000
AXPZ20 KNHC 290316
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC MON DEC 29 2008

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...
ITCZ AXIS IS CENTERED ALONG 05N80W 06N94W 05N105W 08N120W  
09N140W. SCATTERED MODERATE CONVECTION IS WITHIN 90 NM N AND 240 
NM S OF THE AXIS BETWEEN 119W-126W.

...DISCUSSION...
A W TO SWLY UPPER-LEVEL JET LIES OVER MUCH OF THE TROPICS W OF 
105W ENHANCED BY A RIDGE ALONG 140W AND A SHORTWAVE TROUGH 
EXTENDING SW FROM THE CENTRAL CONUS THROUGH BAJA CALIFORNIA. 
INSTABILITY ASSOCIATED WITH THE JET COUPLED WITH LOW-LEVEL 
DIRECTIONAL AND SPEED CONVERGENCE IS PRODUCING SCATTERED SHOWERS 
AND TSTMS FROM 12N-20N BETWEEN 105W-118W. SIMILAR ACTIVITY 
EXISTS FARTHER SW WITHIN THE ITCZ (OUTLINED ABOVE). DEEP LAYER 
HIGH PRES HAS BUILT IN BEHIND THE SHORTWAVE CENTERED OFF THE SO 
CALIFORNIA COAST. THE PRESSURE GRADIENT BETWEEN THIS HIGH AND 
LOWER PRES ASSOCIATED WITH THE ITCZ IS GENERATING A SWATH OF 
20-25 KT NE/E TRADES FROM 11N-24N W OF 114W. WIND GENERATED 
WAVES COMBINED WITH LONG PERIOD NW TO N SWELL IS ELEVATING SEAS 
TO 8-14 FT OVER MUCH OF THE EPAC W OF 110W. WHILE WINDS ARE NOT 
EXPECTED TO CHANGE MUCH OVER THE NEXT COUPLE OF DAYS...NLY SWELL 
WILL DIMINISH SOME ALLOWING SEAS TO REDUCE SLIGHTLY.

A 1010 MB LOW PRES SYSTEM IS NEARLY STATIONARY OFF THE COAST OF 
COLOMBIA NEAR 05N79W. THIS LOW HAS A WELL DEFINED LOW-LEVEL 
CENTER WITH CURVED BANDS ROTATING ABOUT IT...THOUGH IT HAS 
BECOME LESS DISTINCT OVER THE PAST FEW HOURS. WHILE ITS 
LOW-LEVEL STRUCTURE IS ORGANIZED...IR IMAGERY REVEALS ITS 
SHALLOW NATURE DEVOID OF DEEP CONVECTION. ABUNDANT DRY AIR IN 
THE MID AND UPPER LEVELS ARE LIKELY LIMITING ITS VERTICAL 
DEVELOPMENT AND EVEN IF DEEPER ACTIVITY DOES DEVELOP IT WILL 
LIKELY BE QUICKLY SHEARED OFF BY STRONG SLY WINDS ALOFT. THE 
MAIN EFFECT WILL BE 20-25 KT WINDS NEAR THE LOW...ESPECIALLY 
OVER THE SRN SEMICIRCLE.

GAP WINDS...
AN EARLIER ASCAT PASS REVEALED 20-25 KT NE WINDS FUNNELING 
THROUGH THE GULF OF PAPAGAYO. THESE WINDS MAY EXPAND W OVER THE 
NEXT COUPLE OF DAYS ENHANCED BY THE TIGHTENED PRES PATTERN S/SW 
OF A FRONTAL BOUNDARY. THIS FRONTAL BOUNDARY WILL ALSO HAVE 
INFLUENCE ON THE GULF OF TEHUANTEPEC. A GALE WARNING IS POSTED 
FOR THIS GAP BEGINNING MON AS THE FRONT CONTINUES ITS SURGE S IN 
THE W BAY OF CAMPECHE. MODEL GUIDANCE IS IN AGREEMENT IN SHOWING 
A MINIMAL GALE EVENT LIKELY ENDING LATE TUE AS THE FRONT LIFTS 
BACK N AND DISSIPATES. GULF OF CALIFORNIA...NW TO N 20-30 KT 
WINDS WERE REVEALED IN SCAT DATA. THIS ENHANCED WIND REGIME WILL 
LIKELY DIMINISH OVER THE NEXT COUPLE OF DAYS AS THE TAIL END OF 
THE FRONT OVER N MEXICO AND THE GREAT BASIN HIGH WEAKENS.

$$
CANGIALOSI