000
AXPZ20 KNHC 041639
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI MAY 04 2007

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1500 UTC.

...ITCZ...
AXIS ALONG 7N78W 9N92W 7N122W 3N137W 3N140W. SCATTERED MODERATE 
WITHIN 45 NM EITHER SIDE OF AXIS E OF 80W. SCATTERED MODERATE 
WITHIN 60 NM EITHER SIDE OF AXIS BETWEEN 92W AND 101W. NUMEROUS 
MODERATE TO STRONG FROM 8N TO 12N BETWEEN 113W AND 122W. 
SCATTERED MODERATE TO STRONG WITHIN 60NM OF 7N131W.

...DISCUSSION...
N OF 20N...HIGHLY AMPLIFIED PATTERN IN PLACE WITH REX BLOCK 
FEATURE JUST W OF DISCUSSION AREA ALONG 145W CONSISTING OF A DRY 
MID/UPPER LOW PRES SYSTEM NEAR 26N145W...AND UPPER RIDGE TO THE 
N. ASSOCIATED 1030 MB SFC RIDGE IS CENTERED NEAR 32N145W. 
MORNING QUIKSCAT DATA AND SHIP OBSERVATIONS SHOW FRESH TO STRONG 
TRADES ON THE SOUTHERN PERIPHERY OF THE HIGH AS FAR S AS 8N. TO 
THE EAST OF THE UPPER RIDGE...A BROAD MID TO UPPER LEVEL TROUGH 
DIGGING INTO THE NORTHERN ROCKIES IS PROVIDING UPPER SUPPORT TO 
A 1010 MB SURFACE LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT 
MOVING FROM THE CENTRAL CALIFORNIA COAST INTO SOUTHERN 
CALIFORNIA. THE TIGHT GRADIENT BETWEEN THE SURFACE HIGH PRES TO 
THE W AND THE LOW OFF THE CALIFORNIA COAST HAS SET UP GOOD NW 
FETCH PROMOTING LARGE NLY SWELL OF 10 TO 12 FT ACROSS THE AREA.

FRESH TO STRONG NWLY WINDS ARE ALSO EVIDENT OFF THE BAJA COAST 
ON THE WESTERN EDGE OF THE HIGH PRES. LITTLE CHANGE IS EXPECTED 
IN CONDITIONS THROUGH SAT AS THE RIDGE REMAINS IN PLACE. 
HOWEVER...THE UPPER RIDGE WILL WEAKEN BY LATE SAT...AHEAD OF A 
DEEP UPPER TROUGH ADVANCING THROUGH THE CENTRAL 
PACIFIC...ALLOWING THE SURFACE RIDGE TO WEAKEN SLIGHTLY. THE NW 
FLOW OFF OF BAJA WILL SUBSEQUENTLY DIMINISH ON SUN...AS WILL 
TRADE FLOW S OF THE RIDGE ON SUN.

S OF 20N...UPPER TROUGH EXTENDS THROUGH SOUTHERN MEXICO TO ABOUT 
10N ALONG 92W. A WEAK SURFACE TROUGH IS ANALYZED SE OF THE UPPER 
TROUGH ALONG 92W. FAIRLY DRY MID LEVEL AIR ASSOCIATED WITH THE 
UPPER TROUGH IS SUPPRESSING CONVECTION ALONG THE SURFACE 
FEATURE. HOWEVER...UPPER DIVERGENCE E OF THE UPPER TROUGH IS 
ENHANCING CONVECTION OFF THE COLOMBIAN COAST AND GULF OF PANAMA. 
FURTHER W...UPPER LEVEL ANTICYCLONE CENTERED NEAR 11N120W IS 
SIMILARLY AIDING CONVECTION N OF THE ITCZ AS MENTIONED.

$$
CHRISTENSEN