Prognostic Meteorological Discussion
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FXSA20 KWBC 211529
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1028 AM EST TUE FEB 21 2017

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

SYNOPSIS (VALID FROM FEBRUARY 18 AT 0000 UTC): AT 200 HPA...A CELL
OF THE SUBTROPICAL RIDGE/BOLIVIAN HIGH CENTERS OVER ANTOFAGASTA IN
CHILE. THIS RIDGE IS VENTILATING DEEP CONVECTION IN MOST OF
TROPICAL WESTERN SOUTH AMERICA...ESPECIALLY OVER THE CENTRAL
ANDES/ALTIPLANO AND THE WESTERN AMAZON BASIN. CONVECTION IS ALSO
BEING VENTILATED IN SOUTHERN ECUADOR/NORTHERN PERU IN INTERACTION
WITH THE SOUTH PACIFIC ITCZ AND THE DIURNAL CYCLE OF BREEZES. THE
CAVADO DO NORDESTE HAS REFORMED AND CENTERS ON A LOW AT 18S 33W. A
DIFFLUENT AND UPPER DIVERGENT PATTERN CONTINUES ESTABLISHED OVER
MOST OF NORTHERN BRAZIL/AMAZON DELTA...WHERE ACTIVE CONVECTION IS
OCCURRING.

THE UPPER JET ANALYSIS SHOWS THE NORTHERN POLAR JET EXTENDING
ALONG A 125KT MAXIMA AT 49S 120W...48S 98W...EXITING AT 51S 77W.
IT REFORMS AT 50S 72W ALONG A 142KT MAXIMA AT 51S 65W...A 146KT
MAXIMA AT 52S 55W...A 151KT MAXIMA AT 50S 45W...46S 33W. THE
SUBTROPICAL JET EXTENDS ALONG 43S 120W...A 157KT MAXIMA AT 43S
110W...A 167KT MAXIMA AT 46S 100W...47S 77W...49S 50W...44S 38W.
ANOTHER BRANCH OF THE SUBTROPICAL JET EXTENDS ALONG 36S 120W...42S
100W...EXITING AT 43S 77W. IT REFORMS AT 43S 69W ALONG 43S
40W...41S 24W.

AT 500 HPA...LONG FETCH WESTERLIES ARE ESTABLISHED BETWEEN 40S AND
50S. A FEW SHORT WAVE PERTURBATIONS ARE EMBEDDED IN THIS TROUGH
PATTERN. ONE EXTENDS AT 120W CENTERING ON A LOW AT 39S. A WEAKER
PERTURBATION EXTENDS ALONG 90W.

THE SURFACE ANALYSIS SHOWS A 998 HPA OCCLUDED LOW AT 58S 63W
EXTENDING A FRONT ALONG A 1002 HPA LOW AT 55S 59W...52S 61W...A
1006 HPA LOW AT 49S 69W...46S 69W...A 1010 HPA LOW AT 45S
75W...42S 77W...41S 80W. A 1021 HPA HIGH CENTERS AT 31S 84W. A
1013 HPA HIGH CENTERS AT 42S 41W. AN ILL-DEFINED BOUNDARY EXTENDS
ALONG 40S 43W...39S 51W...41S 62W. AIR MASS THUNDERSTORMS WERE
OCCURRING IN NORTHEASTERN ARGENTINA/RIO GRANDE DO SUL/SOUTHERN
PARAGUAY.

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




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