000
AXPZ20 KNHC 190300
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED SEP 19 2012

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...SPECIAL FEATURE...
TROPICAL STORM LANE AT 20.6N 129.8W AT 0300 UTC MOVING W-NW OR 
300 DEG AT 8 KT.  MAXIMUM SUSTAINED WIND 35 GUSTS TO 45 KT AND 
PRES OF 1006 MB.  SCATTERED MODERATE ISOLATED STRONG CONVECTION 
WITHIN 45 NM NE QUADRANT OF CENTER.  LANE QUICKLY WEAKENED AS IT 
MOVED OVER COOLER WATERS AND FACES INCREASED S WIND SHEAR.  IT 
IS EXPECTED TO DOWNGRADE TO TROPICAL DEPRESSION LATE TUE AND A 
REMNANT LOW PRES CENTER WED.  SEE LATEST NHC FORECAST/ADVISORY 
UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC FOR ADDITIONAL 
DETAILS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH FROM 12N87W TO 13N93W TO 08N113W THEN ITCZ AXIS 
TO 10N120W THEN RESUME FROM 08N125W TO 08N131W TO 12N138W TO 
BEYOND 12N140W.  SCATTERED MODERATE CONVECTION WITHIN 240 NM S 
OF AXIS FROM 94W TO 104W AND WITHIN 120 NM S OF AXIS FROM 104W 
TO 112W.
 
...DISCUSSION...
DEEP LAYER TROUGH EXTEND FROM UPPER LEVEL CYCLONE AT 32N136W TO 
14N145W MAINTAINS VERY DRY AIR MASS N OF ITCZ AXIS W OF 120W.  
BROAD UPPER LEVEL ANTICYCLONE OVER W CENTRAL MEXICO ALSO KEEP 
DRY AIR MASS N OF 12N FROM 110W TO 120W.  STRONG SOUTHERLY 
WINDS BETWEEN BOTH FEATURES ADVECT TROPICAL MOISTURE FROM T.S. 
LANE NORTHWARD...BUT THE STRONG SHEAR AND COOL SEA SURFACE 
TEMPERATURES HAVE SIGNIFICANTLY WEAKENED LANE. 

HIGH PRES 1027 MB AT 41N133W EXTENDS RIDGE E-SE INTO NW PORTION 
OF BASIN EXPECTED TO SHIFT S OVER NEXT FEW DAYS TIGHTENING PRES 
GRADIENT N OF ITCZ INCREASING NE TRADES TO A FRESH BREEZE W OF 
125W LATE WED.  LIGHT TO MODERATE WINDS AND SEAS TO 5-7 FT 
EXPECTED TO PREVAIL ELSEWHERE ACROSS BASIN THROUGH WED.

GAP WINDS...BUILDING HIGH PRES BEHIND GULF OF MEXICO COLD FRONT 
WILL FORCE STRONG N WINDS THROUGH CHIVELAS PASS LATE TONIGHT 
INTO GULF OF TEHUANTEPEC BY LATE WED. DRAINAGE WINDS MAY ENHANCE 
GUSTS TO REACH NEAR GALE FORCE.

$$
WALLY BARNES