000
AXPZ20 KNHC 280924
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC MON MAR 28 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 
0715 UTC.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE AXIS WAS ANALYZED FROM 08N78W 
TO 03N101W TO 04N113W TO 02N131W TO 03N140W. SCATTERED MODERATE 
WITH ISOLATED STRONG CONVECTION WAS WITHIN 90 NM N OF THE ITCZ 
AXIS BETWEEN 80W AND 83W. SCATTERED MODERATE CONVECTION WAS 
WITHIN 60 NM EITHER SIDE OF THE ITCZ AXIS E OF 79W AND BETWEEN 
100W AND 102W AS WELL AS WITHIN 60 NM N AND 90 NM S OF THE ITCZ 
AXIS BETWEEN 129W AND 139W. A TROUGH IS EMBEDDED IN THE ITCZ 
FROM 08N112W TO 02N115W. SCATTERED MODERATE CONVECTION WAS 
WITHIN 300 NM W OF THE TROUGH FROM 02N TO 08N.

...DISCUSSION...

A 1027 MB HIGH PRES SYSTEM NEAR 32N147W EXTENDS A RIDGE INTO THE 
FORECAST AREA NEAR 30N131W THEN THROUGH 25N120W TO 12N106W. 
FRESH NE TRADE WINDS LIE S OF THE RIDGE AXIS FROM 04N TO 20N W 
OF 122W ACCORDING TO THE 0536 UTC ASCAT PASS. THESE TRADES ARE 
EXPECTED TO EXPAND NORTHWARD OVER THE NEXT 48 HOURS AS THE 
SUBTROPICAL HIGH STRENGTHENS AND SHIFTS SLIGHTLY EASTWARD 
THROUGH WED MORNING. 

A DISSIPATING COLD FRONT N OF THE AREA FROM SAN FRANCISCO BAY TO 
33N128W HAS FORCED THE SUBTROPICAL RIDGE AXIS SOUTHWARD OVER THE 
NE PORTION OF THE FORECAST AREA. THE PRES GRADIENT BETWEEN THE 
SUBTROPICAL RIDGE AND LOWER PRES OVER MAINLAND MEXICO IS STRONG 
ENOUGH TO SUPPORT FRESH TO STRONG NW TO N WINDS ALONG THE W 
COAST OF BAJA CALIFORNIA AND AS FAR S AS 20N. SHIP 3FBC9 
REPORTED 23 KT WINDS AND 12 FT SEAS NEAR 21N114W AT 0600 UTC AND 
SHIP C6FR3 REPORTED 20 KT WINDS AND 10 FT SEAS NEAR 26N114W AT 
0400 UTC. THIS AREA OF WIND IS EXPECTED TO LIFT N OF 25N AND 
DIMINISH A NOTCH TODAY. THE REMAINING FRESH N WINDS WILL THEN 
SHIFT W ON TUE AND INTO WED MORNING AS DEEP LAYER TROUGHING 
BUILDS OVER THE GULF OF CALIFORNIA AND PUSHES THE TIGHTEST PRES 
GRADIENT FARTHER W.

A WEAK ANTICYCLONE ALOFT NEAR 02N82W EXTENDS A RIDGE 
NORTHEASTWARD TOWARD THE GULF OF PANAMA. THE UPPER DIFFLUENCE 
ASSOCIATED WITH THIS RIDGE AXIS IS ENHANCING CONVECTION WITHIN 
30 NM OF THE COAST OF COLOMBIA FROM 03N TO 06N AS WELL AS THE 
CONVECTION ALONG THE EASTERN EDGE OF THE ITCZ WHICH IS DESCRIBED 
IN THE ITCZ SECTION ABOVE. THESE AREAS COINCIDE WITH A 
PRECIPITABLE WATER MAXIMUM ALONG THE ITCZ.

THE RIDGE AXIS EXTENDS W OF THE AFOREMENTIONED ANTICYCLONE TO 
SOUTH OF THE EQUATOR NEAR 01S95W THEN NORTHWESTWARD TO 12N110W. 
AN UPPER TROUGH LIES N OF THE RIDGE AXIS FROM THE ISTHMUS OF 
TEHUANTEPEC TO 03N95W. 30-40 KT SW WINDS ALOFT ON THE LEADING 
EDGE OF THIS TROUGH ARE MOVING UPPER MOSITURE FROM THE ITCZ 
MANIFESTED AS CIRRUS CLOUDS NORTHEASTWARD INTO CENTRAL AMERICA.

ANOTHER UPPER TROUGH LIES FROM 24N129W TO 00N117W. IT IS 
REFLECTING A SURFACE TROUGH WHICH IS EMBEDDED IN THE ITCZ FROM 
08N112W TO 02N115W. UPPER LEVEL DIFFLUENCE BETWEEN THIS TROUGH 
ALOFT AND THE RIDGE AXIS TO ITS E IS ENHANCING CONVECTION NEAR 
THE SURFACE TROUGH WHICH IS DESCRIBED IN THE SECTION ABOVE. THE 
SOUTHERN STREAM UPPER JET PASSES THROUGH THE TROUGH ALOFT...WITH 
A 60-80 KT SOUTHWESTERLY UPPER JET EXTENDING FROM THE TROUGH 
AXIS NEAR 16N125W TO CENTRAL MEXICO NEAR 26N102W. THIS JET IS 
TRANSPORTING CONVECTIVE BLOW OFF NORTHEASTWARD FROM THE ITCZ 
TOWARD SOUTHERN MEXICO. 

FARTHER W...A WEAK UPPER RIDGE AXIS EXTENDS INTO SW WATERS AND 
IS ENHANCING CONVECTION ON THE WESTERN EDGE OF THE ITCZ. 
NORTHWESTERLY FLOW ALOFT BETWEEN THIS RIDGE AXIS AND THE TROUGH 
AXIS ALOFT TO ITS E IS DIRECTING THE CONVECTIVE BLOW OFF FROM 
THE ITCZ SOUTHEASTWARD. 

$$
SCHAUER