000
AXPZ20 KNHC 170933
TWDEP 

TROPICAL WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC THU MAR 17 2011

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 
0700 UTC.

...ITCZ...
THE INTERTROPICAL CONVERGENCE ZONE AXIS IS ANALYZED FROM 07N82W 
TO 04N100W TO 06N115W TO 05N135W TO 06N140W. ISOLATED MODERATE 
CONVECTION LIES WITHIN 120 NM N AND 75 NM S OF THE ITCZ AXIS W 
OF 128W. SCATTERED MODERATE CONVECTION IS WITHIN 270 NM N AND 90 
NM S OF THE ITCZ AXIS BETWEEN 110W AND 123W.

...DISCUSSION...
AN UPPER TROUGH EXTENDS DIAGONALLY ACROSS THE FORECAST AREA FROM 
NW MEXICO NEAR 28N108W THROUGH 15N130W TO 13N140W. A 50-70 KT 
SOUTHWESTERLY UPPER JET LIES WITHIN 450 NM SE OF THE TROUGH AXIS 
E OF 130W. DIFFLUENCE BETWEEN THIS SOUTHWESTERLY JET AND A 
WESTERLY JET CENTERED JUST S OF THE EQUATOR IS ENHANCING 
CONVECTION ALONG THE ITCZ W OF 110W. THIS CONVECTION IS 
DESCRIBED IN THE ITCZ SECTION. AS THE SOUTHWESTERLY JET TO THE 
NORTH MOVES INTO MEXICO...IT BECOMES MORE WESTERLY AND 
EVENTUALLY MERGES OVER THE CARIBBEAN WITH A 30-40 KT 
SOUTHWESTERLY JET ALOFT THAT IS CENTERED BETWEEN 85W AND 95W 
OVER THE FORECAST AREA. THE RESULTING CONFLUENT FLOW OVER 
SOUTHERN MEXICO AND CENTRAL AMERICA COUPLED WITH RELATIVELY DRY 
AIR INDICATED ON WATER VAPOR IMAGERY IS INHIBITING THE 
DEVELOPMENT OF DEEP CONVECTION OVER THE AREA S OF 20N AND E OF 
100W. 

A DEEP LAYER TROUGH IS PUSHING SOUTHWARD INTO THE NORTHERN 
PORTION OF THE FORECAST AREA. THIS DEEP LAYER TROUGH WILL 
GRADUALLY PICK UP THE TROUGH STRETCHED DIAGONALLY THROUGH THE 
AREA OVER THE NEXT TWO DAYS. THE COLD FRONT ASSOCIATED WITH THIS 
BROAD TROUGH HAS RECENTLY DISSIPATED OVER NE WATERS. THIS FRONT 
BROUGHT A NEW BATCH OF NW SWELL TO THE AREA THAT IS EXPECTED TO 
DAMPEN OUT AS IT SPREADS SOUTHEASTWARD. SEAS AS HIGH AS 17 FT 
WERE OBSERVED AT 0600 UTC BY SHIP A8VN7 NEAR 27N138W.

HIGH PRES CONTROLS MUCH OF THE FORECAST AREA N OF 15N W OF 
115W...STEMMING FROM A 1036 MB HIGH CENTER NEAR 35N155W WHICH 
EXTENDS A RIDGE TO 32N136W THROUGH 30N122W TO 20N113W. HIGH 
PRES HAS BUILT IN BEHIND THE DISSIPATED FRONT AND HAS EXPANDED 
THE FRESH TO STRONG NE TRADE WINDS INTO NW WATERS. THE TRADE 
WINDS CURRENTLY LIE N OF 05N W OF 130W. THE RIDGE WILL SHIFT 
SOUTHWARD OVER N WATERS OVER THE NEXT FEW DAYS AS THE HIGH PRES 
CENTER WEAKENS...AND THE AREA OF TRADES WILL SHIFT S AND WEAKEN 
A NOTCH IN RESPONSE. FRESH TO STRONG NW WINDS LIE E OF THE RIDGE 
ALONG THE COAST OF THE BAJA CALIFORNIA PENINSULA ACCORDING TO 
SHIP A8RW5 NEAR 28N116W AT 0600 UTC AND THE 0426 UTC ASCAT PASS. 
THESE WINDS ARE EXPECTED TO CHANGE LITTLE OVER THE NEXT FEW DAYS.

GAP WINDS...
GULF OF TEHUANTEPEC...N WINDS WILL CONTINUE TO FUNNEL THROUGH 
THE ISTHMUS OF TEHUANTEPEC THROUGH THE FORECAST PERIOD BETWEEN 
HIGH PRES OVER EASTERN MEXICO AND LOWER PRES SE OF TEHUANTEPEC. 
WINDS WILL PULSE TO 25 KT IN THE MORNING HOURS WHEN DRAINAGE 
FLOW THROUGH THE PASS WILL BE AT ITS DIURNAL MAXIMUM. 

GULF OF PAPAGAYO...THE 0240 UTC ASCAT PASS SHOWS WINDS TO 25 KT 
IN THE GULF OF PAPAGAYO THIS MORNING. LITTLE CHANGE IN THESE NE 
TO E WINDS ARE EXPECTED THROUGH THE PERIOD AS THE PRES GRADIENT 
REMAINS RELATIVELY STRONG BETWEEN HIGHER PRES TO THE N AND LOWER 
PRES TO THE S OF PAPAGAYO.

GULF OF PANAMA...THE PRES GRADIENT IS BELIEVED TO HAVE BECOME 
STRONG ENOUGH BETWEEN THE COLOMBIAN LOW AND HIGH PRES OVER 
CENTRAL AMERICA TO ALLOW FOR N WINDS TO REACH ADVISORY CRITERIA 
IN THE GULF OF PANAMA. LITTLE CHANGE IS EXPECTED IN THESE 
CONDITIONS THROUGH THE END OF THE FORECAST PERIOD SAT MORNING. 

$$
SCHAUER