000
AXPZ20 KNHC 220938
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC SAT DEC 22 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0900 UTC.

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

THE MONSOON TROUGH IS ALONG 07N77W TO 07N89W. THE INTERTROPICAL 
CONVERGENCE ZONE AXIS EXTENDS FROM 07N89W TO 06N110W TO 10N125W 
TO 08N140W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM S OF 
THE MONSOON TROUGH BETWEEN 79W AND 83W. SCATTERED MODERATE AND 
ISOLATED STRONG CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE 
ITCZ W OF 117W. 

SCATTERED MODERATE CONVECTION IS ALSO WITHIN 90 NM EITHER SIDE 
OF A LINE FROM 28N114W TO 14N134W...AHEAD OF AN UPPER LEVEL 
TROUGH WHICH IS ADVECTING CONVECTION FROM THE DEEP TROPICS TO 
ACROSS NW MEXICO.

...DISCUSSION...

THE REMNANTS OF A COLD FRONT NOW IN THE FORM A TROUGH REACHES 
FROM THE BAY AREA OF CALIFORNIA THROUGH 32N125W TO 27N130W. A 
SECOND TROUGH IS FOLLOWING THE FIRST APPROXIMATELY 270 NM TO THE 
W-NW. OVERNIGHT SCATTEROMETER DATA INDICATED MODERATE WINDS IN 
THE VICINITY OF THE LEADING TROUGH ACROSS THE DISCUSSION WATERS. 
AN EARLIER EVENING ALTIMETER PASS SAMPLED LARGE NW SWELL UP TO 
22 FT IN THE NW CORNER OF THE DISCUSSION WATERS...ABOUT 4 FT 
HIGHER THAN THE WAVEWATCH AND ECWAVE SOLUTIONS...WHILE THE UKMET 
WAVE MODEL PROGGED A MAXIMUM OF 20 FT FOR THE SAME TIME PERIOD. 
THIS SET OF VERY HIGH ENERGY NW SWELL HAS PEAK WAVE PERIODS OF 
17-19 FT. THE SWELL WILL GRADUALLY DECAY TO A COMBINED MAXIMUM 
OF 14 FT BY 24 HOURS...WITH SEAS OF 8 FT OR GREATER REACHING THE 
EQUATOR NO LATER THAN 48 HOURS.

HIGH PRESSURE WILL BUILD EAST BEHIND THE TROUGH ALONG 26N 
THROUGH MON NIGHT. THIS HIGH AND ACCOMPANYING RIDGE WILL BECOME 
THE DOMINANT SYNOPTIC FEATURE ACROSS THE REGION SAT THROUGH TUE 
WITH GENERALLY LIGHT TO MODERATE WINDS ACROSS THE NORTHERN 
WATERS. THE HIGH WILL ALSO ENHANCE NE-E TRADES S OF THE RIDGE 
AXIS AND N OF THE ITCZ. TRADES ARE ALREADY 20-25 KT IN THE W 
CENTRAL WATERS AS INDICATED BY RECENT ASCAT PASSES. THE E-SE 
SHIFTING RIDGE WILL HELP TO EXPAND THE TRADES ALL THE WAY TO 
120W BY 48 HOURS WHILE COMBINED SEAS WILL REMAIN 10-14 FT IN 
MIXED NE WIND WAVES AND THE NW SWELL SET ACROSS THE AREA OF 
ENHANCED TRADES.

LOOKING SLIGHTLY FARTHER AHEAD...AS THE RIDGE CONTINUES TO BUILD 
EASTWARD IN THE WAKE OF THE TROUGHS A TIGHT PRESSURE GRADIENT 
WILL ALSO SET UP NEAR THE BAJA CALIFORNIA PENINSULA WITH 
INVERTED TROUGHING LOCATED NEAR THE W COAST OF MEXICO. THIS MAY 
INDUCE FRESH TO LOCALLY STRONG WINDS IN THE SOUTHERN GULF OF 
CALIFORNIA AND WITHIN 120-180 NM W OF THE BAJA CALIFORNIA 
PENINSULA BY MON MORNING.

