000
AXPZ20 KNHC 082156
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI OCT 08 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 
2045 UTC.

...THE ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ANALYZED FROM 10N85W TO 
06N96W TO 1012 MB LOW PRES AT 09N112W TO 1011 MB LOW PRES AT 
11N121W TO TROUGH ALONG 139W CONTINUING W BEYOND 08N140W. 
SCATTERED MODERATE WITHIN 90 NM NE QUADRANT OF LOW PRES AT 
09N112W. SCATTERED MODERATE ISOLATED STRONG FROM 10N TO 12N 
BETWEEN 118W AND 120W AND WITHIN 120 NM EITHER SIDE OF AXIS 
BETWEEN 122W AND 128W.

...DISCUSSION...

A PROGRESSIVE GENERALLY ZONAL FLOW PATTERN PREVAILS N OF 30W 
FROM BEYOND 160W TO THE W COAST OF N AMERICA...ALLOWING A SERIES 
OF UPPER TROUGHS TO SWEEP E ACROSS THE SUBTROPICAL PORTION OF 
THE DISCUSSION AREA. CURRENTLY...THE WESTERNMOST TROUGH EXTENDS 
FROM 34N126W ARCHING SW TO 21N140W AND BEYOND...AND IS 
ACCOMPANIED BY UPPER MOISTURE TO THE W OF THE TROUGH AXIS N OF 
25N. THE ASSOCIATED SURFACE COLD FRONT LAGS BEHIND WELL NW OF 
THE AREA. A SECOND UPPER TROUGH EXTENDS FROM AN UPPER CYCLONE 
MOVING INTO THE CENTRAL PLAINS OF THE U.S. SW ACROSS NEW 
MEXICO...THEN FAR NW OLD MEXICO AND NRN BAJA CALIFORNIA. A THIRD 
MIDDLE/UPPER LEVEL TROUGH EXTENDS FROM THE ERN GULF OF MEXICO SW 
THROUGH SRN MEXICO AND ACROSS THE ISTHMUS OF TEHUANTEPEC AND 
OVER THE TROPICAL E PACIFIC TO A WEAK UPPER CYCLONE NEAR 
11N103W. AN UPPER ANTICYCLONE IS CENTERED JUST NW OF THIS TROUGH 
AXIS NEAR 15N107W...WITH RIDGING W TO NEAR 15N125W AND N-NE 
ACROSS MEXICO TO SW TEXAS. W TO SW UPPER LEVEL FLOW DOMINATES 
THE AREA TO THE W AND NW OF THE UPPER RIDGE...AND SE OF THE 
FIRST UPPER TROUGH. A SHARP AND NEGATIVELY TILTED UPPER LEVEL 
TROUGH UNDERCUTS THE RIDGE...EXTENDING FROM 14N129W SE TO THE 
GALAPAGOS ISLANDS. THIS TROUGH CROSSED THE ITCZ BETWEEN 116W AND 
130W AND WAS AIDING IN VENTILATING MODEST ITCZ CONVECTION THERE. 
UPPER LEVEL RIDGING ACROSS THE FAR W CARIBBEAN EXTENDED SW INTO 
THE TROPICAL EPAC E OF 100W...BUT WAS SOMEWHAT CONFLUENT 
YIELDING MODERATELY STABLE CONDITIONS ALOFT.  

AT THE LOW LEVELS...HIGH PRES IS CENTERED NEAR 30N128W 1026 MB 
WITH A RIDGE SW TO JUST N OF THE HAWAIIAN ISLANDS AND SE TO 
19N110W. MODERATE TO FRESH NE TO E TRADES WERE FOUND S OF THE 
RIDGE FROM 22N TO THE ITCZ W OF 110W...WITH A FEW CYCLONIC 
SWIRLS NOTED ABOVE WITHIN THE ITCZ. SEAS ACROSS THIS AREA WERE 
GENERALLY RUNNING 8 TO 11 FT. LITTLE CHANGE IS ANTICIPATED IN 
THIS SYNOPTIC SCENARIO IN THE NEXT 48 HOURS AS THESE WEAK LOWS 
MOVE W AT 10 KT. EXPECT HIGHEST WINDS TO 25 KT AND SEAS 10 TO 
11 FT TO REMAIN N OF THE SERIES OF LOWS BETWEEN 118W AND 130W. 

E OF THIS AREA...POST FRONTAL...NORTHERLY GAP WIND FLOW THROUGH 
THE GULF OF TEHUANTEPEC HAS DIMINISHED TO 20 TO 30 KT OVER THE 
PAST FEW DAYS...WHICH IS THEN FLOWING SW TO W AND DOWNSTREAM TO 
S OF 14N AND W TO 110W...AND MAINTAINING A STABLE ENVIRONMENT. 
SATELLITE IMAGERY ALSO SUGGESTS NLY FLOW ACROSS THE FAR W AND SW 
CARIBBEAN IS FLOWING ACROSS CENTRAL AMERICA AND THEN TURNING NE 
AND EXITING THE PACIFIC COASTS E OF 90W...ALL CONTRIBUTING TO A 
RELATIVELY DRY AND STABLE LOW LEVEL FLOW. A WEAK CYCLONIC 
CIRCULATION IS SUGGESTED IN VIS IMAGERY THIS AFTERNOON ALONG THE 
ITCZ DUE TO THIS NELY FLOW...NEAR 08.5N86W. EXPECT THE 
TEHUANTEPEC WINDS TO GRADUALLY DIMINISH TO 20 KT SAT NIGHT AND 
TO LESS THAN 20 KT SUN AS FLOW IN THE SW GULF OF MEXICO VEERS 
MORE E.

BROAD LOW PRES CONTINUES OVER THE W TWO-THIRDS OF THE CARIBBEAN. 
STLT IMAGERY THIS AFTERNOON AND A 1524 UTC ASCAT PASS REVEAL A 
DEVELOPING LOW ACROSS THE SW CARIBBEAN NEAR 
12.5N78.5W...EMBEDDED WITHIN THE LINGERING ELONGATED MONSOON 
GYRE DOMINATING THE REGION FOR THE PAST SEVERAL WEEKS. MODEST 
CONVECTION HAS BEEN PULSING ACROSS THE W SEMICIRCLE OF THIS LOW 
THIS AFTERNOON...AND AMPLE TROPICAL MOISTURE PERSISTS ACROSS THE 
AREA WITHIN THE GYRE. WEAK SELY SHEAR IS CURRENTLY PRESENT ALOFT 
ON THE W END OF UPPER RIDGING ACROSS THE CARIBBEAN. GLOBAL 
MODELS HAVE HINTED AT THE DEVELOPMENT OF A MODEST LOW IN THE SW 
CARIBBEAN OVER THE PAST FEW DAYS...BUT HAVE BACKED OFF OF ANY 
TROPICAL DEVELOPMENT IN RECENT RUNS. HOWEVER IF MODEST 
ORGANIZATION OCCURS...EXPECT THE S TO SW FLOW FROM THE EPAC 
ACROSS COSTA RICA AND PANAMA TO INCREASE.
  
$$
STRIPLING