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000
FXSA20 KWBC 281336
PMDSA

SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
936 AM EDT TUE JUL 28 2015

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

SYNOPSIS (VALID FROM JUL 28 AT 0000 UTC): A WESTERLY/NEAR ZONAL
FLOW DOMINATES THE UPPER LEVELS ACROSS NORTHERN PORTIONS OF SOUTH
AMERICA. IN THIS PATTERN...DIURNAL DEEP CONVECTION CONFINES TO
EQUATORIAL SOUTH AMERICA...AFFECTING THE NORTHERN PORTIONS OF
PARA-AMAZONAS/RORAIMA IN BRASIL-NORTHERN PERU AND EASTERN ECUADOR.
SHALLOW CONVECTION OVER NORTHEAST BRASIL ASSOCIATES WITH TRADE
WIND EASTERLY CONVERGENCE.

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH ENTRANCE AT
35S 100W...ALONG 34S 91W...EXITING AT 36S 83W. IT REFORMS AT 39S
74W...ALONG 47S 60W...53S 45W...54S 26W...A 125KT MAXIMUM AT 50S
15W...AND 45S 06W. THE NORTHERN POLAR HAS ITS ENTRANCE AT 37S
120W...ALONG 33S 108W...A 140KT MAXIMUM AT 32S 96W...32S 81W...A
140KT MAXIMUM AT 33S 71W...EXITING AT 39S 57W. THE SUBTROPICAL JET
LIES ALONG A 160KT MAXIMUM AT 33S 120W...A 155KT MAXIMUM AT 28S
100W...28S 90W...29S 53W...EXITING AT 31S 59W. THE JET REFORMS AT
18S 41W...ALONG 25S 30W...27S 23W...A 140KT MAXIMUM AT 27S
15W...AND A 145KT MAXIMUM AT 25S 01W.

AT 500 HPA...BROAD LONG WAVE TROUGH DOMINATES THE FLOW BETWEEN
120W-60W AND TO THE SOUTH OF 20S. THIS IS FOCUSING SHORT WAVE
ENERGY ACROSS CENTRAL PORTIONS OF CHILE INTO ARGENTINA. A LOW
AMPLITUDE RIDGE TO THE EAST EXTENDS FROM BOLIVIA TO THE SOUTHERN
STATES OF BRASIL/URUGUAY. DOWNSTREAM FROM THIS AXIS...A SHORT WAVE
TROUGH LIES OFF THE SOUTHEAST COAST OF BRASIL...WITH AXIS
CENTERING ON A CLOSED LOW NEAR 32S 44W.

AT LOW LEVELS...BROAD TROUGH DOMINATES FLOW ACROSS THE EASTERN
PACIFIC-SOUTHERN CONE OF SOUTH AMERICA. POLAR FRONTS REVOLVE
AROUND THIS AXIS WITH ONE ORIGINATING ON AN OCCLUDED 962 HPA LOW
AT 67S 106W...ALONG A 974 HPA LOW AT 71S 104W...67S 84W...62S
93W...A 978 HPA LOW AT 59S 46W...53S 92W...A 990 HPA LOW AT 49S
94W...43S 92W...A 1002 HPA LOW AT 40S 94W...33S 106W...TO 31S
111W. ANOTHER FRONT TO THE EAST EXTENDS FROM AN OCCLUDED 990 HPA
LOW AT 53S 63W...ALONG A 998 HPA LOW AT 53S 54W...47S 57W...A 1002
HPA LOW AT 44S 65W...40S 64W...36S 68W...33S 72W...30S 83W...29S
95W...TO A 1014 HPA LOW AT 28S 99W. POST FRONTAL LIGHT CONVECTION
WAS REPORTED OVER SOUTHERN-CENTRAL CHILE. OVER THE ATLANTIC...AN
OCCLUDED 1014 HPA LOW AT 32S 44W EXTENDS A FRONT ALONG A 1018 HPA
LOW AT 35S 44W...33S 41W...29S 40W...A 1018 HPA LOW AT 27S
41W...RIO DE JANEIRO/SOUTHERN MINAS GERAIS TO MATO GROSSO DO SUL
WHERE IT WEAKENS.

CHARPENTIER...DMC (CHILE)
ROMERO...DMC (CHILE)
DAVISON...WPC (USA)
$$




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