000
AXPZ20 KNHC 051611
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI OCT 05 2012

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
MONSOON TROUGH EXTENDS FROM 09N76W TO 09.5N87W TO 07N96W TO 
EMBEDDED LOW PRES AT 13.5N113.5W 1009 MB TO 08.5N121W TO 
EMBEDDED LOW PRES NEAR 10N130W 1009 MB TO 07N138W...WHERE IT 
TRANSITIONS TO ITCZ...CONTINUING ON TO BEYOND 06N140W. SCATTERED 
MODERATE TO STRONG CONVECTION NOTED S OF TROUGH TO 04N E OF 86W. 
ISOLATED TO SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED 
WITHIN 90 NM EITHER SIDE OF TROUGH BETWEEN 103W AND 134W. 


...DISCUSSION...

UPPER LEVEL BLOCKING PATTERN GENERALLY PREVAILS ACROSS THE NE 
PACIFIC N OF 30N BETWEEN 170W AND A BROAD UPPER LEVEL TROUGH 
ACROSS N AMERICA. MIDDLE TO UPPER LEVEL CYCLONE IS CUT OFF N OF 
THE DISCUSSION AREA NEAR 38N133W AND SHIFTING SLOWLY NE. A 
TROUGH STRETCHES SW FROM THIS LOW TO W OF THE AREA. WATER VAPOR 
IMAGERY AND MODEL GUIDANCE INDICATE THAT A NE TO SW JET STREAM 
BRANCH IS LOCATED NE TO SW OVER THE NW PORTION OF THE AREA WHERE 
SW WINDS OF 40-65 KT AS INDICATED BY CIMSS SATELLITE-DERIVED 
WINDS ROUGHLY WITHIN 240 NM EITHER SIDE OF A LINE FROM 23N140W 
NE TO N OF THE AREA AT 32N123W AND THEN E TO ACROSS SOUTHERN 
CALIFORNIA. BROAD UPPER LEVEL HIGH PRES RIDGE PREVAILS TO THE SE 
OF THESE FEATURES...CENTERED ON AN UPPER ANTICYCLONE NEAR 
16N113W... SPANNING E TO W BETWEEN 105W AND 125W. 

A NARROW TUTT-LIKE UPPER TROUGH EXTENDS SW ACROSS THE WESTERN 
GULF OF MEXICO AND OVER CENTRAL MEXICO TO A BASE IN THE EPAC AT 
15N102W. A SECOND TUTT EXTENDS SW ACROSS THE WESTERN CARIBBEAN 
TO ACROSS NORTHERN COSTA RICA. A BROAD UPPER RIDGE IN THE DEEP 
TROPICS IS PRESENT TO THE E OF 105W.

A 1009 MB SURFACE LOW IS ANALYZED ALONG THE MONSOON TROUGH AT 
13.5N113.5W WITH SCATTERED TO NUMEROUS MODERATE TO STRONG WITHIN 
270 NM NW SEMICIRCLE. NELY WINDS 20-25 KT WERE DEPICTED BY 
OVERNIGHT SCATTEROMETER PASSES WITHIN 270 NM ACROSS THE NW 
SEMICIRCLE...WITH SEAS ESTIMATED AT 8-9 FT THERE. THIS LOW IS 
EXPECTED TO MOVE WNW NEAR 15 KT OVER THE NEXT 48 HOURS AND 
CONTINUE TO PRODUCE 20-25 KT WINDS AND SEAS TO 9 FT ACROSS THE N 
AND NW SEMICIRCLES. 

ELSEWHERE AT THE LOW LEVELS...BROAD SURFACE RIDGING COVERS MUCH 
OF THE DISCUSSION AREA N OF 20N W OF 110W. SOUTHWESTERLY LOW 
LEVEL WINDS AT 15 TO 20 KT ALONG WITH CROSS EQUATORIAL SE TO S 
SWELLS CONTINUES TO RESULT IN AN AREA OF SEAS TO 8 FT IN THE 
AREA BOUNDED BY 02N TO 10N BETWEEN 105W AND 117W. THIS AREA WILL 
SHIFT SLIGHTLY N ON FRI...THEN WINDS WILL DIMINISH TO 15 KT AND 
SEAS WILL SUBSIDE TO LESS THAN 8 FT BY SAT NIGHT. IN THE 
MEANTIME...NW WINDS NE OF THE SURFACE RIDGE WILL INCREASE TO 20 
TO 25 KT N OF ABOUT 28N AND E OF 117W TO THE COAST OF NORTHERN 
BAJA CALIFORNIA PENINSULA IN ABOUT 12 HRS AS THE PRES GRADIENT 
TIGHTENS BETWEEN THE RIDGING AND LOW PRES TROUGHING OVER THE 
NORTHERN GULF OF CALIFORNIA AND SW U.S. THESE WINDS ARE EXPECTED 
TO LAST OVER THE NEXT 48 HRS AND POSSIBLY BEYOND...HOWEVER THE 
AFFECTED AREA OF THESE WINDS SHOULD DIMINISH IN COVERAGE.

THE INITIAL SURGE OF NORTHERLY WINDS OF 20 TO 25 KT THAT HAS  
FILTERED THROUGH THE TEHUANTEPEC AREA IS STILL PROPAGATING SW IN 
A 75-90 NM WIDE PLUME TO NEAR 13N96W. THESE GAP WINDS ARE 
EXPECTED TO GRADUALLY DIMINISH TO LESS THAN 20 KT WITHIN 36 
HOURS THEN PULSE AGAIN TO 20-25 KT SUN MORNING. 

$$
STRIPLING