000
AXPZ20 KNHC 052229
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SUN OCT 05 2008

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2100 UTC.

...SPECIAL FEATURES...
TROPICAL STORM MARIE AT 18.8N 122.7W AT 05/2100 UTC OR ABOUT 875 
NM W-SW OF SRN TIP OF BAJA CALIFORNIA MOVING W OR 270 DEG AT 3 
KT.  ESTIMATED MINIMUM CENTRAL PRES 1004 MB.  MAXIMUM SUSTAINED 
WIND SPEED 40 WITH GUSTS TO 50 KT.  REFER TO LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC 
AND INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCPEP4/WTPZ34 KNHC FOR MORE DETAILS.  DEEP CONVECTION 
ASSOCIATED WITH MARIE NOW RESTRICTED TO 120 NM IN SW QUADRANT 
AND FORECAST TO CONTINUE ITS DOWNWARD TREND TILL ITS DEMISE 
POSSIBLY WITHIN THE NEXT 48 HRS.  DRY STABLE AIR MASS HAS 
WEAKENED MARIE FOR THE LAST 30 HRS. 

TROPICAL STORM NORBERT AT 14.4N 103.1W AT 05/2100 UTC OR ABOUT 
250 NM S-SW OF ZIHUATANEJO MEXICO MOVING W OR 275 DEG AT 8 KT. 
ESTIMATED MINIMUM CENTRAL PRES 997 MB.  MAXIMUM SUSTAINED WIND 
SPEED 50 WITH GUSTS TO 60 KT.  REFER TO LATEST NHC FORECAST/ 
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP5/WTPZ25 KNHC AND 
INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPEP5/ 
WTPZ35 KNHC FOR MORE DETAILS.  SE WIND SHEAR OVER NORBERT HAS 
BECOME VERY LIGHT ALLOWING SYSTEM TO ORGANIZE LOW LEVEL DEEP 
CONVECTION.  CLOUDS ARE CLOSE TO CENTER AND OUTFLOW HAS TAKEN 
WELL ROUNDED SHAPE INDICATING STRENGTHENING.  NORBERT EXPECTED 
TO REACH HURRICANE FORCE WITHIN NEXT 24 HR WHILE CONTINUING ITS 
W-NW PATH.  GUIDANCE DIFFER WIDELY ON TRACK AFTER 72 HRS AND IT 
COULD TURN INTO A MORE NW HEADING THEN. 

LOW PRES 1008 MB AT 11N90W MOVE W AT 10 KT.  LATEST SATELLITE 
IMAGERY SHOW AN EXPOSE CIRCULATION E OF DEEP CONVECTION AND IT 
IS DIFFICULT TO WEIGHT IF THERE IS ANY EFFECT FROM ITS NEARNESS 
TO T.S. NORBERT OR A RESULT OF CONTINUED EASTERLY WIND SHEAR 
ALOFT.  ENVIRONMENT MAY HAVE MORE UNFAVORABLE DUE TO THESE 
FACTORS AND MODELS DIFFER IN THEIR SOLUTION.  THERE IS LITTLE 
CONFIDENCE PLACED IN FORECASTING INTENSITY AND TRACK.

...ITCZ...
ITCZ AXIS ALONG 11N86W TO 11N100W TO 07N110W TO 13N125W TO 
10N140W.  SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN  
90 NM N OF AXIS FROM 135W-138W.

...DISCUSSION...
COMPLEX ATLC MID-UPPER LEVEL RIDGE WITH ANTICYCLONE OVER ERN 
YUCATAN PENINSULA AND ANOTHER IN E PAC AT 15N122W SADDLED BY 
WEAK UPPER LEVEL TROUGH ALONG 107W N OF 16N.  ANTICYCLONE OVER 
YUCATAN RESPONSIBLE FOR WIND SHEAR FLOW ABOVE LOW PRES SYSTEM 
MENTIONED ABOVE.  IT IS ALSO THIS COMBINATION OF FEATURES THAT 
IS CAUSING THE UPPER DIFFLUENT FLOW EXPECTED AHEAD OF NORBERT 
AND INFLUENCING ITS DEVELOPMENT.   

FURTHER W...UPPER LEVEL TROUGH FROM SRN BAJA CALIFORNIA TO BROAD 
CYCLONE AT 19N138W PROVIDE ADVERSE CONDITIONS ALOFT FOR T.S. 
MARIE AS IT DISRUPT SYSTEM'S OUTFLOW AND MAINTAINS DRY AIR MASS 
ENVIRONMENT AHEAD.  

ELSEWHERE AT THE SURFACE... 
LOW PRES 1011 MB OVER YUCATAN PENINSULA HAS FINALLY WEAKENED TO 
THE POINT OF BEING UNABLE TO FORCE WINDS ACROSS ISTHMUS OF 
TEHUANTEPEC.  LOW PRES SHOULD CONTINUE WEAKENING AND DISSIPATE 
WITHIN NEXT 12 HRS.  

LARGE LONG PERIOD NW SWELL SPREADING SE FROM HEALTHY HIGH PRES 
1024 MB JUST NW OF BASIN HAVE SUBSIDED BUT STILL REMAIN 10-11 FT.
WITHIN 24 HR SWELLS WILL MERGE WITH THOSE PRODUCED BY MARIE N OF 
15N W OF 120W.  

SIMILARLY...LONG PERIOD CROSS EQUATORIAL SWELLS HAVE LESSENED 
THEIR HEIGHTS AND ONLY REACH 7-8 FT FROM 92W TO 110W.  CONTINUED 
SUBSIDING IS EXPECTED DURING NEXT 48 HRS.

$$
WALLY BARNES