000
AXPZ20 KNHC 080949
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE NOV 08 2011

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 
0945 UTC.

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

THE MONSOON TROUGH EXTENDS SW ACROSS CENTRAL COSTA RICA AT 
10N84W TO THE E PACIFIC AT 08N100W. THE ITCZ BEGINS NEAR 10N116W 
AND MEANDERS BETWEEN 08N AND 10N TO BEYOND 140W. A LOW LEVEL 
TROUGH...ORIENTATED NNE TO SSW FROM 09N115W TO 15N113W AND IS 
ACCOMPANIED BY SCATTERED MODERATE ISOLATED STRONG CONVECTION 
WITHIN 90 NM TO THE W OF ITS AXIS. SCATTERED MODERATE ISOLATED 
STRONG CONVECTION IS NOTED WITHIN 60 NM LINE EITHER SIDE OF A 
LINE FROM 06N77W TO 07N99W...AND 90 NM OF A LINE FROM 10N112W 
TO 09N124W TO 08N133W TO 10N137W.

...DISCUSSION...

A LONG WAVE TROUGH DOMINATES WESTERN N AMERICA WITH ITS MEAN 
AXIS CONTINUING SW INTO THE DISCUSSION AREA FROM 31N110W TO A 
BASE AT 17N115W. UPPER MOISTURE IS ROTATING SE THROUGH THE 
TROUGH AND WILL OVER THE THE NORTHERN BAJA CALIFORNIA PENINSULA 
AND GULF OF CALIFORNIA THIS MORNING. IMMEDIATELY TO THE S IS A 
BAND OF VERY DRY UPPER AIR...ROUGHLY WITHIN 120 NM EITHER SIDE 
OF A LINE FROM 29N140W TO 29N124W TO 25N112W WHERE IT TURNS NE 
ACROSS THE SOUTHERN BAJA CALIFORNIA PENINSULA AND THE GULF OF 
CALIFORNIA AND NW OLD MEXICO EVENTUALLY DISSECTING THE UPPER 
LEVELS OVER TEXAS.

AN UPPER LEVEL CYCLONE CONTINUES OVER THE DEEP TROPICS NEAR 
01N115W AND SEPARATES UPPER ANTICYCLONIC FLOW. TO THE W AN UPPER 
ANTICYLONE IS CENTERED NEAR 08S133W WITH A SHORT WAVE RIDGE 
EXTENDING N TO A CREST NEAR 28N133W. AN UPPER ANTICYCLONE IS 
CENTERED NEAR 17N90W WITH A RIDGE AMPLIFYING NE ACROSS THE 
EASTERN GULF OF MEXICO. UPPER DIFFLUENCE IS ENHANCING THE 
PREVIOUSLY DESCRIBED CONVECTION ALONG THE LOW LEVEL TROUGH. THE 
RESULTANT DEBRIS MOISTURE IS ADVECTED NE MERGING WITH A TROPICAL 
PLUME THAT ORIGINATES IN THE CENTRAL PACIFIC AND FANS FROM 10N 
TO 26N W OF 130W IN THE BROAD ANTICYCLONIC FLOW. THE PLUME 
NARROWS AND EVAPORATES AS IT CONTINUE E THROUGH THE BASE OF THE 
UPPER TROUGH...WITHIN 240 NM OF LINE 19N126W TO 17N113W...THEN 
CONTINUES NE ACROSS CENTRAL OLD MEXICO TO OVER THE WESTERN GULF 
OF MEXICO. DENSE DEBRIS MOISTURE FROM THE ITCZ CONVECTION 
BETWEEN 118W AND 137W IS BEGINNING TO SPREAD SE ACROSS THE 
EQUATOR NEAR 130W. DEBRIS MOISTURE FROM CONVECTION ALONG THE 
MONSOON TROUGH EVAPORATES IN THE DRY UPPER AIR THAT DOMINATES 
THE TROPICS S OF 17N E OF 106W.

AT THE LOW LEVELS A RIDGE EXTENDS FROM 34N140W TO 17N108W. NW TO 
N WINDS AT 20 TO 25 KT...SEAS 7 TO 11 FT IN NW SWELL...IS 
OBSERVED N OF 24N E OF 120W. NE TO E TRADES WINDS AT 15 TO 20 KT 
AND SEAS 9 TO 11 FT IN MIXED NE AND NW SWELL...IS OBSERVED S OF 
THE RIDGE IN THE AREA FROM 08N TO 27N W OF 112W. SOUTHERLY WINDS 
AT 15 TO 20 KT ARE NOTED TO THE S OF 08N BETWEEN 112W AND 124W 
WITH SEAS TO 8 FT IN S SWELL. MIXED N SWELL IS FOUND OVER THE 
REMAINDER OF FORECAST WATERS W OF 103W WITH SEAS 8 TO 11 FT IN N 
SWELL...BUT MIXING WITH S SWELL IN WATERS S OF 12N.

GULF OF CALIFORNIA...NORTHERLY WINDS AT 15 TO 20 KT ARE NOTED IN 
THE GULF WATERS BETWEEN 24N AND 28N. NW WINDS ARE EXPECTED TO 
INCREASE TO 20 TO 30 KT ACROSS ALL WATERS WED NIGHT INTO THU. 

GULF OF TEHUANTEPEC...N WINDS ARE PULSING AT 15 TO 20 KT BUT 
SHOULD RELAX SOME TODAY THEN INCREASE AGAIN TO 20 TO 25 KT WED 
AFTERNOON IN THE WAKE OF A GULF OF MEXICO COLD FRONT. GALE 
CONDITIONS WILL LIKELY BEGIN AROUND SUNRISE THU...INCREASING TO 
A STRONG GALE BY LATE THU. 

A COLD FRONT WILL MOVE INTO THE NW WATERS LATE WED ACCOMPANIED Y 
A 20 TO 25 KT WIND SHIFT AND NW SWELLS INCREASING SEAS 8 TO 12 
FT NW OF THE FRONT. 

$$
NELSON