000
AXPZ20 KNHC 072202
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC FRI MAR 07 2008

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 
2145 UTC.

...ITCZ...
ITCZ AXIS ALONG 1N79W 2N87W 1N98W 5N111W 7N133W 6N140W. 
SCATTERED MODERATE ISOLATED STRONG WITHIN 240 NM N OF AXIS FROM 
115W TO 118W AND FROM 123W TO 126W.

...DISCUSSION...

EAST OF 110W...
MAIN FORECAST ISSUE THROUGH SAT IS GALE FORCE WINDS THROUGH THE 
GULF OF TEHUANTEPEC. A STRONG COLD FRONT IS NOW MOVING THROUGH
THE CHIVELAS PASS/ISTHMUS OF TEHUANTEPEC AND HAS BROUGHT GALES 
TO THE WESTERN AND CENTRAL GULF OF MEXICO. 1030 MB SURFACE HIGH 
PRES CENTERED OVER NRN MEXICO WILL SHIFT SE INTO THE SW GULF OF 
MEXICO TONIGHT...TIGHTENING THE PRESSURE GRADIENT IN THE 
TEHUANTEPEC ISTHMUS. GALE FORCE WINDS WILL COMMENCE SHORTLY 
AND PERSIST THROUGH SAT. SFC OBSERVATIONS FROM MINATITLAN 
INDICATED SUSTAINED WINDS OF 30 WITH GUSTS TO 45 KNOTS. BASED ON 
THIS THERE IS THE POTENTIAL FOR A STRONGER GALE THAN CURRENTLY
FCST AND WILL ASSESS THE LATEST DATA BEFORE THE NEXT ISSUANCE OF 
THE HIGH SEAS FORECAST. IN ANY EVENT THE SURFACE HIGH PRES 
DRIVING THE EVENT WILL SHIFT EWD BY LATE SAT...ALLOWING THE PRES 
GRADIENT TO RELAX AND ALLOWING MODERATE SELY RETURN FLOW OVER 
THE WRN GULF OF MEXICO. THIS WILL ALLOW PERMIT NLY GAP WINDS 
THROUGH TEHUANTEPEC TO DIMINISH THROUGH SUN.

ELSEWHERE E OF 110W...A TIGHT GRADIENT ON THE EASTERN SIDE OF 
THE HIGH PRES IS ALLOWING 20-25 KNOT NLY FLOW OVER THE SOUTHERN 
GULF OF CALIFORNIA...AS DEPICTED BY A 1258 UTC HIGH RESOLUTION 
SCATTEROMETER PASS. THESE WINDS WILL DIMINISH THROUGH SAT AS THE 
HIGH PRES SHIFTS E. HIGH PRES W OF BAJA WILL SHIFT EWD 
SAT...ALLOWING MODERATE TO FRESH NLY FLOW OFF THE WRN COAST OF 
BAJA. AT THE MID AND UPPER LEVELS...A MID/UPPER TROUGH IS 
DIGGING THROUGH TEXAS...N OF A BROAD UPPER ANTICYCLONE CENTERED 
OVER THE SW CARIBBEAN NEAR 13N77W. DIVERGENCE ALOFT ON THE SW 
SIDE OF THE UPPER ANTICYCLONE IS INTERACTING WITH LOW LEVEL 
CONVERGENCE ALONG THE ITCZ TO PROMOTE MODEST CONVECTION AS 
DESCRIBED ABOVE. WATER VAPOR IMAGERY SHOWS A SHORT WAVE TROUGH 
DIGGING INTO NORTHERN BAJA...BUT WILL HAVE LITTLE IMPACT ON 
SENSIBLE SURFACE WEATHER. FURTHER SOUTH...ELY TRADES OVER THE SW 
CARIBBEAN WILL PICK UP SAT INTO SUN AS HIGH PRES BUILDS N OF THE 
CARIBBEAN. THIS WILL IN TURN ALLOW FRESH TO STRONG ELY FLOW 
THROUGH GULF OF PAPAGAYO...AND FRESH NLY FLOW THROUGH GULF OF 
PANAMA BY EARLY SUN.

W OF 110W...
A WEAK MID/UPPER SHORTWAVE TROUGH ORIENTED NE TO SW IS DIGGING 
THROUGH ROUGHLY ALONG 125W N OF 25N...CUTTING OFF AN UPPER LOW E 
OF HAWAII NEAR 20N145W. MEANWHILE FLATTENING UPPER RIDGE 
ALONG 120W APPEARS TO BE RELOADING ALONG 130W IN THE FACE OF THE 
DIGGING TROUGH NOTED ABOVE. THE RESULTING MID/UPPER SW FLOW 
BETWEEN THE FLAT RIDGE AND THE TROUGHING TO THE N IS ADVECTING 
MAINLY UPPER LEVEL MOISTURE NWD. DIVERGENCE ALOFT ON THE SRN 
EDGE OF THE UPPER RIDGE IS ENHANCING CONVECTION ALONG THE ITCZ 
AS DESCRIBED ABOVE. THE UPPER DIVERGENCE IS ALSO SUSTAINING A 
WEAK TROUGH ALONG THE ITCZ NEAR 137W. THE GRADIENT BETWEEN THE 
TROUGH AND SURFACE RIDGING WELL TO THE N IS MAINTAINING A BROAD 
AREA OF FRESH TRADE WINDS ROUGHLY BETWEEN 7N AND 20N W OF 120W.

$$
COBB