623  
FXSA20 KWBC 261416  
PMDSA  
 
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
915 AM EST TUE DEC 26 2017  
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/  
 
SYNOPSIS (VALID FROM DEC 26 AT 0000 UTC): AT 200 HPA...A HIGH AT  
17S 62W ANCHORS A RIDGE OVER BOLIVIA-PERU-SOUTHEAST BRASIL...WITH  
AXIS UNDERCUTTING A TROUGH TO THE EAST. THE TROUGH EXTENDS ALONG  
18S 30W...15S 40W...10S 47W...TO PARA IN BRASIL. UNDER INFLUENCE  
OF THIS TROUGH AND THE RIDGE TO THE WEST ORGANIZED DEEP CONVECTION  
IS BUILDING OVER THE CONTINENT TO THE NORTH OF 20S...WITH MOST  
INTENSE FROM MATO GROSSO DO SUL TO AMAZONAS IN BRASIL AND SOUTHERN  
PERU/NORTHERN JUNGLE OF BOLIVIA.  
 
THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH ENTRANCE AT  
51S 119W...THEN ALONG A 128KT MAXIMUM AT 52S 109W...56S  
92W...EXITING AT 55S 79W. IT REFORMS AT 56S 74W...ALONG 53S  
56W...54S 41W...EXITING AT 57S 29W. THE NORTHERN POLAR HAS ITS  
ENTRANCE AT 46S 129W...THEN ALONG 47S 113W...EXITING AT 51S 91W.  
IT REFORMS AT 45S 76W...ALONG 48S 66W...A 134KT MAXIMUM AT 51S  
57W...50S 46W...EXITING AT 48S 36W. THE SUBTROPICAL JET LIES ALONG  
42S 120W...A 133KT MAXIMUM AT 45S 115W...46S 99W...EXITING AT 40S  
94W. IT REFORMS AT 40S 85W...ALONG 41S 73W...EXITING AT 43S 61W.  
IT REFORMS AT 26S 69W...THEN ALONG 29S 57W...30S 45W...35S  
31W...40S 21W...A 148KT MAXIMUM AT 40S 15W...EXITING AT 40S 08W.  
THE SUBEQUATORIAL JET HAS A FINGER AT 200 HPA WITH ENTRANCE AT 17S  
46W...ALONG 12S 52W...06S 54W...EXITING AT 02S 55W. A FINGER AT  
150 HPA LIES TO THE WEST...WITH AXIS ALONG 02S 110W...04S  
103W...EXITING AT 05S 95W.  
 
AT 500 HPA...A LOW AMPLITUDE RIDGE EXTENDS SOUTH BETWEEN 90W-100W  
TO 60S. THIS IS INDUCING THE NORTHWARD AMPLIFICATION OF A TROUGH  
ACROSS SOUTHERN CHILE TO PATAGONIA IN ARGENTINA. THE SHORT WAVE  
TROUGH REVOLVES AROUND A BROAD TROUGH ON THE SOUTHERN STREAM THAT  
EXTENDS BETWEEN 80W-30W AND TO THE SOUTH OF 45S...WHILE ANCHORING  
ON A CLOSED LOW AT 64S 51W. A SHORT WAVE TROUGH ON THE NORTHERN  
STREAM EXTENDS FROM 40S 35W TO 30S 43W.  
 
AT LOW LEVELS...THE SURFACE ANALYSIS SHOWS A RIDGE ON THE NORTHERN  
STREAM OVER THE EASTERN PACIFIC THAT CENTERS ON TWO 1023 HPA  
HIGHS...WITH ONE AT 30S 110W AND THE OTHER AT 31S 98W. BROAD  
TROUGH TO THE SOUTHEAST CENTERS ON AN OCCLUDED 062 HPA LOW AT 63S  
50W. THIS EXTENDS A POLAR FRONT ALONG A 970 HPA OCCLUDED LOW AT  
64S 32W...A 974 HPA LOW AT 61S 25W...56S 23W...53S 29W...54S  
36W...A 978 HPA LOW AT 54S 41W...48S 45W...47S 53W...47S 59W...A  
990 HPA LOW AT 47S 64W... NORTHERN PATAGONIA/LA PAMPA IN  
ARGENTINA...A 1006 HPA LOW AT 42S 73W...40S 75W...A 1014 HPA LOW  
AT 40S 84W...36S 91W...36S 97W...38S 106W...39S 110W...A 1010 HPA  
LOW AT 39S 116W...AND 31S 120W. ALSO OVER THE ATLANTIC...A  
NARROW/ELONGATED RIDGE LIES TO THE NORTH OF THE SURFACE FRONT  
WHILE CENTERING ON A 1017 HPA HIGH AT 36S 41W AND A 1017 HPA HIGH  
AT 42S 16W. ANOTHER FRONT TO THE NORTH LIES ALONG A 1002 HPA LOW  
AT 36S 29W...30S 31W...26S 37W....25S 46W...TO SAO PAULO TO  
SOUTHEAST PARAGUAY-CHACO ARGENTINO. ORGANIZED DEEP CONVECTION WAS  
CLUSTERING OVER SOUTHEAST BRASIL TO THE NORTH OF THIS BOUNDARY.  
 
OVIEDO...SHN (ARGENTINA)  
POMIER...SENAMHI (BOLIVIA)  
RIVAS...SENAMHI (PERU)  
DAVISON...WPC (USA)  

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab HPC Page Main Text Page