000
AXPZ20 KNHC 301535
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU JUL 30 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 
1230 UTC.

...SPECIAL FEATURE...

TROPICAL DEPRESSION SIX-E CENTERED NEAR 12N140W OR 1000 NM 
EAST-SOUTHEAST OF HILO HAWAII AT 1500 UTC MOVING WEST AT 16 KT. 
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED 
WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SEE LATEST NHC PUBLIC 
ADVISORY UNDER AWIPS/WMO HEADERS MIATCPEP1/WTPZ31 FOR MORE 
DETAILS. THE SYSTEM CURRENTLY LIES WITHIN A REGION OF UPPER 
LEVEL DIFFLUENCE ON THE SOUTHERN EDGE OF AN UPPER LEVEL 
ANTICYCLONE CENTERED NEAR 18N138W AND THE CONVECTION ASSOCIATED 
WITH THIS SYSTEM HAS INCREASED MARKEDLY SINCE THIS TIME 
YESTERDAY. NUMEROUS MODERATE TO STRONG CONVECTION IS NOTED 
WITHIN 90 NM W QUADRANT AND SCATTERED MODERATE CONVECTION IS 
FOUND ELSEWHERE WITHIN 150 NM OF T.D. SIX-E. AT ITS CURRENT 
FORWARD SPEED...T.D. SIX-E WILL BE CROSSING INTO THE CENTRAL 
PACIFIC HURRICANE CENTER AREA OF RESPONSIBILITY IN LESS THAN SIX 
HOURS.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 94W N OF 05N MOVING W NEAR 20 KT. LOW 
LEVEL MOISTURE CONVERGENCE NEAR THE TROPICAL WAVE COUPLED WITH 
BROAD UPPER LEVEL DIFFLUENCE BETWEEN AN INVERTED TROUGH TO THE 
SW OF THE WAVE AND AN UPPER LEVEL RIDGE AXIS TO ITS N IS 
SUPPORTING SCATTERED MODERATE CONVECTION WITHIN 270 NM W OF THE 
TROPICAL WAVE AXIS FROM 10N TO 14N. 

TROPICAL WAVE IS ALONG 119W FROM 06N TO 19N MOVING W NEAR 10 KT 
TO 15 KT. NUMEROUS MODERATE TO STRONG CONVECTION CAN BE FOUND 
WITHIN 90 NM E OF THIS TROPICAL WAVE FROM 14N TO 17N. THIS 
CONVECTION LIES IN THE UPPER LEVEL DIFFLUENT REGION ON THE 
EASTERN SIDE OF AN UPPER LEVEL LOW NEAR 15N124W.

...ITCZ...

THE INTERTROPICAL CONVERGENCE ZONE IS ALONG THE LINE...09N78W TO 
06N105W TO 12N117W TO 09N126W TO 12N140W. SCATTERED MODERATE 
CONVECTION CAN BE FOUND WITHIN 180 NM N AND 90 NM S OF THE ITCZ 
AXIS E OF 91W.

...DISCUSSION...

A 1008 MB LOW PRES SYSTEM NEAR 08N81W WILL MOVE WESTWARD OVER 
THE NEXT 48 HOURS AND INTENSIFY AS IT TRACKS ALONG WITH A REGION 
OF MODERATE UPPER LEVEL DIFFLUENCE. CURRENTLY...THE MAJORITY OF 
THE CONVECTION IN THE EASTERN PACIFIC ASSOCIATED WITH THE SYSTEM 
LIES WITHIN 180 NM N AND 90 NM S OF THE ITCZ AXIS E OF 91W WITH 
SCATTERED MODERATE CONVECTION EXTENDING THROUGH PANAMA INTO THE 
SW CARIBBEAN. AS THIS LOW MOVES W OVER THE NEXT TWO 
DAYS...EXPECT THE LOW LEVEL VORTICITY TO BE ENHANCED AS IT 
ENCOUNTERS THE CROSS EQUATORIAL SOUTHERLY FLOW IN THE FAR 
EASTERN PACIFIC AND THE EASTERLY GAP WINDS FROM PAPAGAYO. SEE 
THE DISCUSSION ON GAP WINDS BELOW FOR DETAILS ON THE GULF OF 
PAPAGAYO WINDS.

THE NEXT ROUND OF SOUTHWESTERLY SWELL WILL BE CROSSING THE 
EQUATOR OVER THE NEXT 24 HOURS. SIGNIFICANT WAVE HEIGHTS ARE 
ALREADY AROUND 8 FT IN SE SWELL S OF 08N BETWEEN 116W AND 126W. 
THE SW SWELL MOVES INTO THE REGION LATE TODAY WITH LONGER PERIOD 
SW SWELL ENCROACHING ON THIS GENERAL REGION IN THE S CENTRAL 
PORTION OF THE FORECAST AREA ON SAT.

SURFACE HIGH PRESSURE AND GENERALLY SUBSIDENT CONDITIONS WITH 
WIDESPREAD STRATOCUMULUS CLOUDS DOMINATES THE REGION N OF 20N W 
OF 120N AND FROM 20N120W TO THE CENTRAL BAJA CALIFORNIA 
COAST...WITH THE EXCEPTION OF FAR NW WATERS WHERE AN UPPER LEVEL 
LOW WELL N OF THE AREA NEAR 36N136W HAS BROUGHT A DISRUPTION TO 
THE STRATOCUMULUS CLOUD FIELD N OF 29N W OF 135W.

GAP WINDS...
THE HIGH RESOLUTION QUIKSCAT PASS FROM 0244 UTC INDICATED WINDS 
IN THE NORTHERN GULF OF CALIFORNIA TO 25 KT. UNFORTUNATELY...THE 
PASS ONLY COVERED THE NW PORTION OF THE GULF N OF 30N. THIS FLOW 
APPEARS TO BE DRIVEN BY THE TIGHTENED PRESSURE GRADIENT BETWEEN 
LOW PRESSURE OVER INTERIOR SOUTHERN CALIFORNIA AND HIGH PRESSURE 
OVER NW MEXICO. THIS PRESSURE GRADIENT IS STRONGEST WITH 
AFTERNOON HEATING. MODEL GUIDANCE SHOWS THIS PRESSURE GRADIENT 
WEAKENING OVER THE NEXT 24 HOURS...ALLOWING THESE WINDS TO 
DIMINISH BELOW 20 KT BY FRI MORNING.

THE 1210 UTC HIGH RESOLUTION QUIKSCAT PASS SHOWED NE TO E WINDS 
IN THE 20 TO 25 KT RANGE DOWNWIND OF THE GULF OF PAPAGAYO. THESE 
WINDS ARE EXPECTED TO MODERATE ALONG WITH THE TRADE WIND FLOW IN 
THE SW CARIBBEAN OVER THE NEXT 24 HOURS...BUT AS THE LOW PRES 
SYSTEM NEAR PANAMA PUSHES WEST OF THE GULF OF PAPAGAYO ON 
SATURDAY EXPECT THE WINDS TO TRACK EAST AWAY FROM THE GULF AND 
THE FLOW ASSOCIATED WITH THE LOW TO INCREASE TO 20 KT ON ITS 
NORTHERN SIDE.

$$
SCHAUER CLARK