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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1353Z Jan 13, 2015)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
853 AM EST TUE JAN 13 2015

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

SYNOPSIS (VALID FROM JANUARY 13 AT 00UTC): NORTH OVER THE
CONTINENT...AT 200 HPA...AN UNUSUAL FLOW PATTERN PERSISTS...WITH A
COLD CORE TROUGH ALOFT EXTENDING WEST ALONG 15S TO MINAS
GERAIS/BAHIA-TOCANTINS/GOIAS IN BRASIL WHILE ANCHORING ON A CLOSED
LOW AT 15S 45W. SOUTH OF THIS AXIS...THE SUBTROPICAL RIDGE EXTENDS
ACROSS SOUTHERN/SOUTHEAST BRASIL TO PARAGUAY...WHILE ANCHORING ON
A CLOSED HIGH NEAR 29S 45W. THE UNUSUAL JUXTAPOSITION OF THE RIDGE
AND TROUGH ALOFT IS DISTURBING CLIMATOLOGICAL AREAS OF
CONVECTION...WITH ORGANIZED ACTIVITY CONFINING TO PARA-ILHA DE
MARAJO IN BRASIL... WHILE THE SOUTHEAST STATES REMAIN UNUSUALLY
DRY. ALSO AT UPPER LEVELS...A SHORT WAVE TROUGH OVER CENTRAL PERU
IS ENHANCING CONVECTIVE DEVELOPMENT ACROSS THE SOUTHERN
SIERRA/JUNGLE TO PORTIONS OF BOLIVIA.

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH AXIS ALONG
63S 120W...59S 95W...50S 75W...48S 66W...A 138KT MAXIMUM AT 46S
54W...45S 43W...49S 32W...A 162KT MAXIMUM AT 48S 24W...46S
13W...AND 50S 02W. THE NORTHERN POLAR HAS ITS ENTRANCE AT 43S
113W...ALONG A 121KT MAXIMUM AT 48S 109W...51S 95W...A 134KT
MAXIMUM AT 51S 85W...EXITING AT 44S 77W. IT REFORMS AT 42S
70W...THEN ALONG 42S 63W...A 154KT MAXIMUM AT 43S 44W...44S
27W...A 121KT MAXIMUM AT 43S 09W...AND 43S 01W. THE SUBTROPICAL
JET HAS ITS ENTRANCE AT 27S 70W...THEN ALONG A 128KT MAXIMUM AT
38S 53W...39S 40W...35S 21W...AND 35S 05W.

AT MID LEVELS...THE 500 HPA ANALYSIS SHOWS A RIDGE WITH AXIS SOUTH
BETWEEN 100W-80W TO 53S...WHILE ANCHORING ON A HIGH AT 27S 92W.
BROAD TROUGH TO THE SOUTH AND EAST EXTENDS BETWEEN 90W-40W TO 38S.
SHORT WAVE TROUGH REVOLVE AROUND THIS AXIS...LIFTING ACROSS THE
SOUTHEAST PACIFIC TO THE SOUTHERN CONE OF SOUTH AMERICA. THESE
PROVIDE DYNAMICAL SUPPORT TO ORGANIZED CONVECTION ACROSS MID
SECTIONS OF ARGENTINA/LOWER MESOPOTAMIA VALLEY.

AT LOW LEVELS...A RIDGE ON THE NORTHERN STREAM DOMINATES FLOW OVER
THE EASTERN PACIFIC AS IT ANCHORS ON A 1025 HPA HIGH AT 35S 90W.
EAST OF THIS RIDGE...AN OCCLUDED 974 HPA LOW AT 50S 44W EXTENDS A
FRONT ALONG A 980 HPA LOW AT 49S 41W...39S 45W...36S 59W...
NORTHERN PATAGONIA...A 1010 HPA LOW AT 46S 78W...42S 83W...AND 45S
95W. THIS SUSTAINS ORGANIZED DEEP CONVECTION ACROSS THE BUENOS
AIRES PROVINCE-ENTRE RIOS IN ARGENTINA. A 1015 HPA POLAR HIGH TO
THE SOUTH CENTERS AT 40S 58W.

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