000
AXPZ20 KNHC 200345
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED NOV 20 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0230 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...           
MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 08N75W TO 10N88W TO 
LOW PRES 1007 MB NEAR 07.5N95.5W TO 07N112W...WHERE IT 
TRANSITIONS TO ITCZ...CONTINUING ON TO 07N117W TO 05.5N128W TO 
09N140W. SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 
180 NM S OF TROUGH BETWEEN 80W AND 86W. ISOLATED TO WIDELY 
SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 180 
NM S OF TROUGH BETWEEN 88W AND 97W. SCATTERED MODERATE ISOLATED 
STRONG CONVECTION ALSO NOTED WITHIN 90 NM N OF ITCZ BETWEEN 120W 
AND 127W.

...DISCUSSION...                                                
RELATIVELY TRANQUIL WEATHER CONDITIONS PERSIST ACROSS THE 
DISCUSSION AREA TONIGHT. THE UPPER LEVEL FLOW IS GENERALLY ZONAL 
AND PROGRESSIVE N OF 30N. AN UPPER LEVEL TROUGH EXTENDS FROM THE 
CENTRAL PLAINS OF THE U.S. SW THROUGH NW MEXICO...ACROSS THE SRN 
TIP OF BAJA CALIFORNIA TO A SMALL MIDDLE LEVEL CYCLONE EMBEDDED 
IN THE TROUGH NEAR 22.5N122.5W TO A DEEP LAYERED CYCLONE 
CENTERED NEAR 16N136W...WITH TROUGH CONTINUING SW TO 11.5N147W. 
CYCLONIC TURNING ABOUT THE DEEP LAYERED CYCLONE IS PRODUCING 
SYNOPTIC SCALE LIFT THAT HAS BEEN PRODUCING WIDELY SCATTERED 
MODERATE CONVECTION WITHIN SEVERAL DEGREES OF THE CYCLONE DURING 
THE DAY...BUT HAS SINCE DIMINISHED TO ISOLATED MODERATE 
CONVECTION WITHIN 150 NM OF THE LOW. WEAK LOW LEVEL TROUGHING AT 
THE SURFACE WAS INDICATED EARLY THIS AFTERNOON BELOW THE 
CYCLONE...WHERE THE NE TRADES WERE GENERALLY AROUND 15 KT ON 
EITHER SIDE OF THE SURFACE TROUGH.  

ELSEWHERE ALOFT...UPPER RIDGING WAS W THROUGH NW OF THE 
CYCLONE...WHILE A BROAD EQUATORIAL UPPER RIDGE WAS CENTERED NEAR 
02N123W AND EXTENDING NNE TO 20N AND E TO CENTRAL AMERICA. LIGHT 
FLOW ALOFT WAS ALLOWING CONVECTION S OF THE MONSOON TROUGH E OF 
95W TO VENTILATE AND PERSIST THERE.

ELSEWHERE AT THE SURFACE...A WEAKENING 1020 MB HIGH WAS ANALYZED 
OVER THE N PART OF THE AREA NEAR 27N130W WITH ASSOCIATED RIDGE 
EXTENDING SE TO NEAR 19N107W. DUE TO THE RELATIVE WEAK HIGH 
PRESSURE CENTER...THE PRESSURE GRADIENT BETWEEN THIS FEATURE AND 
LOWER PRESSURE IN THE VICINITY OF THE ITCZ...AS WELL AS LOW 
PRESSURE ACROSS THE W SLOPES OF THE SIERRA MADRE 
OCCIDENTALES...REMAINS WEAK. WINDS OFFSHORE OF BAJA CALIFORNIA 
AND SW MEXICO WERE GENERALLY N TO NW AT AROUND 15 KT THIS 
AFTERNOON...AND NE TO E 15 TO 20 KT IN THE TRADE WIND ZONE NEAR 
THE ITCZ.  LITTLE CHANGE IN THIS PATTERN IS EXPECTED DURING THE 
NEXT 24 HOURS. HOWEVER BEYOND THAT...THE SURFACE HIGH IS 
FORECAST TO COLLAPSE AND WILL ALLOW FRESH TO STRONG NLY FLOW 
WELL OFFSHORE OF CALIFORNIA TO SPREAD BRIEFLY INTO N PORTIONS OF 
THE AREA...BRINGING LARGE N SWELL INTO THE AREA LATE THU INTO 
FRI. 

DURING THE UPCOMING WEEKEND...FRESH NLY WINDS WILL SPILL ACROSS 
THE GULF OF TEHUANTEPEC EARLY SAT AND ARE EXPECTED TO INCREASE 
TO GALE FORCE LATE SAT NIGHT THROUGH SUN AS A STRONG COLD FRONT 
MOVES INTO THE GULF OF MEXICO.

$$
STRIPLING