604
FXSA20 KWBC 191306
PMDSA
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
906 AM EDT TUE AUG 19 2008
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
SYNOPSIS (VALID FROM 00Z AUG 19). THE ANALYSIS AT 200 HPA SHOWS
THE SUBTROPICAL RIDGE DOMINATING CONTINENTAL FLOW NORTH OF
20S...CENTERING ON TWO CLOSED HIGHS...WITH ONE NEAR 09S 67W AND
THE OTHER AT 17S 52W. THE PERSISTENT RIDGE PATTERN...THIS EARLY
IN THE SEASON...IS SUGGESTIVE OF AN EARLY ONSET OF THE RAINY
SEASON OVER TROPICAL SOUTH AMERICA. THE SATELLITE IMAGERY CLEARLY
REFLECTS THIS PATTERN...AS IT SHOWS DEEP CONVECTION BUILDING IN
CLUSTERS ACROSS PARA-AMAZONAS IN WESTERN BRASIL...THE JUNGLE OF
PERU AND ECUADOR. ADDITIONALLY...SCATTERED DEEP CONVECTION WAS
ALSO BUILDING ON THE SIERRA OF PERU AND THE ALTIPLANO OF BOLIVIA.
AT 250 HPA...THE SOUTHERN POLAR LIES ALONG 59S 120W...61S 104W...
65S 80W...61S 62W...EXITING AT 55S 51W. IT REFORMS AT 45S
96W...ALONG 39S 89W...33S 80W...37S 70W...EXITING AT 42S 61W. IT
REFORMS AT 43S 58W...ALONG47S 35W...A 158KT MAXIMUM AT 53S
14W...AND 58S 11W. THE NORTHERN POLAR HAS ITS ENTRANCE AT 27S
89W...ALONG 32S 68W...38S 46W...A 140KT MAXIMUM AT 42S 30W...AND
48S 16W. THE SUBTROPICAL JET LIES ALONG 22S 120W...22S 102W...22S
86W...A 148KT MAXIMUM AT 32S 61W...A 150KT MAXIMUM AT 35S
46W...33S 39W...EXITING AT 28S 33W.
AT MID LEVELS...IN A TIGHT BELT OF WESTERLIES...PROGRESSIVE SHORT
WAVE PERTURBATIONS ARE MOVING ACROSS THE PACIFIC SOUTH OF 40S TO
THE ANTARCTIC PENINSULA. THESE THEN AMPLIFY INTO A BROAD TROUGH
ON THE SOUTHERN STREAM OVER THE SOUTH ATLANTIC...WITH AXIS
ENVELOPING AREA BETWEEN 60W-10W AND SOUTH OF 40S. ON THE NORTHERN
STREAM...MEANWHILE...A BROAD TROUGH LIES BETWEEN 95W-65W AND
SOUTH OF 20S. THIS TROUGH IS FOCUSING ITS SHORT WAVE ENERGY OVER
CHILE SOUTH OF CONCEPCION. OTHER ENERGY IS MOVING ACROSS NORTHERN
CHILE TO THE NORTHERN PROVINCES OF ARGENTINA-URUGUAY. FARTHER
NORTH...A RIDGE EXTENDS ACROSS SOUTHERN BRASIL TO EASTERN
BOLIVIA. THIS FAVORS A SUBSIDENCE CAP.
SURFACE ANALYSIS SHOWS A TIGHT BELT OF UPPER LATITUDE WESTERLIES
TO THE SOUTH OF 65S/70S...WITH PROGRESSIVE FRONT STREAMING
TOWARDS THE ANTARCTIC PENINSULA. FARTHER NORTH...A 1035 HPA HIGH
AT 35S 102W ANCHORS A BROAD RIDGE. SOUTH OF THIS RIDGE...A POLAR
FRONT EXTENDS FROM AN OCCLUDED 1020 HPA LOW AT 48S 98W...ALONG A
1022 HPA TRIPLE POINT LOW AT 47S 93W...43S 92W...43S 99W...A 1016
HPA LOW AT 48S 102W...43S 107W...AND 44S 117W. AN ELONGATED FRONT
LIES TO THE EAST AND NORTH...WITH AXIS ALONG A 988 HPA LOW AT 56S
29W...45S 32W...41S 43W...42S 56W...NORTHERN PATAGONIA/LA
PAMPA...CONCEPCION CHILE...A 1020 HPA LOW AT 36S 76W...29S 80W...
AND 25S 93W. THE FRONT SPLITS A RIDGE...WITH TWO 1029 HPA
HIGHS...WITH ONE NEAR 45S 62W AND THE OTHER AT 38S 47W. A FRONT
TO THE NORTH LIES ALONG 37S 30W...30S 40W...27S 47W...A 1014 HPA
LOW AT 26S 54W...PARAGUAY TO CENTRAL/NORTHERN BOLIVIA. ISOLATED
CONVECTION WAS BUILDING OVER SOUTHERN BRASIL.
GUZMAN...SENAMHI (BOLIVIA)
URRA...DMC (CHILE)
DAVISON...HPC (USA)
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