Chance of snow in Brazil - August 19th/22nd

[LucasMarcomini]

As I said before, a polar air mass is being forecasted to cause snowfall in Southern Brazil late this week. Medium range models are showing a strong extratropical cyclone developing in the coast of Argentina, with a polar high advancing through the continent. This system could reach the Equador line, a phenomenon known in Brazil as "Friagem", which is when a cold front advances through the Amazon rainforest.

 

[LucasMarcomini]

Model discussion by NCEP


NOTE: SLIGHT RISK OF SEVERE CONVECTION ACROSS MID SECTIONS OF
SOUTH AMERICA THROUGH TOMORROW MORNING. HIGHER RISK OF SEVERE
WEATHER IS EXPECTED ON DAY 04 AS STRONG POLAR TROUGH MOVES ACROSS
THE CONTINENT. (this will be for another thread, in Target Area)


THE
LOW FORMS OVER RIO DE LA PLATA BASIN BY 90/96 HRS...AND IT IS TO
RAPIDLY INTENSIFY WHILE PULLING TO THE SOUTHEAST THROUGH 120-132
HRS. AS THE LOW DEEPENS...AND A POLAR RIDGE BUILDS ACROSS
ARGENTINA...THIS WILL THEN FORCE THE POLAR FRONT TO ACCELERATE
ACROSS MID SECTIONS OF SOUTH AMERICA...TO ADVANCE ACROSS SOUTHERN
BRASIL-NORTHERN BOLIVIA BY 108-120 HRS. AT 90-108 HRS...THIS WILL
FAVOR A SQUALL LINE AND SEVERE CONVECTION ACROSS URUGUAY-SOUTHERN
STATES OF BRASIL TO SOUTHEAST PARAGUAY (MOST INTENSE EXPECTED
OVER SOUTHEAST PARAGUAY-CORRIENTES/MESOPOTAMIA VALLEY IN
ARGENTINA). DURING THIS PERIOD...EXPECT RAINFALL MAXIMA OF 35-
70MM/DAY. AS THE FRONT ACCELERATES ACROSS SOUTHERN BRASIL TO
NORTHERN BOLIVIA...IT WILL THEN FAVOR MAXIMA OF 25-50MM/DAY BY
120-132 HRS. OTHER ACTIVITY IS EXPECTED ACROSS CENTRAL CHILE
THROUGH DAY 04...WITH MAXIMA TO PEAK AT 15-25MM/DAY. THIS IS TO
ALSO FAVOR ORGANIZED SNOWFALL AMOUNTS ACROSS THE CENTRAL
ANDES...WITH RISK OF HEAVY SNOWFALL AMOUNTS ON DAY 03.

 

[LucasMarcomini]

GFS 12Z

 

[LucasMarcomini]

GLOBAL MODELS AGREE
ON RISK OF EXPLOSIVE CYCLOGENESIS OVER THE SOUTH ATLANTIC TO
START LATE ON DAY 03 AND BOMB THROUGH DAY 04...WHEN THEY PROJECT
A 944 HPA LOW TO DEVELOP NEAR THE SOUTH GEORGIA ISLANDS. THE LATE
SEASON STORM WILL SUSTAIN A STRONG POLAR SURGE ACROSS THE
CONTINENT...WITH SNOW SHOWERS TO AFFECT SOUTHERN BUENOS AIRES
PROVINCE AND THE SOUTHERN STATES OF BRASIL. SNOW SHOWERS/VIRGA IS
TO AFFECT RIO DE LA PLATA BASIN ON DAYS 05 AND 06.

NCEP

 

[LucasMarcomini]

 

[LucasMarcomini]