000
AXPZ20 KNHC 160320
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC FRI OCT 16 2009

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0130 UTC.

...SPECIAL FEATURE... 

NEWLY NAMED TROPICAL STORM RICK IS CENTERED NEAR 12.4N 97.7W AT 
0300 UTC OR ABOUT 345 MILES...555 KM...SOUTH-SOUTHEAST OF 
ACAPULCO MEXICO MOVING W-NW AT 8 KT. ESTIMATED MINIMUM CENTRAL 
PRESSURE IS 999 MB. MAXIMUM SUSTAINED WINDS ARE 45 KT WITH GUSTS 
TO 55 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO 
HEADERS MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS. THE TROPICAL 
DEPRESSION IS IN AN AREA OF LOW SHEAR...ABUNDANT MOISTURE...AND 
WARMER THAN NORMAL SSTS. THIS SYSTEM IS FORECAST TO INTENSIFY TO 
A HURRICANE BY MIDDAY FRI AND CONTINUE ON A W-NW TRACK FOR THE 
NEXT FEW DAYS. SCATTERED MODERATE ISOLATED STRONG WITHIN 240 NM 
NW AND 120 NM SE SEMICIRCLE OF TROPICAL STORM RICK AND WITHIN 60 
NM OF THE COAST OF THE GULF OF TEHUANTEPEC BETWEEN 92W AND 95W.  

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 112W FROM 08N TO 15N...MOVING W AT 15 
KT. WHILE THERE IS NO SIGNIFICANT CONVECTION ASSOCIATED WITH THE 
WAVE AT THIS TIME...THERE IS A POOL OF PRECIPITABLE WATER VALUES 
OVER 2.25 INCHES TRACKING W WITH THE WAVE.

...ITCZ...

THE AXIS OF THE THE INTERTROPICAL CONVERGENCE ZONE IS CENTERED 
FROM 08N80W TO 13N95W TO 10N105W TO 12N115W TO 08N131W TO 
12N140W. AN AREA OF BROAD UPPER LEVEL DIFFLUENCE S OF 10N 
BETWEEN 120W AND 135W IS SUPPORTING SCATTERED MODERATE 
CONVECTION WITHIN 90 NM N AND 150 NM S OF THE ITCZ AXIS BETWEEN 
126W AND 132W.

A TROUGH LIES FROM 12N107W TO 06N106W AND INTERSECTS THE ITCZ 
AROUND 10N. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 
150 NM EITHER SIDE OF THE TROUGH FROM 08N TO 10N.

...DISCUSSION...

THE DEEP LAYER RIDGE WILL HOLD OVER N WATERS THROUGH THE 
FORECAST PERIOD DESPITE BEING CHALLENGED BY A TROUGH CURRENTLY 
APPROACHING NW WATERS N OF 25N. THE MID TO UPPER LEVEL TROUGH 
WILL BROADEN AND SLOWLY LIFT NE THE NEXT FEW DAYS AND THE NW 
SWELL ASSOCIATED WITH THIS TROUGH...WHICH IS CURRENTLY BRINGING 
SIGNIFICANT WAVE HEIGHTS TO 13 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 12N133W 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. THE 1856 UTC ASCAT PASS CONFIRMS THESE 20 TO 
25 KT WINDS. ON THE EASTERN EDGE OF THE RIDGE...THE 1710 UTC 
ASCAT PASS SHOWS 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.

$$
SCHAUER