000
AXPZ20 KNHC 070937
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI OCT 07 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 
0815 UTC.
 
...SPECIAL FEATURES...

HURRICANE IRWIN NEAR 13.7N 119.8W MOVING W NW OR 300 DEG AT 9 
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 MB. IRWIN IS 
EXPECTED TO MOVE LITTLE OVER THE NEXT 48 HOURS. AFTERWARD...IT 
IS EXPECTED TO PASS IN THE GENERAL DIRECTION OF W CENTRAL MEXICO 
THROUGH 120 HOURS. MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH 
GUSTS TO 85 KT. ADDITIONAL STRENGTHENING IS FORECAST THROUGH 
EARLY SAT AND THEN THE SYSTEM IS FORECAST TO GRADUALLY WEAKEN 
BUT REMAIN HURRICANE STRENGTH THROUGH EARLY WED. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC 
FOR MORE DETAILS. SCATTERED MODERATE TO STRONG CONVECTION WAS 
WITHIN 150 NM OF CENTER.

TROPICAL STORM JOVA NEAR 13.4N 109.5W MOVING W NW OR 300 DEG AT 
10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB. THIS 
GENERAL MOTION WITH A GRADUAL DECREASE IN FORWARD SPEED IS 
EXPECTED INTO EARLY SAT WITH A TURN TOWARD THE NE EXPECTED 
AFTERWARD WITH JOVA EXPECTED TO MOVE INTO W CENTRAL MEXICO BY 
EARLY TUE. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 
55 KT. ADDITIONAL STRENGTHENING IS FORECAST UNTIL POSSIBLE 
LANDFALL WITH JOVA FORECAST TO REACH HURRICANE STRENGTH BY SAT 
AFTERNOON. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO 
HEADERS MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS. NUMEROUS STRONG 
150 NM EXCEPT 30 NM NE QUADRANT. SCATTERED MODERATE WITH 
ISOLATED STRONG CONVECTION WAS WITHIN 330 NM EXCEPT 150 NM NE 
QUADRANT.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS WAS ANALYZED FROM 10N85W TO 1008 MB LOW 
PRES NEAR 11N93W TO 14N103W AND RESUMES FROM 12N123W TO 07N135W 
TO 08N140W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION 
WAS FOUND WITHIN 90 NM NW QUADRANT OF LOW PRES NEAR 11N93W. 
SCATTERED MODERATE CONVECTION WAS WITHIN 150 NM N AND 90 NM S OF 
AXIS BETWEEN 127W AND 131W.

...DISCUSSION...

A DISSIPATING COLD FRONT IS OVER FAR NORTHWESTERN MEXICO 
REACHING ACROSS THE GULF OF CALIFORNIA ALONG 28N. FRESH NW TO N 
WINDS ARE FORECAST TO SPREAD SOUTHWARD BEHIND THIS WEAKENING 
FRONT IN THE GULF OF CALIFORNIA FOR THE NEXT FEW DAYS. THE PRES 
GRADIENT BETWEEN THIS FRONT AND THE 1029 MB SUBTROPICAL HIGH 
PRES SYSTEM NEAR 39N142W IS MAINTAINING FRESH NW TO N WINDS JUST 
OFF THE W COAST OF THE BAJA AS WELL. THESE WINDS ARE FORECAST TO 
DIMINISH LATER TODAY AS THE FRONT WEAKENS. NW SWELL ASSOCIATED 
WITH THIS FRONT IS CONTINUING TO PROPAGATE INTO NORTHERN 
FORECAST WATERS WITH SEAS AS HIGH AS 12 FT IN MERGING SW AND NW 
SWELL. THE AREA OF 8 FT OR GREATER SEAS WILL CONTINUE TO 
PROPAGATE TO THE S.

THE 0546 UTC ASCAT PASS SHOWED AN AREA OF FRESH NE TRADE WINDS 
LIES OVER N WATERS W OF 130W AND N OF 22N. THESE TRADES WILL 
SHIFT S AS THE SUBTROPICAL HIGH IS FORCED SOUTHWARD BY A COLD 
FRONT PASSING TO ITS N.

A SMALL AREA OF 20 KT GAP WINDS ARE PERSISTING IN THE GULF OF 
TEHUANTEPEC ACCORDING TO THE 0400 UTC ASCAT PASS. THESE WINDS 
SHOULD BE CONSISTENTLY BELOW 20 KT BY MIDDAY TODAY...THEN MAY 
PULSE TO 20 KT DURING THE LATE NIGHT AND EARLY MORNING HOURS 
WITH DRAINAGE FLOW OFF OF MEXICO.

AN AREA OF LOW PRES HAS DEVELOPED IN THE MONSOON TROUGH NEAR 
11N93W 1008 MB MOVING NW AROUND 10 KT. ASSOCIATED CONVECTION IS 
AS DESCRIBED IN THE ITCZ/MONSOON TROUGH SECTION ABOVE. WHILE THE 
0358 UTC ASCAT PASS SHOWED WINDS WERE UNDER 20 KT WITH THIS 
LOW...CROSS-EQUATORIAL SW SWELL IS KEEPING SEAS AT 8 FT IN THE 
REGION PRIMARILY SW OF THE LOW. WINDS ARE EXPECTED TO GRADUALLY 
INCREASE NEAR THIS LOW OVER THE NEXT FEW DAYS. THIS LOW 
CURRENTLY HAS A LOW CHANCE OF TROPICAL CYCLONE DEVELOPMENT 
DURING THE NEXT 48 HOURS.

THE CROSS-EQUATORIAL SW SWELL MENTIONED ABOVE WITH PEAK WAVE 
PERIODS OF 16-18 SECONDS CONTINUES TO PROPAGATE TO THE N AND 
NE...SPANNING THE COASTLINES OF MEXICO AND CENTRAL AMERICA. THIS 
SWELL WILL MERGE WITH THE NW SWELL CURRENTLY MOVING INTO N 
WATERS AS WELL AS WITH FRESHLY GENERATED SEAS AROUND IRWIN AND 
JOVA. THIS WILL RESULT IN A CONFUSED SEA STATE ACROSS THE 
CENTRAL PORTION OF THE AREA OVER THE WEEKEND.

$$
SCHAUER SCHAUER