000
AXPZ20 KNHC 041005
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SUN NOV 04 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

...SPECIAL FEATURE...

TROPICAL DEPRESSION ROSA NEAR 12.5N 121.5W AT 0900 UTC MOVING W 
AT 3 KT. CENTRAL PRES 1009 MB. MAXIMUM SUSTAINED WINDS 25 GUSTS 
TO 30 KT. PERSISTENT WESTERLY SHEAR IS WEAKENING THE CIRCULATION 
WITH LITTLE OR NO DEEP CONVECTION...RESTRICTED TO WITHIN 90 NM 
NE QUADRANT AND SEPARATED FROM THE LOW CENTER. ROSA IS EXPECTED 
TO DRIFT NW AND CONTINUE TO WEAKEN...BECOMING A POST-TROPICAL 
REMNANT LOW PRES EARLY TODAY. SEE LATEST NHC FORECAST/ADVISORY 
UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC FOR MORE DETAILS.

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

MONSOON TROUGH FROM 11N86W TO 08N96W TO LOW PRES NEAR 16N109W 
1007 MB TO 13N117W. ITCZ FROM 09N127W TO 08N140W. SCATTERED 
MODERATE CONVECTION FROM 08N TO 10N BETWEEN 120W AND 128W.

...DISCUSSION...

SHORT WAVE ENERGY IS DIGGING SOUTH INTO THE BASE OF A BROAD MID 
TO UPPER TROUGH EXTENDING FROM THE SOUTHWEST UNITED STATES TO 
13N130W. SW WINDS ALOFT ARE APPLYING SHEAR TO THE CONVECTION 
NEAR A 1007 MB LOW PRES SYSTEM CENTERED NEAR 16N109W. THE 
CONVECTION IS FLARING WELL TO THE NE OF THE LOW...FROM 16N TO 
19N BETWEEN 100W AND 110W...POSSIBLE ALONG THE REMAINS OF AN OLD 
FRONTAL BOUNDARY. A HIGH RESOLUTION ASCAT PASS FROM AROUND 05 
UTC INDICATED WINDS OF UP TO 30 KT ON THE NE SIDE OF THE LOW. 
SEAS ARE ESTIMATED TO BE UP TO 9 FT IN SE SWELL. GIVEN THE 
STRENGTH OF THE WINDS AND THE PERSISTENCE AND INTENSITY OF THE 
ONGOING CONVECTION...THE LOW MAIN TAKE MORE TROPICAL 
CHARACTERISTICS AND DEVELOP INTO A TROPICAL CYCLONE THROUGH 48 
HOURS. SOME UNCERTAINTY LINGERS WITH THIS SCENARIO HOWEVER...AS 
GLOBAL MODELS ARE GENERALLY NOT FAVORABLE TO THIS LOW GIVEN THE 
STRONG SW SHEAR AHEAD OF THE MID TO UPPER LEVEL TROUGH. 

FARTHER WEST...A BLOCKING UPPER RIDGE IS CENTERED ALONG 135W N 
OF 20N WITH AN ASSOCIATED 124 MB SURFACE HIGH CENTERED NEAR 
30N135W. THE SURFACE HIGH PRES IS SUPPORTING FRESH TO STRONG 
TRADE WINDS ON ITS SOUTHERN PERIPHERY FROM 13N TO 20N W OF 130W. 
THESE TRADE WINDS WILL DIMINISH THROUGH 24 HOURS AS THE SURFACE 
HIGH PRES LIFTS N. A POWERFUL LOW PRES SYSTEM IN THE N CENTRAL 
PACIFIC HAS BEEN GENERATING LONG PERIOD NW SWELL THAT IS 
PROPAGATING INTO THE DISCUSSION AREA. MOST OF THIS WILL 
PENETRATE AS FAR E AS 125W N OF 10N THROUGH 24 HOURS...THEN 
LARGELY DECAY BELOW 8 FT BY 48 HOURS.

GAP WINDS...A HIGH RESOLUTION ASCAT PASS FROM 0310 UTC SHOWED 
GAP WIND FLOW UP TO 25 KT IN THE GULF OF TEHUANTEPEC. BOTH THE 
GFS AND ECMWF SHOW 25 TO MAYBE 30 KT BY SUN NIGHT EARLY MON 
MORNING. LOOKING AHEAD...A COLD FRONT WILL MOVE THROUGH THE GULF 
OF MEXICO TUE INTO WED. THE MUCH DENSER COOL AND DRY AIR WILL 
FILTER THROUGH THE CHIVELA PASS...DELIVERING WINDS POSSIBLY 
REACHING GALE FORCE BY LATE TUE IN THE GULF OF TEHUANTEPEC.

$$
CHRISTENSEN