000
AXPZ20 KNHC 311531
TWDEP 

TROPICAL WEATHER DISCUSSION    
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1605 UTC THU MAY 31 2007

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 FEATURES...
TROPICAL STORM BARBARA CENTERED NEAR 13.1N 95.8W AT 31/1500 UTC 
MOVING E AT 3 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 
MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. 
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS 
MIATCMEP2/WTPZ22 FOR MORE DETAILS. WHILE CONVECTION IS 
BURSTING...THE OVERALL STRUCTURE OF THE STORM HAS DETERIORATED 
SINCE LAST NIGHT. THE LOW-LEVEL CENTER IS NOT EASILY SEEN ON 
VISIBLE IMAGERY AND THE UPPER ENVIRONMENT NOW APPEARS LESS 
SUPPORTIVE FOR SUBSTANTIAL STRENGTHENING. 

TROPICAL DEPRESSION ALVIN CENTERED NEAR 13.0N 115.5W AT 31/1500 
UTC MOVING WSW OR 250 DEG AT 2 KT. ESTIMATED MINIMUM CENTRAL 
PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED HAS BEEN 
LOWERED TO 25 KT WITH GUSTS TO 35 KT. SEE LATEST NHC 
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 FOR 
MORE DETAILS. SATELLITE IMAGERY CLEARLY SHOWS THAT ALVIN IS ON 
ITS WAY DEGENERATING INTO A REMNANT LOW WITH CONVECTION AT A 
MINIMUM LEADING TO AN EXPOSED LOW-LEVEL SWIRL.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 9N77W 12N94W 9N110W 6N130W 5N140W. 
SCATTERED MODERATE CONVECTION IS WITHIN 180 NM OF AXIS BETWEEN 
105W-121W AND WITHIN 60 NM OF AXIS W OF 136W.

...DISCUSSION...

W OF 110W...
AN UPPER LOW LIES ABOVE THE NW PORTION OF THE AREA NEAR 26N134W 
WITH ASSOCIATED TROUGHING STRETCHING TO THE SW ACROSS 18N140W. 
TO THE E OF THE TROUGH...AN AMPLIFIED SPRAWLING UPPER RIDGE 
CONTROLS THE PATTERN WITH ITS AXIS STRETCHING FROM THE MEXICAN 
COAST NEAR 22N TO AN UPPER HIGH NEAR 17N113W CONTINUING SW TO 
7N140W. THERE ARE A FEW AREAS OF PATCHY HIGH LEVEL CLOUDS IN 
WEAK DIFFLUENT ZONES BETWEEN THE TROUGH AND RIDGE...BUT NONE OF 
THESE LOOK PARTICULARLY SIGNIFICANT AND DEEP MOISTURE IS ALMOST 
NON-EXISTENT N OF THE ITCZ. IN THE LOWER LEVELS...A MODEST PRES 
GRADIENT BETWEEN HIGH PRES N OF THE REGION AND T.D. ALVIN IS 
KEEPING NE TRADES FAIRLY LIGHT.

E OF 110W...
THE UPPER PATTERN IN THIS REGION IS MORE COMPLEX WITH RIDGING 
POKING E AS AND EXTENDING W FROM THE CARIB. PRONOUNCED TROUGHING 
IS LOCATED JUST N OF THE EPAC WATERS STRETCHING SWD FROM AN 
UPPER LOW IN THE NW GULF OF MEXICO. THIS DIVERGENT PATTERN ALONG 
WITH LOW-LEVEL INFLUENCES FROM A PERTURBED ITCZ AND A TROUGH OF 
LOW PRES IN THE NW CARIB IS PRODUCING ACTIVE WEATHER...IN THE 
FORM OF SCATTERED MODERATE CONVECTION...TO THE E OF TROPICAL 
STORM BARBARA...NEAR THE CENTRAL AMERICAN COASTLINE FROM 11N-14N 
BETWEEN 90W-94W. 

$$
CANGIALOSI