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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1458Z Feb 08, 2018)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
958 AM EST THU FEB 08 2018

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

SYNOPSIS (VALID FROM FEB 07 AT 0000 UTC): AT 200 HPA...THE
BOLIVIAN HIGH/SUBTROPICAL RIDGE CENTERS OVER EXTREME SOUTHERN
PERU...AND EXTENDS AN AXIS EAST ACROSS BOLIVIA INTO MATO GROSSO. A
REGION OF ENHANCED INSTABILITY AND MOISTURE CONTENT EXTENDS ALONG
THE ALTIPLANO INTO THE CENTRAL ANDES OF PERU. THE UPPER HIGH IS
HELPING TO VENTILATE DIURNAL CONVECTION...WHICH IS FLARING UP FROM
CENTRAL PERU TO NORTHERN ARGENTINA PRODUCING LOCALLY HEAVY
RAINFALL AMOUNTS FOR THE REGION. TO THE EAST...AN UPPER TROUGH
LIES OVER SOUTHWESTERN PARA...AND CONNECTS WITH A TROUGH IN THE
WESTERLIES THAT EXTENDS FROM 30S 43W ALONG SAO PAULO INTO EASTERN
MATO GROSSO. VENTILATION IN THE PERIPHERY OF THE TROUGH IS
INTERACTING WITH THE NET TO PRODUCE DEEP CONVECTION IN
AMAZONAS-BRASIL...AND ALSO IN THE INTERIOR OF THE BRAZILIAN
NORDESTE...WHERE INSTABILITY REMAINS HIGH. THE STRONGEST
CONVECTION IN THE REGION IS OCCURRING OFF THE COASTS OF THE AMAZON
DELTA OR NORTHEASTERN PARA/AMAPA/MARANHAO IN BRASIL...WHERE ITCZ
CONVERGENCE IS INTERACTING WITH AN UPPER DIVERGENT PATTERN
ASSOCIATED WITH A NORTHERN HEMISPHERE TROUGH.

THE UPPER JET ANALYSIS SHOWS THE SOUTHERN POLAR FORMING 45S 109W
ALONG 45S 98W...A 137KT MAXIMA AT 43S 87W...50S 70W...A 147KT
MAXIMA AT 46S 59W...A 150KT MAXIMA AT 62S 35W...A 132KT MAXIMA AT
58S 15W...48S 12W...EXITING AT 42S 07W. THE NORTHERN POLAR FORMS
AT 35S 116W ALONG 43S 109W...41S 89W...A 140KT MAXIMA AT 46S
71W...53S 55W...57S 28W...41S 11W. A BRANCH OF THE SUBTROPICAL JET
HAS FORMED FROM 33S 95W ALONG 36S 86W...EXITING AT 36S 67W.
ANOTHER FINGER FORMS AT 21S 43W EXITING AT 31S 34W. IT REFORMS AT
33S 34W ALONG 36S 23W...A 134KT AT 34S 10W.

AT 500 HPA...AN EXTENSIVE SOUTHERN STREAM TROUGH EXTENDS FROM THE
ANTARCTIC PENINSULA NORTHWEST INTO THE SOUTHEASTERN PACIFIC TO 40S
80W...WHILE CROSSING THE SOUTHERN CONE. A ROBUST RIDGE TRAILS
BEHIND THE TROUGH WHILE EXTENDING ALONG 110-100W AND SOUTH INTO
60S. IN THE NORTHERN STREAM A RIDGE CENTERS ON A HIGH AT 28S 82W
AND EXTENDS ACROSS THE SUBTROPICAL EASTERN PACIFIC SOUTH TO 35S
AND EAST INTO LA SERENA. TO THE EAST...A SHORT WAVE TROUGH IS
CROSSING THE SANTA FE/WESTERN BUENOS AIRES PROVINCES IN ARGENTINA.
A BROADER TROUGH EXTENDS TO THE EAST WHILE CENTERING ON A LOW AT
31S 43W.

THE SURFACE ANALYSIS SHOWS A 962 HPA OCCLUDED LOW AT 63S 73W
EXTENDING AN OCCLUDED FRONT ALONG 64S 78W...67S 67W...61S
61W...55S 72W. A FRONT EXTENDS FROM 49S 61W ALONG A 100 HPA LOW AT
48S 66W...45S 67W...42S 72W...38S 83. A 1021 HPA HIGH CENTERS AT
33S 83W. A 1009 HPA HIGH CENTERS AT 40S 60W. A 998 HPA OCCLUDED
LOW AT 48S 48W EXTENDS A FRONT ALONG A 998 HPA LOW AT 50S
48W...46S 45W...43S 50W...A 1006 HPA LOW AT 41S 54W...38S 56W...A
1006 HPA LOW AT 35S 62W...31S 63W...29S 67W.

POMIER...SENAMHI (BOLIVIA)
BALBINO...INMET (BRASIL)
GALVEZ...WPC (USA)