SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1044 AM EST FRI JAN 16 2009
 
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
 
LAST NO AMENDS...NEXT BULLETIN JAN 21.

SYNOPSIS (VALID FROM 00Z JAN 16). AN UPPER LEVEL RIDGE REMAINS
OVER NORTHERN SOUTH AMERICA...WITH AXIS AT 200 HPA TRAVERSING THE
CONTINENT ALONG 18S/20S...WHILE CENTERING ON A CLOSED HIGH OVER
LAKE TITICACA. THE RIDGE ALOFT IS VENTING A MESO SCALE CONVECTIVE
SYSTEM OVER THE ALTIPLANO OF BOLIVIA...AND IT IS ALSO VENTING
ORGANIZED CONVECTION OVER RIO DE JANEIRO-MINAS GERAIS/GOIAS TO
MATO GROSSO IN CENTRAL BRASIL. A NEGATIVELY TILTED TROUGH BOUNDS
THE WESTERN PERIPHERY OF THIS RIDGE...AS IT EXTENDS ALONG 20S
105W...10S 95W...TO ECUADOR/NORTHERN PERU. EAST AND NORTH OF THIS
RIDGE...THE ANALYSIS SHOWS ANOTHER TROUGH...WITH AXIS ALONG A
CLOSED LOW NEAR 05S 38W...ILHA DE MARAJO...TO SOUTHERN GUIANAS/
RORAIMA. CONVECTION IS FLARING UP ALONG THIS AXIS ACROSS THE
NORTHERN COAST OF BRASIL AND SOUTH OF THE EQUATOR. 

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH ENTRANCE
AT 56S 111W...THEN ALONG 56S 98W...52S 85W...PUNTA ARENAS
CHILE...EXITING AT 55S 56W. IT REFORMS AT 57S 48W...ALONG A 152KT
MAXIMUM AT 66S 39W...AND 68S 28W. THE NORTHERN POLAR LIES ALONG
50S 120W...52S 105W...A 164KT MAXIMUM AT 49S 85W...A 173KT
MAXIMUM AT 49S 74W...50S 61W...EXITING AT 47S 48W. IT REFORMS AT
47S 46W...ALONG 52S 41W...63S 29W...EXITING AT 49S 09W. THE
SUBTROPICAL JET HAS ITS ENTRANCE AT 44S 104W...ALONG 45S
88W...EXITING AT 42S 73W. IT HAS A FINGER BETWEEN 38S 67W AND 31S
66W. ANOTHER FINGER EXTENDS BETWEEN 32S 57W AND 30S 46W.

AT 500 HPA...OVER THE FAR EASTERN PACIFIC...A BROAD/LOW AMPLITUDE
RIDGE DOMINATES THE NORTHERN STREAM FLOW...CENTERING ON TWO
CLOSED HIGHS...WITH ONE NEAR 34S 107W AND THE OTHER AT 27S 86W.
ON THE SOUTHERN STREAM...IN A TIGHT BELT OF WESTERLIES...
PROGRESSIVE SHORT WAVE PERTURBATIONS ARE STREAMING TOWARDS THE
SOUTHERN CONE...WITH ONE MOVING ALONG 85W AND SOUTH OF 45S...
WHILE ANOTHER IS SHEARING ACROSS THE DRAKE PASSAGE/TIERRA DEL
FUEGO. A PERTURBED PATTERN OVER THE SOUTHERN ANDES OF CHILE/
PATAGONIA STRONGLY SUGGESTS THE PRESENCE OF MOUNTAIN WAVE
TURBULENCE OVER THIS REGION. A THIRD PERTURBATION LIES FARTHER TO
THE EAST ALONG 45W TO 40S. THIS TROUGH IS INTERACTING WITH A
NORTHERN STREAM TROUGH THAT EXTENDS FROM A LOW AT 37S 43W TO
SOUTHERN BRASIL. TRAILING THIS SYSTEM...A STRONG CYCLONIC MAXIMUM
CENTERS OVER PARAGUAY. FARTHER DOWNSTREAM...A LONG WAVE RIDGE
EXTENDS ALONG 25W...ORIGINATING ON A HIGH AT 22S 27W.

AT LOW LEVELS...A RIDGE ON THE NORTHERN STREAM OVER THE EASTERN
PACIFIC CENTERS ON TWO HIGHS...A 1027 HPA AT 33S 104W AND A 1025
HPA AT 32S 92W. A TROUGH TO THE EAST/SOUTHEAST CENTERS ON AN
OCCLUDED 962 HPA LOW AT 55S 71W...WITH A FRONT ALONG A 978 HPA
TRIPLE POINT LOW AT 53S 64W...45S 64W...LA PAMPA/CONCEPCION
CHILE...37S 74W...A 998 HPA LOW AT 47S 77W...43S 79W...43S
85W...TO A 1014 HPA LOW AT 45S 93W. THIS SYSTEM FAVORS SCATTERED
CONVECTION WITH HEAVY RAINS ACROSS EXTREME SOUTHERN CHILE...AND
STRONG WINDS ACROSS PATAGONIA IN ARGENTINA. FARTHER EAST...A
FRONT LIES ALONG A 982 HPA LOW AT 57S 40W...52S 39W...46S
43W...RIO DE LA PLATA/NORTHERN BUENOS AIRES PROVINCE TO MENDOZA.
A 1015 HPA POLAR HIGH CENTERS NEAR 39S 58W. AN OCCLUDING 1002 HPA
LOW AT 37S 40W EXTENDS A FRONT ALONG A 1006 HPA TRIPLE POINT LOW
AT 37S 37W...30S 39W...TO SAO PAULO IN SOUTHEAST BRASIL...WHERE
IT IS INTERACTING WITH A TROUGH IN SUPPORT OF ORGANIZED DEEP
CONVECTION.

PEREZ...SENAMHI (BOLIVIA)
MOREYRA...SENAMHI (PERU)
DAVISON...HPC (USA)