000
AXPZ20 KNHC 160907
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI OCT 16 2009

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0845 UTC.

...SPECIAL FEATURE... 

TROPICAL STORM RICK IS CENTERED NEAR 12.5N 98.7W AT 0900 UTC OR 
ABOUT 275 NM...505 KM...SOUTH-SOUTHEAST OF ACAPULCO MEXICO 
MOVING W-NW AT 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 
MB. MAXIMUM SUSTAINED WINDS ARE 55 KT WITH GUSTS TO 65 KT. SEE 
THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS. GOOD UPPER OUTFLOW IS 
OBSERVED. CONVECTION HAS INCREASED AND IS WELL ORGANIZED BY THE 
LOW LEVEL CIRCULATION. NUMEROUS MODERATE TO STRONG CONVECTION IS 
WITHIN 120 NM NE SEMICIRCLE AND WITHIN 170 NM SW SEMICIRCLE.
RICK IS FORECAST TO INTENSIFY TO A HURRICANE BY MIDDAY TODAY AND 
CONTINUE ON A W-NW TRACK FOR THE NEXT FEW DAYS. 

...TROPICAL WAVES...

NONE.

...ITCZ...

THE AXIS OF THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE 
...07N77W TO 09N110W TO 08N140W. SCATTERED MODERATE TO STRONG 
CONVECTION IS WITHIN 75 NM OF THE POINT 10N93W. SCATTERED 
MODERATE CONVECTION IS WITHIN 60 NM OF THE POINTS 08N104W AND 
09N110.5W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 120 
NM OF THE POINT 07N131W.

TROUGH WITHIN THE ITCZ ALONG 109W FROM 06N TO 13N MOVE WEST 12 
KT. ASSOCIATED CONVECTION IS WITHIN THE ITCZ.

LOW 12N134W 1010 MB MOVE WEST 10 KT. THERE IS CONVECTION WEST OF 
THE LOW WITH SCATTERED MODERATE TO STRONG CONVECTION WITHIN 45 
NM EITHER SIDE OF A LINE FROM NEAR 12N137W TO 15N138W. THE 
CONVECTION IS NOT ORGANIZED BY THE LOW LEVEL CIRCULATION.

...DISCUSSION...

THE DEEP LAYER RIDGE WILL HOLD OVER N WATERS THROUGH THE NEXT 
SEVERAL DAYS. TROUGH CURRENTLY APPROACHING NW WATERS N OF 25N 
WILL BROADEN AND SLOWLY LIFT NE THE NEXT FEW DAYS. THE NW SWELL 
ASSOCIATED WITH A SURFACE LOW ASSOCIATED WITH THIS TROUGH IS 
CURRENTLY BRINGING SIGNIFICANT WAVE HEIGHTS TO 11 FT IN N WATERS 
WILL SUBSIDE AS IT MOVES SOUTH. THE WEAKENING COLD FRONT AT THE 
SURFACE WILL ENTER NW WATERS FRI NIGHT AND DISSIPATE SAT. HIGH 
PRES BEHIND THE FRONT WILL APPROACH NW WATERS SAT NIGHT. AS A 
RESULT...THE MEAN SURFACE RIDGE WILL SHIFT W OVER THE NEXT FEW 
DAYS. A 1010 MB SURFACE LOW NEAR 12N134W LIES SW OF THE RIDGE 
AND WILL ALSO TRACK W AT 10-15 KT REACHING 140W SAT. THE PRES 
GRADIENT BETWEEN THE RIDGE AND THIS LOW WILL KEEP WINDS IN ITS 
NE QUADRANT IN THE 20 TO 25 KT RANGE. ON THE EASTERN EDGE OF THE 
RIDGE N WINDS IN THE 20 TO 25 KT RANGE ALONG THE W COAST OF THE 
BAJA PENINSULA WHERE THE PRES GRADIENT IS TIGHT BETWEEN LOW PRES 
OVER THE GULF OF CALIFORNIA TO THE E AND THE 1009 MB REMNANTS OF 
PATRICIA NEAR 22N115W. THESE WINDS SHOULD DIMINISH AND SHIFT NW 
BY SAT.

AN DEEP LAYER MID LATITUDE TROUGH WILL AMPLIFY OVER THE GULF OF 
MEXICO SAT AND SEND A STRONG COLD FRONT THROUGH THE BAY OF 
CAMPECHE. THE NORTHERLY FLOW SHOULD FUNNEL THROUGH THE ISTHMUS 
OF TEHUANTEPEC BY SAT EVENING...WITH N TO NE WINDS REACHING 25 
KT WITHIN 75 NM S OF THE GULF OF TEHUANTEPEC BY THE END OF THE 
FORECAST PERIOD.

$$
LL