966
FXSA20 KWBC 111244
PMDSA
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
843 AM EDT FRI MAY 11 2012
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
SYNOPSIS (VALID FROM 00UTC MAY 11): AT 200 HPA...IN A WINTER
TRANSITION PATTERN...WEAK CELL OF THE SUBTROPICAL RIDGE CONFINES
TO CONTINENTAL AREA TO THE NORTH OF 10S. A SHORT WAVE TROUGH TO
THE SOUTHEAST OF THIS AXIS EXTENDS ALONG 20S 37W TO NORTHEAST
BRASIL. THIS IS ENHANCING COASTAL CONVECTION ACROSS NORTHERN
BRASIL...WHILE THE RIDGE ALOFT IS VENTING DIURNAL CONVECTION
ACROSS PARA AND AMAZONAS TO THE WEST.
THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH AXIS ALONG
135KT MAXIMUM AT 47S 120W...50S 107W...57S 90W...EXITING AT 57S
78W. IT HAS A FINGER BETWEEN 51S 45W AND 50S 31W. THE NORTHERN
POLAR HAS ITS ENTRANCE AT 41S 123W...ALONG A 144KT MAXIMUM 42S
110W...47S 98W...52S 88W...A 130KT MAXIMUM AT 49S 79W...EXITING
NEAR PUERTO MONTT. A FINGER TO EAST EXTENDS FROM NEUQUEN AND
EXITING NEAR 38S 55W. IT REFORMS AT 41S 49W...ALONG 44S 41W...A
124KT MAXIMUM AT 41S 32W...37S 20W...AND 38S 07W. THE SUBTROPICAL
JET HAS ITS ENTRANCE AT 22S 89W...ALONG 24S 75W...A 120KT MAXIMUM
AT CHACO ARGENTINO...FLORIANOPOLIS...EXITING AT 28S 37W.
AT 500 HPA...A RIDGE IS BUILDING ACROSS THE EASTERN PACIFIC TO
THE SOUTHEAST ALONG 30S 105W...50S 80W TO THE DRAKE PASSAGE/
ANTARCTIC PENINSULA. EAST OF THIS AXIS...A SHORT WAVE TROUGH
EXTENDS ACROSS PATAGONIA IN ARGENTINA WHILE CENTERING ON A LOW
NEAR 50S 68W. FARTHER NORTH...IN A LOW AMPLITUDE TROUGH
PATTERN...SHORT WAVE PERTURBATIONS ARE STREAMING ACROSS
CENTRAL/NORTHERN CHILE-ARGENTINA INTO THE WESTERN ATLANTIC.
AT LOW LEVELS THE SURFACE ANALYSIS SHOWS A BROAD TROUGH OVER THE
SOUTHEAST PACIFIC. POLAR FRONTS REVOLVE AROUND THIS AXIS...THEN
STREAM TOWARDS THE DRAKE PASSAGE/SOUTHERN CONE OF SOUTH AMERICA.
IN THIS PATTERN...ONE EXTENDS ALONG A 994 HPA LOW AT 62S 77W...
58S 84W...A 986 HPA LOW AT 60S 93W...54S 97W...TO A 986 HPA LOW
AT 52S 102W. ANOTHER FRONT TRAILS...EXTENDING ALONG A 994 HPA LOW
AT 49S 100W...45S 98W...40S 102W...AND 35S 112W. THIS IS PRESSING
AGAINST A SHORT WAVE RIDGE TO THE EAST THAT CENTERS ON A 1021 HPA
HIGH AT 42S 85W. OVER THE ATLANTIC...AN OCCLUDING 998 HPA LOW AT
51S 63W EXTENDS A FRONT ACROSS LA PAMPA IN ARGENTINA-CONCEPCION
CHILE...TO A 1014 HPA LOW AT 36S 83W. THIS FAVORS SCATTERED
CONVECTION ACROSS EASTERN PATAGONIA TO SOUTHERN LA PAMPA. FARTHER
NORTH...A 994 HPA OCCLUDED LOW AT 38S 49W EXTENDS A FRONT ALONG A
998 HPA LOW AT 39S 47W...RIO GRANDE DO SUL...ENTRE RIOS...TO
JUJUY/SALTA IN NORTHWEST ARGENTINA. THIS FAVORS LIGHT TO MODERATE
RAINFALL ACROSS PARAGUAY-SOUTHERN BRASIL. A RIDGE TO THE EAST
CENTERS ON TWO 1017 HPA HIGHS...WITH ONE AT 38S 33W AND THE OTHER
AT 24S 37W.
PARRENO...INAMHI (ECUADOR)
VILLELA...INMET (BRASIL)
DAVISON...HPC (USA)
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