482
FXSA20 KWBC 021400
PMDSA
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1000 AM EDT THU OCT 02 2008
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
NOTE: THERE WILL BE NO AMENDMENTS TO THIS PRODUCT UNTIL 06 OCT
2008.
SYNOPSIS (VALID FROM 00Z OCT 02)...AT 200 HPA...A STRONG HIGH
CENTERED OVER SOUTHERN PERU NEAR 14S 74W EXTENDS A RIDGE AXIS
EASTWARD THROUGH NORTHERN BOLIVIA AND MATO GROSSO. ANOTHER RIDGE
AXIS IN THE SUBTROPICAL ATLANTIC EXTENDS WESTWARD ACROSS THE
NORTHERN HALF OF NORTHEAST BRASIL. THE TROUGH THAT RAN ALONG THE
EASTERN BORDER OF TOCANTINS AND GOIAS YESTERDAY HAS SLID EASTWARD
AND IS NOW ALIGNED FROM ESPIRITO SANTO NORTHWEST THROUGH MINAS
GERIAS AND SOUTHWESTERN SECTIONS OF NORTHEAST BRASIL. IN
ADDITION...THERE IS ANOTHER WEAK TROUGH ACROSS EASTERN AMAZONIA.
A COL REGION IS PRESENT OVER TOCANTINS AT THE INTERSECTION OF ALL
FOUR OF THESE FEATURES. CONVECTION IS MOSTLY ISOLATED TO
SCATTERED OVER THE TROPICS HOWEVER THERE IS A HIGHER
CONCENTRATION IN THE VICINITY OF THIS COL REGION WHERE UPPER
VENTILATION IS ENHANCED. MODELS ANALYSES ALSO SUGGEST SOME
LOW-LEVEL SPEED CONVERGENCE WHICH MAY BE HELPING TO ENHANCE LIFT
AS WELL. SCATTERED CONVECTION CAN ALSO BE FOUND OVER THE HIGHER
TERRAIN IN SOUTHERN AND CENTRAL PERU.
AT 250 HPA THE SOUTHERN POLAR JET INITIATES AT 64S 97W AND
EXTENDS THROUGH 60S 91W 55S 90W EXITING AT 52S 88W. IT
REDEVELOPS AT 47S 86W AND CONTINUES ACROSS 46S 77W 48S 68W 52S
63W EXITING AT 57S 60W. IT AGAIN REDEVELOPS FARTHER SOUTH AT 63S
65W THEN RUNS ALONG 67S 50W 66S 34W THROUGH A 146 KT JET MAXIMUM
NEAR 64S 21W BEFORE EXITING AT 59S 11W. THE NORTHERN POLAR JET
BEGINS AT 41S 103W AND EXTENDS THROUGH 41S 90W 41S 79W EXITING AT
41S 70W. THE SUBTROPICAL JET INITIATES AT 21S 92W CONTINUES
ALONG 25S 86W 30S 80W THEN PASSES THROUGH A 137 KT JET MAXIMUM AT
29S 73W. THIS BRANCH CONTINUES ACROSS 27S 68W 24S 63W EXITING AT
22S 58W. IT REDEVELOPS OVER SOUTHERN BRASIL AT 28S 51W AND
EXTENDS ALONG 30S 47W CROSSING A 124 KT JET MAXIMUM AT 30S
42W THEN CONTINUING THROUGH 28S 38W BEFORE EXITING AT 27S 34W.
