXTENDS ALONG 08N78W TO 10N101W TO 08N106W TO 
11N117W TO 06N130W TO 06N140W. SCATTERED MODERATE ISOLATED 
STRONG CONVECTION IS NOTED WITHIN 30 NM EITHER SIDE OF LINE FROM 
06N80W TO 07N91W TO 09N95W AND WITHIN THE AREA BOUNDED BY 06N TO 
13N BETWEEN 95W AND 114W...AND ALSO WITHIN 30 NM EITHER SIDE OF 
LINE 09N120W TO 06N125W.

...DISCUSSION...

ALOFT...A DEEP LAYERED CYCLONE HAS CUT OFF NEAR 29N124W. AN 
UPPER TROUGH EXTENDS SE TO 18N112W AND IS MOVING NE WITH TIME.
AN UPPER LEVEL ANTICYCLONE IS CENTERED AT 10N135W WITH A 
SHORTWAVE RIDGE EXTENDING N WITH ITS CREST FROM 26N137W TO A 
SHARP CREST AT 12N122W. SOME UPPER MOISTURE IS SPREADING INTO 
THE AREA NEAR 19N135W. OTHERWISE THESE UPPER FEATURES COMBINE TO 
DRY OUT THE UPPER LEVELS W OF 128W AND N OF 12N BETWEEN 128W AND 
117W.

A QUASI STATIONARY UPPER ANTICYCLONE IS CENTERED NEAR 11N101W 
WITH A SHORTWAVE RIDGE AMPLIFYING N TO A CREST OVER SOUTHERN NEW 
MEXICO. UPPER DIFFLUENCE UNDER THIS BROAD RIDGE HAS BEEN 
ENHANCING CONVECTION ALONG AND TO THE N OF THE ITCZ BETWEEN 83W 
AND 120W...WITH MOST OF THE DEBRIS MOISTURE SPREADING N OVER THE 
ENTIRE UPPER LEVELS OF OLD MEXICO...WITH SOME OF THE MOISTURE 
SPILLING SE OVER THE GULF OF MEXICO AND THE W CARIBBEAN.

A STATIONARY UPPER RIDGE EXTENDS W ACROSS NORTHERN VENEZUELA TO 
A CREST OVER W COLOMBIA. AN UPPER TROUGH EXTENDS S ALONG 73W 
ACROSS THE PANAMA AND COLOMBIA BORDER. THIS MID TO UPPER TROUGH 
SEPARATES THE FLOW ASSOCIATED WITH THE S AMERICAN RIDGE FROM THE 
TROPICAL E PACIFIC RIDGE DESCRIBED ABOVE. E PACIFIC ITCZ 
CONVECTION IS ENHANCED BETWEEN 83W AND 77W WITH SOME OF THE 
RESULTANT DEBRIS MOISTURE ADVECTED NE ACROSS THE E CARIBBEAN 
INTO THE SUBTROPICAL CENTRAL N ATLC.
     
AT THE LOW LEVELS...A RIDGE EXTENDS OVER THE AREA N OF 20N W OF 
132W. A LOW LEVEL TROUGH EXTENDS ALONG 33N127W TO 23N130W...AND
IS DRIFTING W WITH TIME. THE GRADIENT BETWEEN THIS TROUGH AND 
RIDGE IS SUPPORTING NE WINDS TO 20 KT AND SEAS TO 8 FT. THE 
TROUGH IS EXPECTED TO CONTINUE DRIFTING W BUT GRADUALLY FILL TUE 
NIGHT. 1015 MB HIGH PRES HAS FORMED E OF THE TROUGH NEAR 27N122W 
INCREASING THE GRADIENT ALONG THE W COAST OF THE BAJA PENINSULA 
FROM 23N TO 27N WITH SURGES OF NW WINDS TO 20 KT. THESE 
CONDITIONS ARE EXPECTED TO CONTINUE THROUGH LATE TUE.

GAP WINDS...HIGH PRESSURE OVER THE GULF OF MEXICO WILL CONTINUE 
TO DRIVE N WINDS AT 20 TO 30 KT THROUGH THE GULF OF TEHUANTEPEC 
FOR AT THE LEAST THE NEXT TWO DAYS. 

$$
NELSON