Prognostic Meteorological Discussion
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000
FXSA20 KWBC 191631
PMDSA

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1230 PM EDT TUE AUG 19 2014

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

MODEL DISCUSSION (VALID FROM AUGUST 19 AT 00UTC): GLOBAL MODELS
AND ENSEMBLE MEMBERS ARE IN GOOD AGREEMENT IN FORECAST EVOLUTION.
CONFIDENCE IS HIGH THROUGH 96-120 HRS...WHEN DETAILS BEHIND THE
SPEED AT WHICH SHORT WAVE TROUGH WILL CROSS THE ANDES BECOME
SOMEWHAT TROUBLESOME.

LARGE UNSEASONABLY STRONG RIDGE EXTENDS FROM THE EASTERN PACIFIC
ACROSS NORTHERN/CENTRAL CHILE AND NORTHERN/CENTRAL
ARGENTINA/SOUTHERN BRASIL. THE RIDGE IS ALLOWING THE AMPLIFICATION
OF A LARGE TROUGH TO THE SOUTHWEST...AND SLOWING DOWN ITS
PROGRESSION TOWARDS THE CONTINENT. INITIALLY...SURFACE FRONTS WILL
CONFINE TO SOUTHERN CHILE...AND WILL ONLY START AFFECTING CENTRAL
CHILE ON FRIDAY. THROUGH WEDNESDAY MORNING EXPECTING MAXIMA OF
15-20MM/DAY BETWEEN ISLA CHILOE AND THE MAGALLANES REGION. ON
WEDNESDAY-EARLY THURSDAY EXPECTING MAXIMA OF 10-15MM/DAY BETWEEN
LOS ANGELES AND THE AYSEN REGION. ON THURSDAY INTO FRIDAY
EXPECTING AN INCREASE TO 15-20MM/DAY FROM CONCEPCION TO ISLA
CHILOE.  UPPER TROUGH WILL START CROSSING THE ANDES AT DURING
THURSDAY-FRIDAY. THIS WILL ENHANCE ACCUMULATIONS ACROSS CENTRAL
CHILE PRODUCING ISOLATED MAXIMA OF 15-25MM/DAY BETWEEN TALCA AND
PUERTO MONTT ON FRIDAY-EARLY SATURDAY. WANING ACTIVITY WILL LEAD
TO ISOLATED MAXIMA OF 05-10MM/DAY ACROSS MOST OF CENTRAL CHILE
DURING SATURDAY...AND 10-15CM/DAY OF SNOW IN AREAS OF THE CENTRAL
ANDES.

TROUGH WILL ALSO ENHANCE ACTIVITY ACROSS CENTRAL ARGENTINA. STRONG
THUNDERSTORMS WILL START DEVELOPING ALONG A STATIONARY FRONT...TO
AFFECT LA PAMPA/CENTRAL BUENOS AIRES PROVINCE ON THURSDAY-EARLY
FRIDAY. THESE WILL PRODUCE MAXIMA OF 15-20MM/DAY. ON
FRIDAY-SATURDAY...UPPER TROUGH CROSSING THE ANDES WILL PRODUCE
HEIGHT FALLS AND INDUCE CYCLOGENESIS ACROSS CENTRAL ARGENTINA.
THIS WILL SUSTAIN SCATTERED THUNDERSTORMS WITH LOCALLY HEAVY
RAINFALL. EXPECTING ACCUMULATIONS OF 20-45MM/DAY FROM VIEDMA/LA
PAMPA INTO THE CENTRAL BUENOS AIRES PROVINCE. ON
SATURDAY-SUNDAY...OCCLUDED LOW WILL FORM OVER THE BUENOS AIRES
PROVINCE. THIS...IN COMBINATION WITH UPPER TROUGH AND COUPLED
UPPER JETS...WILL LEAD TO HEAVY RAINFALL AND SEVERE WEATHER IN
PORTIONS OF EAST/CENTRAL ARGENTINA. EXPECTING STRONG
THUNDERSTORMS...A FEW OF THEM SEVERE...TO AFFECT THE RIO DE LA
PLATA BASIN...PRODUCING MAXIMA OF 20-40MM/DAY. FURTHER
SOUTH...EXPECTING THE RISK OF ECHO TRAINING TO PRODUCE MAXIMA OF
75-100MM/DAY ACROSS THE EXTREME NORTHEASTERN PATAGONIA AND
SOUTHERN BUENOS AIRES PROVINCE.

ELSEWHERE IN THE CONTINENT...SEASONALLY QUIET CONDITIONS ARE
EXPECTED. ACTIVITY WILL CONCENTRATE TO THE NORTH OF 02S IN THE
FORM OF ISOLATED TO SCATTERED DIURNAL THUNDERSTORMS. SHOWERS ARE
ALSO EXPECTED ALONG THE EASTERN COAST OF BRASIL...IN ASSOCIATION
WITH TRADE WIND CONVERGENCE. ISOLATED DIURNAL SHOWERS ARE ALSO
EXPECTED ACROSS THE CENTRAL ANDES OF PERU/NORTHERN BOLIVIA...WITH
ISOLATED SNOWFALL IN HIGH TERRAIN DURING WEDNESDAY.

JALFIN...SMN (ARGENTINA)
CAROCA...DMC (CHILE)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)
$$





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