000
AXPZ20 KNHC 092143
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC SAT OCT 09 2010

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2115 UTC.

...THE ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ANALYZED FROM 09N84W TO 
07N90W TO  08N121W TO 10N125W TO 09N140W. SCATTERED MODERATE TO 
STRONG CONVECTION NOTED WITHIN 90 NM OF AXIS BETWEEN 122W AND 
137W.

...DISCUSSION...

UPPER LEVEL FLOW ACROSS THE REGION N OF 20N HAS BECOME MORE 
POSITIVELY TILTED DURING THE PAST 24 HOURS AS A LONGWAVE UPPER 
TROUGH HAS SHIFTED E INTO THE NE PACIFIC. AN UPPER LEVEL TROUGH 
EXTENDS FROM AN UPPER CYCLONE OVER THE GREAT PLAINS THROUGH 
32N116W AND CONTINUES SW TO A MIDDLE LEVEL LOW NEAR 21N143W. 
THIS MID LEVEL LOW WAS MOVING SLOWLY SW AND STRETCHING THE 
ADJOINING TROUGH INTO A NARROW TUTT LIKE FEATURE. 
ACCORDINGLY...CONVERGENCE OCCURRING WITHIN THIS NARROW TROUGH IS 
LEADING TO DEEP LAYERED SUBSIDENCE WITHIN 200 NM NW OF THE 
TROUGH AXIS. W TO SW UPPER LEVEL FLOW IS OCCURRING S AND SE OF 
THIS TROUGH TO 115W...AND IS AIDING IN CREATING A FAVORABLE 
UPPER ENVIRONMENT FOR DEEP CONVECTION ALONG THE ITCZ W OF 125W. 
SCATTERED DEEP CONVECTION IS OCCURRING THERE DUE TO GOOD LOW 
LEVEL FORCING ASSOCIATED WITH THE 1012 MB LOW NEAR 10N129W...AND 
WITH IMPARTING DIVERGENCE IN THE UPPER LEVEL WLY WIND FLOW. AN 
UPPER ANTICYCLONE IS CENTERED AT 34N1296W...AND SHIFTING 
NE...WITH A RIDGE EXTENDING NE TO ALONG THE OREGON AND 
WASHINGTON COASTS...AND RIDGING SW TO JUST N OF THE HAWAIIAN 
ISLANDS. THIS RIDGE SEPARATES THE AFOREMENTIONED TROUGH AND THE 
LONGWAVE TROUGH MOVING INTO THE NE PACIFIC. TO THE E...AN UPPER 
RIDGE EXTENDS W ACROSS THE SOUTHERN CARIBBEAN AND CENTRAL 
AMERICA ALONG 13N THEN TURNS W-NW TO 18N115W. VERY MODEST 
CONVECTION IS OCCURRING ALONG THE ITCZ ACROSS THE FAR EPAC S OF 
THIS RIDGE...MAINLY BETWEEN 105W AND 115W...IN PART DUE TO MILD 
CONFLUENCE ALOFT. 

AT THE LOW LEVELS...A 1027 MB HIGH IS CENTERED NEAR 31N131W WITH 
A RIDGE SW TO BEYOND 25N150W...AND A RIDGE SE TO NEAR 17N109W. 
THE LOW LEVEL PRES GRADIENT BETWEEN THIS HIGH AND THE ITCZ IS 
SUPPORTING NE TO E TRADES AT 15-25 KT WITH SEAS T8 TO 11 FT IN 
MIXED SWELL. THE RIDGE WILL SLIP A LITTLE FURTHER S AND COLLAPSE 
LATE SUN...ALLOWING A COLD FRONT TO ENTER THE AREA AND SWEEP 
RAPIDLY E ACROSS WATERS N OF 27N THROUGH MON. THIS WILL INCREASE 
THE AREA OF NE WINDS TO ALL WATERS N OF 10N W OF 125W BY SUN 
NIGHT. TO THE E OF THE RIDGE...NWLY FLOW HAS INCREASED ALONG THE 
W COAST OF BAJA CALIFORNIA TO NEAR 20 KT...AS WELL AS INSIDE THE 
GULF OF CALIFORNIA. THESE WINDS WILL DIMINISH BY SUN EVENING AS 
THE HIGH COLLAPSES.

GAP WINDS...NORTHERLY WINDS AT 20 TO 25 ARE NOTED OVER AND 
DOWNSTREAM OF THE GULF OF TEHUANTEPEC. EXPECT THESE WINDS TO 
GRADUALLY DIMINISH TO 20 KT TONIGHT...THEN BRIEFLY INCREASE TO 
20 TO 25 KT SUN MORNING...AND THEN DIMINISH TO 15 KT BY MON 
MORNING. MODERATE NE TRADEWINDS WILL CONTINUE BLOWING OFFSHORE 
OF THE PACIFIC COASTS E OF 90W THROUGH SUN MORNING BEFORE 
WEAKENING IN RESPONSE TO THE LOW PRESSURE SYSTEM ATTEMPTING TO 
BETTER ORGANIZE IN THE SW CARIBBEAN. THIS LOW IS LIKELY TO BRING 
INCREASING RAINS TO PORTIONS OF NICARAGUA AND HONDURAS IN THE 
NEXT FEW DAYS.
  
$$
STRIPLING