Prognostic Meteorological Discussion
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FXSA20 KWBC 181350
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
949 AM EDT THU SEP 18 2014

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

SYNOPSIS (VALID FROM SEPTEMBER 18 AT 00UTC): THE 200 HPA ANALYSIS
SHOWS AN OPEN CELL OF THE SUBTROPICAL RIDGE...WITH AXIS SOUTHWEST
FROM THE AMAZON RIVER DELTA/AMAPA IN NORTHERN BRASIL...ALONG 07S
70W...07S 90W INTO THE EASTERN TROPICAL PACIFIC. A SECONDARY RIDGE
EXTENDS TO THE SOUTHEAST FROM RONDONIA IN BRASIL TO RIO GRANDE DO
SUL. THE LATTER SUSTAINS AN INDUCED TROUGH TO THE EAST...WITH AXIS
NORTH ALONG 30S 35W...13S 40W TO ILHA DE MARAJO. SATELLITE IMAGERY
SHOWS SCATTERED DEEP CONVECTION ACROSS EQUATORIAL SOUTH AMERICA...
WITH OTHER CONVECTION DOTTING THE SIERRA OF PERU AND THE ALTIPLANO
OF BOLIVIA.

AT 250 HPA...THE JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH
ENTRANCE AT 53S 87W...ALONG A 128KT MAXIMUM AT 51S 78W...53S
65W...A 138KT MAXIMUM AT 55S 51W...EXITING AT 53S 29W. IT HAS A
FINGER TO THE NORTH WITH ENTRANCE AT 47S 91W...ALONG A 126KT
MAXIMUM AT 48S 73W...EXITING AT 45S 65W. THE NORTHERN
POLAR...MEANWHILE...LIES ALONG 36S 120W...A 137KT MAXIMUM AT 37S
116W...39S 101W...EXITING AT 39S 90W. IT REFORMS AT 29S
74W...ALONG 34S 69W...36S 55W...33S 43W...EXITING AT 31S 34W. THE
SUBTROPICAL JET HAS ITS ENTRANCE AT 19S 98W...ALONG 19S 87W...20S
80W...23S 73W...A 132KT MAXIMUM AT 27S 68W...A 137KT MAXIMUM AT
30S 53W...EXITING AT 24S 38W.

AT 500 HPA...IN A SPLIT FLOW PATTERN...FLOW IS DIVIDING BETWEEN A
RIDGE AND A TROUGH. THE RIDGE EXTENDS FROM 54S 105W TO 70S 110W.
THE TROUGH...MEANWHILE...ORIGINATES ON A CLOSED LOW AT 49S
105W...ALONG 43S 100W...TO 38S 100W. A BROAD TROUGH LIES TO THE
EAST...AS IT EXTENDS BETWEEN 90W-30W AND TO THE SOUTH OF
40S...ANCHORING ON A LOW OVER THE BELLINGSHAUSEN SEA WHILE
FOCUSING SHORT WAVE ENERGY ACROSS TIERRA DEL FUEGO/EXTREME
SOUTHERN PORTIONS OF CHILE. A TROUGH TO THE NORTH LIES OFF THE
CENTRAL/NORTHERN COAST OF CHILE WHILE CENTERING ON A LOW NEAR 33S
76W. A SHORT WAVE RIDGE LIES TO THE EAST... EXTENDING ACROSS
NORTHERN ARGENTINA. AN AREA OF DIVERGENCE DEVELOPED BETWEEN THESE
SYSTEMS AS ENHANCED BY JET MAXIMA ALOFT. THIS IS VENTING DEEP
CONVECTION ACROSS NORTHERN PROVINCES IN ARGENTINA AND PARAGUAY.

AT LOW LEVELS...A RIDGE ON THE NORTHERN STREAM CENTERS ON A 1025
HPA HIGH AT 31S 92W. AN ELONGATED POLAR FRONT LIES TO THE SOUTH...
EXTENDING FROM A 1002 HPA LOW AT 48S 78W...46S 83W...A 1002 HPA
LOW AT 47S 87W...45S 89W...A 1002 HPA LOW AT 46S 93W...42S
94W...AND 39S 97W. THIS SUSTAINS SCATTERED RAINS ACROSS SOUTHERN
PORTIONS OF CHILE. A BROAD TROUGH ON THE SOUTHERN STREAM SPANS
FROM THE ANTARCTIC PENINSULA TO THE SOUTHERN CONE OF SOUTH
AMERICA. A POLAR FRONT REVOLVING AROUND THIS AXIS ORIGINATES ON AN
OCCLUDED 962 HPA LOW AT 61S 53W...A 972 HPA LOW AT 62S 45W...57S
42W...52S 44W...50S 50W...49S 57W...A 990 HPA LOW AT 53S 64W...51S
65W...A 994 HPA LOW AT 50S 69W...TO CENTRAL PATAGONIA. THIS FAVORS
COASTAL CONVECTION OVER EASTERN PATAGONIA. ON THE NORTHERN
STREAM...OVER THE ATLANTIC...A 998 HPA LOW AT 40S 27W EXTENDS AN
OCCLUDED FRONT ALONG 37S 29W...44S 30W...46S 22W...A 1006 HPA LOW
AT 45S 17W...43S 17W... 41S 18W...A 1006 HPA LOW AT 40S 21W...35S
23W...27S 29W...22S 37W... RIO DE JANEIRO-FOZ DO
IGUAZU...PARAGUAY. SCATTERED DEEP CONVECTION WAS BUILDING TO THE
SOUTH ACROSS NORTHERN ARGENTINA. A RIDGE LIES OFF THE COAST OF
BRASIL WHILE CENTERING ON A 1025 HPA HIGH AT 35S 44W.

JALFIN...SMN (ARGENTINA)
CAROCA...DMC (CHILE)
DAVISON...WPC (USA)
$$





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