000
AXPZ20 KNHC 172128
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL 
2205 UTC THU OCT 17 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2030 UTC.

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

THE MONSOON TROUGH EXTENDS FROM 11N86W TO 1011 MB LOW PRES NEAR 
09.5N90W TO 09N100W TO 1011 MB LOW PRES NEAR 10N110W TO 09N125W 
TO 10N140W. SCATTERED MODERATE CONVECTION IS NOTED FROM 07N TO 
13N BETWEEN 90W AND 96W...FROM 07N TO 10N BETWEEN 122W AND 
128W...AND FROM 07N TO 10N W OF 137W.

...DISCUSSION...                                              

A LARGE ANTICYCLONE CENTERED OVER THE GULF OF MEXICO EXTENDS A 
RIDGE ACROSS SOUTHERN MEXICO INTO THE PACIFIC WATERS TO NEAR 
10N116W. A MID-LEVEL TROUGH EXTENDS SW FROM NORTHERN BAJA 
CALIFORNIA TO NEAR 20N126W. POST-TROPICAL REMNANT LOW PRISCILLA 
HAS A WELL-DEFINED LOW LEVEL CIRCULATION CENTERED NEAR 
19N124W...BUT LACKS DEEP CONVECTION MOVING OVER COOL WATER IN A 
HIGH SHEAR ENVIRONMENT ASSOCIATED WITH THE MID-LEVEL TROUGH 
MENTIONED ABOVE. EARLIER SCATTEROMETER DATA SHOWED SMALL AREA OF 
WINDS TO 25 KT IN THE NW QUADRANT OF THE REMNANT LOW. THE SYSTEM 
APPEARS TO BE RAPIDLY WEAKENING. MAX WINDS ARE 20 KT PER THE 
1742 UTC ASCAT PASS WITH SEAS TO 7 FT. 

RELATIVELY BENIGN MARINE CONDITIONS CHARACTERIZE THE FORECAST 
AREA WITH WIDESPREAD GENTLE TO MODERATE WINDS AND 4-6 FT SEAS. A 
RIDGE DOMINATES MOST OF THE N WATERS AND BAJA CALIFORNIA. WEAK 
LOW PRES AREA EMBEDDED IN THE MONSOON TROUGH IS CENTERED NEAR 
10N110W. ASSOCIATED CONVECTION IS LIMITED. THE MOST RECENT OSCAT 
PASS SHOWED THE CYCLONIC CIRCULATION ASSOCIATED WITH THIS LOW 
AND WINDS OF 10-15 KT WITH A FEW 20 KT WIND BARBS TO THE NE OF 
THE CENTER. THE LOW IS EXPECTED TO MOVE W WITH LITTLE CHANGE IN 
INTENSITY THROUGH SAT. 

AN AREA OF LOW PRES ASSOCIATED WITH REMNANTS OF A TROPICAL WAVE 
THAT MOVED THROUGH CENTRAL AMERICA THE PAST DAY OR SO IS 
CENTERED NEAR 9.5N90W. SCATTERED MODERATE CONVECTION IS NOTED 
WITHIN 120 NM W SEMICIRCLE OF CENTER. UPPER-LEVEL WINDS ARE 
EXPECTED TO BECOME CONDUCIVE FOR SOME SLOW DEVELOPMENT BY EARLY 
NEXT WEEK. MONSOONAL SOUTHERLY FLOW IS FORECAST TO INCREASE TO 
MODERATE TO FRESH AS IT MOVES SLOWLY WESTWARD WHICH WILL BUILD 
SEAS TO 6-7 FT.

MOST SIGNIFICANT LONG-TERM MARINE IMPACT WILL BE ARRIVAL OF LONG 
PERIOD NW SWELL INTO NW PORTION SUN AND MON. WAVE MODEL GUIDANCE 
SHOWS LEADING EDGE OF SWELL TRAIN WITH 22-23 SEC PERIOD...WHICH 
WILL PRODUCE UNUSUALLY LARGE SURF HEIGHTS AS IT REACHES SHALLOW 
WATER ALONG THE PACIFIC COAST NEXT WEEK.
 
$$ 
GR