000
AXPZ20 KNHC 162158
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2205 UTC MON MAR 16 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 
2030 UTC.

...ITCZ...

THE ITCZ AXIS LIES ALONG A LINE FROM 06N76W TO 06N85W TO 03N106W 
TO 07N135W TO 06N140W. THERE IS NO SIGNIFICANT CONVECTION ALONG 
ITCZ.

...DISCUSSION...

THE DEEP LAYER TROUGH CURRENTLY OVER THE NW GULF OF MEXICO WILL 
SLOWLY PULL EASTWARD OVER THE NEXT DAY OR TWO...CARRYING THE 
ASSOCIATED SURFACE COLD FRONT EASTWARD THROUGH THE SOUTHWESTERN 
GULF OF MEXICO AND SLACKENING THE PRESSURE GRADIENT OFF THE W 
CENTRAL COAST OF BAJA CALIFORNIA BETWEEN THIS TROUGH AND THE 
SUBTROPICAL PACIFIC HIGH WHERE WINDS ARE CURRENTLY AS HIGH AS 25 
KT.  AT THE SAME TIME...STRONG NORTHERLY FLOW IS BEGINNING TO 
BLEED THROUGH THE ISTHMUS OF TEHUANTEPEC AS THE COLD FRONT IS 
FORCED EASTWARD THROUGH THE BAY OF CAMPECHE.  THE QUIKSCAT PASS 
FROM 1242 UTC REVEALED WINDS TO 20 KT IN THE FAR NORTHERN GULF 
OF TEHAUNTEPEC WHILE THE LATER ASCAT PASS AT 1540 UTC SHOWED 
WINDS HAD INCREASED TO 20 TO 25 KT. A MINIMAL GALE WIND EVENT IS 
EXPECTED IN THE GULF OF TEHUANTEPEC LATE TONIGHT THROUGH WED 
MORNING...WITH WINDS POSSIBLY DROPPING BELOW GALE FORCE DURING 
THE DAY TUE BEFORE RETURNING TO GALE FORCE OVERNIGHT TUE NIGHT 
AND DIMINISHING ON WED.

THE DEEP LAYER LOW N OF HAWAII WILL WEAKEN AND MOVES NORTHEAST 
OVER THE NEXT DAY OR TWO...TEMPORARILY SHIFTING THE SUBTROPICAL 
RIDGE OVER N CENTRAL WATERS FARTHER NORTHWARD.  MUCH OF THE 
SHORTWAVE ENERGY ASSOCIATED WITH THIS CUT OFF LOW IS EXPECTED TO 
PHASE WITH THE NORTHERN STREAM AND MOVE EASTWARD THROUGH N 
WATERS.  MEANWHILE...THE TROUGHING ASSOCIATED WITH THIS LOW WILL 
BE RELOADED WITH ENERGY CURRENTLY SW OF THE LOW.  THIS PATTERN 
WILL MAINTAIN THE MEAN TROUGHING OVER NW WATERS TUE THROUGH THU. 
FARTHER N...A STRONG MID LATITUDE SYSTEM WILL BEGIN TO BRING NW 
SWELL TO N WATERS OVERNIGHT TONIGHT.

WINDS SHOULD CONTINUE TO BE ABOVE 20 KT THROUGH THE FORECAST 
PERIOD JUST DOWNWIND OF THE GULF OF PAPAGAYO AS STRONG TRADE 
WINDS MOVE THROUGH CENTRAL AMERICA.  THE HIGH PRESSURE RIDGE 
CURRENTLY OVER THE EASTERN GULF OF MEXICO IS BEGINNING TO SHIFT 
SOUTHWARD INTO THE NW CARIBBEAN AS THE COLD FRONT OVER THE 
WESTERN GULF EDGES EASTWARD...ALLOWING THE PRESSURE GRADIENT TO  
BUILD BETWEEN THIS RIDGE AND THE CLIMATOLOGICAL LOW PRESSURE 
OVER NORTHERN COLOMBIA.  HIGH PRESSURE BEHIND THE WEAKENING COLD 
FRONT WILL MAINTAIN MODERATE TRADES IN THE CARIBBEAN THROUGH THE 
FORECAST PERIOD. THE QUIKSCAT PASS FROM 1100 UTC ALSO SHOWED 
WINDS TO 20 KT DOWNWIND OF THE GULF OF PANAMA...WITH LITTLE 
CHANGE EXPECTED OVER THE NEXT TWO DAYS.

THERE IS LITTLE CONVECTION OVER THE FORECAST AREA AT THIS TIME.  
WIDESPREAD SUBSIDENCE CAN BE FOUND OVER MUCH OF THE REGION SE OF 
A LINE FROM 18N102W TO 00N128W.  UPPER LEVEL CONFLUENCE ALONG 
100W IS INHIBITING CONVECTION IN THAT AREA WHILE 250 MB FLOW IN 
EXCESS OF 50 KT CAN BE FOUND BETWEEN 20N AND 25N...ALSO 
INHIBITING CONVECTION.  THE BEST CHANCE OF CONVECTION DEVELOPING 
THIS PERIOD WILL BE IN THE AREA S OF 20N AND W OF THE 
AFOREMENTIONED LINE WHERE PRECIPITABLE WATER VALUES ARE NEAR 2 
INCHES AND BROAD UPPER LEVEL DIFFLUENCE CAN BE FOUND ON THE 
LEADING EDGE OF THE TROUGH SUPPORTING TO LOW N OF HAWAII.  
CURRENTLY SCATTERED MODERATE CONVECTION LIES FROM 09N TO 12N 
BETWEEN 120W AND 125W.

$$
SCHAUER CLARK