000
AXPZ20 KNHC 310306
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC MON OCT 31 2011

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 2000 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH WAS ANALYZED FROM 10N84W TO 06N93W TO 
07N105W. INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED FROM 
07N105W TO 10N120W TO LOW PRES NEAR 09N125W TO 08N140W. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS FROM 05N TO 
10N E OF 89W.

...DISCUSSION...

AN UPPER LEVEL LOW LIES W OF THE FORECAST AREA AND E OF THE BIG 
ISLAND OF HAWAII. THIS LOW IS ON THE WESTERN EDGE OF A BROAD 
UPPER TROUGH THAT EXTENDS NE OVER THE NORTHERN PORTION OF THE 
FORECAST AREA. TROPICAL MOISTURE ALOFT IS BEING ADVECTED INTO 
THE LEADING EDGE OF THIS UPPER TROUGH AND IS MANIFESTED AS 
CIRRUS OVER THE FAR W PORTION OF THE FORECAST AREA PRIMARILY 
BETWEEN 15N AND 25N. 

THE 1028 MB SUBTROPICAL HIGH LIES NEAR 35N140W. THE PRES 
GRADIENT BETWEEN THIS HIGH AND THE ITCZ IS STRONG ENOUGH TO 
YIELD FRESH TRADE WINDS OVER MUCH OF THE AREA W OF 127W BETWEEN 
12N AND 21N ACCORDING TO THE 1838 UTC ASCAT PASS. THE 
SUBTROPICAL HIGH IS EXPECTED TO MERGE WITH A STRONGER HIGH TO 
ITS NW MON AS THE PORTION OF THE COLD FRONT BETWEEN THESE TWO 
HIGH CENTERS DISSIPATES N OF THE AREA. THIS WILL SHIFT THE AREA 
OF FRESH TRADE WINDS FARTHER W TOMORROW AND OUT OF THE FORECAST 
AREA BY TUE EVENING. IN ADDITION...THE COLD FRONT WILL DIG SOUTH 
THROUGH THE WESTERN U.S. MON INTO TUE AND INCREASE THE PRES 
GRADIENT OVER N WATERS BETWEEN IT AND HIGH PRES TO ITS NW. FRESH 
NE WINDS ARE EXPECTED OVER N CENTRAL AND NW WATERS MON AFTERNOON 
INTO TUE AS A RESULT...WITH SEAS EXPECTED TO REACH 11 FT IN NW 
SWELL.

THE 1518 UTC ASCAT PASS FAILED TO SHOW FRESH SW WINDS CONTINUING 
IN THE AREA S OF PANAMA...BUT SCATTERED MODERATE CONVECTION 
CONTINUES TO BE FOUND OVER MUCH OF THE AREA OFFSHORE OF 
COLOMBIA...PANAMA...AND COSTA RICA. THIS CONVECTION IS DESCRIBED 
IN THE SECTION ABOVE AND ALSO EXTENDS INLAND OVER 
PANAMA...SOUTHERN AND EASTERN COSTA RICA...AND SOUTHEASTERN 
NICARAGUA. IT LIES UNDER UPPER LEVEL DIFFLUENCE ASSOCIATED WITH 
A RIDGE AXIS ALOFT THAT EXTENDS FROM EASTERN CUBA THROUGH THE 
WESTERN CARIBBEAN INTO NICARAGUA AND COINCIDES WITH THE REGION 
OF HIGHEST PRECIPITABLE WATER VALUES IN THE FORECAST AREA. 
WIDESPREAD PRECIPITATION SHOULD CONTINUE IN THIS AREA THROUGH 
TUE.

GAP WINDS...THERE HAS NOT BEEN A SCATTEROMETER PASS OVER THE 
GULF OF TEHUANTEPEC SINCE 29/1538 UTC...AND THERE HAVE BEEN VERY 
FEW SHIP REPORTS IN THE AREA. THE FORECAST GUIDANCE SHOWS WINDS 
HOVERING AROUND GALE FORCE BEFORE A NORTHERN STREAM REINFORCING 
TROUGH SWEEPS THROUGH THE WESTERN GULF OF MEXICO...BUILDING HIGH 
PRESSURE SOUTHWARD OVER THE SOUTHERN PLAINS AND BRINGING WINDS 
SOLIDLY BACK INTO THE GALE RANGE IN TEHUANTEPEC OVERNIGHT 
TONIGHT. NIGHTTIME DRAINAGE FLOW FROM THE MOUNTAINS WILL ALSO 
HELP KEEP WINDS AT GALE FORE. THE GALE WARNING WILL CONTINUE TO 
BE IN EFFECT UNTIL AROUND SUNSET TUE WHEN HIGH PRES OVER THE 
WESTERN GULF WEAKENS.

$$
SCHAUER