000
AXPZ20 KNHC 020918
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC TUE AUG 02 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 
0730 UTC.

...SPECIAL FEATURES...
HURRICANE EUGENE AT 13.8N 108.3W AT 02/0900Z MOVING W-NW OR 290 
DEGREES AT 13 KT WITH CENTRAL PRES 978 MB. MAXIMUM SUSTAINED 
WIND 80 GUSTS TO 100 KT. NUMEROUS STRONG CONVECTION LIES WITHIN 
90 NM E AND 210 NM W OF THE CENTER OF EUGENE. THE CURRENT 
FORECAST CALLS FOR EUGENE TO GENERALLY MAINTAIN ITS CURRENT 
MOTION AND INTENSIFY SLIGHTLY OVER THE NEXT 24 HOURS BEFORE 
ENCOUNTERING COOLER WATER AND BEGINNING A GRADUAL WEAKENING 
TREND. SEE LATEST NHC PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS 
TCPEP5/WTPZ35 KNHC AND FULL FORECAST/ADVISORY UNDER AWIPS/WMO 
HEADERS TCMEP5/WTPZ25 FOR MORE DETAILS.

...ITCZ/MONSOON TROUGH...
MONSOON TROUGH AXIS EXTENDS FROM 09N84W TO 1008 MB LOW PRES NEAR 
14N94W THEN CONTINUES FROM 13N114W TO 1009 MB LOW PRES NEAR 
10N121W TO 10N126W. ITCZ AXIS EXTENDS FROM 10N126W TO 08N140W. 
SCATTERED MODERATE CONVECTION IS WITHIN 150 NM N AND 120 NM SE 
QUADRANTS OF LOW PRES NEAR 10N121W.

...DISCUSSION...
THE DEEP LAYERED NORTHERN STREAM TROUGH THAT SAT ALONG 130W AND 
WEAKENED THE SUBTROPICAL RIDGE THE LAST FEW DAYS HAS WEAKENED 
AND IS MOVING N OF THE AREA. AT THE SURFACE...THE SUBTROPICAL 
HIGH HAS BUILT ENOUGH RIDGING OVER WESTERN WATERS TO INCREASE 
THE PRES GRADIENT BETWEEN IT AND THE ITCZ AND ALLOW FOR FRESH NE 
TRADE WINDS TO RETURN. THE 0254 UTC WINDSAT PASS SHOWS 20 KT 
WINDS FROM 12N TO 20N W OF 136W. THESE TRADES WILL BUILD 
SLIGHTLY FARTHER NE OVER THE NEXT DAY OR SO. 

AN ANTICYCLONE ALOFT LIES NEAR 22N127W AND EXTENDS A RIDGE 
THROUGH NORTHERN BAJA CALIFORNIA TO ANOTHER ANTICYCLONE OVER 
WESTERN NEW MEXICO. A SECOND RIDGE AXIS PARALLELS THIS ONE TO 
ITS SE. IT LIES FROM 15N117W THROUGH MAZATLAN MEXICO INTO NE 
TEXAS. HURRICANE EUGENE IS S OF THIS RIDGE AXIS AND LIES UNDER 
ABOUT 20-25 KT OF E-NE SHEAR. WHILE THERE IS AMPLE DEEP 
CONVECTION NEAR THE CENTER...THE BULK OF THE CONVECTION IS 
DISPLACED INTO THE WESTERN SEMICIRCLE AS A RESULT OF THIS SHEAR. 
CLOSER TO THE RIDGE AXIS...SCATTERED MODERATE TO STRONG 
CONVECTION LIES WITHIN 90 NM OF THE MEXICAN COAST FROM 20N TO 
23N. THESE RIDGE AXES ALOFT WILL GRADUALLY MERGE AT A NEW 
ANTICYLONE EXPECTED TO DEVELOP OVER NW MEXICO OVERNIGHT TONIGHT. 

THE 0504 UTC ASCAT PASS CAPTURED THE SHRINKING AREA OF FRESH TO 
STRONG SW WINDS FEEDING INTO EUGENE FROM N OF 06N. THE JASON2 
PASS FROM 0410 UTC SHOWS SEAS ABOVE 12 FT EXTEND AT LEAST 180 NM 
IN THE NE QUADRANT AND 90 NM IN THE SW QUADRANT WITH SEAS AS 
HIGH AS 18 FT OBSERVED. THE FORECAST MODELS SUGGEST THE AREA OF 
12 FT SEAS IN THE SE QUADRANT STILL EXTENDS AT LEAST 240 NM FROM 
THE CENTER OF EUGENE WITH SW SWELL STILL ENHANCING THE SEAS. A 
NEW BATCH OF SW SWELL IS CURRENTLY CROSSING THE EQUATOR. THIS 
SWELL IS EXPECTED TO REACH EUGENE LATER TODAY. THE 
AREA OF SW WINDS AND INCREASED SEAS S OF EUGENE WILL LIFT NW IN 
TANDEM WITH THE SYSTEM OVER THE NEXT FEW DAYS. 

SCATTERED MODERATE TO STRONG CONVECTION LIES N OF 11N TO THE 
MEXICAN COAST BETWEEN 92W AND 102W. A 1008 MB SURFACE LOW LIES 
WITHIN THIS REGION. THIS LOW AND THE MONSOON TROUGH ARE HELPING 
TO CONVERGE LOW LEVEL MOISTURE OVER THE REGION AND THE WEAK 
DIFFLUENCE ALOFT BETWEEN THE 20 KT NE WINDS JUST W OF 94W AND 
THE WEAK WESTERLY WINDS ALOFT JUST E OF 94W IS HELPING TO 
ENHANCE THE DEEP CONVECTION HERE. THIS LOW IS FORECAST TO 
PERSIST FOR THE NEXT FEW DAYS...BUT IS NOT EXPECTED TO INTENSIFY 
APPRECIABLY. 

$$
SCHAUER