000
AXPZ20 KNHC 101553
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU JAN 10 2013

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 
1545 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS W ALONG 07N FROM THE COAST OF 
COLOMBIA TO 90W WHERE LOW LEVEL WINDS INDICATE A TRANSITION TO 
AN ITCZ. THE ITCZ CONTINUES W ALONG 07N TO 104W...THEN TURNS NW 
TO 08N120W...THEN SW TO BEYOND 06N140W. A FEW HEAVY SHOWERS HAVE 
DEVELOPED ALONG THE MONSOON TROUGH AT THE COLOMBIAN COAST. 
SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED ALONG 
THE ITCZ WITHIN 240 NM EITHER SIDE OF A LINE FROM 13N115W TO 
05N124W.  ISOLATED MODERATE CONVECTION IS OBSERVED WITHIN 15 NM 
EITHER SIDE OF A LINE FROM 09.5N132W TO 05.5N140W.

...DISCUSSION...

UPPER LEVELS...AN UPPER SHORTWAVE TROUGH IS MOVING ACROSS THE 
WESTERN SEABOARD OF THE CONUS WITH THE TROUGH CONTINUING S INTO 
THE DISCUSSION AREA FROM 32N124W TO 30N134W. AN UPPER LEVEL 
ANTICYCLONE IS OVER THE DEEP TROPICS AT 08N120W WITH A SHORTWAVE 
RIDGE EXTENDING NW TO A CREST AT 31N140W AND A SECOND RIDGE 
EXTENDING NE TO A CREST OVER ARIZONA...WITH THE PREVIOUSLY 
MENTIONED UPPER TROUGH ERODING THE RIDGE BETWEEN THE TWO CRESTS. 
AN UPPER CYCLONE NE OF THE HAWAIIAN ISLANDS AT 24N150W HAS AN 
UPPER TROUGH EXTENDING SE ACROSS THE DISCUSSION AREA FROM 
16N140W TO 10N129W. THIS PATTERN SETS UP A LARGE AREA OF UPPER 
DIFFLUENCE WHICH EXTENDS S OVER THE ITCZ CONVECTION PREVIOUSLY 
MENTIONED. THE RESULTANT DEBRIS MOISTURE IS ADVECTED NE UNDER 
THE WESTERN RIDGE...BECOMING ORGANIZED INTO A TROPICAL PLUME 
WHICH CONTINUES NE ACROSS SOUTHERN CALIFORNIA...THE BAJA 
PENINSULA...THE GULF OF CALIFORNIA...NW OLD MEXICO...ARIZONA AND 
NEW MEXICO EVENTUALLY FEEDING CYCLONICALLY INTO A DEEP LAYERED 
CYCLONE OVER CENTRAL TEXAS. 

THE DEEP LAYERED CYCLONE OVER TEXAS HAS AN UPPER TROUGH 
EXTENDING S ACROSS OLD MEXICO ALONG 102W TO A BASE OVER THE 
TROPICAL PACIFIC AT 09N106W. A BROAD UPPER RIDGE EXTENDS NW FROM 
S AMERICA TO AN ILL-DEFINED CREST OVER GUATEMALA. THESE TWO 
UPPER FEATURES COMBINE TO DRY OUT THE UPPER LEVELS S OF 23N E OF 
110W...EXCEPT FOR A NARROW MOISTURE PLUME PRECEDING THE UPPER 
TROUGH ACROSS EASTERN OLD MEXICO...WITHIN 120 NM EITHER SIDE OF 
A LINE FROM 12N102W TO 16N95W TO 20N92W.         

LOW LEVELS...A SURFACE FRONT HAS WEAKENED TO A FRONTAL TROUGH 
ALONG 32N122W TO 27.5N130W TO 27N140W. NE-E WINDS AT 20-30 KT 
WITH SEAS 8-13 FT IN NE SWELL IS NOTED N OF THE TROUGH. TRADES 
ARE AT 20-25 KT...SEAS 7-11 FT IN MIXED NE AND NW SWELL...FROM
08-27N W OF 130W. NE AND NW SWELL IS PROPAGATING S ACROSS THE 
REMAINDER OF THE AREA FROM 04-20N BETWEEN 106W-130W RESULTING 
IN COMBINED SEAS 7-10 FT WITH NE-E WINDS AT 15-20 KT. THE 
FRONTAL TROUGH SHOULD DISSIPATE TOMORROW WITH NE WINDS AT 25-30 
KT COVERING THE AREA N OF 17N W OF 130W WITH SEAS 9-15 FT IN 
MOSTLY NE SWELL. THE NE AND NW SWELL WILL PROPAGATE S ACROSS THE 
REMAINDER OF THE WATERS N OF 08N W OF 112W BY SAT WITH SEAS AT 
8-14 FT.
  
GULF OF CALIFORNIA...CURRENT MODEL GUIDANCE IS NOT AS AGGRESSIVE 
AS PREVIOUS MODEL RUNS AND SUGGESTS THAT THE SW-W WINDS WILL 
INCREASE ONLY TO 20-25 KT N OF 29.5N AS THE WEAKENING FRONT 
PASSES THROUGH THE AREA. NW WINDS BEHIND THE FRONT WILL THEN 
DIMINISH TO 15-20 KT BY LATE FRI AS THE PRESSURE GRADIENT 
RELAXES OVER NW MEXICO.

GAP WINDS...THE GULF OF PAPAGAYO WILL PULSE ON A DIURNAL CYCLE 
THE NEXT FEW DAYS WITH NE-E WINDS AT 20-25 KT ACROSS THE WATERS 
E OF 91W.

$$
NELSON