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South American Synoptic Discussion
 
(Latest Discussion - Issued 1308Z Mar 27, 2015)
 
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Abbreviations and acronyms used in this product


SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
908 AM EDT FRI MAR 27 2015

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

SYNOPSIS (VALID FROM MARCH 27 AT 00UTC): AT 200 HPA...THE
SUBTROPICAL RIDGE IS WELL ESTABLISHED AT 15S 68W OR OVER MATO
GROSSO. THE RIDGE IS DOMINATING MOST OF TROPICAL AND SUBTROPICAL
SOUTH AMERICA FROM SOUTHEASTERN BRASIL INTO EASTERN PERU. THIS IS
VENTILATING DIURNAL CONVECTION ACROSS MOST OF TROPICAL SOUTH
AMERICA TO THE WEST OF 42W. MOST ACTIVE CONVECTION IS OCCURRING IN
THE SOUTHERN PERIPHERY OF THE RIDGE...WHERE CONVECTION IS BEING
ENHANCED BY SURFACE FEATURES AND THE DIVERGENT ENTRANCE OF AN
UPPER JET. OTHER REGION WITH ENHANCED CONVECTION EXTENDS ALONG THE
FOOTHILLS OF EASTERN PERU AND NORTHERN BOLIVIA.

AT 250 HPA...THE SOUTHERN POLAR JET FORMS AT 62S 90W ALONG A 154KT
MAXIMA AT 67S 66W...66S 51W...61S 37W...EXITING AT 57S 30W. THE
NORTHERN POLAR FORMS AT 39S 118W ALONG 39S 108W...46S
94W...EXITING AT 48S 79W. ANOTHER BRANCH EXTENDS FROM 52S 60W
ALONG 46S 61W...EXITING AT 41S 61W. THE SUBTROPICAL JET EXTENDS
ALONG 32S 119W...A 132KT MAXIMA AT 36S 112W...39S 99W...44S
86W...EXITING AT 45S 75W. IT REFORMS AT 38S 67W ALONG 33S
73W...EXITING AT 29S 77W. IT REFORMS AT 23S 73W ALONG 34S 59W...A
153KT MAXIMA AT 35S 41W...EXITING AT 33S 33W. ANOTHER BRANCH
EXTENDS FROM 19S 72W ALONG 30S 58W...33S 44W...EXITING AT 29S 29W.

AT 500 HPA...A ROBUST TROUGH EXTENDS ALONG 100W AND NORTH INTO
35S. THIS TROUGH CENTERS ON A LOW AT 45S 100W. TO THE
SOUTHEAST...A SHORT WAVE TROUGH EXTENDS ALONG 85W AND TO THE SOUTH
OF 48S AS IT MOVES TOWARDS THE DRAKE PASSAGE/TIERRA DEL FUEGO. A
RIDGE CONTINUES DOMINATING THE SOUTHERN CONE WHILE EXTENDING FROM
CONCEPCION/TEMUCO IN CHILE ACROSS PATAGONIA SOUTH INTO THE
MALVINAS/FALKLANDS. A WEAKENING BUT STILL WELL DEFINED CUT-OFF LOW
CENTERS JUST TO THE NORTH WEST OF LA SERENA IN CHILE AT 29S 74W.
THIS TROUGH IS SLOWLY SPILLING CYCLONIC VORTICITY ACROSS THE ANDES
INTO PORTIONS OF NORTHERN ARGENTINA. ANOTHER TROUGH IS EXITING THE
REGION OF INTEREST WHILE CENTERING ON A LOW AT 39S 39W.

AT LOW LEVELS...THE SURFACE ANALYSIS SHOWS A 990 HPA OCCLUDED LOW
AT 52S 85W EXTENDING A FRONT INTO A 1004 HPA LOW AT 54S 77W...48S
77W...A 1010 HPA LOW AT 44S 83W...41S 84W. A 1021 HPA POLAR HIGH
CENTERS AT 41S 58W. ANOTHER 1021 HPA HIGH CENTERS AT 50S 51W. A
998 HPA OCCLUDED LOW AT 38S 41W EXTENDS A FRONT INTO A 990 HPA LOW
AT 40S 35W...35S 35W...A 1008 HPA LOW AT 32S 37W...28S 44W...SANTA
CATARINA...A 1010 HPA LOW OVER NEEMBUCU IN PARAGUAY...NORTHERN
PARAGUAY-SOUTHERN BOLIVIA. WIDESPREAD SHOWERS AND A FEW
THUNDERSTORMS WERE OCCURRING ALONG AND AHEAD OF THIS SYSTEM. AREAS
OF RAINFALL WERE ALSO OCCURRING BEHIND THE FRONT IN NORTHERN
ARGENTINA/SOUTHERN PARAGUAY AND SOUTHERN BRASIL. A 1010 HPA LOW AT
31S 12W EXTENDS A FRONT INTO 24S 16W...19S 25W...15S 35W INTO
SOUTHERN BAHIA. A SHEAR LINE EXTENDS FROM17S 28W INTO 13S
32W...10S 36W.

ARREAGA...INAMHI (ECUADOR)
SCHNEIDER...INMET (BRASIL)
GALVEZ...WPC (USA)