GAP WINDS...
STRONG 1030 MB HIGH PRESSURE CENTERED OVER SW LOUISIANA BEHIND A 
STRONG COLD FRONT IS PRODUCING A VERY IMPRESSIVE GAP WIND EVENT 
THROUGH THE CHIVELA PASS INTO THE GULF OF TEHUANTEPEC. A 0316 
UTC ASCAT OVERPASS SHOWED A COUPLE 40-45 KT RANGE WIND BARBS 
WHILE A 0549 UTC OCEANSAT PASS DID AS WELL. GIVEN THE 5 KT OR SO 
LOW BIAS OF THE ASCAT OPTED TO KEEP THE STORM WARNING UP FOR 
ANOTHER 12 HOURS WITH WINDS POTENTIALLY KICKING UP A FEW MORE 
KNOTS DURING THE FAVORABLE LATE NIGHT AND EARLY MORNING HOURS. 
MEANWHILE A SHIP NEAR 15N94W REPORTED 22 FT SEAS AT 06 UTC AND 
SEAS ARE LIKELY EVEN HIGHER TO THE W IN AND DOWNSTREAM OF THE 
STORM FORCE WIND AREA. THESE HIGH SEAS CONTINUE TO QUICKLY FAN 
OUTWARD FROM THE SOURCE REGION AS N-NE SWELL EXTENDING DOWNWIND 
FROM THE GULF OF TEHUANTEPEC TO NEAR 110W ARE MERGING WITH NW 
SWELL FROM THE DYING FRONT MENTIONED ABOVE. THE PRESSURE  
GRADIENT IS FORECAST TO RELAX SIGNIFICANTLY OVER THE REGION LATE 
IN THE WEEKEND INTO EARLY NEXT WEEK WITH WINDS DIMINISHING BELOW 
GALE FORCE BY EARLY SUN MORNING...THEN TO 20 KT OR LESS BY EARLY 
MON MORNING. LOOKING AHEAD...A WEAKER COLD FRONT MAY MOVE 
THROUGH THE SW GULF OF MEXICO WED ALLOWING FOR A SHORT-LIVED 
MINIMAL GALE FORCE WIND EVENT IN THE GULF OF TEHUANTEPEC BEHIND 
ITS PASSAGE TO THE N BEGINNING WED EVENING.

INCREASED TRADES IN THE SW CARIBBEAN IS AIDING NE-E 20-25 KT 
WINDS IN THE GULF OF PAPAGAYO EARLY THIS MORNING. THE WINDS IN 
THE CARIBBEAN WILL INCREASE FURTHER LATER TODAY AS A STRONG COLD 
FRONT CURRENTLY IN THE NW CARIBBEAN CONTINUES A TREK TO THE SE. 
ONCE THE FRONT MOVES BY WINDS WILL LIKELY INCREASE TO 20-30 KT 
IN THE GULF OF PAPAGAYO WHILE SPREADING DOWNSTREAM ALL THE WAY 
TO 94W. RESULTANT SEAS WILL ALSO BUILD TO UP TO 13 FT. WINDS AND 
SEAS WILL THEN GRADUALLY DIMINISH AND SUBSIDE BY EARLY NEXT WEEK 
AS THE TRADES IN THE CARIBBEAN BACK OFF.

LATEST MODEL GUIDANCE HAS TRENDED SLIGHTLY UPWARD WITH RESPECT 
TO THE STRENGTH OF NORTHERLY WINDS IN THE GULF OF PANAMA. FRESH 
TO STRONG WINDS ARE NOW ALSO LIKELY THERE FOR AN APPROXIMATELY 
18 HOUR PERIOD COMMENCING SAT EVENING.

$$
LEWITSKY