000
AXPZ20 KNHC 211603
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU JAN 21 2010

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. 

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1545 UTC.

...ITCZ...

AXIS IS CENTERED ALONG 3N78W 5N87W 5N96W 4N113W 8N121W 7N140W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION WAS WITHIN 120 NM S
OF THE AXIS BETWEEN 131W-135W.

...DISCUSSION...

A NARROW UPPER LEVEL TROUGH EXTENDED WELL E OF THE AREA OVER
SW ACROSS NORTHERN NICARAGUA TO NEAR 9N97W...AND TO NEAR 6N109W. 
STRONG NW TO WLY FLOW ALOFT N OF 20N DESCRIBED BELOW DOMINATES 
THE EPAC...WITH WEAK TROPICAL UPPER RIDGE S OF 20N BETWEEN 
HAWAIIAN ISLANDS AND 110W. GOOD DIVERGENCE ALOFT BETWEEN THE 
TROUGH AND THE S SIDE OF RIDGE WAS ALLOWING FOR ITCZ CONVECTION
TO CONTINUE TO REMAIN SOMEWHAT ACTIVE W OF ABOUT 130W.

POLAR VORTEX REMAINS WELL N OF THE REGION OVER THE FAR NE 
PACIFIC WITH AN ASSOCIATED NEGATIVE TILT TROUGH EXTENDING SE TO 
A SECOND VIGOROUS UPPER LOW JUST OFFSHORE THE NW PACIFIC COAST.
THIS SYSTEM WAS MOVING NNW WITH TIME. THE PLACEMENT OF THIS
SYSTEM HAS ALLOWED FOR A VERY STRONG JET CORE ACROSS THE REGION
N OF 25N WITH CORE JET SPEEDS WITHIN THE RANGE OF 150-200 KT. 
VERY PRONOUNCED DIFFLUENT UPPER EXISTS E OF THE TROUGH TO 
ACROSS SRN CA AND EXTREME NRN BAJA CALIFORNIA.

THIS UPPER PATTERN WILL CONTINUE TO USHER A SERIES OF SHORTWAVES 
TO MOVE SE INTO EXTREME SRN CA AND NORTHERN BAJA ACCOMPANIED BY 
A PROGRESSION OF COLD FRONTS. LONGWAVE TROUGH THEN REORGANIZES
ACROSS THE NW U.S. WITHIN 72 HRS FORCING FRONTS...MOISTURE...AND 
COLD AIR SOUTHEASTWARD ACROSS BAJA AND THROUGH CENTRAL MEXICO.
AMPLE MOISTURE AND STRONG DYNAMICS WILL LEAD TO SIGNIFICANT 
PRECIP ACROSS THE SIERRA MADRES. 

FIRST IN THE SERIES OF COLD FRONTS HAS REACHED NRN BAJA AND 
EXTENDS SW TO 24N126W TO 19N140W. A SECONDARY COLD FRONT MARKED
BY WIDESPREAD COLD AIR STRATOCUMULUS CLOUDS BEHIND IT EXTENDED
FROM 30N124W TO 25N130W TO 21N140W. GALE WARNING CURRENTLY IS IN 
EFFECT W OF THE SECOND FRONT AND BETWEEN BOTH FRONTS WITH WINDS
UP TO 40 KT. OVERNIGHT SCATTEROMETER PASSES SHOWED A HUGE FETCH 
OF 30-40 KT NW WINDS REFERRED TO ABOVE...WITH SCATTERED AREAS 
40-50 KT N OF 30N AND W OF 140W. SEAS IN THE RANGE OF ABOUT 24 
TO 34 FT WERE NOTED THIS MORNING BEHIND THE SECOND FRONT IN VERY 
LARGE LONG PERIOD SWELLS OVER A VERY LONG FETCH WITH MAXIMUM SEA 
HEIGHTS NEAR 30N138W. EXPECT LARGE SEAS POSSIBLY UP TO NEAR 20
FT TO IMPACT BAJA CALIFORNIA WITHIN THE NEXT LEADING TO GIANT 
SURF...MAJOR BEACH EROSION AND EXTREMELY DANGEROUS SURF AND 
MARINE CONDITIONS. LONG PERIOD NW TO N SWELLS WILL BE THE MAIN 
ISSUE INTO THE UPCOMING AS LATEST WAVEWATCH MODEL GUIDANCE SHOWED
RESULTING LARGE SEAS OVERSPREADING JUST ABOUT THE ENTIRE WHILE
SLOWLY DECREASING. THE COLD FRONTS ARE FORECAST TO MERGE FROM 
NEAR 30N114W TO 20N120W TO NEAR 15140W BY 24 HRS. GALE FORCE 
WINDS WILL SLOWLY DIMINISH OVER THE NEXT 36 HRS...THEN BE GONE 
BY 48 HRS AS THE COLD FRONTS WILL HAVE WEAKENED AND EXITED THE 
AREA. ANOTHER COLD FRONT IS EXPECTED TO APPROACH THE FAR NW 
CORNER OF THE AREA LATE SAT.

FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE

$$
AGUIRRE