East Pacific Tropical Weather Discussion

000
AXPZ20 KNHC 160322
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0405 UTC TUE SEP 16 2008

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 
0300 UTC.

...TROPICAL WAVES...

TROPICAL WAVE OVER NICARAGUA AND HONDURAS ALONG 85W N OF 04N 
MOVING W 10-15 KT. A LARGE AREA OF SHOWERS/TSTMS AND WIDESPREAD 
CLOUDINESS EXTENDS ACROSS MUCH OF THE WESTERN CARIBBEAN 
SEA...CENTRAL AND SOUTHERN CENTRAL AMERICA...AND THE ADJACENT 
PACIFIC WATERS S OF PANAMA AND COSTA RICA. IN PARTICULAR... 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION LIES N OF 04N 
BETWEEN 78W-88W.

TROPICAL WAVE ALONG 107W S OF 15N MOVING W 10 KT. THE WAVE 
CONTINUES TO BE EMBEDDED WITHIN A BROAD BUT WEAK MONSOON TROUGH 
WHICH LIES OFF THE MEXICAN COAST BUT IS BEGINNING TO MOVE AWAY 
FROM THIS REGIME AND SHOULD SOON TAKE ON A STRONGER SIGNATURE AS 
IT NEARS THE TRADE WIND BELT. MULTI-LAYERED CLOUDINESS EXTENDS 
ACROSS MUCH OF THE AREA N OF 05N TO MEXICO BETWEEN 96W-112W. 
SCATTERED MODERATE CONVECTION IS LOCATED NEAR THE ITCZ ON THE 
SOUTHERN END OF THE WAVE AXIS.

...ITCZ...

ITCZ AXIS IS CENTERED FROM 11N84W TO 09N94W TO 12N105W TO 
10N115W TO 12N126W TO 08N140W. SCATTERED MODERATE/ISOLATED 
STRONG CONVECTION N OF 04N BETWEEN 78W-85W. SCATTERED MODERATE 
FROM 05N-12N BETWEEN 106W-118W. ISOLATED SHOWERS/TSTMS WITHIN 
150 NM OF AXIS W OF 124W.

...DISCUSSION...

TROPICS...
THE UPPER LEVEL ANTICYCLONE OVER THE WESTERN CARIBBEAN SEA HAS 
SHIFTED SLIGHTLY WESTWARD...NOW LOCATED OVER HONDURAS WITH BROAD 
ANTICYCLONIC FLOW EXTENDING OVER THE PACIFIC WATERS E OF 96W. 
THE UPPER LEVEL JET ON THE S SIDE OF THE UPPER HIGH HAS ALSO 
SHIFTED FARTHER W...WITH 30-35 KT EASTERLY WINDS LOCATED S OF 
08N BETWEEN 90W-105W. BROAD UPPER LEVEL DIFFLUENCE ASSOCIATED 
WITH THE HIGH IS ENHANCING DEEP CONVECTION OVER PARTS OF CENTRAL 
AMERICA...NEAR THE TROPICAL WAVE ALONG 85W...WITH UPPER LEVEL 
MOISTURE FLOWING W TO 90W AND NORTHWARD ACROSS THE REST OF 
CENTRAL AMERICA INTO THE CIRCULATION AROUND A SHARP TROUGH OVER 
THE GULF OF MEXICO. SCATTERED MODERATE CONVECTION HAS DEVELOPED 
S OF THE GULF OF TEHUANTEPEC FROM 10N-14N BETWEEN 94W-97W WITHIN 
THIS AREA OF DEEPER MOISTURE. AN INVERTED UPPER TROUGH EXTENDS 
FROM NEAR ACAPULCO MEXICO SW TO 00N106W AND MARKS THE LEADING 
EDGE OF A SURGE OF DRY AIR COMING FROM THE AREA NEAR THE 
GALAPAGOS ISLANDS. DEEP-LAYERED MOISTURE LIES W OF THE 
TROUGH...EXTENDING AS FAR N AS THE MOUTH OF THE GULF OF 
CALIFORNIA...THEN BECOMING ISOLATED INTO A NARROW BELT NEAR THE 
ITCZ W OF 120W. A WEAK SURFACE TROUGH IS EMBEDDED WITHIN THE 
ITCZ ALONG 128W AND IS ENHANCING SOME CONVECTION NEAR THE AXIS.

HIGH PRES BEHIND A WEAK COLD FRONT OVER THE GULF OF MEXICO IS 
EXPECTED TO BUILD SOUTHWARD WITH GAP WINDS INCREASING OVER THE 
GULF OF TEHUANTEPEC BY TUE AFTERNOON. WINDS WILL INCREASE AND 
HOLD NEAR 20 KT...THEN INCREASE TO 20-25 KT TUE NIGHT AND 
CONTINUE THROUGH WED.

SUBTROPICS...
A LARGE UPPER LEVEL HIGH IS LOCATED NEAR 24N136W AND LIES 
ADJACENT TO AN UPPER TROUGH EXTENDING FROM OFFSHORE SOUTHERN 
CALIFORNIA TO 20N127W. SUBSIDENCE WITHIN THE HIGH...AND 
CONFLUENCE INTO THE TROUGH...IS PRODUCING A LARGE AREA OF DRYING 
MAINLY NW OF A LINE FROM 30N104W TO 13N130W. THE SURFACE RIDGE 
EXTENDS FROM 30N132W TO 20N120W WITH ONLY A FEW LOW/MID-LEVEL 
CLOUDS OVER THE AREA. WINDS ARE GENERALLY LIGHT...EXCEPT FOR A 
SLIGHTLY ENHANCED PRESSURE GRADIENT OFF OF NORTHERN BAJA 
CALIFORNIA BETWEEN THE RIDGE AND THE HEAT LOW OVER THE NORTHERN 
GULF OF CALIFORNIA.

$$
BERG