Prognostic Meteorological Discussion
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FXSA20 KWBC 231340
PMDSA

SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
940 AM EDT WED JUL 23 2014

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

SYNOPSIS (VALID FROM 23 JULY 00UTC): AT 200 HPA A LOW AMPLITUDE
RIDGE NOW EXTENDS OVER PARA/AMAZONAS IN BRASIL.  THIS IS VENTING
LATE AFTERNOON DIURNAL DEEP CONVECTION OVER NORTHERN SOUTH
AMERICA. SHALLOW CONVECTION...MEANWHILE...WAS CLUSTERING ACROSS
NORTHEAST COAST OF BRASIL AS ENHANCE BY A SHEAR LINE.

AT 250 HPA...THE SOUTHERN POLAR HAS ITS ENTRANCE AT 64S
104W...ALONG 57S 88W...EXITING AT 49S 73W. IT REFORMS AT 42S
58W...ALONG 48S 50W...A 168KT MAXIMUM AT 50S 40W...46S 24W...A
126KT MAXIMUM AT 40S 20W...EXITING AT 37S 16W. THE NORTHERN POLAR
HAS ITS ENTRANCE AT 32S 110W...ALONG 35S 107W...45S 103W...A 125KT
MAXIMUM AT 47S 90W...41S 83W...30S 78W...27S 69W...RIO DE LA
PLATA...42S 50W...A 125KT MAXIMUM AT 46S 40W...46S 30W...32S
19W...AND 29S 10W. THE SUBTROPICAL JET HAS ITS ENTRANCE AT 27S
88W...ALONG A 132KT MAXIMUM AT 25S 80W... NORTHERN CHILE...SANTA
CRUZ BOLIVIA...EXITING AT 17S 53W.

AT 500 HPA...A LONG WAVE RIDGE OVER THE EASTERN PACIFIC EXTENDS
SOUTH ALONG A CLOSED HIGH NEAR 18S 92W...30S 95W...50S 100W...TO
60S 120W. EAST OF THIS AXIS...TROUGH ON THE SOUTHERN STREAM
EXTENDS NORTH ACROSS THE BELLINGSHAUSEN SEA TO SOUTHERN
CHILE/PATAGONIA IN ARGENTINA...WHERE IT IS FOCUSING SHORT WAVE
ENERGY. THIS IS INTERACTING WITH A TROUGH TO THE NORTH THAT
EXTENDS FROM 50S 60W...ACROSS LA PAMPA IN ARGENTINA...SANTIAGO
CHILE...TO 22S 80W. THIS TROUGH SUPPORTS ORGANIZED DEEP CONVECTION
ACROSS SOUTHERN BRASIL-MISIONES IN ARGENTINA/SOUTHEAST PARAGUAY.

AT LOW LEVELS...A BROAD RIDGE OVER THE EASTERN PACIFIC ANCHORS ON
A 1037 HPA HIGH AT 36S 89W. SOUTHEAST OF THIS RIDGE...A BROAD
TROUGH EXTENDS ACROSS THE DRAKE PASSAGE TO SOUTHERN CONE OF SOUTH
AMERICA...WHILE ANCHORING ON AN OCCLUDED 974 HPA LOW AT 63S 71W. A
POLAR FRONT TO THE NORTH EXTENDS FROM AN OCCLUDED 986 HPA LOW AT
57S 68W...A 86 HPA LOW AT 56S 65W... SOUTHERN PATAGONIA...A 1002
HPA LOW AT 53S 76W...50S 83W...TO 51S 90W. THIS SUSTAINS SCATTERED
SNOW SHOWERS ACROSS TIERRA DEL FUEGO AND SOUTHERN PATAGONIA IN
ARGENTINA. OVER THE SOUTH ATLANTIC...A POLAR FRONT LIES ALONG A
1010 HPA LOW AT 47S 29W...43S 35W...A 1010 HPA LOW AT 44S
42W...39S 46W...A 1006 HPA LOW AT 37S 52W... NORTHERN URUGUAY...A
1006 HPA LOW AT 30S 57W...RESISTENCIA ARGENTINA TO SOUTHERN
BOLIVIA. THIS SUSTAINS ORGANIZED DEEP CONVECTION ACROSS
PARAGUAY-MESOPOTAMIA VALLEY IN ARGENTINA-SOUTHERN BRASIL AND
URUGUAY. SOUTH OF THIS FRONT...POLAR RIDGE IS BUILDING ACROSS
CENTRAL ARGENTINA...SUSTAINING A COLD ADVECTIVE PATTERN AND
GENERATION OF POST FRONTAL SNOWFALL EAST OF THE ANDES OVER MENDOZA
IN ARGENTINA. A RIDGE OVER THE ATLANTIC CENTERS ON A 1029 HPA HIGH
AT 29S 26W. AN OLD FRONT TO THE NORTH LIES ALONG 23S 13W...18S
23W...TO SOUTHERN BAHIA...WHERE IT FAVORS SCATTERED RAINFALL. A
PREFRONTAL SHEAR LINE EXTENDS FROM 20S 17W...ALONG 11S 26W...TO
RIO GRANDE DO NORTE...WHERE IT IS ENHANCING LOW LEVEL MOISTURE
CONVERGENCE.

FERNANDES...INMET (BRASIL)
JALFIN...SMN (ARGENTINA)
DAVISON...WPC (USA)

$$




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