942
FXSA20 KWBC 081345
PMDSA
SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
944 AM EDT WED OCT 08 2008
GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/
SYNOPSIS (VALID FROM 00Z OCT 08). AS THE GLOBAL MODELS
INDICATED...THE SUBTROPICAL RIDGE OVER NORTHERN SOUTH AMERICA
STRENGTHENED IN RESPONSE TO SURGE IN TROPICAL CONVECTION ACROSS
BRASIL...WITH ORGANIZED DEEP CONVECTION BUILDING NORTH OF 10S AND
WEST OF 50W. AT 200 HPA THE RIDGE NOW ENVELOPS CONTINENTAL AREA
NORTH OF 20S...CENTERING ON TWO HIGHS...WITH ONE NEAR 10S 50W AND
THE OTHER NEAR 13S 37W. A SHORT WAVE TROUGH IS SLIDING UNDER THIS
RIDGE...MOVING ALONG 70W/72W INTO NORTHERN CHILE/SOUTHERN PERU.
THIS FAVORED WIDELY ISOLATED CONVECTION BETWEEN SALTA AND MENDOZA
IN NORTHWEST ARGENTINA.
THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR WITH A FINGER
HAVING ITS ENTRANCE NEAR 62S 110W...THEN ALONG 71S 90W...66S
53W...EXITING AT 60S 35W. ANOTHER FINGER OF THE SOUTHERN POLAR
HAS ITS ENTRANCE AT 59S 74W...THEN ALONG 57S 42W...EXITING AT 44S
43W. IT REFORMS NEAR 40S 36W...THEN ALONG 47S 23W...AND 50S 10W.
THE NORTHERN POLAR HAS A CYCLONICALLY CURVED FINGER WITH ENTRANCE
AT 37S 99W...THEN ALONG 35S 92W...EXITING AT 38S 85W. IT REFORMS
NEAR 36S 57W...THEN ALONG 31S 46W...A 140KT MAXIMUM AT 38S
32W...A 162KT MAXIMUM AT 40S 25W...AND 45S 10W. THE SUBTROPICAL
JET LIES ALONG 31S 120W...28S 100W...EXITING AT 30S 80W. IT
REFORMS NEAR 21S 69W...SAO PAULO...26S 42W...35S 23W...AND 37S
00W.
AT 500 HPA A PERTURBED WEATHER PATTERN DOMINATES THE SOUTHERN AND
NORTHERN STREAM FLOW ACROSS THE EASTERN PACIFIC...WITH A LONG
WAVE TROUGH ALONG 115W TO 35S...AND WITH SHORT WAVE PERTURBATIONS
TO THE EAST OF THIS AXIS. ONE EXTENDS BETWEEN 40S 95W AND 30S
93W...ANOTHER LIES ALONG 80W AND SOUTH OF 50S...WHILE A THIRD
ENTERED PATAGONIA ALONG 70W. A BLOCKING RIDGE EXTENDS SOUTH ALONG
60W TO THE ANTARCTIC PENINSULA. THIS...IN-TURN...SUSTAINS THE
NORTHWARD AMPLIFICATION OF A TROUGH BETWEEN 55W-20W AND SOUTH OF
26S. A RIDGE EXTENDS WEST INTO BRASIL BETWEEN 10S-20S...
SUSTAINING A SUBSIDENCE CAP THAT IS INHIBITING ORGANIZED DEEP
CONVECTION.
AT LOW LEVELS...THE SURFACE ANALYSIS SHOWS A 1025 HPA HIGH NEAR
29S 85W...ANCHORING A RIDGE ON THE NORTHERN STREAM FLOW. SOUTH OF
THIS RIDGE... ABROAD TROUGH PATTERN DOMINATES THE SOUTHERN
STREAM...WITH EMBEDDED POLAR FRONTS REVOLVING AROUND THIS AXIS.
ONE ORIGINATES ON A 978 HPA OCCLUDED LOW AT 64S 84W...THEN A 988
HPA LOW AT 63S 68W...60S 67W...A 998 HPA LOW AT 57S 78W...51S
76W...A 1014 HPA LOW AT 43S 88W...36S 84W...AND 26S 96W. OVER THE
ATLANTIC...A 1035 HPA HIGH AT 39S 57W ANCHORS A BROAD RIDGE.
SOUTH OF THIS AXIS...AN ELONGATED POLAR FRONT EXTENDS ALONG A
1000 HPA LOW AT 57S 45W...54S 47W...54S 59W...TIERRA DEL FUEGO TO
PATAGONIA...WHERE IT WEAKENS. FARTHER EAST...AN OCCLUDED 982 HPA
LOW AT 50S 27W EXTENDS A FRONT ALONG A 988 HPA LOW AT 53S 24W...
48S 21W...A 1010 HPA LOW AT 42S 27W...38S 31W...A 1014 HPA LOW AT
36S 36W...29S 42W...RIO GRANDE DO SUL-CORDOBA TO MENDOZA. AN OLD
FRONT TO THE NORTH LIES ALONG 26S 30W...23S 39W...NORTHERN SAO
PAULO...MATO GROSSO DO SUL TO NORTHERN BOLIVIA. ISOLATED TO
SCATTERED CONVECTION WAS NOTED OVER SOUTHEAST BRASIL.
URRA...DMC (CHILE)
MOREYRA...SENAMHI PERU
DAVISON...HPC (USA)
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