455
FXSA20 KWBC 191327
PMDSA
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
927 AM EDT FRI SEP 19 2008
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
SYNOPSIS (VALID FROM 00Z SEP 19). ALOFT...AT 200 HPA...A RIDGE IS
BUILDING ACROSS THE EASTERN PACIFIC ALONG 20S 100W...40S 90W...TO
60S 80W. THIS...IN-TURN...FAVORS THE NORTHWARD AMPLIFICATION OF A
TROUGH ACROSS CENTRAL CHILE TO 10S 90W. THE LATTER IS SLOWLY
PUSHING UNDER A LOW AMPLITUDE RIDGE THAT EXTENDS ACROSS WESTERN
BRASIL-PERU TO THE EASTERN TROPICAL PACIFIC. FURTHERMORE...A
NORTHERN HEMISPHERE LOW CENTERS NEAR 03S 47W...EXTENDING A TROUGH
SOUTHWEST ACROSS THE AMAZON RIVER DELTA TO 09S 60W. IN THIS
PATTERN...SCATTERED DEEP CONVECTION IS BUILDING OVER THE
CONTINENT NORTH OF 10S AND WEST OF 50W...WITH MOST INTENSE OVER
AMAZONAS-PARA IN BRASIL.
THE SOUTHERN POLAR...AT 250 HPA...HAS ITS ENTRANCE AT 48S
99W...ALONG A 143KT MAXIMUM AT 56S 95W...65S 69W...EXITING AT 60S
55W. IT REFORMS AT 44S 62W...ALONG A 127KT MAXIMUM AT 48S
43W...55S 29W...AND 60S 15W. THE NORTHERN POLAR LIES ALONG 27S
120W...A 163KT MAXIMUM AT 40S 99W...EXITING AT 50S 85W. IT
REFORMS AT 41S 81W...ALONG 29S 74W...EXITING AT 29S 63W. THE JET
REFORMS AT 26S 38W...CROSSING25S 31W...A 151KT MAXIMUM AT 34S
20W...AND 37S 08W. THE SUBTROPICAL JET LIES 20S 120W...25S
105W...EXITING AT 18S 92W. IT REFORMS AT 21S 73W...CROSSING 22S
51W...VITORIA...20S 33W...28S 19W...AND 31S 10W.
AT 500 HPA...ON THE SOUTHERN STREAM...A TROUGH EXTENDS ALONG 70S
110W...57S 110W...TO 43S 123W. THIS TROUGH IS PHASING WITH A
NORTHERN STREAM TROUGH THAT EXTENDS FROM A LOW NEAR 33S 123W TO
23S 130W. A SKEWED RIDGE LIES TO THE EAST...WITH AXIS ALONG A
HIGH NEAR 24S 90W...40S 85W...50S 80W...DRAKE PASSAGE TO THE
ANTARCTIC PENINSULA. SHORT WAVE VORTICES ARE SHEARING UNDER THIS
AXIS...WITH STRONG CYCLONIC MAXIMA AT 50S 95W AND 60S 85W.
DOWNSTREAM FROM THE RIDGE...A SHORT WAVE TROUGH ENTERED
PATAGONIA/LA PAMPA IN ARGENTINA...WHILE FARTHER NORTH A LOW
CENTERING NEAR SANTIAGO DE CHILE ANCHORS A TROUGH OVER NORTHWEST
ARGENTINA/NORTHERN CHILE. ON THE SOUTHERN STREAM...MEANWHILE...A
LOW NEAR 63S 37W EXTENDS A TROUGH ALONG 50S 45W...TO 48S 60W. THE
LATTER IS SLIDING UNDER A SKEWED RIDGE THAT EXTENDS ACROSS
PARAGUAY-SOUTHERN BRASIL...40S 40W...TO 47S 30W. A TROUGH TO THE
EAST AND NORTH LIES ALONG 40S 20W...30S 30W...TO RIO DE JANEIRO.
THE SURFACE ANALYSIS SHOWS A DEEPENING/INTENSIFYING FRONTAL
TROUGH OVER THE EASTERN PACIFIC...WITH A 974 HPA LOW AT 51S
96W...AND A FRONT ALONG 52S 95W...43S 93W...TO 36S 103W. THIS IS
INTERACTING WITH AN ELONGATED FRONT THAT LIES ALONG A 970 HPA LOW
AT 62S 91W...A 988 HPA TRIPLE POINT LOW AT 63S 80W...56S 77W...A
990 HPA LOW AT 53S 88W...42S 88W...37S 94W...30S 108W...TO A 1014
HPA LOW AT 27S 113W. THESE FRONTS ARE PUSHING AGAINST A BROAD
RIDGE THAT EXTENDS FROM THE EASTERN PACIFIC TO THE SOUTHERN
CONE...STRUNG ALONG A 1033 HPA HIGH AT 33S 85W...A 1033 HPA HIGH
AT 42S 78W....A 1035 HPA HIGH AT 34S 63W...AND A 1033 HPA HIGH AT
39S 69W. FARTHER EAST...OVER THE ATLANTIC...A TROUGH ON THE
SOUTHERN STREAM ANCHORS ON A 974 HPA LOW AT 61S 37W...THEN ALONG
A 982 HPA LOW AT 59S 07W...58S 18W...A 986 HPA LOW AT 59S
27W...53S 30W...A 1006 HPA LOW AT 50S 36W...42S 48W...BUENOS
AIRES PROVINCE...A 1018 HPA LOW AT 34S 64W...TO NORTHERN MENDOZA
IN ARGENTINA. IN A TIGHT PRESSURE GRADIENT STRONG BOUNDARY LAYER
WINDS ARE REPORTED ACROSS CENTRAL ARGENTINA...WITH WIDELY
ISOLATED RAINS ACROSS MENDOZA. A RIDGE TO THE EAST CENTERS ON TWO
1029 HPA HIGHS...WITH ONE NEAR 38S 45W...AND THE OTHER AT 45S
13W. ON THE NORTHERN STREAM...A TROUGH IS INITIALIZED...WITH A
1014 HPA OCCLUDED LOW AT 32S 31W...AND A 1010 HPA LOW AT 36S 16W.
AN ELONGATED FRONT LIES ALONG A 1016 HPA LOW AT 35S 11W...A 1018
HPA LOW AT 31S 16W...26S 24W...A 1018 HPA LOW AT 23S 28W...18S
35W...ESPIRITO SANTO/MINAS GERAIS...20S 50W...TO CHACO
PARAGUAYO/SOUTHEAST BOLIVIA. THIS FAVORS COASTAL RAINFALL OVER
ESPIRITO SANTO IN BRASIL.
GUZMAN...SENAMHI (BOLIVIA)
URRA...DMC (CHILE)
DAVISON...HPC (USA)
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