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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1413Z Jan 20, 2015)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
913 AM EST TUE JAN 20 2015

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

SYNOPSIS (VALID FROM JANUARY 20 AT 00UTC): NORTH OVER THE
CONTINENT...AT 200 HPA...ANOMALOUS CONDITIONS PREVAIL...WITH THE
SUBTROPICAL RIDGE CONFINING TO SOUTHEAST BRASIL/PARAGUAY WHILE
CENTERING ON A CLOSED HIGH OVER SAO PAULO. A TROUGH TO THE NORTH
EXTENDS FROM CENTRAL TO EASTERN BRASIL...WITH AXIS ANCHORING ON A
WANING LOW NEAR SANTA CRUZ IN EASTERN BOLIVIA AND A STRONGER LOW
NEAR 15S 35W. IN THIS PATTERN...MOST ACTIVE CONVECTION IS BUILDING
OVER THE CONTINENT TO THE NORTH OF 10S AND TO THE WEST OF 40W.
THERE IS ALSO A NORTHERN HEMISPHERE CROSS EQUATORIAL TROUGH WITH
AXIS TO THE SOUTHEAST FROM 10S 93W TO ECUADOR/NORTHERN PERU.

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR JET FORMING AT
65S 90W ALONG 60S 71W...56S 52W...EXITING AT 47S 48W. THE NORTHERN
POLAR FORMS AT 54S 109W ALONG 57S 88W...56S 67W...53S
58W...EXITING AT 45S 57W. IT REFORMS AT 41S 54W ALONG A 149KT
MAXIMA AT 41S 41W...A 139KT MAXIMA AT 42S 35W...44S 22W. THE
SUBTROPICAL JET FORMS AT 28S 86W EXITING AT 31S 80W. IT REFORMS AT
35S 67W ALONG BUENOS AIRES...37S 43W...40S 23W.

AT 500 HPA...LOW AMPLITUDE RIDGE ON THE SOUTHERN STREAM EXTENDS
OVER THE SOUTHEAST PACIFIC...WITH AXIS BETWEEN 100W-70W TO 60S. A
SHORT WAVE TROUGH TO THE NORTH EXTENDS BETWEEN 100W-80W AND TO THE
NORTH OF 35S WHILE CENTERING ON A LOW NEAR 33S 87W. SHORT WAVE
PERTURBATIONS TO THE SOUTH ARE STREAMING ACROSS THE BELLINGSHAUSEN
SEA TO THE DRAKE PASSAGE/TIERRA DEL FUEGO. OVER THE SOUTH
ATLANTIC...MEANWHILE...A BROAD TROUGH EXTENDS BETWEEN 30W AND
CENTRAL ARGENTINA. THIS IS FOCUSING SHORT WAVE ENERGY ACROSS
CENTRAL/NORTHERN PROVINCES...WHERE IT PROVIDES DYNAMICAL SUPPORT
TO ORGANIZED DEEP CONVECTION. FARTHER NORTH...A RIDGE EXTENDS WEST
ACROSS THE ATLANTIC ALONG 25S TO PARAGUAY...FAVORING A CAP
INVERSION ACROSS SOUTHEAST PORTIONS OF BRASIL-MATO GROSSO DO SUL
TO NORTHERN PARAGUAY/SOUTHERN BOLIVIA.

THE SURFACE ANALYSIS SHOWS A 976 HPA OCCLUDED LOW AT 66S 66W
EXTENDING A FRONT INTO A 974 HPA LOW AT 65S 58W...A 982 HPA LOW AT
60S 52W...56S 59W...A 996 HPA LOW AT 58S 67W...54S 83W...53S 103W.
RAINFALL WAS OCCURRING ACROSS SOUTHERN CHILE/DRAKE PASSAGE. A 1029
HPA HIGH CENTERS AT 46S 81W AND A 1025 HPA HIGH AT 41S 63W. A 994
HPA LOW AT 49S 37W EXTENDS A FRONT ALONG ANOTHER 994 HPA LOW AT
46S 34W...42S 36W...A 1002 HPA LOW AT 42S 39W...38S 42W...A 1010
HPA LOW AT 36S 47W...32S 51W...A 1010 HPA LOW AT 30S 54W...29S
60W...30S 66W. STRONG THUNDERSTORMS WERE OCCURRING ALONG THIS
SYSTEM IN CENTRAL/NORTHERN ARGENTINA AND NORTHERN URUGUAY/SOUTHERN
BRASIL.

ARREAGA...INAMHI (ECUADOR)
DURAN...SENAHMI (PERU)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)