East Pacific Tropical Weather Discussion

000
AXPZ20 KNHC 242158
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC TUE NOV 24 2009

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

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2100 UTC.

...ITCZ...
AXIS ANALYZED FROM 09N79W TO 08N87W TO 08N119W TO 06N129W TO 
07N140W. NUMEROUS MODERATE SCATTERED STRONG WITHIN 90 NM S OF 
AXIS BETWEEN 79W AND 82W. SCATTERED MODERATE ISOLATED STRONG 
WITHIN 180 NM S OF AXIS BETWEEN 85W AND 88W. SCATTERED MODERATE 
WITHIN 120 NM S OF AXIS BETWEEN 105W AND 107W.

...DISCUSSION...
A SHORTWAVE MID TO UPPER LEVEL TROUGH EXTENDS FROM 35N123W TO 
16N140W WHICH WILL SHIFT EASTWARD AND WILL CUTOFF JUST OFF THE 
BAJA COAST NEAR 26N115W BY EARLY THU AS IT ENCOUNTERS AN UPPER 
RIDGE EXTENDING FROM THE U.S. ROCKIES TO NORTHERN MEXICO. THIS 
WILL HAVE LITTLE IMPACT ON WEATHER IN THE IMMEDIATE VICINITY 
HOWEVER IT WILL RESULT IN A MORE AMPLIFIED PATTERN OVER THE 
DISCUSSION AREA AND OVER DOWNSTREAM/ADJACENT AREAS. A LONGWAVE 
TROUGH WILL DIG ACROSS THE EASTERN U.S. BY THU INTO FRI WITH A 
STRONG COLD FRONT PUSHING THROUGH THE S GULF OF MEXICO JUST 
AHEAD OF THE ATTENDANT UPPER LEVEL TROUGH. THIS WILL ENHANCE GAP 
WIND FLOW FROM THE S GULF OF MEXICO ACROSS THE ISTHMUS OF 
TEHUANTEPEC AND THROUGH THE GULF OF TEHUANTEPEC...WHERE STRONG 
NORTHERLY FLOW CAN BE EXPECTED BY WED EVENTUALLY REACHING GALE 
FORCE LEVEL BY WED NIGHT. 

OTHERWISE...EARLY AFTERNOON ASCAT AND WINDSAT PASSES CONTINUE 
TO SHOW A LARGE SWATH OF FRESH TO STRONG TRADE WINDS OVER THE 
DISCUSSION AREA MAINLY FROM 10N TO 25N W OF 120W. THESE WINDS 
ARE SOUTH OF A 1025 MB SURFACE HIGH PRES CENTERED NEAR 35N130W 
AT 18 UTC. A 1215 UTC JASON ALTIMETER PASS INDICATED SEAS OF 8 
TO 10 FT IN THE AREA OF FRESH TO STRONG TRADES...ALTHOUGH A 
PORTION OF THESE SEAS ARE RELATED TO PERSISTENT LONG PERIOD NW 
SWELL. A NEW ROUND OF LONG PERIOD NW SWELL WITH HEIGHTS BUILDING 
UP TO 15 FT IS EXPECTED TO PASS SE OF 30N140W BY LATE WED AND 
WILL PROPAGATE INTO THE FAR NW SECTIONS OF THE DISCUSSION AREA 
THEREAFTER. THE HIGH WILL WEAKEN OVER THE NEXT 48 TO 72 HOURS 
AHEAD OF A DEEP LAYER TROUGH THAT WILL DIG EASTWARD FROM JUST N 
OF THE AREA EXTENDING TO JUST N OF THE HAWAIIAN ISLANDS. THE 
RESULTANT TRADES WILL DIMINISH SLIGHTLY IN INTENSITY AND 
COVERAGE AS THE PRES GRADIENT WEAKENS...HOWEVER TRADES WILL THEN 
REBOUND AND INCREASE AGAIN BY THE END OF THE WEEK AS HIGH PRES 
BUILDS BEHIND A SURFACE COLD FRONT THAT WILL STALL ALONG 30/31N 
BY THU INTO FRI.

MEANWHILE FRESH NORTHERLY WINDS IN THE NORTHERN GULF OF 
CALIFORNIA CONTINUE TO BE IN THE 20 TO 30 KT RANGE N OF 29N DUE 
TO A TIGHT PRES GRADIENT IN PLACE BETWEEN HIGH PRES OVER THE 
U.S. GREAT BASIN...A TROUGH OF LOW PRES ALONG THE COAST OF THE E 
GULF OF CALIFORNIA AND A HIGH PRES RIDGE W OF THE BAJA 
PENINSULA. THIS PATTERN AND THESE STRONG WINDS ARE EXPECTED TO 
PERSIST THROUGH THE NEXT 36 HOURS AND THEN WILL DIMINISH AS THE 
PRES GRADIENT RELAXES.

NE TO E WINDS IN THE 20 TO 25 KT RANGE CONTINUE IN THE GULF 
OF PAPAGAYO AND IMMEDIATE SURROUNDING WATERS MAINLY DUE TO 
DRAINAGE FLOW OFF THE CENTRAL AMERICA COAST. THESE CONDITIONS
ARE EXPECTED TO PERSIST THROUGH THE REMAINDER OF THE WEEK.

STRONG DIURNALLY DRIVEN CONVECTION HAS REDEVELOPED ALONG AND 
JUST INLAND OF THE COAST OF NICARAGUA EXTENDING S TO THE COAST 
OF PANAMA...MAINLY DUE TO AFTERNOON SEABREEZE INITIALIZATION AND 
CONVERGENCE WITH INLAND TOPOGRAPHIC FEATURES. THIS ACTIVITY IS 
EXPECTED TO GRADUALLY PUSH BACK TO THE W AND OFFSHORE THIS 
EVENING AND INTO THE OVERNIGHT HOURS BEFORE WEAKENING AS LAND 
BREEZE CIRCULATIONS BECOME PREDOMINANT. TO THE W...CONVECTION 
HAS INCREASED ALONG A TROUGH EXTENDING FROM NEAR 11.5N87W TO 
04.5N87W. THIS ACTIVITY AND THE TROUGH ARE EXPECTED TO DISSIPATE
AS THE FEATURE ENCOUNTERS A MORE HOSTILE ENVIRONMENT TO THE W 
WHERE STRONGER SW SHEAR ALOFT AND VERY DRY AIR IS EVIDENT ON 
WATER VAPOR SATELLITE IMAGERY. 

$$
LEWITSKY