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South American Synoptic Discussion
 
(Latest Discussion - Issued 1404Z Apr 17, 2015)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1004 AM EDT FRI APR 17 2015

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

SYNOPSIS (VALID FROM APRIL 17 AT 00UTC): NORTH OVER THE CONTINENT
AT 200 HPA...BROAD RIDGE ENVELOPS AREA TO THE NORTH OF 35S WHILE
ANCHORING ON A HIGH AT 14S 56W. THIS IS VENTING DEEP CONVECTION
OVER THE CONTINENT TO THE NORTH OF 20S AND WEST OF 45W. MOST
ACTIVE CLUSTERS TO THE NORTH ALONG THE NEAR EQUATORIAL TROUGH OVER
BRASIL-SOUTHERN VENEZUELA TO COLOMBIA.

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR JET ALONG A
129KT MAXIMA AT 58S 129W...63S 106W...63S 80W...58S 64W...56S
42W...50S 33W...EXITING AT 42S 27W. THE NORTHERN POLAR JET FORMS
AT 37S 120W ALONG A 140KT MAXIMA AT 42S 100W...44S 81W...EXITING
AT 33S 69W. IT REFORMS AT 33S 68W ALONG 37S 64W...EXITING AT 43S
63W. IT REFORMS AT 47S 61W ALONG 46S 50W...38S 43W. THE
SUBTROPICAL JET FORMS AT 20S 82W ALONG A 138KT MAXIMA AT 27S
70W...30S 57W...39S 49W...EXITING AT 28S 40W.

AT 500 HPA A SKEWED RIDGE EXTENDS TO THE SOUTHEAST ALONG 40S
130W...53S 110W...TO 54S 90W. THIS UNDERCUTS A TROUGH TO THE EAST
AND NORTH...AS THE LATTER STRETCHES ACROSS THE DRAKE
PASSAGE-TIERRA DEL FUEGO...50S 90W...A LOW AT 47S 100W...38S
120W...TO 30S 127W. SHORT WAVE RIDGES OVER THE FAR EASTERN PACIFIC
AND THE WESTERN ATLANTIC BOOKEND A SHORT WAVE TROUGH OVER THE
SOUTHERN CONE. THIS EXTENDS FROM A CLOSED LOW AT 41S 69W TO
CENTRAL CHILE/MENDOZA IN ARGENTINA. THE TROUGH IS FOCUSING SHORT
WAVE ENERGY ACROSS THE CENTRAL PROVINCES IN ARGENTINA...WHERE IT
SUSTAINS ORGANIZED DEEP CONVECTION.

THE SURFACE ANALYSIS SHOWS A 962 HPA OCCLUDED LOW AT 65S 50W
EXTENDING A FRONT INTO A 970 HPA LOW AT 62S 47W...58S 55W...55S
75W...52S 85W. SHOWERS WERE BEING REPORTED AT PUERTO WILLIAMS. A
1006 HPA LOW AT 50S 82W EXTENDS A FRONT INTO A 1002 HPA LOW AT 49S
79W...46S 80W...45S 84W. A WARM FROM EXTENDS FROM THE
AFOREMENTIONED 1002 HPA LOW INTO 44S 78W. A 1025 HPA HIGH CENTERS
AT 36S 80W. ANOTHER 1025 HPA HIGH CENTERS AT 41S 46W. A 1010 HPA
OCCLUDED LOW AT 41S 65W EXTENDS A FRONT TO THE NORTHEAST INTO A
1010 HPA LOW AT 37S 61W. A COLD FRONT THEN EXTENDS INTO 34S 63W
AND 31S 68W. HEAVY THUNDERSTORMS WERE OCCURRING OVER PARTS OF
CENTRAL ARGENTINA.

CALLE...UNALM (PERU)
CHARPENTIER...DMC (CHILE)
SCHNEIDER...INMET (BRASIL)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)