Prognostic Meteorological Discussion
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FXSA20 KWBC 221602
PMDSA

SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1101 AM EST WED FEB 22 2017

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

SYNOPSIS (VALID FROM FEBRUARY 22 AT 0000 UTC): AT 200 HPA...THE
SUBTROPICAL RIDGE/BOLIVIAN HIGH CONTINUES MEANDERING TO THE SOUTH
OF ITS CLIMATOLOGICAL POSITION. IT NOW CENTERS OFF THE COAST OF
ANTOFAGASTA/IQUIQUE IN CHILE...AT 22S 73W. THE HIGH EXTENDS A
RIDGE TO THE EAST INTO PARAGUAY AND SOUTHERN BRASIL. TO THE
NORTH...A LOW EXTENDS OVER RONDONIA. VENTILATION IS ENHANCED
BETWEEN THE HIGH AND LOW OVER MOST OF THE WESTERN AMAZON BASIN.
STRONGEST CONVECTION IS CLUSTERING IN TWO DIFFERENT REGIONS. ONE
ARE THE EASTERN SLOPES/SELVA ALTA OF ECUADOR AND NORTHERN
PERU...WHERE ORGANIZED CONVECTION IS FLARING UP. ANOTHER EXTENDS
IN THE CENTRAL AMAZON BASIN FROM RONDONIA TO THE NORTHEAST INTO
PARA AND THE AMAZON DELTA. CONVECTION HAS ALSO ACTIVATED IN THE
COASTS OF NORTHERN PERU AND ECUADOR...AIDED BY THE ACTIVATION OF
THE SOUTHERN BRANCH OF THE ITCZ. THE CAVADO DO NORDESTE CENTERS ON
A LOW OVER CENTRAL/SOUTHERN BAHIA. DIFFLUENCE AND DIVERGENCE TO
ITS NORTH CONTINUES VENTILATING SEASONAL CONVECTION ACROSS
NORTHEASTERN BRASIL. FINALLY...ALTIPLANO CONVECTION HAS
REACTIVATED UNDER THE INFLUENCE OF A MOIST TRANSPORT FROM THE
EAST-SOUTHEAST AT MID-LEVELS AND VENTILATION FROM THE SUBTROPICAL
RIDGE. CONVECTION IS FLARING ALONG THE WESTERN CORDILLERA FROM THE
ATACAMA REGION IN CHILE NORTH ACROSS BOLIVIA/NORTHERN CHILE INTO
MOST OF SOUTHERN PERU.

THE UPPER JET ANALYSIS SHOWS THE SOUTHERN POLAR JET EXTENDING
ALONG 50S 120W...EXITING AT 59S 97W. THE NORTHERN POLAR EXTENDS
ALONG 47S 120W...A 136KT MAXIMA AT 51S 103W...EXITING AT 54S 96W.
IT REFORMS AT 52S 94W ALONG A 146KT MAXIMA AT 52S 90W...A 157KT
MAXIMA AT 52S 80W...A 139KT MAXIMA AT 50S 70W...49S 61W...50S
55W...47S 46W...A 135KT MAXIMA AT 45S 40W...A 154KT MAXIMA AT 46S
30W. THE SUBTROPICAL JET EXTENDS ALONG 36S 120W...EXITING AT 37S
112W. IT REFORMS AT 37S 110W ALONG 41S 100W...45S 85W...EXITING AT
42S 69W.

AT 500 HPA...A BELT OF MID-LEVEL RIDGES IS ESTABLISHED OVER
CENTRAL-NORTHERN CHILE AND NORTHERN ARGENTINA-PARAGUAY-SOUTHERN
BRASIL. EMBEDDED IN THIS BELT...A SHORT WAVE TROUGH POSITIONS OVER
THE RIO DE LA PLATA BASIN/URUGUAY/RIO GRANDE DO SUL AS IT MOVES
INTO THE OPEN WATERS OF THE ATLANTIC. IN THE SOUTHERN STREAM...A
TIGHT AND ZONAL BELT OF WESTERLIES EXTENDS BETWEEN 42-43S AND
TIERRA DEL FUEGO. THIS IS LEADING TO WINDY CONDITIONS IN SOUTHERN
CHILE AND PATAGONIA. EMBEDDED IN THIS ZONAL FLOW...A SHORT WAVE
TROUGH CENTERS ON A LOW AT 44S AND 98W. IN THE SOUTHERN STREAM...A
BROAD LOW/TROUGH PATTERN EXTENDS OVER THE SOUTHEASTERN PACIFIC.
EMBEDDED IN THIS PATTERN...A SHORT WAVE TROUGH EXTENDS AN AXIS TO
THE NORTHEAST INTO A LOW THAT LIES AT 58S 78W...UPSTREAM OF THE
DRAKE PASSAGE.

THE SURFACE ANALYSIS SHOWS A 978 HPA OCCLUDED LOW AT 60S 82W
EXTENDING A FRONT INTO A 990 HPA TRIPLE POINT LOW AT 59S 69W...53S
67W...49S 72W. A FRONT EXTENDS ALONG A 1010 HPA LOW AT 42S
56W...39S 59W...A 1010 HPA LOW AT 42S 66W...42S 71W...43S 78W.
ISOLATED TO SCATTERED THUNDERSTORMS WERE OCCURRING TO THE NORTH OF
THIS FRONT IN CENTRAL ARGENTINA. A 1025 HPA HIGH CENTERS AT 34S
85W.

ABDEMUR...FAA (ARGENTINA)
TEPES...DMC (CHILE)
GALVEZ...WPC (USA)
$$





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