000
AXPZ20 KNHC 151600
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN MAR 15 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1545 UTC.

...ITCZ...

THE ITCZ AXIS EXTENDS FROM 08N81W TO 03N97W AND MAY CONTINUE S 
OF THE EQUATOR. THE AXIS IS AGAIN NOTED FROM 07N112W TO 03N140W. 
ISOLATED MODERATE CONVECTION IS NOTED WITHIN 30 NM EITHER SIDE 
OF LINE FROM 05N89W TO 06N95W.

...DISCUSSION...

AN UPPER TROPICAL ANTICYCLONE IS NEAR 06N140W WITH A SHORTWAVE 
RIDGE EXTENDING NE TO 27N127W WITH THE RIDGE COLLAPSING SE AT 
THE MOMENT. ANOTHER TROPICAL UPPER ANTICYCLONE IS OVER THE E 
PORTION NEAR 05N83W. ALTHOUGH A LONGWAVE RIDGE IS DOMINATING N 
AMERICA AN EMBEDDED POSITIVE TILT SHORTWAVE TROUGH CURRENTLY 
DISSECTS THE CENTRAL CONUS CONTINUING SW ACROSS THE BAJA 
PENINSULA AND THE TROPICAL PC INTO A SMALL UPPER CYCLONE AT THE 
BASE OF THE TROUGH NEAR 10N118W. 

DRY UPPER AIR IS ROTATING THROUGH THE UPPER TROUGH WITHIN 180 NM 
EITHER SIDE OF LINE 29N103W TO 25N113W TO 32N126W. UPPER 
MOISTURE IS NOTED UNDER THE WESTERN UPPER RIDGE...ROUGHLY FROM 
10N TO 26N BETWEEN 122W AND 150W. THE DRY AIR ASSOCIATED WITH 
THE UPPER TROUGH HAS ALMOST EVAPORATED OVER OLD MEXICO BUT THE 
MOISTURE BAND SPREADING NE IS STILL QUITE DENSE OVER THE GULF OF 
MEXICO. ELSEWHERE THE UPPER LEVELS ARE DRY.

AT THE SURFACE...A 1026 MB HIGH PRES CENTER NEAR 31N136W HAS A 
RIDGE EXTENDING SE TO NEAR 12N105W. TO THE E OF THE RIDGE 
NORTHERLY WINDS ARE 15 TO 20 KT WITH N SWELLS...BUT N COMPONENT 
MERGING WITH LONG PERIOD S SWELL WHICH IS BECOMING THE 
PREDOMINATE SWELL AS FAR N AS SOUTHERN CALIFORNIA. SW OF THE 
RIDGE THE GRADIENT IS SUPPORTING A SWATH OF 20 TO 25 KT WINDS 
WHICH IS EXPECTED TO DIMINISH SOME OVER THE NEXT FEW DAYS. 

CENTRAL AMERICAN GAPS...NE WINDS CONTINUE TO BRIDGE INTO AND 
JUST DOWNSTREAM OF THE GULF OF PAPAGAYO. N WINDS AT 15 KT GULF 
OF PAPAGAYO BUT MAY PULSE TO 20 KT. INTRODUCED N WINDS LATE MON 
NIGHT IN THE GULF OF TEHUANTEPEC AS GUIDANCE MOVES A COLD FRONT 
ACROSS THE GULF OF MEXICO. EXPECT THESE WINDS TO INCREASE TO 20 
TO 30 KT EARLY DAYLIGHT TUE WITH SOME GUIDANCE HINTING AT BRIEF 
GALE FORCE.    

$$
NELSON