000
AXPZ20 KNHC 061551
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU OCT 06 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1445 UTC.
 
...SPECIAL FEATURES...

TROPICAL DEPRESSION TEN-E IS CENTERED NEAR 11.5N 106.6W AT 
06/1500 UTC MOVING W-NW OR 295 DEG AT 7 KT. A WEST-NORTHWEST TO 
NORTHWEST MOTION IS FORECAST DURING THE NEXT DAY OR TWO. MAXIMUM 
SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. ESTIMATED 
MINIMUM CENTRAL PRES IS 1006 MB. THE DEPRESSION IS EXPECTED TO 
BECOME A TROPICAL STORM LATER TODAY. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP5/ WTPZ25 KNHC 
FOR MORE DETAILS. SCATTERED TO NUMEROUS MODERATE TO STRONG 
CONVECTION IS WITHIN 90 NM OF CENTER.

TROPICAL DEPRESSION ELEVEN-E HAS BEEN UPGRADED TO TROPICAL STORM 
IRWIN AT 06/1500 UTC. AT THIS TIME...IT IS LOCATED NEAR 12.4N 
116.8W MOVING W-NW OR 295 DEG AT 5 KT. A TURN TOWARD THE NORTH 
AND NORTH-NORTHEAST WITH A DECREASE IN FORWARD SPEED IS EXPECTED 
BY FRIDAY. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 
45 KT. SOME SLOW STRENGTHENING IS FORECAST DURING THE NEXT 48 
HOURS. ESTIMATED MINIMUM CENTRAL PRES IS 1005 MB. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC 
FOR MORE DETAILS. NUMEROUS MODERATE TO STRONG CONVECTION IS 
WITHIN 180 NM SW QUADRANT OF IRWIN. SCATTERED MODERATE TO 
ISOLATED STRONG CONVECTION IS ALSO NOTED ELSEWHERE FROM 10N TO 
17N BETWEEN 113W AND 121W. 

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM 10N86W TO 12N102W THEN RESUMES 
WEST OF T.S. IRWIN AT 12N120W TO 09N140W. ISOLATED MODERATE 
CONVECTION N OF 07N E OF 100W. SCATTERED MODERATE TO ISOLATED 
STRONG N OF THE TROUGH TO THE COAST OF MEXICO BETWEEN 100W AND 
102W. SIMILAR CONVECTION IS WITHIN 60 NM EITHER SIDE OF TROUGH 
AXIS BETWEEN 122W AND 130W...AND WITHIN 90 NM S OF TROUGH 
BETWEEN 131W AND 134W.

...DISCUSSION...

TWO TROPICAL CYCLONES EMBEDDED WITHIN A VERY ACTIVE MONSOON 
TROUGH HIGHLIGHT THE MARINE WEATHER CONDITIONS IN THE NORTHEAST 
PACIFIC. T.D. 10-E AND T.S. IRWIN ARE SEPARATED AROUND 600 NM  
FROM EACH OTHER AND SOME INTERACTION BETWEEN THESE TWO SYSTEMS 
IS PROBABLE. GLOBAL MODEL FORECASTS FROM GFS...ECMWF AND THE 
UKMET ARE ALL IN GOOD AGREEMENT REGARDING THE GENERAL TREND OVER 
THE NEXT 2-3 DAYS. BOTH TROPICAL CYCLONES ARE EXPECTED TO DRIFT 
WNW THEN TURN NE. IT IS MODERATELY LIKELY THE TWO WILL MOVE IN 
TANDEM AT LEAST IN THE SHORT TERM...IF THE NUMERICAL MODELS ARE 
CORRECT. WEAK VERTICAL SHEAR OVER THE MONSOON TROUGH WILL ALLOW 
BOTH A FAVORABLE ENVIRONMENT FOR FURTHER STRENGTHENING.

A COLD FRONT THAT EXTENDS FROM THE NORTHERN PORTION OF THE GULF 
OF CALIFORNIA OR SEA OF CORTEZ TO NEAR 25N127W IS EXPECTED TO 
WEAKEN THIS AFTERNOON AND DISSIPATE BY FRI MORNING. NW SWELL TO 
11 FT BEHIND THE FRONT WILL PUSH SOUTH AND EAST TO COVER MOST OF 
THE AREA N OF 19N BY SATURDAY. STRONG HIGH PRES BUILDING BEHIND 
THE FRONT WILL SUPPORT NW WINDS TO 20 KT ALONG THE COAST OF 
NORTHERN BAJA INTO THE GULF OF CALIFORNIA...AND ENHANCE NE TRADE 
WINDS N OF 20N.

GAP WINDS IN TEHUANTEPEC ARE EXPECTED TO SUBSIDE BELOW 20 KT 
THIS AFTERNOON...BUT COULD PERK UP ONE LAST TIME BY EARLY FRI. 

CROSS-EQUATORIAL SW SWELL WILL CONTINUE TO SPREAD ACROSS THE 
REGION AND EVENTUALLY MIX WITH NW SWELL THIS WEEKEND. FRESH TO 
STRONG SW WINDS WILL CONTINUE S OF THE MONSOON TROUGH DUE TO THE 
COMBINED EFFECT OF T.D. 10-E AND T.S. IRWIN. EXPECT SEAS TO 
STEADILY BUILD OVER THE NEXT FEW DAYS...UP TO 12-15 FT NEAR THE 
TROPICAL CYCLONES BY SUN.

$$
GR/DM