000
AXPZ20 KNHC 080948
TWDEP 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
1005 UTC FRI MAR 08 2013

TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM 
THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS 
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0945 UTC.

...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...
THE ITCZ EXTENDS E TO W ALONG 01N BETWEEN 91W AND 127W. ISOLATED 
MODERATE CONVECTION IS NOTED WITHIN 120 NM EITHER SIDE OF A LINE 
FROM 08N78W TO 00N96W. SCATTERED MODERATE ISOLATED STRONG 
CONVECTION IS OBSERVED FROM 06N TO 13N BETWEEN 113W AND 122W AND 
ALSO WITHIN 180 NM EITHER SIDE OF A LINE FROM 09N129W TO 
04N139W. ISOLATED MODERATE CONVECTION IS POSSIBLE UNDER A DENSE 
CIRRUS SHIELD OBSERVED WITHIN 240 NM EITHER SIDE OF A LINE FROM 
13N140W TO 18N120W...THEN ACROSS THE SOUTHERN BAJA CALIFORNIA 
PENINSULA AND GULF OF CALIFORNIA.   

...DISCUSSION...

A DEEP LAYERED CYCLONE IS N OF THE AREA AT 35N123W WITH A DEEP 
LAYERED TROUGH EXTENDING S TO A BASE AT 19N124W. A BROAD SURFACE 
TROUGH IS REFLECTED N OF 25N ALONG 120W. A BAND OF UPPER 
MOISTURE IS OBSERVED E OF THE TROUGH...ROUGHLY N OF 27N E OF 
117W ACROSS THE BAJA PENINSULA AND THE GULF OF CALIFORNIA...
BECOMING DENSE AS THE BAND MOVES N ACROSS SOUTHERN CALIFORNIA 
AND WESTERN ARIZONA. SOME MORE UPPER MOISTURE IS NOW SPREADING 
INTO THE NW PORTION...ROUGHLY TO THE N OF 28N W OF 130W. A BAND 
OF VERY DRY UPPER AIR IS INDICATED BETWEEN THESE TWO MOISTURE 
PLUMES...ROUGHLY FROM 20N TO 30N BETWEEN 118W AND 137W. 

AN UPPER TROUGH IS NOTED OVER THE TROPICS FROM 21N109W TO 
00N102W AND EFFECTIVELY SEPARATES THE UPPER FLOW OVER THE 
TROPICS WITHIN THE DISCUSSION AREA. A BROAD RIDGE EXTENDS N 
ACROSS THE EQUATOR TO THE W OF THE TROUGH SETTING UP A LARGE 
AREA OF UPPER DIFFLUENCE WHICH IS ENHANCING CONVECTION ALONG THE 
ITCZ AS PREVIOUSLY DESCRIBED. THE RESULTANT DEBRIS MOISTURE 
COVERS THE UPPER LEVELS FROM 03N TO 20N W OF 113W...THEN 
CONCENTRATES INTO A 660 NM WIDE TROPICAL PLUME THAT TURNS NE 
AHEAD OF THE PREVIOUSLY MENTIONED UPPER TROUGH AND CONTINUES 
ACROSS THE SOUTHERN GULF OF CALIFORNIA AND MOST OF NORTHERN OLD 
MEXICO...THEN FANS OUT ACROSS SE NEW MEXICO...ALL OF TEXAS AND 
LOUISIANA...AND THE OVER THE NW GULF OF MEXICO.       
    
A UPPER RIDGE EXTENDS NW FROM COLOMBIA ACROSS CENTRAL AMERICA TO 
A CREST OVER THE BAY OF CAMPECHE. WEAK UPPER DIFFLUENCE IS 
ENHANCING THE ISOLATED CONVECTION ALREADY DESCRIBED OVER THE 
PACIFIC WATERS S OF CENTRAL AMERICA. SOME OF THE RESULTANT 
DEBRIS MOISTURE IS ADVECTED N ACROSS COSTA RICA AND NICARAGUA. 
OTHERWISE...THE UPPER LEVELS ARE VERY DRY S OF 19N E OF 103W.

ELSEWHERE AT THE LOW LEVELS...A RIDGE EXTENDS FROM 29N140W TO 
18N108W. THE GRADIENT IS EXPECTED TO TIGHTEN NE OF THE RIDGE ON 
SAT NIGHT INCREASING THE NW FLOW TO 20 TO 25 KT ACROSS THE 
PACIFIC WATERS N OF 22N BETWEEN 100W AND 122W. NE TRADES S OF 
THE RIDGE SHOULD ALSO INCREASE TO 20 TO 25 KT ON SAT NIGHT 
ACROSS THE TROPICS FROM 03N TO 22N W OF 110W.  

.GULF OF CALIFORNIA...A TROUGH WILL DEEPEN OVER INTERIOR OLD 
MEXICO AND TIGHTEN THE GRADIENT WITH NW WINDS INCREASING TO 15 
TO 20 KT ON SAT NIGHT...AND FURTHER INCREASING TO 20 TO 25 KT BY 
LATE SUN. THE GRADIENT WILL BEGIN TO RELAX SOME SUN NIGHT BUT 
MAINTAIN NW 20 KT THROUGH LATE MON NIGHT.

GULF OF PAPAGAYO...NE WINDS ARE AT 20 TO 30 KT WITHIN 90 NM LINE 
11N86W TO 09N89W INCLUDING THE GULF OF PAPAGAYO RESULTING IN 
SEAS OF 7 TO 10 FT. THE GRADIENT WILL RELAX SOME TONIGHT AND SAT 
WITH THE BAND OF ENHANCED WINDS BOTH SHRINKING EASTWARD AND  
SHIFTING SLIGHTLY NORTHWARD. THE GRADIENT SHOULD ONLY SUPPORT 15 
TO 20 KT BY LATE SUN NIGHT.

GULF OF TEHUANTEPEC...N WINDS CURRENTLY AT 20 TO 25 KT SHOULD 
DIMINISH BECOMING LIGHT AND VARIABLE BY LATE TODAY. THE NEXT 
TEHUANTEPEC EVENT WILL BEGIN ON MON NIGHT BUT MAY ONLY MAX AT 30 
KT AROUND SUNRISE TUE.
    
$$
NELSON