Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3
000
FXSA20 KWBC 311646
PMDSA

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1245 PM EDT FRI JUL 31 2015

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

MODEL DISCUSSION (VALID FROM JUL 31 AT 0000 UTC): GLOBAL MODELS
AND ENSEMBLE MEMBERS ARE IN GOOD AGREEMENT THROUGH 84-96 HRS. THEY
AGREE IN THE EVOLUTION OF THE LONG WAVE PATTERN THROUGH 120 HRS.

A STRONG NORTHERN HEMISPHERE TROUGH IS CROSSING THE ANDES OF
CENTRAL CHILE AND NORTH-CENTRAL ARGENTINA FAVORING ACTIVITY IN THE
REGION. STRONGEST CONVECTION HAS DEVELOPED IN THE RIO DE LA PLATA
REGION AND WILL MEANDER SOUTHEASTWARD THROUGH EARLY SATURDAY
PRODUCING ACCUMULATIONS OF 15-25MM/DAY. NOTE THAT ISOLATED HIGHER
AMOUNTS ARE POSSIBLE...BUT THE EVENT WILL DECLINE THROUGH FRIDAY
EVENING AS STRONGEST DYNAMICAL FORCING MOVES OFFSHORE TO THE
SOUTHEAST. A SURFACE FRONT WILL MEANDER IN THE REGION OVER THE
NEXT SEVERAL DAYS. THE FRONT WILL EXTEND ACROSS CENTRAL
URUGUAY-NORTHERN ENTRE RIOS-NORTHERN CORDOBA THROUGH SUNDAY. THIS
WILL FAVOR MOISTURE CONVERGENCE AND THE DEVELOPMENT OF DIURNAL
SHOWERS AND THUNDERSTORMS AIDED BY MOISTURE TRANSPORT BY A
LOW-LEVEL JET FROM THE NORTH. CONVECTION IS TO RESTRENGTHEN ON
SATURDAY TO PRODUCE ISOLATED MAXIMA OF 20-30MM/DAY IN THE RIO DE
LA PLATA BASIN. BY SUNDAY INTO EARLY MONDAY EXPECTING A DECREASE
IN MAXIMA FO 15-20MM/DAY MOSTLY ACROSS PARTS OF URUGUAY. AMOUNTS
ARE TO LARGELY DECREASE AFTER.

CHILE CONTINUES EXPERIENCING A SEASONALLY ACTIVE PRECIPITATION
PATTERN ESPECIALLY FOR SOUTH-CENTRAL PORTIONS OF THE COUNTRY.
POTENT SOUTHERN HEMISPHERE TROUGH  AND ASSOCIATED FRONTS WILL
START AFFECTING THE REGION LATE ON FRIDAY. THIS WILL PRODUCE
MODERATE RAINFALL BETWEEN CONCEPCION AND THE SOUTHERN LOS LAGOS
REGION WITH MAXIMA OF 15-30MM/DAY. EXPECTING MAXIMA OF 05-10MM/DAY
TO THE SOUTH INTO THE NORTHERN MAGALLANES REGION. BY SATURDAY INTO
EARLY SUNDAY EXPECTING RAINFALL ACCUMULATIONS TO PEAK ESPECIALLY
IN INLAND LOCATIONS BETWEEN CURICO AND THE NORTHERN AYSEN PROVINCE
WHEN EXPECTING MAXIMA OF 20-40MM/DAY. SNOW IS EXPECTED IN THE
CENTRAL CORDILLERA WITH ACCUMULATIONS OF 20-30CM/DAY.
ACCUMULATIONS WILL DECREASE INTO SUNDAY TO ISOLATED MAXIMA OF
05-10MM/DAY  IN INLAND LOCATIONS BETWEEN ARAUCANIA AND LOS LAGOS.
IN THE SOUTHERN AYSEN AND MAGALLANES REGIONS EXPECTING MAXIMA OF
05-10MM/DAY WITH THE RISK OF RAIN AND SNOW SHOWERS UNDER COLD
ADVECTIVE PATTERN WEST OF OCCLUDED LOW IN PATAGONIA. AMOUNTS WILL
INCREASE ON MONDAY BETWEEN PUERTO MONTT AND AYSEN WITH MAXIMA OF
15-30MM/DAY. AMOUNTS ARE TO INCREASE ONCE AGAIN BY TUESDAY TO
MAXIMA OF 20-40MM/DAY BETWEEN CONCEPCION AND CHILOE AS A NEW COLD
FRONT MOVES NORTH FROM LOS LAGOS INTO BIO BIO ACCOMPANIED BY A
SUBTROPICAL MOISTURE CONNECTION.

ELSE OVER THE CONTINENT SEASONALLY QUIET CONDITIONS CONTINUE WITH
ACTIVITY CONSTRAINING TO TRADE WIND SHOWERS IN THE NORTHEASTERN
COAST OF BRASIL AND ISOLATED THUNDERSTORMS IN THE AMAZON BASIN TO
THE NORTH OF 02S. UPPER FLOW WILL REMAIN MOSTLY FROM THE WEST
THROUGH THE BASIN WITH LITTLE IMPACT ON PRECIPITATION.

ROMERO...DMC (CHILE)
GALVEZ...WPC (USA)
$$




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.