000
AXPZ20 KNHC 122212
TWDEP 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE DEC 12 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 1800  UTC SURFACE ANALYSIS AND SATELLITE IMAGERY 
THROUGH 2115 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG...8N82W 7N90W 6N100W 7N115W 6N128W
5N140W. SCATTERED MODERATE/ISOLATED CONVECTION IS WITHIN 120 NM
NORTH OF THE AXIS BETWEEN 113W-118W...W OF 136.5W AND WITHIN 
120 NM SOUTH OF THE AXIS BETWEEN 79W-84W. SCATTERED MODERATE
CONVECTION IS WITHIN 30 NM EITHER SIDE OF THE AXIS BETWEEN 
93W-96W...AND ALSO BETWEEN 127W-136.5W.

...DISCUSSION...

A MID/UPPER LEVEL TROUGH STRETCHES FROM WELL NORTHEAST OF THE
REGION SOUTHWESTWARD ACROSS NORTHWEST MEXICO AND NORTHERN BAJA
CALIFORNIA RESEMBLING MORE LIKE A SHEAR AXIS THROUGH 27N120W 
TO 24N130W WELL BEYOND THE REGION AT 19N140W. TO THE NORTH OF
THE TROUGH THE FLOW IS LIGHT TO MODERATE NORTHWESTERLY...WHILE 
TO THE SOUTH OF THE TROUGH THE FLOW IS RATHER BROAD AND 
WESTERLY. A SUBTROPICAL JET STREAM BRANCH RUNS EAST-NORTHEAST
ALONG THE SOUTHERN PERIPHERY OF THE TROUGH EXTENDING 
NORTHEASTWARD ACROSS MEXICO AT 22N106W AND CONTINUING NORTHEAST 
TO ACROSS THE NORTH/CENTRAL GULF OF MEXICO. SATELLITE DERIVED 
WINDS OF 60-90 KT ARE NOTED WITHIN 240 NM SE OF THE TROUGH EAST 
OF 115W. A WEAK MID/UPPER LEVEL TROUGH EXTENDS FROM 13N116W TO
SOUTHWEST TO 9N120W. MID/UPPER LEVEL ANTICYCLONIC CIRCULATIONS 
ARE LOCATED NEAR 7N134W AND NEAR 9N107W. MID/UPPER LEVEL RIDGING 
EXTENDS ALONG 7N ON EITHER WEST OF THE WEAK TROUGH.

STRONG STRONG UPPER LEVEL SUBSIDENCE AND ASSOCIATED DRY IS NOTED 
ON SATELLITE WATER VAPOR IMAGERY WITHIN 350 NM EITHER SIDE OF 
LINE 20N140W TO 23N125W TO 24N120W AND NORTHEASTWARD TO ACROSS 
BAJA CALIFORNIA AND NORTHWEST MEXICO. A WEAK MID TO UPPER TROUGH 
FROM 10N99W TO 5N98W IS MOVING WESTWARD ABOUT 17 KT. ITS SURFACE 
REFLECTION IS ANALYZED AS A WEAK TROUGH MOVING WESTWARD ABOUT 15 
KT ALONG 95.5W FROM 3N-7.5N. SCATTERED MODERATE CONVECTION IS 
WITHIN 90 W OF THE TROUGH FROM 6N-7N PRIMARILY ASSOCIATED WITH
THE ITCZ. WEAK MID/UPPER ANTICYCLONIC FLOW IS OVER THE 
SOUTHWESTERN CARIBBEAN SEA EXTENDING WESTWARD TO 94W GENERALLY
FROM 7N-15N. ITCZ CONVECTION EAST OF 85W IS BEING ENHANCED
UNDERNEATH THIS AREA OF ANTICYCLONIC FLOW IN COMBINATION WITH
WEAK MID TO UPPER LEVEL DIFFLUENT EAST OF THE MID TO UPPER LEVEL
ALONG 10N99W 5N98W. SATELLITE WATER VAPOR IMAGERY INDICATES 
MODERATE TO STRONG SUBSIDENCE COVERING THE AREA SOUTHEAST OF A 
LINE FROM 20N105W TO 10N115W EAST TO ACROSS CENTRAL AMERICA AND 
INTO THE CARIBBEAN SEA WITH VERY LIMITED MOISTURE OUTSIDE ITCZ 
RELATED CLOUDS AND CONVECTION.

AT THE SURFACE...STRONG HIGH PRESSURE WITH A CENTER OF 1034 MB
IS ANALYZED NEAR 30N131W...WITH HIGH PRESSURE COVERING THE AREA 
NORTH OF 15N WEST OF 114W. THE RESULTANT STRONG PRESSURE 
GRADIENT CONTINUES TO MAINTAIN STRONG EASTERLY TRADE WINDS 
GENERALLY IN THE RANGE OF 20-25 KT FROM ABOUT 6N-26N WEST OF 
125W. THE MAIN PROBLEM FACING JUST ABOUT THE ENTIRE DISCUSSION 
AREA CONTINUES TO BE THE VERY LARGE NORTHWEST TO NORTH SWELLS 
THAT WILL CONTINUE TO SPREAD SOUTHEASTWARD THROUGHOUT MUCH OF 
THE WESTERN AND CENTRAL SECTIONS OF THE DISCUSSION AREA OVER THE 
NEXT FEW DAYS. SCATTERED TO BROKEN STRATOCUMULUS CLOUDS WITH 
POSSIBLE EMBEDDED ISOLATED SHOWERS MOVING QUICKLY WEST-SOUTHWEST 
IN THE STRONG EASTERLY FLOW ARE SEEN NORTH OF 9N WEST OF 124W. 
120W.

NOAA WAVEWATCH MODEL FORECASTS SEAS IN THE 11-17 FT RANGE 
SUBSIDING TO NEAR 15 FT IN 48 HOURS. SEAS WILL SLOWLY SUBSIDE 
ACROSS THE NORTHWEST PART TOWARDS THE OF THE WEEK...BUT PEAK OUT 
AT ABOUT 14 FT. NEXT COLD FRONT IS EXPECTED TO ENTER THE 
NORTHWEST CORNER THURSDAY AFTERNOON WITH WINDS SHIFTING TO NLY 
AND INCREASING TO 20-30 KT BEHIND THE FRONT.

GAP WINDS...
N-NE WINDS OF 20-25 KT ACROSS THE GULF OF TEHUANTEPEC...ARE 
EXPECTED TO REMAIN AT THIS RANGE THROUGH THE NEXT 48 HOURS.
 
NE WINDS OF UP TO 20 KT AT TIMES ACROSS THE GULF OF PAPAGAYO 
WEST TO 88W ARE EXPECTED TO DIMINISH IN ABOUT 48 HOURS.

STRONG PRESSURE GRADIENT THAT MATERIALIZED OVER NORTHERN BAJA 
CALIFORNIA AND NORTHWEST MEXICO IS PRODUCING NW WINDS IN THE
20-25 KT RANGE OVER THE SEA OF CORTEZ. THESE WINDS ARE FORECAST 
TO DIMINISH TO LESS THAN 20 KT EARLY THURSDAY.

$$
AGUIRRE