000
AXPZ20 KNHC 151002
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT OCT 15 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 
0915 UTC.

...SPECIAL FEATURES...

TROPICAL STORM IRWIN CENTERED NEAR 17.2N 106.6W AT 15/0900 UTC
MOVING S AT 6 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB. 
MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. SEE 
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. SCATTERED STRONG 
CONVECTION DEVELOPED DURING THE PAST FEW HOURS WITHIN 120 NM OF 
THE CENTER OVER THE SE QUADRANT. THE ASSOCIATED CONVECTION IS 
EXPECTED TO REMAIN RATHER LIMITED DURING THE MORNING AND 
AFTERNOON AS DRY AIR ALOFT HAMPERS THE CYCLONE FROM INTENSIFYING 
THROUGH THE NEXT 24-48 HRS. IRWIN IS ALSO FORECAST TO MOVES OVER 
COOLER WATER LEFT BEHIND FROM RECENT HURRICANE JOVA...AND UNDER 
HOSTILE INCREASING NE SHEAR. THE LATEST NHC FORECAST HAS IRWIN 
WEAKENING INTO A TROPICAL DEPRESSION BY EARLY THIS AFTERNOON
...AND HOLDING THAT STATUS THROUGH THE NEXT 48 HRS.
 
...ITCZ/MONSOON TROUGH...

MONSOON TROUGH EXTENDS FROM A 1005 MB LOW OVER GUATEMALA NEAR 
15N89W TO 15N97W TO 17N103W WHERE IT ENDS. IT THEN RESUMES
SW OF TROPICAL STORM IRWIN FROM 15N111W TO 12N121W TO 14N131W
TO 11N140W. SCATTERED STRONG CONVECTION IS WITHIN 120 NM S OF
THE TROUGH E OF 94W. SCATTERED MODERATE CONVECTION EXISTS
S OF THE TROUGH WITHIN 45 NM OF A LINE FROM 8N107W TO 8N112W...
AND ALSO WITHIN 60 NM S OF THE TROUGH BETWEEN 120W-123W.

...DISCUSSION...

VERY BROAD SCALE RIDGING COVERS JUST ABOUT THE ENTIRE AREA E OF 
135W...WHILE W OF 135W A DEEP LAYER TROUGH STRETCHES FROM AN 
UPPER LEVEL LOW MOVING SE NEAR 33N139W TO JUST SW OF THE 
DISCUSSION AREA. AT THE SURFACE...A 1008 MB LOW NW OF THE AREA 
NEAR 34N139W EXTENDS A COLD FRONT THROUGH 32N135W TO SW OF THE 
AREA AT 24N140W AS IDENTIFIED ON SATELLITE IMAGERY. NW WINDS OF 
20-30 KT ARE TO THE NW OF THE FRONT WITH SEAS OF 9-14 FT. THE 
LOW IS FORECAST TO DROP SE TO NEAR 31N137W 1005 MB IN 24 HRS 
WITH THE COLD FRONT EXTENDING FROM 32N133W TO 21N40W. W-NW WINDS 
OF 20-25 KT ARE FORECAST TO THE N OF 26N W OF THE FRONT WITH 
SEAS OF 10-15 FT IN A NW SWELL. BY 48 HRS...THE LOW AND FRONT 
ARE FORECAST TO WEAKEN AS THE LOW REACHES TO 31N136W 1008 
MB...AND THE FRONT REACHES FROM 32N131W TO NEAR 20N138W. WINDS 
ARE EXPECTED TO LESSEN TO BELOW 20 KT AT THAT TIME WITH SEAS OF 
8-10 FT IN A NW-N SWELL. ELSEWHERE W OF A LINE FROM 32N135W TO 
16N140W WINDS ARE FORECAST TO BE LESS THAN 20 KT IN 48 HRS WITH 
SEAS OF 8-10 FT IN A NW-N SWELL.

AN EXTENSIVE AREA OF SW-W 20-25 KT WINDS WILL PREVAIL TO THE
S OF THE MONSOON TROUGH TO 6N...AND BETWEEN 105W-115W WITH SEAS
OF 8-11 FT WITHIN THE LARGE MONSOONAL GYRE PRESENT OVER THE 
EASTERN AND CENTRAL PORTIONS OF THE AREA. THE SEAS WITHIN THIS 
AREA ARE FORECAST TO BUILD TO WITHIN THE RANGE OF 9-13 FT IN A 
SWELL SWELL BY 24 HRS...AND CONTINUE THROUGH T48 HRS AS THE AREA 
OF SW WINDS SHIFTS TO E OF 92W. 20-25 KT WINDS WILL BECOME MORE 
OUT OF THE W AND NW FROM 7N-12N BETWEEN 92W-105W IN 48 HRS.

EMBEDDED LOWS WITHIN THE MONSOON GYRE WILL CONTINUE TO BRING 
VERY HEAVY RAINFALL OVER PORTIONS OF THE PACIFIC COASTS OF 
SOUTHEASTERN MEXICO...GUATEMALA...EL SALVADOR...SOUTHERN 
HONDURAS AND NICARAGUA RESULTING IN LIFE-THREATENING FLASH 
FLOODS AND MUD SLIDES.

THE REMAINDER OF THE REGIONAL WATERS ARE DOMINATED BY MERGING NW 
AND SW SWELL. THIS SWELL EVENT WILL GRADUALLY SUBSIDE FROM THE 
NW TO SE THROUGH THE NEXT 24-48 HOURS...WHILE THE NEW SET OF NW 
SWELL ENTERING THE AREA MOVES SE.

$$
AGUIRRE