000
AXPZ20 KNHC 101544
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC FRI JUL 10 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 
1500 UTC.

...SPECIAL FEATURE...

TROPICAL DEPRESSION FOUR-E CENTERED NEAR 10.4N 112.8W AT 10/1500 
UTC MOVING W OR 275 DEG AT 10 KT. MAXIMUM SUSTAINED WIND SPEED 
IS 30 KT WITH GUSTS TO 40 KT. ESTIMATED MINIMUM CENTRAL PRESSURE 
IS 1007 MB. SEE THE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO 
HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS. SCATTERED 
MODERATE ISOLATED STRONG CONVECTION IS OBSERVED IN BANDING 
FEATURES WITHIN ROUGHLY 120 NM NW SEMICIRCLE AND WITHIN 140 NM 
OVER THE SE SEMICIRCLE OF THE CENTER. SCATTERED TO NUMEROUS 
MODERATE TO STRONG CONVECTION WITHIN 60 NM OF CENTER. THE SYSTEM 
IS GETTING BETTER ORGANIZED AS THE MORNING WEARS ON...AND THE 
FORECAST CALLS FOR INTENSIFICATION DUE TO A LIGHT SHEAR 
ENVIRONMENT AND WARM SSTS. THE DEPRESSION IS EXPECTED TO BECOME 
A TROPICAL STORM THIS EVENING AND A HURRICANE IN ABOUT 3 TO 4 
DAYS. 

...TROPICAL WAVES...
A TROPICAL WAVE IS N OF 05N TO THE COAST OF MEXICO NEAR ACAPULCO 
ALONG 101W MOVING W AT 10-15 KT. A RECENT QSCAT PASS SHOWS A 
BROAD CYCLONIC TURNING JUST BEHIND THE WAVE AXIS WITH A COUPLE 
OF CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION NEAR 
13N98W AND 08N103W.

...ITCZ...
THE ITCZ AXIS IS ALONG 08N78W TO 10N102W TO 06N117W TO 08N130W 
TO 08N140W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS 
FROM 10N TO 15N BETWEEN 90W AND 100W...AND FROM 05N TO 08N 
BETWEEN 95W AND 104W.  

...DISCUSSION...
A BROAD UPPER-LEVEL TROUGH DOMINATES THE W PART OF THE FORECAST 
AREA WITH AXIS ALONG 130W WHILE A RIDGE ANCHORED ON A HIGH 
CENTERED OVER WESTERN TEXAS COVERS THE BAJA CALIFORNIA PENINSULA 
AND THE FAR NE WATERS. FARTHER SOUTH...THERE IS AN UPPER-LEVEL 
HIGH LOCATED NW OF T.D. FOUR-E NEAR 14N116W. THE ASSOCIATED 
UPPER DIFFLUENCE IS ENHANCING CONVECTION AROUND THE DEPRESSION. 
BROAD UPPER RIDGING IS NOTED OVER THE TROPICS TO THE E OF 104W 
AND HAS BEEN ENHANCING CONVECTION ALONG THE ITCZ AND NEAR THE 
COASTS OF COLOMBIA AND MEXICO. 

THE REMNANT LOW OF BLANCA CONTINUE TO SPIN OVER THE NORTH WATERS 
WITH LOW-TOPPED CONVECTION DISPLACED TO THE NW OF ITS LOW LEVEL 
CENTER. THE SYSTEM LIES IN A REGION OF INCREASING SOUTHERLY FLOW 
ALOFT ON THE LEADING EDGE OF THE ABOVE MENTIONED UPPER-LEVEL 
TROUGH. AN EARLIER QSCAT PASS SHOWED AN AREA OF NE WINDS 20 TO 
25 KT WITHIN 150 NM NW SEMICIRCLE OF LOW CENTER. THIS AREA OF OF 
FRESH TO STRONG WINDS EXTENDS WWD MAINLY N OF 24N AND W OF 121W 
DUE TO THE PRES GRADIENT BETWEEN THE REMNANTS OF BLANCA AND A 
SURFACE RIDGE THAT COVERS THE NW CORNER OF THE FORECAST REGION. 
LITTLE CHANGE IN THESE CONDITIONS IS EXPECTED OVER THE NEXT FEW 
DAYS AS WHAT IF LEFT OF BLANCA CONTINUES ON ITS NW PATH NEAR 10 
KT.

THE COMBINATION OF A SURFACE TROUGH ALONG THE WESTERN COAST OF 
MEXICO AND A SURFACE RIDGE TO THE E OF BLANCA IS EXPECTED TO 
PRODUCE NW WINDS TO 20 KT N OF 24N WITHIN 150 NM W OF THE BAJA 
CALIFORNIA PENINSULA.

GAP WINDS...FRESH E TRADE WINDS ARE EXPECTED OCCASIONALLY SURGE 
THROUGH THE GULF OF PAPAGAYO DURING THE NEXT FEW DAYS. 

$$
GR