000
AXPZ20 KNHC 181600
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC TUE SEP 18 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...SPECIAL FEATURE...

TROPICAL STORM LANE CENTERED NEAR 20.1N 127.9W AT 1500 UTC MOVING
N OR 360 DEG AT 8 KT. MAXIMUM SUSTAINED WINDS 60 KT WITH GUSTS 
TO 75 KT AND A MINIMUM PRESSURE OF 993 MB. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 60 NM OF THE 
CYCLONE CENTER. LANE WILL WEAKEN SIGNIFICANTLY AS IT MOVES OVER
MUCH COOLER WATERS AND ENCOUNTERS INCREASED SOUTHERLY WIND SHEAR.
LANE IS EXPECTED TO WEAKEN TO A TROPICAL DEPRESSION ON WED...AND 
BECOME A REMNANT LOW PRES CENTER BY LATE WED NIGHT. SEE LATEST 
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 
KNHC FOR ADDITIONAL DETAILS.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM 08N78W TO 13N92W TO 08N108W TO 
08N119W. THE ITCZ AXIS IS FROM 08N119W TO 11N136W TO 10N140W.
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS WITHIN 60 NM S 
OF THE TROUGH BETWEEN 93W AND 108W. SCATTERED MODERATE TO STRONG 
CONVECTION IS LOCATED ALONG THE COAST OF MEXICO WITHIN 45 NM OF 
18N105.5W.
 
...DISCUSSION...

HIGH PRES CENTERED NEAR 40N143W EXTENDS A RIDGE ESE INTO THE 
NORTH-CENTRAL PORTION OF THE DISCUSSION AREA. REMNANT LOW KRISTY 
IS BECOMING MORE DIFFUSE AS IT DRIFTS NEAR 26.5N119W. ASCAT AND 
OSCAT SCATTEROMETER DATA SUGGEST WINDS HAVE DIMINISHED TO 20 KT 
OR LESS AROUND THE REMNANT LOW. IT IS EXPECTED TO WEAKEN FURTHER 
INTO AN OPEN TROUGH THROUGH TONIGHT. SCATTEROMETER PASSES OVER 
T.S. LANE THIS MORNING...PROVIDED A NICE DEPICTION OF THE OUTER 
WIND FIELD ASSOCIATED WITH THE TROPICAL CYCLONE...WITH ITS 
INFLUENCE EXTENDING OUT TO AROUND 200-250 NM FROM THE CENTER.

THE SUBTROPICAL HIGH IS EXPECTED TO SHIFT SOUTHWARD OVER THE NEXT
FEW DAYS...STRENGTHENING THE PRES GRADIENT N OF THE CONVERGENCE 
ZONE AND ALLOWING NE TRADE WINDS TO FRESHEN W OF 125W LATE IN THE
WEEK. LIGHT TO MODERATE WINDS AND SEAS AROUND 5-7 FT ARE EXPECTED
TO PREVAIL ELSEWHERE ACROSS THE DISCUSSION AREA THROUGH FRI.

GAP WINDS...BUILDING HIGH PRESSURE BEHIND A COLD FRONT OVER THE 
CENTRAL GULF OF MEXICO WILL SURGE AT 20 TO 25 KT THROUGH THE 
ISTHMUS OF TEHUANTEPEC LATE TONIGHT INTO THE GULF OF TEHUANTEPEC 
AROUND SUNRISE WED. THESE DRAINAGE WINDS WILL INCREASE TO 20 TO 
30 KT LATE WED...AND THEN PULSE THROUGH THE END OF THE WEEK WITH 
THE STRONGEST WINDS PRIMARILY OCCURRING LATE AT NIGHT UNTIL A 
FEW HOURS AFTER SUNRISE EACH DAY.

$$
MUNDELL