Prognostic Meteorological Discussion
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SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1219 PM EST WED FEB 10 2016

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

MODEL DISCUSSION (VALID FROM FEB 10 AT 0000 UTC): FORECAST
CONFIDENCE IS HIGH THROUGH THE CYCLE. MODEL DISCREPANCIES ARE
PARTICULARLY REMARKABLE AFTER 96 HRS ON THE EVOLUTION OF THE
SUBTROPICAL RIDGE/BOLIVIAN HIGH OVER THE CONTINENT.

THE SUBTROPICAL UPPER RIDGE/BOLIVIAN HIGH HAS RELOCATED INTO
CENTRAL PORTIONS OF THE CONTINENT. THE RIDGE CENTERS ON A BROAD
HIGH OVER PARAGUAY/SOUTHERN BOLIVIA AND EXTENDS A RIDGE FROM 15S
80W INTO PARANA AND SAO PAULO IN BRASIL. THIS NEW POSITION FAVORS
AN UPPER DIVERGENT PATTERN ACROSS THE SOUTHWESTERN AMAZON INTO THE
ALTIPLANO/SOUTHERN PERUVIAN ANDES. DEEP-LAYER INSTABILITY AND
PRECIPITABLE WATER REMAIN ENHANCED IN THESE REGIONS. ACROSS THE
AMAZON OF PERU/ECUADOR/S COLOMBIA THIS WILL LEAD TO RAINFALL
MAXIMA OF 25-50MM/DAY THROUGH EARLY THURSDAY. AMOUNTS WILL
GRADUALLY DECREASE TO MAXIMA OF 15-20MM/DAY BY SATURDAY...AND 10MM
BY SUNDAY. ACTIVITY IN THE ALTIPLANO IS BECOMING SEASONALLY
ACTIVE. UNDER THE INFLUENCE OF AN EASTERLY MOISTURE TRANSPORT AT
MID-LEVELS...EXPECTING ALSO THE POSSIBILITY FOR TRASVASE/LIGHT
RAIN PASSING INTO COASTAL REGIONS. IN TERMS OF
ACCUMULATIONS...RAINFALL MAXIMA WILL BE IN THE ORDER OF
15-30MM/DAY THROUGH EARLY THRUSDAY. IT WILL DECREASE SLIGHTLY BY
FRIDAY INTO SATURDAY TO INCREASE AGAIN INTO EARLY NEXT WEEK.

ALSO IN TROPICAL SOUTH AMERICA...THE CAVADO DO NORDESTE/UPPER
TROUGH WILL EXTEND ACROSS 07S-11S THROUGH THE CYCLE. THIS IS
SUSTAINING AN UPPER CONVERGENT PATTERN BUT MORE REMARKABLE THE
ADVECTION OF A DRY AIR MASS FROM THE ATLANTIC ABOVE THE BOUNDARY
LAYER. THIS IS LIMITING THE DEVELOPMENT OF DEEP CONVECTION ACROSS
MOST OF EASTERN AND NORTHERN BRASIL. STRONGER CONVECTION IS
EXPECTED NEAR AMAPA/NORTHERN PARA WHERE ITCZ CONVERGENCE WILL
PRODUCE MAXIMA OF 15-20MM/DAY THROUGH SATURDAY. NOTE THAT AN
INCREASE IN AMOUNTS IS EXPECTED DURING FRIDAY AIDED BY AN UPPER
DIVERGENT PATTERN IN THE BASE OF AN UPPER TROUGH IN THE CARIBBEAN.

