000
AXPZ20 KNHC 271508
TWDEP 

TROPICAL WEATHER DISCUSSION   
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI OCT 27 2006

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 
1445 UTC.

...SPECIAL FEATURE...

TROPICAL DEPRESSION EIGHTEEN-E IS CENTERED 15.8N 105.2W OR 205 
NM S OF MANZANILLO MEXICO AT 27/1500 UTC MOVING SW 4 KT. MAXIMUM 
SUSTAINED WIND SPEED IS 25 KT WITH GUSTS TO 35 KT. ESTIMATED 
MINIMUM CENTRAL PRESSURE IS 1008 MB. JUST BEFORE SUNRISE ENOUGH 
CIRRUS DISSIPATED OVER THE DEPRESSION TO SHOW THAT THE LOW-LEVEL 
CENTER HAD BECOME COMPLETELY EXPOSED ABOUT 75 NM SE OF THE DEEP 
CONVECTION. SINCE THEN...THE CONVECTION HAS WANED IN INTENSITY A 
LITTLE AND HAS BECOME MORE DISORGANIZED. SCATTERED MODERATE 
CONVECTION IS WITHIN 180 NM NW QUADRANT. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP3/WTPZ23 KNHC 
FOR MORE DETAILS.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N80W 8N100W 10N115W 7N125W 9N140W. 
WIDELY SCATTERED MODERATE CONVECTION FROM 5N-10N BETWEEN 
78W-92W. SCATTERED MODERATE FROM 13N-16N BETWEEN 132W-137W.

...DISCUSSION...

A FLAT UPPER LEVEL LONGWAVE PATTERN IS IN PLACE OVER THE N PART 
OF THE DISCUSSION AREA WITH A STRUNG-OUT AND TILTED TROUGH 
EXTENDING FROM 30N130W TO 25N140W. A FAIRLY VIGOROUS UPPER JET 
LIES ON THE SE SIDE OF THE TROUGH FROM 18N140W TO 30N120W THEN 
EWD INTO NRN MEXICO AND TEXAS. THE JET MARKS THE N EDGE OF AN 
EXPANSIVE CIRRUS SHIELD WHICH EXTENDS N OF 10N W OF 110W...AND 
THEN NEWD ACROSS THE BAJA PENINSULA AND NW MEXICO. A SHORTWAVE 
TROUGH IS NOTED RIDING ALONG THE JET NEAR 135W AND IS RUNNING 
INTO THE W SIDE OF A LARGE RIDGE PROTRUDING W FROM MEXICO. THE 
RIDGE AXIS LIES FROM W/CENTRAL MEXICO SW TO 10N130W AND IS 
BOUNDED BY DRIER AIR TO ITS S AND SE. EASTERLY UPPER FLOW 
EXTENDS OVER THE FAR E PACIFIC ON THE S SIDE OF THE RIDGE AND A 
GENERAL LACK OF MOISTURE IS KEEPING THE AREA MOSTLY 
CONVECTION-FREE.

A STRONG COLD FRONT IS MOVING ACROSS THE NW GULF OF MEXICO...AND 
IS EXPECTED TO SURGE SWD E OF THE SIERRA MADRE MOUNTAINS AND 
REACH THE ISTHMUS OF TEHUANTEPEC BY 0600 UTC TONIGHT. WINDS OVER 
THE GULF OF TEHUANTEPEC WILL INCREASE SUDDENLY TO GALE FORCE BY 
1200 UTC. GALE CONDITIONS WILL LIKELY PERSIST OVER THE GULF FOR 
48 HRS...OR THROUGH MON 1200 UTC. 

$$
BERG