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South American Forecast Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1606Z Oct 07, 2014)
 
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SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1206 PM EDT TUE OCT 07 2014

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

MODEL DISCUSSION (VALID FROM OCTOBER 07 AT 00UTC): GLOBAL MODELS
AND ENSEMBLE MEMBERS CONTINUE IN GOOD AGREEMENT ON FORECAST
EVOLUTION. CONFIDENCE IS HIGH.

LARGE LONG WAVE TROUGH IS SLOWLY ENTERING THE CONTINENT AS IT IS
APPROACHING CENTRAL CHILE. AS THE TROUGH CROSSES...IT WILL START
LEADING TO HEIGHT FALLS ACROSS PATAGONIA LATER TODAY THROUGH
THURSDAY. INITIALLY...MOISTURE WILL BE LIMITED THIS EXPECTING
ACCUMULATIONS TO CONSTRAIN TO THE AYSEN REGION IN CHILE WITH
MAXIMA OF 05-10MM/DAY IN NUMEROUS BRIEF RAIN SHOWERS. BY WEDNESDAY
INTO EARLY THURSDAY...EXPECTING ACTIVITY TO START DEVELOPING ALONG
SURFACE BOUNDARIES IN ARGENTINA. ONE WILL BE A SURFACE FRONT THAT
WILL EXTEND ACROSS THE SOUTHERN BUENOS AIRES PROVINCE INTO LA
PAMPA. EXPECTING SHOWERS AND THUNDERSTORMS TO PRODUCE MAXIMA OF
05-10MM/DAY. OTHER REGION WILL BE A SURFACE TROUGH THAT WILL
EXTEND ACROSS FORMOSA/CHACO/CORRIENTES INTO URUGUAY...WHERE
EXPECTING MAXIMA OF 15-20MM/DAY. BY THURSDAY EVENING...FRONT WILL
ADVANCE TO THE NORTH ACROSS CENTRAL URUGUAY-SANTA FE-TUCUMAN.
EXPECTING INSTABILITY TO PEAK DURING THIS PERIOD...WHICH WILL LEAD
TO STRONG THUNDERSTORMS WITH ACCUMULATIONS OF 40-80MM/DAY AND THE
RISK FOR MCS FORMATION. BY FRIDAY EVENING...FRONT WILL STALL
ACROSS WESTERN PARAGUAY/SOUTHERN BOLIVIA-RIO GRANDE DO SUL.
EXPECTING LINGERING THUNDERSTORMS TO PRODUCE ACCUMULATIONS IN THE
ORDER OF 20-35MM/DAY ACROSS CORRIENTES/MISIONES/SOUTHERN PARAGUAY
INTO MOST OF RIO GRANDE DO SUL.

TO THE NORTHEAST...A WEAK SURFACE FRONT EXTENDS INTO COASTAL
BAHIA. THIS IS FOCUSING ENHANCED LOW-LEVEL CONVERGENCE ACROSS
CENTRAL/NORTHERN BAHIA INTO SERGIPE/ALAGOAS. EXPECTING
ACCUMULATIONS OF 15-30MM/DAY THROUGH WEDNESDAY
MORNING...15-20MM/DAY BY WEDNESDAY INTO THURSDAY
MORNING...DECREASING AFTERWARDS.

NORTH OVER THE CONTINENT...SUBTROPICAL HIGH IS ESTABLISHING OVER
PERU...AIDED BY WIDESPREAD CONVECTION ACROSS CENTRAL AND WESTERN
SOUTH AMERICA. THE HIGH WILL SUSTAIN VENTILATION AND EASTERLY FLOW
INTO THE ANDES TO MAINTAIN CURRENT WET PATTERN THROUGH SEVERAL
DAYS. LARGEST ACCUMULATIONS ARE EXPECTED IN THE
ECUADORIAN/SOUTHERN COLOMBIAN/PERUVIAN AND BOLIVIAN AMAZON REGIONS
WITH SCATTERED DAILY MAXIMA OF 20-40MM/DAY. BY THURSDAY INTO
FRIDAY...MAXIMA OF 20-40MM/DAY WILL CONSTRAIN TO LATITUDES NORTH
OF 02S...WITH A DECREASING TREND ELSEWHERE. DEEP-LAYER EASTERLY
FLOW WILL ALSO ENHANCE ACTIVITY ACROSS THE PERUVIAN AND ECUADORIAN
ANDES PRODUCING SCATTERED MAXIMA OF 15-30MM/DAY THROUGH THURSDAY
NIGHT...WITH AMOUNTS DECREASING AFTERWARDS AND FOCUS OF CONVECTION
MIGRATING NORTHWARD INTO COLOMBIA.

CAROCA...DMC (CHILE)
DURAN...SENAHMI (PERU)
GALVEZ...WPC (USA)