000
AXPZ20 KNHC 211018
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU JAN 21 2010

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

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0915 UTC.

...ITCZ...
AXIS ANALYZED ALONG 03N78W TO 05N90W TO 04N106W TO 08N125W TO 
07N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS 
WITHIN 90 NM N AND 150 NM S OF AXIS W OF 112W.

...DISCUSSION...
NARROW UPPER LEVEL TROUGH EXTENDING FROM WINDWARD PASSAGE SW 
ACROSS CENTRAL AMERICA ALONG NICARAGUA-HONDURAS BORDER TO 
04N108W THEN CONTINUED W AS A TUTT AXIS TO JUST BEYOND 140W. 
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 TUTT 
AND S SIDE OF RIDGE VENTING ITCZ CNVTN NICELY TONIGHT AND 
ALLOWING ISOLATED DEEP CNVTN. 

POLAR VORTEX REMAINS OVER FAR NE PACIFIC NEAR 50N146W TONIGHT 
WITH NEGATIVE TILE TROUGH EXTENDING SE TO A SECOND VIGOROUS 
UPPER LOW JUST OFFSHORE OF ORE-CA COAST...LIFTING SLOWLY N 
WITHIN BROAD UPPER CYCLONIC FLOW. THIS IS PRODUCING A VERY 
STRONG JET CORE ACROSS THE EPAC BETWEEN 25N AND 34N WITH CORE 
JET SPEEDS OVER 200 KT. DIFFLUENT UPPER FLOW ACROSS SRN CA AND 
EXTREME NRN BAJA WITH WLY JET TO 135 KT MOVING ACROSS N CENTRAL 
BAJA AND INTO NRN MEXICO. 

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. BEST MOISTURE ASSOCIATED WITH THIS 
WILL BEGIN TO CLEAR SRN CA TO THE E AND SE BY 24 HOURS...WITH 
LONGWAVE EPAC TROUGH REORGANIZING ACROSS THE NW U.S. AND FORCING 
FRONTS...MOISTURE...AND COLD AIR SOUTHEASTWARD ACROSS BAJA AND 
THROUGH CENTRAL MEXICO BY 72 HOURS. AMPLE MOISTURE AND STRONG 
DYNAMICS WILL LEAD TO SIGNIFICANT PRECIP ACROSS THE SIERRA 
MADRES. FRONT WILL GRADUALLY LOSE IDENTITY BUT IF FORECAST BY 
GLOBAL MODELS TO MAKE IT TO NEAR MANZANILLO BY MON EXTENDING 
W-SW INTO THE TROPICS. 

STRONG GALES TO AT OR NEAR STORM FORCE WINDS IN A VERY LONG NW 
FETCH CONTINUE TO DRIVE ADDITIONAL NW SWELL GROWTH 
TONIGHT...WITH BROAD FETCH EXTENDING FROM ALMOST THE ALEUTIANS 
SE TO NEAR 28N140W. THE GRADUAL DEVELOPMENT OF THIS COMPLEX 
PATTERN HAD PRODUCED 20 FT SEAS AS FAR SE AS 26N119W PER AN 
EVENING ALTIMETER PASS...WITH 30 FT SEAS PUSHING S OF 30N AND 
INTO FAR N PORTIONS OF THE FORECAST AREA. LARGE LONG PERIOD NWLY 
SWELL WILL DOMINATE THE AREA AND MOST OF THE EPAC THROUGH THE 
WEEKEND. 

FIRST IN THE SERIES OF COLD FRONTS HAS REACHED NRN BAJA AND 
EXTENDS SW TO 21N140W...WITH SECONDARY FRONT WITHIN 5 DEGREES 
BEHIND IT W OF 120W. GALE WARNING CURRENTLY IN EFFECT E OF FIRST 
FRONT E OF 122W...AND ACROSS MOST OF AREA NW OF THIS FIRST 
FRONT...WHERE WINDS WERE TO 40 KT WITH SMALL ISOLATED AREAS TO 
45 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 COULD PEAK NEAR 35 FT INVOF 
32N135W THIS MORNING THEN SHIFT SE TO AROUND 25 FT NEAR 27N 
BETWEEN 120W AND 130W. 20 FT SEAS TO SLAM SRN CA AND ALL BUT SRN 
PORTIONS OF THE BAJA NEXT 30 HOURS IN LONG PERIOD NW 
SWELL...YIELDING GIANT SURF...MAJOR BEACH EROSION AND EXTREMELY 
DANGEROUS SURF AND MARINE CONDITIONS.

THESE GALES WILL SWEEP SE AND E ACROSS THE BASIN N OF 25N DURING 
THE NEXT 36 HOURS BEFORE WEAKENING AND EXITING TO THE E BY 48 
HOURS.      

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

$$
STRIPLING