A COLD FRONT HAS ORGANIZED ACROSS SOUTHEASTERN SOUTH AMERICA. BY
WEDNESDAY EVENING THE FRONT WILL EXTEND INTO PARANA IN BRASIL WITH
WEAKENING TAIL OVER THE CONTINENT. BY THURSDAY EVENING IT WILL
EXTEND ACROSS RIO DE JANEIRO AND SAO PAULO. BY FRIDAY EVENING IT
WILL EXTEND INTO MINAS GERAIS WITH TAIL INTO NORTHERN SAO
PAULO...TO THEN START WEAKENING. THIS SYSTEM WILL BE THE FOCUS FOR
MOISTURE CONVERGENCE AND PRECIPITATION. THROUGH EARLY THURSDAY
LARGEST RAINFALL AMOUNTS ARE EXPECTED ACROSS THE SERRA DO MAR OF
SAO PAULO AND PARANA WHERE EXPECTING MAXIMA OF 30-60MM/DAY UNDER
THE INFLUENCE OF OROGRAPHIC UPLIFT. THURSDAY INTO EARLY FRIDAY
EXPECTING MAXIMA OF 20-40MM/DAY ACROSS RIO DE JANEIRO AND COASTAL
SAO PAULO/SERRA DO MAR. BY FRIDAY INTO EARLY SATURDAY EXPECTING
MAXIMA OF 20-35MM/DAY ACROSS MINAS GERAIS AND ESPIRITO SANTO...AND
MAXIMA OF 15MM INLAND INTO MATO GROSSO DO SUL. BY SATURDAY INTO
SUNDAY EXPECTING MAXIMA OF 20-45MM/DAY ACROSS ESPIRITO
SANTO/SOUTHERN BAHIA INLAND INTO SOUTHERN GOIAS/MATO GROSSO.
ALTHOUGH THE FRONT WEAKENS...EXPECTING AN THE REMNANT TROUGHS OVER
THE CONTINENT TO INTERACT WITH AN INCREASINGLY DIVERGENT PATTERN
AT UPPER LEVELS OVER EASTERN BRASIL...AS THE BOLIVIAN HIGH PRESSES
INTO THE CAVADO DO NORDESTE. THIS WILL SET UP A NEW WET SPELL
ACROSS CENTRAL/EASTERN BRASIL INTO EARLY NEXT WEEK.

SHORT WAVE UPPER TROUGH CENTERS OFF THE COAST OF CONCEPCION IN
CHILE. THIS TROUGH WILL GRADUALLY CROSS THE ANDES STARTING ON
WEDNESDAY BUT MAINLY DURING THURSDAY. BY FRIDAY EVENING THE TROUGH
WILL EXTEND ACROSS EASTERN ARGENTINA TO THEN EXIT INTO THE SOUTH
ATLANTIC. THIS TROUGH IS TO SUSTAIN FRONTOGENESIS AND STIMULATE
THUNDERSTORM DEVELOPMENT UNDER INTERACTION WITH A LOW-LEVEL JET
FROM THE NORTH. THROUGH EARLY THURSDAY EXPECTING MAXIMA OF
15-20MM/DAY FROM CUYO INTO LA PAMPA/NORTHERN PATAGONIA. BY
THURSDAY INTO EARLY FRIDAY EXPECTING SIMILAR AMOUNTS FROM NORTHERN
CUYO INTO THE BUENOS AIRES PROVINCE. BY FRIDAY INTO SATURDAY...A N
UPPER TROUGH WILL PUSH IN FROM THE EASTERN PACIFIC. THIS WILL
SUSTAIN AN INCREASE IN UPPER DYNAMICS THAT WILL FAVOR THE
DEVELOPMENT OF STRONG CONVECTION. LIFTED INDEX VALUES ARE SINKING
BELOW -9...WHICH SUGGEST THE POTENTIAL FOR SEVERE CONVECTION.
EXPECTING ACCUMULATIONS OF 40-80MM/DAY STRETCHING FROM
CORDOBA/SOUTHERN SANTA GE INTO THE RIO DE LA PLATA BASIN. BY
SATURDAY INTO EARLY SUNDAY EXPECTING MAXIMA OF 25-50MM/DAY ACROSS
ENTRE RIOS/CORRIENTES EAST INTO URUGUAY/SOUTHERN RIO GRANDE DO SUL.

LOPEZ...SMN (ARGENTINA)
ENRIQUEZ...DGAC (ECUADOR)
GALVEZ/DAVISON...WPC (USA)

$$





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