000
AXPZ20 KNHC 270330
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC WED OCT 27 2010

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0300 UTC.

...ITCZ...
AXIS FROM 09N84W TO LOW PRES 1007 MB AT 10N90W TO LOW PRES 1010 
MB AT 11N118W TO 07N132W TO 09N140W.  ISOLATED MODERATE 
CONVECTION WITHIN 90 NM S OF AXIS E OF 90W AND WITHIN 150 NM N 
OF AXIS W OF 135W.

...DISCUSSION...
COMPLEX UPPER LEVEL PATTERN INCLUDE TWO WELL DEFINED CYCLONIC 
VORTICES AND TWO BROAD ANTICYCLONIC GYRES STRUGGLING TO CONTROL 
WIND FLOW ACROSS E PAC.  THE TWO CYCLONES...ONE AT 04N127W AND 
THE OTHER AT 21N138W...KEEP A MOIST COOLER NW FLOW ALOFT ON 
THEIR WESTERN SIDE WHILE PULLING DRY AIR MASS N ON THEIR EASTERN 
SIDES.  

DOWNSTREAM FROM CYCLONES...ANTICYCLONES LOCATED AT 18N117W AND 
26N107W EXPAND DRY SLOT WITH SUBSIDING AIR MASS E OF 110W.  ONLY 
FLY IN THE OINTMENT IS DIVERGING FLOW ALOFT BETWEEN SOUTHERNMOST 
GYRE AND CYCLONE COINCIDING OVER SURFACE LOW PRES AT 11N117W.
SCATTERED MODERATE CONVECTION NOTED WITHIN 90 NM OF CENTER 
EXPECTED TO LAST 24-36 HRS BEFORE COLLAPSING UNDER INCREASED SW 
SHEARING WINDS ALOFT. 

ELSEWHERE AT THE SURFACE...
PACIFIC COLD FRONT BRINGS STRONG N WINDS N OF 28N E OF 124W 
REACHING GALE FORCE N OF 30N.  FRONT BRING NEW TRAIN OF LARGE 
LONG PERIOD NW SWELLS...UP TO 12 FT...SPREADING SE ACROSS BASIN 
N OF 13N.  FRONT FORECAST TO DISSIPATE TONIGHT WITH WINDS 
DIMINISHING BELOW 20 KT WED...BUT LINGERING SWELL REMAIN BEYOND 
48 HRS. 

NEW COLD FRONT FORECAST TO MOVE INTO NW WATERS WED NIGHT WITH 
LITTLE IN THE WAY OF WINDS STRENGTH...BUT FORCING NEW TRAIN OF 
HIGHER SWELLS N OF 25N BEYOND FORECAST PERIOD.

STRING OF LOW PRES SYSTEMS EMBEDDED IN ITCZ DO NOT SEEM TO POSE 
THREAT OF DEVELOPING TROPICAL CHARACTERISTIC DUE TO DRY AIR MASS 
...COOL SSTS AND SHEAR FROM OF UPPER LEVEL WINDS.  MODEL 
GUIDANCE INITIALIZE LOW PRES CENTERS WELL...BUT DO NOT FAVOR 
DEVELOPMENT OF ANY OF THEM.  EASTERNMOST LOW PRES CENTER AT 
10N90W FORCES FRESH SW MONSOONAL FLOW AGAINST COAST OF COLOMBIA 
...PANAMA AND COSTA RICA...BUT FLOW BECOMES MODERATE AS LOW PRES 
WEAKENS AND DRIFT NW. 

ONSET OF STRONG N TEHUANTEPEC WINDS JUST AT THE END OF FORECAST 
PERIOD IS A PRELUDE OF NEXT GALE EVENT IN REGION. 

$$
WALLY BARNES