000
AXPZ20 KNHC 211605
TWDEP 

TROPICAL WEATHER DISCUSSION     
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC SAT MAR 21 2009

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1545 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N78W TO 2N100W 2N110W 3N120W
TO 4N140W. NO SIGNIFICANT CONVECTION IS NOTED.

...DISCUSSION...

THE UPPER LEVEL FLOW CONTINUES TO AMPLIFY N OF THE DISCUSSION 
AREA AS AN UPPER LEVEL JET MAXIMUM DIVES SOUTHEASTWARD...FORCING 
A RATHER VIGOROUS MID/UPPER LEVEL TROUGH TO PUSH SEWD INTO THE
FAR NW CORNER OF THE AREA THIS MORNING. A MID/UPPER LEVEL
CYCLONIC CIRCULATION IS BECOMING EVIDENT ON THE SOUTHERN PORTION 
OF THROUGH W OF THE AREA NEAR 20N146W. THE ASSOCIATED SURFACE
COLD FRONT ENTERS THE FAR NW WATERS THROUGH 32N132W...AND REACHES
TO 30N140W WHERE IT BECOMES STATIONARY WESTWARD FROM THERE. THE
FRONT IS FORECAST TO WEAKEN AS IT PROGRESSES FURTHER S INTO THE
NORTHERN WATERS THROUGH MON AS STRONG HIGH PRES BUILDS IN BEHIND
IT. LATEST MODEL GUIDANCE IS SHOWING N WINDS INCREASING TO 
20 TO 25 KT BEHIND THE FRONT WITH OCCASIONAL GUSTS TO 30 KT
ESPECIALLY IN THE FAR NE PORTION OF THE AREA NEAR THE BAJA
CALIFORNIA WHERE GRADIENT IS EXPECTED TO BE THE TIGHTEST.
LATEST WAVEWATCH GUIDANCE INDICATES SEAS BUILDING UP TO 12 OR
13 FT IN THE FAR NORTHERN WATERS.

A WEAK SURFACE RIDGE N OF THE DISCUSSION AREA CONTINUES TO
WEAKEN IN RESPONSE TO DECREASING DEEP LAYER SUBSIDENCE WITH THE 
AMPLIFICATION OF THE MID/UPPER TROUGH.
 
E OF THE MID/UPPER TROUGH...BROAD ANTICYCLONE FLOW PATTERN
DOMINATES THE AREA WITH A MEAN RIDGE AXIS ALONG THROUGH 32N116W 
TO 26N113W TO 18N11W. EXTENSIVE MID/UPPER LEVEL MOISTURE 
CONTINUES TO BE ADVECTED ENE IN DIFFLUENT FLOW PATTERN E OF THE 
MID/UPPER TROUGH AND E ACROSS THE RIDGE TOWARDS BAJA CALIFORNIA 
AND THE
SW U.S. AT THE SURFACE...A RIDGE EXTENDS SE FROM 29N131W TO 
20N112W. HIGH PRES COVERS THE AREA N OF 16N W OF 111W. THE
ENHANCED SURFACE PRES GRADIENT AT THE SOUTHERN PERIPHERY OF THE 
SURFACE HIGH IS ENHANCING NE TO E TRADE WINDS ACROSS THE REGION
FROM 8N TO 17N W OF 125W WHERE NE WINDS OF 20 TO 25 KT ARE FOUND
WITH SEAS TO 9 FT. THESE TRADES ARE EXPECTED TO INCREASE IN 
AREAL COVERAGE ON SUN AS THE STRONG HIGH BEHIND THE FRONT SURGES
SWD.

THE UPPER LEVEL DIFFLUENT FLOW E OF THE ABOVE MENTIONED TROUGH
IS SUPPORTING SCATTERED MODERATE/ISOLATED STRONG CONVECTION 
WITHIN 90 NM EITHER SIDE OF LINE 12N122W TO 10N130W...AND 
WITHIN 30 NM EITHER SIDE OF LINE 8N132W TO 6N139W.

FARTHER TO THE E...DEEP LAYER DRY AIR AND STABLE ATMOSPHERIC 
CONDITIONS EMBEDDED WITHIN AN UPPER RIDGE ARE RESULTING IN FAIR 
WEATHER CONDITIONS S OF 16N E OF 96W.

GAP WINDS...
A PERSISTENT RIDGE OF SURFACE HIGH PRESSURE OVER MEXICO AND THE 
GULF OF MEXICO CONTINUES TO SUPPORT A RELATIVELY STRONG SURFACE 
PRES GRADIENT ACROSS THE ISTHMUS OF TEHUANTEPEC DURING THE NEXT 
FEW DAYS. QUIKSCAT DATA FROM 1214 UTC THIS MORNING SHOWED 
WINDS OF 30 TO 35 KT THROUGH THE GULF. WINDS WILL DIMINISH TO
LESS THEN GALE FORCE IN ABOUT 24 HOURS.

ALSO...TRADE WINDS ACROSS THE CARIBBEAN CONTINUE WITH A 
PERSISTENT SURFACE LOW OVER NW COLOMBIA. THESE WINDS BLEED INTO 
THE GULFS OF PAPAGAYO AND PANAMA DURING THE NEXT FEW DAYS. THESE 
GAP WINDS ARE FORECAST TO BE STRONGEST LATE AT NIGHT WHEN 
DRAINAGE FLOW OFF HIGHER TERRAIN IS MAXIMIZED IN THE PRESENCE OF 
DEEP LAYER DRY AIR.

$$
AGUIRRE