000
AXPZ20 KNHC 131559
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL 
1605 UTC SUN OCT 13 2013

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 
1500 UTC.

...SPECIAL FEATURES...

TROPICAL STORM OCTAVE NEAR 18.3N 112.1W AT 13/1500 UTC OR 300 NM 
S OF THE SOUTHERN TIP OF BAJA CALIFORNIA MOVING NNW OR 330 
DEGREES AT 12 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 998 MB. 
MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. SEE 
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP5/WTPZ25 KNHC FOR MORE DETAILS. CONVECTION IS DYING DOWN 
FOR THE MOMENT FROM OVERNIGHT PEAKS WITH SCATTERED MODERATE TO 
ISOLATED STRONG CONVECTION WITHIN 90 NM SW SEMICIRCLE...AND FROM 
20N TO 22N BETWEEN 110W AND 113W. FAVORABLE UPPER LEVEL WINDS 
AND WARM SSTS SHOULD ALLOW FOR CONTINUED DEVELOPMENT DURING THE 
NEXT 24 HOURS AS OCTAVE MOVES TO THE NW TO N. AFTER 
THAT...OCTAVE WILL BE MOVING OVER COOLER SSTS AND WILL ENCOUNTER 
INCREASING VERTICAL WIND SHEAR AND DRIER AIR CAUSING OCTAVE TO 
WEAKEN TO A REMNANT LOW BY TUE NIGHT WHILE MOVING MORE TO THE N-
NE THROUGH BAJA CALIFORNIA SUR AND THE SOUTHERN 
GULF OF CALIFORNIA...DISSIPATING COMPLETELY BY THU NIGHT.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...           

THE MONSOON TROUGH EXTENDS FROM 10N85W TO 12N103W TO 11N108W 
THEN RESUMES FROM LOW PRES NEAR 13N117W TO 11N130W TO 08N140W. 
NO ITCZ E OF 140W. SCATTERED MODERATE WITHIN 60 NM EITHER SIDE 
OF AXIS BETWEEN 100W AND 105W AND BETWEEN 117W AND 120W.

...DISCUSSION...

AN UPPER LEVEL TROUGH REMAINS IN PLACE FROM SOUTHERN CALIFORNIA 
THROUGH 32N120W TO 14N130W...MAKING LITTLE EASTWARD PROGRESS AS 
A BROAD AND DOMINANT UPPER LEVEL ANTICYCLONE ANCHORED OVER 
CENTRAL MEXICO. THE UPPER LEVEL TROUGH CONTINUES TO MAINTAIN A 
VERY DRY...STABLE...AND SUBSIDING AIR MASS OVER THE BASIN W OF 
ITS AXIS W OF 120W.

THE MONSOON TROUGH HAS BEEN BREAKING DOWN BETWEEN 110W AND 120W 
WITH THE DEVELOPMENT OF OCTAVE...AND THE DEVELOPMENT OF SECOND 
LOW PRES AREA NEAR 13N117W. CONVECTION IS A LITTLE MORE ACTIVE 
NEAR THIS LOW THAN NEAR OCTAVE AT THE MOMENT LARGELY DUE TO 
SUPPORT FROM FRESH TO STRONG SW FLOW INTO THE SYSTEM. HOWEVER 
DUE THE PROXIMITY OF THE LOW TO OCTAVE...LITTLE SIGNIFICANT 
DEVELOPMENT IS EXPECT OVER THE NEXT 48 HOURS AS THE LOW DRIFTS 
NE IN THE WAKE OF OCTAVE. ASIDE FROM PERIODIC FLARE UPS OF 
CONVECTION...THE MAIN IMPACT OVER THE NEXT 24 TO 36 HOURS WILL 
REMAIN BROAD 20 TO 25 KT SURGES OF SW FLOW WITHIN 270 NM ON THE 
SE SIDE OF THE LOW CONVERGING TO THE NORTH INTO OCTAVE...WITH 
SEAS BUILDING 8 TO 10 FT. 

FARTHER WEST...THE WEAK REMNANT LOW OF NARDA PERSISTS NEAR 
12N135W. WINDS AREA LIKELY 20 KT OR LESS ON THE NORTHERN SIDE OF 
THE LOW...BUT RESIDUAL MIXED N AND NE SWELL WITHIN 180 NM ON THE 
NW SEMICIRCLE OF THE LOW PERSISTS. THE LOW PRES WILL CONTINUE TO 
WEAKEN OVER THE NEXT 24 HOURS...EVENTUALLY OPENING INTO A WEAK 
TROUGH...AS IT DRIFTS SW WITH SEAS SUBSIDING BELOW 8 FT.

MODERATE TO FRESH NW TO N FLOW ALONG THE PACIFIC COAST OF BAJA 
CALIFORNIA NORTE WILL PERSIST THROUGH TONIGHT BETWEEN HIGH PRES 
WELL NW OF THE AREA AND TROUGHING OVER NW MEXICO/SW UNITED 
STATES. 
 
GULF OF TEHUANTEPEC...THE REMNANTS OF A TROPICAL WAVE OVER 
WESTERN CENTRAL AMERICA ALONG WITH WEAK HIGH PRES OVER CENTRAL 
MEXICO ARE FORECAST TO HELP USHER IN FRESH TO STRONG NORTHERLY 
WINDS AND RESULTANT SEAS TO 8 FT IN THE GULF OF TEHUANTEPEC 
TONIGHT. THESE CONDITIONS WILL PERSIST THROUGH MON...DIMINISHING 
BY MON NIGHT.
 
$$
CHRISTENSEN