000
AXPZ20 KNHC 010921
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI DEC 01 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0845 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 3N78W 8N90W 5N108W 7N121W 8N134W 
7N140W. ISOLATED MODERATE CONVECTION NEAR 3N79W 5N86W 7N89W 
7N94W AND 6N101W. ISOLATED MODERATE TO STRONG CONVECTION NEAR 
7N124W AND 8N135W.  

ISOLATED MODERATE CONVECTION NEAR 14N116W AND 13N118W. 
 
...DISCUSSION...

A BLOCKING MID LEVEL RIDGE CENTERED NEAR 34N130W FORCING A 
STRONG CLOSED LOW NW OF THE AREA TO MOVE NNE. A FAIRLY STRONG 
SRN BRANCH OF THE WESTERLIES CROSSES THE HAWAIIAN CHAIN CURVES 
ANTICYCLONICALLY OVER A MID LEVEL RIDGE ALONG 135W THEN CURVES 
CYCLONICALLY UNDER A BROAD SHORTWAVE TROUGH ALONG 115W BEFORE 
HEADING ENE ACROSS CENTRAL MEXICO. ON THE SURFACE TONIGHT A 
FAIRLY STRONG PACIFIC RIDGE CENTERED UNDER THE MID LEVEL CENTER 
COVERS THE AREA N OF 10N AND W OF 105W. A POLAR AIRMASS DIVING S 
OVER ERN MEXICO IS ALSO TIGHTENING THE PRESSURE GRADIENT OVER 
THE SEA OF CORTEZ WITH NW WINDS 15 TO 25 KT. THE PRESSURE 
GRADIENT IS TIGHTENING OVER THE BAY OF CAMPECHE AS THE COLD AIR 
STREAMS SWD AND WINDS THROUGH TEHUANTEPEC ARE FORECAST TO 
INCREASE SIGNIFICANTLY IN ABOUT SIX HOURS TO GALE AND EVENTUALLY 
STORM FORCE LATER DAY 1. 

LATER DAY 1 WHILE THE MID LEVEL BLOCKING RIDGE HOLDS NEAR 
32N132W THE SHORTWAVE THAT HAS BEEN CAUGHT UNDER THE RIDGE THE 
PAST TWO DAY FINALLY BEGINS TO MOVE ENE WITH THE SRN BRANCH OF 
THE WESTERLIES. A FLAT MID LEVEL RIDGE WILL COVER THE AREA S OF 
20N E OF 140W ACROSS SRN MEXICO. ON THE SURFACE LATER DAY 1 LOOK 
FOR GALES INCREASING TO STORM FORCE THROUGH TEHUANTEPEC AS HIGH 
PRESSURE BUILDS OVER THE SRN GULF OF MEXICO. SEAS WILL ALSO 
INCREASE SIGNIFICANTLY TO 15 FT. OTHERWISE THE PACIFIC RIDGE 
WILL MAINTAIN GUSTY NE TRADES TO 25 KT FROM 10N TO 23N W OF 
120W. WINDS ALONG THE BAJA COAST AND OVER THE SEA OF CORTEZ WILL 
DECREASE SOME TO MOSTLY 15 TO 20 KT. 

FOR DAY 2 THE MID LEVEL BLOCKING RIDGE OPENS UP AND TILTS NE/SW 
ALONG 130W AS SHORTWAVE TROUGHS MOVE THROUGH THE RIDGE AND 
WEAKEN IT. MID LEVEL TROUGHING CONTINUES NEAR 120W AS NEW 
SHORTWAVE TROUGHS REPLACE THE OLD ONE THAT HAS MOVED ENE. ON THE 
SURFACE DAY 2 GALE CONDITIONS WILL CONTINUE THROUGH TEHUANTEPEC 
WITH SEAS TO 14 FT. WINDS ALONG THE BAJA COAST AND SEA OF CORTEZ 
DIMINISH TO 10 TO 15 KT. THE PACIFIC RIDGE WEAKENS SOME AND NE 
TRADES SHOULD BE MOSTLY 20 KT BETWEEN 10N AND 22N W OF 120W. 
WINDS W OF EL SALVADOR AND NICARAGUA INCREASE TO 20 KT AND GUSTY 
AS HIGH PRESSURE TIGHTENS THE GRADIENT OVER THE NW CARIBBEAN.

$$
RRG