429  
FXSA20 KWBC 111931  
PMDSA  
 
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
231 PM EST THU JAN 11 2018  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
 
SYNOPSIS (VALID FROM 00Z NOV 28)... AT THE 200 HPA THE BOLIVIAN  
HIGH IS CURRENTLY CENTERED OVER NORTH CENTRAL AMAZONIA AND IS  
EXTENDING A WEAK BROAD RIDGE SOUTH DOWN THE SOUTHERN CONE INTO  
NORTHERN ARGENTINA. TO THE NORTH IS A BROAD AREA OF UPPER  
DIFFLUENCE HELPING TO VENT DEEP CONVECTION. THERE IS AN UPPER LOW  
OFF THE COAST OF URUGUAY NEAR 34S 42W. NEAR ZONAL FLOW IS FOUND  
OVER THE SOUTHERN CONE WHILE A BROAD UPPER TROUGH EXTENDS NORTH  
FROM ANTARCTICA ALONG 95W THEN NORTHWEST ALONG 34S 96W... 27S  
110W. THERE IS A BROAD ANTICYCLONE NORTHWEST OF THE GALAPAGOS  
ISLANDS AT 5N 96W.  
 
JET ANALYSIS AT 250 SHOWS THE SUBTROPICAL JET ENTERING AT 24S 70W  
AND CONTINUING ALONG 26S 49W.. 28S 39W.. 33S 28W.. EXITING 38S  
21W. THE NORTH POLAR JET ENTERS 41S 138W CONTINUES 34S 139W.. 28S  
134W... 28S 128W.. 32S 124W.. 40S 127W.. EXITING 48S 126W. IT  
REFORMS 51S 109W.. CONTINUES ALONG 49S 103W AND EXITS 44S 100W. IT  
REFORMS AT 40S 102W... CONTINUING ALONG 38S 99W... 32S 76W.. 32S  
63W... 32S 52W... 32S 41W.. 39S 30W... 47S 21W EXITING 49S 3W. THE  
SOUTH POLAR JET IS FOUND AT 60S 126W.. CONTINUING ALONG 56S  
106W... WITH 120 KT MAXIMUM AT 52S 95W...EXITING 46S 92W. IT  
REFORMS AT 67S 109W.. AND EXITS 56S 90W. IT REFORMS 51S 76W AND  
EXITS 54S 90W. REFORMS AGAIN 53S 76W.. CONTINUES 46S 47W... AND  
EXITS 43S 44W. REFORMS 44S 32W... CONTINUES 53S 19W... EXITING 54S  
5W.  
 
AT 500 HPA THERE IS A STRONG UPPER VORTEX LOCATED OFF THE COAST OF  
SOUTHERN BRASIL CENTERED NEAR 34S 41W. THERE IS A BROAD UPPER  
TROUGH OVER THE SOUTH PACIFIC EXTENDING NORTH AND WEST FROM A  
VORTEX JUST WEST OF THE ANTARCTIC PENINSULA AT 71S 89W. THIS  
TROUGH EXTENDS ALONG 90W TO A STRONG SHORTWAVE TROUGH WEST OF THE  
DRAKE PASSAGE AT 56S 86W THEN NORTHWEST ALONG 46S 91W... 40S  
93W... 35S 97W... 28S 102W... 19S 111W. FARTHER WEST OF THE DRAKE  
PASSAGE IS ANOTHER... STRONGER.. SHORTWAVE TROUGH APPROACHING THE  
SOUTHERN CONE AT 51S 105W.  
 
AT THE SURFACE THERE IS A 1006 HPA OCCLUDED LOW OFF THE COAST OF  
SOUTHERN BRASIL AT 34S 42W.. WITH OCCLUION ALONG 33S 40W... 32S  
44W.. 37S 43W.. TO 1010 HPA TRIPLE POINT LOW AT 38S 78W.. COLD  
FRONT 356S 35W... 31S 33W.. WAVE AT 25S 34W... COLD FRONT  
CONTINUING 21S 35W.. 17S 40W.. STATIONARY FRONT 17S 44W.. 19S 51W.  
THERE IS A 1033 HPA HIGH OVER THE SOUTH ATLANTIC AT 37S 8W. THERE  
IS A 1006 HPA LOW AT 49S 48W... OCCLUSION ALONG 50S 48W... 1004  
HPA LOW 53S 44W.. COLD FRONT 50S 41W... 45S 46W.. 42S 51W. 1017  
HPA HIGH 38S 50W. 1017 HPA HIGH 42S 62W. THERE IS A 986 HPA LOW AT  
62S 62W.. OCCLUSION ALONG 61S 65W.. 63S 61W... 986 HPA TRIPLE  
POINT LOW 62S 57W.. COLD FRONT 60S 56W... 54S 59W... WARM FRONT  
59S 51W. THERE IS A 978 LOW AT 56S 84W.. OCCLUSION ALONG 54S  
84W... 55S 88W... 58S 84W... 984 HPA LOW 57S 79W... WARM FRONT 57S  
76W... 56S 72W... COLD FRONT 56S 78W... 50S 79W... 46S 84W... 43S  
88W... WAVE 39S 93W... COLD FRONT 34S 93W... 31S 96W... 29S 104W..  
STATIONARY FRONT 28S 110W... 25S 116W. THERE IS A 988 HPA LOW AT  
50S 110W... OCCLUSION 52S 110W... 54S 105W... 52S 102W... 978 HPA  
LOW AT 52S 104W... WARM FRONT 49S 100W... 44S 98W... COLD FRONT  
47S 103W... 43S 108W... 39S 116W. THERE IS A 1029 HPA HIGH OVER  
THE SOUTH PACIFIC AT 39S 131W. OVER THE ATLANTIC AND PACIFIC THE  
ITCZ LIES BETWEEN 7 AND 10 NORTH.  
 
CONTRERAS...DMC (CHILE)  
TOLMOS......SENAMHI-DIRMA (PERU)  
ROBSON......HPC (USA)  

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page