000
AXPZ20 KNHC 061533
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SUN JAN 06 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 
1500 UTC.

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

THE MONSOON TROUGH IS ALONG 05N77W TO 10N85W TO 06N91W. THE 
INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N91W TO 
07N110W TO 07N125W TO 07N140W. SCATTERED MODERATE CONVECTION IS 
WITHIN 60 NM S OF THE ITCZ BETWEEN 102W AND 106W...AND ALSO 
WITHIN 60-120 NM N OF THE ITCZ BETWEEN 120W AND 130W.

...DISCUSSION...

WESTERLY FLOW DOMINATES THE UPPER LEVELS ACROSS THE DISCUSSION 
WATERS. AN UPPER TROUGH EXTENDS FROM SOUTHERN CALIFORNIA SW 
THROUGH 30N120W TO 25N140W. DRY AND STABLE AIR FOLLOWS THE 
TROUGH...WHILE LOW TO MID LEVEL MOISTURE IS BEING ADVECTED AHEAD 
OF IT FROM THE DEEP TROPICS SE OF HAWAII TO THE NE UP ACROSS 
BAJA CALIFORNIA INTO NW MEXICO...BY A JET OF 80-100 KT UPPER 
LEVEL WINDS. THIS TROPICAL MOISTURE IS RIDING AROUND THE NW 
PERIPHERY OF A BROAD UPPER RIDGE WHICH REACHES FROM 23N135W 
THROUGH 10N123W TO 00N125W. ADDITIONAL MOISTURE IS PROGRESSING 
AND SPREADING EASTWARD ACROSS THE WATERS N OF 05N BETWEEN 100W 
AND 120W AWAY FROM THE MENTIONED JET. ANOTHER UPPER TROUGH IS TO 
THE EXTENDING FROM THE SW GULF OF MEXICO TO JUST OFFSHORE OF 
CENTRAL AMERICA THROUGH 04N84W...WITH A TERMINUS NEAR THE 
GALAPAGOS ISLANDS. SATELLITE IMAGERY INDICATES VERY DRY AND 
STABLE AIR E OF 110W.

AT THE SURFACE...THE UPPER TROUGH IN THE NW PORTION OF THE 
WATERS IS SUPPORTING A COLD FRONT WHICH EXTENDS FROM NEAR THE 
CALIFORNIA CHANNEL ISLANDS THROUGH 30N130W TO 24N133W. FRESH TO 
STRONG WINDS FOLLOW THE FRONT ALONG WITH LARGE NW SWELL UP TO 15 
FT. NW SWELL OF 8 FT OR GREATER EXTENDS ALL THE WAY TO 110W. THE 
FRONT WILL DISSIPATE AS IT EXTENDS FROM THE NORTHERN GULF OF 
CALIFORNIA TO 24N125W MON MORNING. FRESH TO STRONG TRADES... 
LOCALLY NEAR GALE...DOMINATE THE W CENTRAL WATERS. A TIGHT PRES 
GRADIENT IS IN PLACE THERE N OF ITCZ AND S OF A RIDGE WHICH 
EXTENDS FROM 1035 MB HIGH PRES NEAR 33N142W AROUND THE FRONT TO 
20N112W. THESE TRADES WILL PERSIST ACROSS THE SAME GENERAL AREA 
THROUGH THE NEXT FEW DAYS WITH SEAS UP TO 15/16 FT IN THE ZONE 
OF ENHANCED TRADES COMMINGLING WITH THE NW SWELL.

A PINCHED PRES GRADIENT IS ALSO PRESENT OVER THE SOUTHERN GULF 
OF CALIFORNIA BETWEEN THE RIDGE AND SEMI-PERMANENT SURFACE 
TROUGHING ALONG THE W COAST OF MEXICO. AN OVERNIGHT ASCAT PASS 
SHOWED NW-N 20-25 KT WINDS IN THE GULF S OF 28N SPILLING OUT THE 
MOUTH OF THE GULF TO 22N. EXPECT THESE WINDS TO DIMINISH TO 20 
KT OR LESS LATER TODAY AS THE GRADIENT RELAXES SLIGHTLY WITH THE 
APPROACHING WEAKENING COLD FRONT TO THE W.

GAP WINDS...
GULF OF TEHUANTEPEC...A 0638 UTC OCEANSAT SCATTEROMETER PASS 
INDICATED 30-40 KT NORTHERLY WINDS IN THE GULF OF TEHUANTEPEC 
WHILE A 0850 UTC ASCAT PASS ALSO SAMPLED 30-40 KT NORTHERLY 
WINDS THERE. GALE FORCE WINDS MAY BRIEFLY DIMINISH BY 5 KT OR SO 
THIS AFTERNOON ALTHOUGH A REINFORCING SURGE OF NORTHERLY WINDS 
IS EXPECTED TONIGHT WITH WINDS INCREASING BACK TO AT LEAST 40 KT 
LATE TONIGHT INTO MON MORNING...WHICH WILL BUILD SEAS TO 15 FT. 
WINDS WILL DRAMATICALLY DIMINISH BELOW GALE FORCE BY TUE MORNING 
WITH WINDS N OF THE CHIVELA PASS IN THE SW GULF OF MEXICO 
TURNING TO THE E-SE BY THE MIDDLE OF THE WEEK.

GULF OF PAPAGAYO...OVERNIGHT SCATTEROMETER PASSES ALL MISSED THE 
GULF OF PAPAGAYO ALTHOUGH WINDS THERE ARE EXPECTED TO CONTINUE 
TO PULSE TO 20-25 KT THROUGH THE NEXT FEW MORNINGS. THE 
STRONGEST WINDS WILL OCCUR DURING THE LATE NIGHT AND EARLY 
MORNING HOURS DURING PEAK DRAINAGE FLOW.

$$
LEWITSKY