000
AXPZ20 KNHC 120314
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC SUN OCT 12 2008

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0315 UTC.

...SPECIAL FEATURES...

HURRICANE NORBERT CENTERED NEAR 26.5N 109.5W AT 12/0300 UTC IS 
MOVING NE AT 15 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 961 
MB. MAXIMUM SUSTAINED WIND SPEED IS 75 KT WITH GUSTS TO 90 KT.  
NORBERT IS BEING STEERED BY A MIDDLE/UPPER LEVEL TROUGH OVER THE 
WESTERN UNITED STATES. NORBERT IS EXPECTED TO MAINTAIN HURRICANE 
STRENGTH AS IT MAKES LANDFALL OVER MAINLAND MEXICO OVERNIGHT. 
NORBERT IS EXPECTED TO PRODUCE RAINFALL ACCUMULATIONS OF 4 TO 6 
INCHES OVER PORTIONS OF NORTHWESTERN MEXICO...WITH POSSIBLE 
ISOLATED AMOUNTS OF 10 INCHES. THESE RAINS COULD RESULT IN 
LIFE-THREATENING FLASH FLOODS AND MUD SLIDES.  IN 
ADDITION...NORBERT COULD PRODUCE RAINFALL ACCUMULATIONS OF 1 TO 
2 INCHES OVER PORTIONS OF THE SOUTHWESTERN UNITED STATES THROUGH 
SUNDAY MORNING. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO 
HEADERS MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS.

TROPICAL STORM ODILE CENTERED NEAR 18.2N 103.8W AT 12/0300 UTC IS
MOVING WNW AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 
MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. 
ODILE REMAINS FAIRLY DISORGANIZED ALONG THE MEXICAN COAST...AND 
IS EXPECTED TO MAKE A WESTWARD TURN LATE SUN OUT AWAY FROM THE 
COAST. ODILE COULD PRODUCE RAINFALL ACCUMULATIONS OF 4 TO 8 
INCHES OVER PORTIONS OF SOUTHERN MEXICO...WITH ISOLATED AMOUNTS 
OF 12 INCHES POSSIBLE. THESE RAINS COULD RESULT IN 
LIFE-THREATENING FLASH FLOODS AND MUD SLIDES. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC 
FOR MORE DETAILS.

...TROPICAL WAVES...
A TROPICAL WAVE IS ANALYZED ALONG 89W N OF 10N INTO CENTRAL 
AMERICA AND IS MOVING W ABOUT 10 KT. THE WAVE IS WEAK AND 
MINIMAL CONVECTION AND ORGANIZATION IS ASSOCIATED WITH IT.

...ITCZ...

ITCZ AXIS ALONG 08N83W TO 11N105W TO 09N140W. SCATTERED MODERATE 
TO ISOLATED STRONG CONVECTION IS LOCATED WITHIN 90 N AND 60 NM S 
OF THE AXIS BETWEEN 83W AND 86W. 

...DISCUSSION...

W OF 110W...SCATTEROMETER AND SHIP OBSERVATIONS CONTINUE TO SHOW 
A BROAD SWATH OF 20 TO 25 KT WINDS OVER THE WATERS MAINLY N OF 
20N. THESE ARE WINDS AND ACCOMPANYING SWELL ON THE EAST SIDE OF 
A BROAD 1031 MB HIGH PRES AREA CENTERED NEAR 38N136W. AS NORBERT 
MOVES INLAND AND WEAKENS...THE PRESSURE GRADIENT WILL LOOSEN 
ALLOWING THESE WINDS TO DIMINISH FURTHER. A JASON ALTIMETER PASS 
FROM EARLIER IN THE DAY SHOWED COMBINED SEA HEIGHTS UP TO 12 
FT...ALTHOUGH THIS MAY SLIGHTLY WEST OF THE MAXIMUM HEIGHTS. 
SWELL HEIGHTS WILL DECAY AS WELL OVER THE NEXT COUPLE OF 
DAYS...ALTHOUGH THE NORTHERLY SWELL WILL MIX WITH SOUTHERLY 
SWELL S OF 15N MOVING OUT OF THE SOUTH PACIFIC. FURTHER 
SOUTH...THE REMNANTS OF MARIE ARE BARELY DISCERNIBLE NEAR 
12N122W. A QUIKSCAT PASS EARLIER IN THE DAY HINTED THAT THERE 
ARE STILL WINDS TO 20 KT ON THE NW SIDE OF THIS LOW...ALTHOUGH 
THE LOW ITSELF IS BARELY DISCERNIBLE AS A DISTINCT FEATURE AND 
WILL BECOME INDISCERNIBLE THROUGH SUNDAY AS MODERATE TO FRESH 
NORTHERLY WINDS CONTINUE TO PUSH INTO THE AREA. ALOFT...AN UPPER 
LOW IS CENTERED NEAR 19N130W. WHILE SUBSIDENCE ASSOCIATED WITH 
THIS IS MAINTAINING FAIRLY DRY CONDITIONS OVER THE THE 
AREA...DIVERGENCE ALOFT ON THE EAST SIDE OF THIS LOW IS AIDING 
LIGHT SHOWERS ALONG THE ITCZ BETWEEN 120W AND 130W. EXPECT 
CONVECTION TO INCREASE SLIGHTLY OVER THE ITCZ WEST OF 120W OVER 
THE NEXT COUPLE OF DAYS...MAINLY DUE TO INCREASED LOW LEVEL 
CONVERGENCE AS THE MODERATE TO FRESH NORTHERLY WINDS IMPACT THE 
AREA...JUST AS CROSS-EQUATORIAL WINDS PICK UP TO ABOUT 20 KT. 

E OF 110W...ASIDE FROM THE FINAL PROGRESS OF NORBERT AND ODILE 
AS MENTIONED ABOVE...THE MAIN FORECAST ISSUE CONCERNS THE 
POTENTIAL FOR INCREASED S TO SW WINDS EAST OF THE GALAPAGOS OVER 
THE NEXT COUPLE OF DAYS AS SOME GLOBAL MODELS CONTINUE TO 
INDICATE. THE WINDS WILL RESULT FROM A 1008 MB LOW OFF THE 
CARIBBEAN COAST OF COSTA RICA AND WESTERN PANAMA. THIS FEATURE 
WILL NOT ONLY ENHANCE SURFACE WIND FLOW BUT ALSO RESULT IN AN 
INCREASE IN CONVECTION ALONG THE ITCZ OVER THE NEXT COUPLE OF 
DAYS AS WELL AS THE CENTRAL AMERICAN COAST SOUTH OF NICARAGUA. 
NORTH TO NORTHEAST SHEAR ALOFT ON THE EAST SIDE OF AN UPPER 
ANTICYCLONE OVER CENTRAL MEXICO WILL LIMIT CONVECTION EAST OF 
100W...BUT EAST TO SOUTHEAST DIVERGENT FLOW ALOFT BETWEEN 100W 
AND 110W SHOULD ENHANCE CONVECTION STARTING SUNDAY. 

$$
CHRISTENSEN