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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1504Z Jan 08, 2015)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1004 AM EST THU JAN 08 2015

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

SYNOPSIS (VALID FROM JANUARY 08 AT 00UTC): THE 200 HPA ANALYSIS
SHOWS A NARROW AND ELONGATED SUBTROPICAL RIDGE EXTENDING FROM
NORTHERN BOLIVIA INTO SANTA CATARINA IN BRASIL. THE RIDGE WAS
VENTILATING CONVECTION IN ITS PERIPHERY...ESPECIALLY TO ITS WEST
WHERE ENHANCED DIVERGENCE WAS OCCURRING BETWEEN RIDGE AND A
PERSISTENT TROUGH OVER THE EASTERN PACIFIC. THIS WAS VENTILATING
CONVECTION OVER THE ALTIPLANO DURING THE AFTERNOON...AND OVER THE
EASTERN FOOTHILLS DURING THE EARLY MORNING SUSTAINING AN ACTIVE
SEASONAL PATTERN OF CONVECTION. TO THE NORTHEAST OF THE RIDGE...A
POTENT CAVADO DO NORDESTE CENTERED ON A BROAD LOW OVER
TOCANTINS/NORTHWESTERN BAHIA...BUT WAS COVERING MOST OF
NORTHEASTERN BRASIL EXTENDING INTO CENTRAL AMAZONAS. UNDER THE
INFLUENCE OF THIS LARGE SCALE UPPER CONVERGENT PATTERN...DIURNAL
ACTIVITY WAS OCCURRING IN AN ISOLATED MANNER ACROSS NORTHERN MATO
GROSSO/SOUTHEASTERN AMAZONAS AND SOUTHERN PARA.

AT 250 HPA...THE JET ANALYSIS SHOWS THE SOUTHERN POLAR JET ALONG
70S 73W...57S 21W...EXITING AT 49S 55W. ANOTHER BRANCH FORMS AT
53S 74W...46S 55W...48S 35W...EXITING AT 53S 10W. THE NORTHERN
POLAR FORMS AT 10S 108W ALONG A 122KTR MAXIMA AT 45S 96W...47S
75W...EXITING AT 44S 68W. IT REFORMS AT 42S 60W ALONG A 164KT
MAXIMA AT 43S 39W...A 131KT MAXIMA AT 48S 19W. THE SUBTROPICAL JET
FORMS AT 40S 102W ALONG 44S 91W...EXITING AT 44S 78W. ANOTHER
BRANCH FORMS AT 26S 73W ALONG 34S 66W...A 130KT MAXIMA AT 38S
57W...39S 40W...40S 25W...EXITING AT 37S 16W.

AT 500 HPA AND IN THE SOUTHERN STREAM...A LARGE LONG WAVE TROUGH
EXTENDS OVER THE WEDDELL SEA INTO THE SOUTHERN ATLANTIC TO THE
SOUTH OF 40W. THIS IS LEADING TO A TIGHT BELT OF
WEST-SOUTHWESTERLIES OVER THE SOUTHERN CONE. AN INTENSE SHORT WAVE
TROUGH REVOLVES AROUND THE MAIN AXIS AND EXTENDS JUST TO THE SOUTH
OF TIERRA DEL FUEGO...FOCUSING ITS ENERGY OVER THIS REGION. IN THE
NORTHERN STREAM...A TROUGH EXTENDS FROM A LOW OVER CENTRAL CHILE
AT 35S 73W INTO A LOW AT 25S 82W. THIS TROUGH WAS SPILLING
CYCLONIC VORTICITY EAST OF THE ANDES INTO PORTIONS OF CENTRAL AND
NORTHERN ARGENTINA. TO THE NORTHEAST...A RIDGE CENTERED ON A HIGH
OVER EASTERN PARAGUAY WHILE A WEAK LOW CENTERED OVER THE RIO DO
JANEIRO REGION.

AT LOW LEVELS...THE SURFACE ANALYSIS SHOWS A 992 OCCLUDED LOW AT
60S 73 WAS PRODUCING RAIN OVER SOUTHERN TIERRA DEL FUEGO. A 982
HPA OCCLUDE LOW AT 57S 54W EXTENDS A FRONT INTO A 994 HPA LOW AT
51S 53W...50S 59W...A 994 HPA LOW AT 53S 62W...A 998 HPA LOW AT
52S 68W...54S 77W. A 998 HPA LOW AT 51S 85W EXTENDS A FRONT INTO A
1002 HPA LOW AT 49S 80W...A 1010 HPA LOW AT 46S 83W...42S 93W. A
1012 HPA LOW AT 36S 42W EXTENDS A FRONT INTO 32S 49W...38S 64W.
TWO 1013 HPA HIGHS EXTEND OFF THE COAST OF THE RIO DE LA
PLATA...ONE AT 36S 49W AND ANOTHER AT 40S 58W..

ARREAGA...INAMHI (ECUADOR)
DURAN...SENAMHI (PERU)
GALVEZ...WPC (USA)