000
AXPZ20 KNHC 131001
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC WED OCT 13 2010

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0945 UTC.

...TROPICAL WAVE....A TROPICAL WAVE IS N OF 07N ALONG 80.5W. 
SCATTERED MODERATE TO STRONG CONVECTION IS FLARING TO THE N OF 
05N E OF 81W. 

...THE ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE EXTENDS FROM 09N83W TO 07N90W 
TO LOW PRES 13N126.5W WITH AXIS CONTINUING W TO 10N140W. 
SCATTERED STRONG CONVECTION ID NOTED WITHIN 240 NM OVER THE SW 
SEMICIRCLE OF 1011 MB LOW PRES AT 13N126.5W WITH AND SCATTERED 
MODERATE AND ISOLATED STRONG CONVECTION NOTED WITHIN 240 NM OVER 
THE NE SEMICIRCLE. SCATTERED MODERATE CONVECTION IS OBSERVED 
WITHIN 150 NM OF 11N133W AND 14N137W. 

...DISCUSSION...

UPPER LEVEL CYCLONES HAVE CUT OFF AT 26N118W AND AT 27N133W WITH 
DRY UPPER AIR NOTED WITHIN 150 NM OF EACH CENTER. JUST TO THE N 
IS AN UPPER ANTICYCLONE AT 33N133W. AN UPPER TROUGH IS SWINGING 
SE ACROSS THE SE CONUS ALONG 33N113W TO 32N127W ACCOMPANIED BY A 
90 NM WIDE BAND OF UPPER MOISTURE SWINGING SE FROM NW TEXAS TO 
EXTREME SOUTHERN CALIFORNIA.

A NEGATIVE TILT UPPER TROUGH EXTENDS SE FROM THE PREVIOUSLY 
MENTIONED UPPER CYCLONE AT 26N118W TO NEAR 21N105W WITH THE 
TROUGH THEN CONTINUING S INTO AN ILL DEFINED UPPER CYCLONE AT 
09N108W...WITH EVIDENCE OF THE TROUGH EXTENDING FURTHER S AND 
CROSSING THE EQUATOR AT 104W. THIS N TO S TROUGH EFFECTIVELY 
SEPARATES THE UPPER FLOW OVER THE TROPICAL PACIFIC. AN UPPER 
ANTICYCLONE IS CENTERED AT 12N126W WITH AN UPPER UPPER RIDGE 
EXTENDING W BEYOND 14N140W. AND UPPER RIDGE ALSO EXTENDS E TO A 
CREST AT 14N111W. THE ASSOCIATED UPPER DIFFLUENCE IS ENHANCING 
CONVECTION AS PREVIOUSLY DESCRIBED NEAR THE SURFACE LOW AT 
13N126.5W...AND IN THE AREA FROM 10N TO 15N W OF 113W. THE 
DEBRIS MOISTURE FROM THESE CONVECTIVE AREAS...AND UPPER DEBRIS 
MOISTURE STREAMING IN FROM ITCZ CONVECTION W OF THE DISCUSSION 
AREA NEAR 10N150W...MERGE UNDER THE RIDGE...ROUGHLY FROM 07N TO 
24N BETWEEN 115W AND 150W. HOWEVER...SOME OF THE MOISTURE IS NOW 
ADVECTED E IN THE CYCLONIC FLOW ASSOCIATED WITH THE UPPER 
CYCLONE AT 26N118W...WITH A TROPICAL PLUME INDICATED WITHIN 150 
NM EITHER SIDE OF A LINE FROM 21N118W TO OVER THE BAJA PENINSULA 
NEAR 25N107W. 

FURTHER E...AN UPPER ANTICYCLONE NEAR HAITI HAS A RIDGE 
EXTENDING WSW ACROSS CENTRAL AMERICA TO A CREST OVER THE 
TROPICAL PACIFIC AT 10N98W. THE ASSOCIATED UPPER DIFFLUENCE IS 
ENHANCING CONVECTION OVER THE EXTREME E PACIFIC NEAR PANAMA WITH 
THE DEBRIS MOISTURE STREAMING NW WITHIN 240 NM W OF CENTRAL 
AMERICA. IT APPEARS THIS MOISTURE WILL MOVE N ACROSS HONDURAS 
AND GUATEMALA LATER TODAY. OTHERWISE...THE UPPER LEVELS ARE VERY 
DRY S OF 22N E OF 113W.

ELSEWHERE AT THE LOW LEVELS...A RIDGE EXTENDS FROM 32N137W TO 
17N111W. THE GRADIENT SW OF THIS SURFACE RIDGE...AND N OF THE 
ITCZ...IS SUPPORTING NE TRADES AT 20 KT WITH SEAS TO 9 FT OVER 
THE WATERS FROM 13N TO 18N W OF 125W. THE GRADIENT IS EXPECTED 
TO RELAX OVER THE NEXT 48 HOURS.

GAP WINDS...NORTHERLY WINDS AT 20 TO 25 KT HAVE SURGED THROUGH 
THE ISTHMUS OF TEHUANTEPEC. EXPECTING THESE WINDS TO RAPIDLY 
INCREASE TO MINIMAL GALE JUST AFTER SUNRISE THIS MORNING AND 
CONTINUE TO INCREASE TO STRONG GALE FORCE THU NIGHT AND FRI.
EXPECT THE GALE CONDITIONS TO PERSIST THROUGH SUNRISE SAT THEN 
GRADUALLY DIMINISH TO 20 TO 25 KT AT SUNRISE SUN THEN LESS THAN 
20 KT SUN AFTERNOON.  MAY BEGIN TO SEE NE WINDS AT 15 TO 20 KT 
IN THE GULF OF PAPAGAYO SAT MORNING.

$$
NELSON