000
AXPZ20 KNHC 130239
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED APR 13 2011

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 
0300 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ANALYZED FROM 05N77W 
TO 1010 MB LOW PRES NEAR 07N90W TO 05N95W TO A SECOND LOW PRES 
NEAR 09N104W TO 03N128W. SCATTERED MODERATE CONVECTION IS WITHIN 
60 NM OF FIRST LOW PRES...AND WITHIN 60NM NW QUADRANT OF SECOND 
LOW PRES. ISOLATED MODERATE CONVECTION IS WITHIN 60 NM EITHER 
SIDE OF AXIS BETWEEN 105W AND 108W.    

...DISCUSSION...
A TROUGH/RIDGE PATTERN DOMINATES MOST OF THE FORECAST AREA. AN 
UPPER-LEVEL TROUGH ENTERS THE REGION NEAR 30N128W THEN CONTINUES 
SW TO 20N140W. A 70-110 KT JETSTREAM BRANCH IS AHEAD OF THE 
TROUGH AXIS FROM 24N131W TO SOUTHERN CALIFORNIA INTO THE SW 
CONUS. A LARGE UPPER-LEVEL ANTICYCLONIC CIRCULATION IS CENTERED 
OVER CENTRAL MEXICO NEAR 20N101W. S TO SW FLOW BETWEEN THESE TWO 
UPPER LEVEL FEATURES IS ADVECTING MID TO UPPER LEVEL MOISTURE 
FROM ITCZ CONVECTION TOWARD SOUTHERN TIP OF BAJA CALIFORNIA INTO 
NORTHERN MEXICO. MODERATE TO STRONG UPPER LEVEL SUBSIDENCE AND 
IMPLIED DRY AIR MASS IS NOTED N OF 10N E OF 105W...INCLUDING SE 
MEXICO AND MUCH OF CENTRAL AMERICA.  

A 1028 MB HIGH PRES LOCATED NEAR 34N133W EXTENDS A RIDGE SE OVER 
THE FORECAST WATERS AND DOMINATES THE AREA N OF 10N W OF 110W. A 
BROAD AREA OF TRADE WINDS IN THE 20 TO 25 KT RANGE IS OBSERVED 
ON THE SOUTHERN PERIPHERY OF THE RIDGE COVERING ROUGHLY THE 
REGION FROM 05N TO 20N W OF 120W. THESE WINDS ARE ALLOWING SEAS 
TO BUILD TO 11-12 FT. THE HIGH PRES IS FORECAST TO MOVE EASTWARD 
AND SIGHTLY INTENSIFY JUST N OF THE AREA DURING THE NEXT COUPLE 
OF DAYS. AS A RESULT...THE AREA OF TRADES WILL EXPAND EWD. IN 
ADDITION...WINDS ARE FORECAST TO INCREASE TO 20-25 KT W OF BAJA 
CALIFORNIA PENINSULA AS PRES GRADIENT TIGHTENS BETWEEN THE HIGH 
PRES AND LOWER PRES OVER NE MEXICO. ALSO EXPECT INCREASING WINDS 
ACROSS THE GULF OF CALIFORNIA PARTICULARLY N OF 28N IN ABOUT 36 
HOURS...AND N OF 24N IN ABOUT 48 HOURS. 

GAP WINDS...
GULF OF PAPAGAYO...FRESH NE TO E WINDS WILL CONTINUE TO PULSE TO 
20 KT THROUGH THE GULF OF PAPAGAYO THE NEXT COUPLE OF DAYS WITH 
SEAS REMAINING JUST BELOW 8 FT. THE LARGEST AREAL EXTENT OF THE 
20 KT WINDS WILL BE IN THE EARLY MORNING HOURS WITH THE AID OF 
NOCTURNAL DRAINAGE FLOW.
 
GULF OF TEHUANTEPEC...A WEAK COLD FRONT IN THE GULF OF MEXICO 
CURRENTLY MOVING THROUGH THE ISTHMUS OF TEHUANTEPEC IS PRODUCING 
NLY WINDS OF 20 TO 25 KT ACROSS THE GULF OF TEHUANTEPEC. THE 
MOST RECENT ASCAT PASS AND LATEST SURFACE OBSERVATIONS FROM 
IXTEPEC MEXICO VERIFIED THESE WIND SPEEDS. THIS WILL BE A BRIEF 
GAP WIND EVENT ENDING WED AFTERNOON.

$$
GR