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South American Synoptic Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1357Z Jul 15, 2014)
 
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SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
957 AM EDT TUE JUL 15 2014

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

SYNOPSIS (VALID FROM 15 JULY 00UTC): AT 200 HPA...UPPER LEVEL
RIDGE CONFINES TO EQUATORIAL SOUTH AMERICA/NORTHWEST
BRASIL-PERU...WHILE A NEAR ZONAL WESTERLY FLOW ENVELOPS
CONTINENTAL AREA BETWEEN 24S-05S. THE RIDGE ALOFT IS VENTING DEEP
CONVECTION ACROSS NORTHERN PARA-AMAZONAS IN BRASIL. TRADE WIND
EASTERLY CONVERGENCE SUSTAINS SHALLOW CONVECTIVE DEVELOPMENT ALONG
THE COAST BETWEEN RIO DE JANEIRO AND PERNAMBUCO.

AT 250 HPA THE SOUTHERN POLAR LIES ALONG 41S 120W...42S 112W...42S
101W...42S 90W...40S 82W...EXITING AT 38S 76W. IT REFORMS AT 44S
69W...ALONG 51S 66W...A 125KT MAXIMUM AT 57S 56W...A 122KT MAXIMUM
AT 60S 44W...60S 29W...EXITING AT 58S 17W. THE NORTHERN POLAR LIES
ALONG A 159KT MAXIMUM AT 37S 120W...38S 109W...A 155KT MAXIMUM AT
38S 100W...37S 88W...32S 76W...32S 71W...EXITING AT 34S 67W. IT
REFORMS AT 37S 65W...ALONG 43S 64W...51S 59W...55S 45W...EXITING
AT 55S 38W. THE SUBTROPICAL JET LIES ALONG 28S 120W...32S
110W...32S 100W...EXITING AT 30S 95W. IT REFORMS AT 19S
39W...ALONG 20S 31W...23S 20W...26S 10W...AND 29S 00W.

AT 500 HPA...A PROGRESSIVE SHORT WAVE TROUGH IS PULLING ACROSS THE
BELLINGSHAUSEN SEA TO THE ANTARCTIC PENINSULA. NORTH OF THIS
AXIS...A HIGH AMPLITUDE TROUGH EXTENDS BETWEEN 80W-60W TO
25S...WITH AXIS FOCUSING SHORT WAVE ENERGY ACROSS THE CENTRAL
ANDES OF CHILE TO CENTRAL PROVINCES IN ARGENTINA. A RIDGE TO THE
EAST EXTENDS FROM PARAGUAY...ACROSS SOUTHERN BRASIL...INTO THE
ATLANTIC ALONG 40S 50W...50S 40W...AND 55S 10W. THIS UNDERCUTS A
TROUGH TO THE EAST AND NORTH...AS IT EXTENDS ALONG 50S 05W...35S
25W...30S 40W...TO SOUTHEAST BRASIL.

AT LOW LEVELS...A BROAD TROUGH EXTENDS OVER THE SOUTH PACIFIC
WHILE CENTERING ON AN OCCLUDED 982 HPA LOW AT 44S 122W. THIS
SUSTAINS A POLAR FRONT THAT EXTENDS FROM AN OCCLUDED 998 HPA LOW
AT 44S 100W...A 1002 HPA LOW AT 41S 94W...37S 94W...35S 97W...33S
114W...A 1010 HPA LOW AT 33S 121W...AND 29S 121W. A RIDGE TO THE
NORTH CENTERS ON A 1025 HPA HIGH AT 27S 95W. A TROUGH TO THE EAST
EXTENDS ACROSS THE SOUTHERN CONE OF SOUTH AMERICA...WITH A POLAR
FRONT THAT EXTENDS ALONG A 994 HPA LOW AT 56S 65W...52S 62W...50S
65W...A 1002 HPA LOW AT 46S 66W...41S 63W...36S 66W...31S
70W...WEAKENING AS IT TRAILS INTO THE EASTERN PACIFIC. THIS SYSTEM
SUSTAINS SCATTERED RAINFALL ACROSS THE SOUTHERN CONE OF SOUTH
AMERICA...AND MODERATE TO HEAVY CONVECTION ON CENTRAL PROVINCES IN
ARGENTINA/RIO DE LA PLATA BASIN. A RIDGE OVER THE ATLANTIC CENTERS
ON A 1037 HPA HIGH AT 42S 39W. ELONGATED POLAR FRONTS LIE TO THE
NORTH...WITH ONE ALONG A 1018 HPA LOW AT 28S 15W...24S 21W...21S
31W...TO OFF THE COAST OF SANTA CATARINA. ANOTHER FRONT TO THE
NORTH LIES ALONG 25S 10W...19S 19W...17S 27W...TO ESPIRITO SANTO.
A SHEAR LINE LIES ALONG 17S 28W TO NORTHERN BAHIA/PARAIBA...WHERE
IT SUSTAINS SCATTERED CONVECTION.

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