AT 500 HPA A POLAR VORTEX CENTERED AT 64S 83W ANCHORS A STRONG
TROUGH WITH A MEAN AXIS THAT RUNS ALONG 75-80W NORTHWARD TO ABOUT
40S. ONE SHORT WAVE IMPULSE IS LIFTING UP THE EASTERN SIDE OF
THIS TROUGH AND EXTENDS FROM 59S 72W THROUGH 55S 69W 50S 70W 47S
73W. MUCH OF THE SIGNIFICANT WEATHER WITH THIS SYSTEM HAS MOVED
OUT OF THE SOUTHERN CONE. ANOTHER WAVE IS DIVING TOWARD THE BASE
OF THE TROUGH AND IT RUNS FROM 54S 81W ACROSS 48S 84W 43S 90W 40S
92W. UPPER DYNAMICS WITH THIS FEATURE COMBINED WITH AN UNSTABLE
AIR MASS UNDER THE TROUGH ARE SUPPORTING SHOWERS OVER EXTREME
SOUTHERN CHILE. THE NORTHERN STREAM TROUGH THAT WAS OFF THE
CHILEAN COAST YESTERDAY HAS PROGRESSED QUICKLY EASTWARD AND TAKEN
ON A NEGATIVE TILT EXTENDING FROM 40S 62W THROUGH 34S 58W 29S
54W 23S 52W. STRONG LIFT ASSOCIATED WITH THIS SYSTEM IS
ENHANCING CONVECTION ACROSS SOUTHEAST BRASIL AND ALSO SUPPORTING
SCATTERED ACTIVITY OVER CENTRAL URUGUAY. ELSEWHERE A SUBTROPICAL
RIDGE EXTENDS FROM NORTHERN BOLIVIA ACROSS MATO GROSSO.
AT THE SURFACE THERE ARE A SERIES OF BOUNDARIES ASSOCIATED WITH
THE SOUTHERN STREAM UPPER TROUGH OVER THE SOUTHERN CONE. A COLD
FRONT EXTENDS FROM A 988 HPA LOW NEAR 57S 56W ACROSS 52S 56W 49S
58W THEN BECOMES STATIONARY AT 46S 60W AND CONTINUES NORTHWARD
THROUGH 42S 62W TO A 1014 HPA WAVE AT 39S 62W. A COLD FRONT
STRETCHES FROM THIS LOW THROUGH 37S 58W 35S 57W 32S 57W. SOME
CONVECTION IS FIRING ALONG THE TAIL END OF THIS FRONT IN CENTRAL
URUGUAY. A STRONG 968 HPA CYCLONE IS LOCATED IN THE DRAKE
PASSAGE NEAR 59S 71W AND HAS AN ASSOCIATED OCCLUDED FRONT RUNNING
FROM 55S 72W THROUGH 57S 74W 59S 75W REACHING A TRIPLE POINT AT
60S 69W. FROM HERE A COLD FRONT EXTENDS THROUGH 57S 64W TO A 984
HPA WAVE NEAR 55S 63W BEFORE CONTINUING THROUGH 52S 61W 47S
64W 43S 67W. THIS FRONT BECOMES STATIONARY AT 41S 70W BEFORE
ENCOUNTERING A 1018 HPA WAVE NEAR THE CHILEAN COAST AT 41S 75W.
FROM THIS POINT A COLD FRONT EXTENDS THROUGH 39S 81W 39S 88W 39S
98W. A 990 HPA LOW IS CENTERED AT 52S 80W WITH AN OCCLUDED FRONT
STRETCHING FROM 52S 81W THROUGH 54S 80W 53S 77W INTO A 998 HPA
TRIPLE POINT LOW NEAR 50S 76W. A WARM FRONT EXTENDS FROM THE
TRIPLE POINT ACROSS 47S 76W 44S 80W WHILE A COLD FRONT RUNS FROM
THE TRIPLE POINT THROUGH 47S 80W 45S 87W 45S 94W 45S 103W.
FARTHER NORTH A WAVY STATIONARY FRONT EXTENDS FROM 20S 37W ACROSS
21S 44W 26S 50W 21S 55W THROUGH A 1002 HPA LOW AT 19S 61W BEFORE
CONTINUING THROUGH 14S 66W 11S 70W 8S 74W. MID-UPPER LEVEL SHORT
WAVE ENERGY IS HELPING TO TRIGGER ORGANIZED CONVECTION IN THE
VICINITY OF THIS FRONT MAINLY FROM NORTHERN PARAGUAY EASTWARD
THROUGH SOUTHERN BRASIL AND FARTHER WEST THROUGH SOUTHERN PERU
AND WESTERN BOLIVIA.
URRA.....DMC (CHILE)
MOREYRA...SENAMHI PERU
KLEIN..HPC (USA)
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