000
AXPZ20 KNHC 180357
TWDEP 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC THU JUN 18 2009

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0315 UTC.

...SPECIAL FEATURE...

A 1008 MB LOW PRES CENTER IS NOTED N SATELLITE IMAGERY NEAR 
16N108W...OR ABOUT 300 MILES SW OF MANZANILLO MEXICO...MOVING NW TO 
N AT 6 KT. CONVECTION HAS PERSISTED AROUND THE PERIPHERY OF THIS 
ELONGATED MONSOON CIRCULATION. HOWEVER...DURING JUST THE PAST FEW
HOURS SCATTERED MODERATE TO STRONG CONVECTION HAS FORM WITHIN 60 NM 
OF THE CENTER IN THE SW QUADRANT...MAINLY NE...WHERE WIND SHEAR IS 
VERY LIGHT AND UPPER DIVERGENCE HAS IMPROVED. THIS SYSTEM REMAINS 
ELONGATED WITH A TROUGH CONNECTING THIS CENTER TO A SECOND LOW TO 
MID LEVEL CYCLONIC CIRCULATION CENTER NEAR 10.5N113W. A PARTIAL 
QUIKSCAT PASS FROM NEAR 0100 UTC THIS EVENING AGAIN SHOWED MAINLY S 
TO SW WINDS OF 20-25 KT S OF THE LOW. THIS WAS ENHANCING LOW LEVEL 
CONVERGENCE AND CONVECTION ALL ALONG THE S SIDE OF THIS CONNECTING 
TROUGH. LIGHT TO MODERATE N TO NE WINDS AND DRY LOW LEVEL AIR REMAIN 
NW OF THE LOW. THIS SYSTEM HAS THE POTENTIAL TO BECOME A TROPICAL 
DEPRESSION DURING THE NEXT DAY OR TWO AS IT MOVES WNW AND THEN 
PERHAPS MORE TO THE NW AND N. THERE IS A HIGH CHANCE...GREATER THAN 
50 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE 
NEXT 48 HOURS.

...ITCZ...

AXIS IS CENTERED ALONG 05N76W 05N85W 9N100W 11N110W TO LOW NEAR 
10.5N114W...THEN CONTINUES TO 8N118W 7N124W 9N130W 7N140W. SCATTERED
MODERATE TO STRONG CONVECTION WITHIN 120 NM N OF AXIS E OF 85W 
EXTENDING INTO THE GULF OF PANAMA. SCATTERED MODERATE CONVECTION 
WITHIN 90 NM S OF AXIS BETWEEN 86W AND 101W. SCATTERED MODERATE 
ISOLATED STRONG CONVECTION WAS WITHIN 180 NM EITHER SIDE OF AXIS 
BETWEEN 103W AND 118W. SCATTERED MODERATE CONVECTION WAS WITHIN 120 
NM EITHER SIDE OF AXIS W OF 126W. SCATTERED MODERATE CONVECTION WAS 
OVER GULF OF TEHUANTEPEC N OF 12N BETWEEN 91W AND 95W.

...DISCUSSION...

A REX BLOCK PATTERN DOMINATES THE DISCUSSION AREA W OF 125W WITH AN 
UPPER RIDGE CENTERED N OF 31N135W...AND N OF AN UPPER LOW CENTERED 
NEAR 15N138W. NORTHERLY FLOW ON THE EAST SIDE OF THE UPPER RIDGE IS 
AMPLIFYING A MID TO UPPER LEVEL TROUGH EXTENDING FROM NORTHERN BAJA 
TO 20N125W. STRONG JET ENERGY N OF THE AREA FLATTENS THE UPPER RIDGE 
AND CUTS OFF THE UPPER LOW OVER NORTHERN BAJA BY THU. THE IMPACT AT 
THE SURFACE OF ALL THIS IS THAT THE SURFACE RIDGE WILL PERSIST FROM 
A 1026 MB SURFACE HIGH NE OF HAWAII TO THE BAJA COAST. EARLIER 
SCATTEROMETER DATA SHOWED A SWATH OF FRESH TRADES PERSISTING S OF 
THE RIDGE FROM ROUGHLY 10N TO 20N. THE SURFACE HIGH WILL SHIFT N 
THROUGH SAT ALLOWING THE SWATH OF TRADE WINDS TO SHIFT N. A SMALL
AREA OF MODERATE TO FRESH NORTHERLY WINDS WAS INDICATED ON ASCAT 
DATA FROM YESTERDAY BETWEEN THE PERIPHERY OF THE RIDGE AXIS AND THE 
CENTRAL BAJA COAST. THIS AREA WILL PERSIST OFF AND ON THROUGH THE 
NEXT COUPLE OF DAYS WITH THE SURFACE RIDGE PERSISTING.

$$
STRIPLING/AGUIRRE