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Heavy Rain & Severe Storms Target Argentina, Uruguay This Week

Written by Meteo Expert Josef Lukas

The potential for heavy rain and severe thunderstorms will exist through much of this week across central South America. Argentina, Uruguay, Paraguay, and southern Brazil are the countries most at risk for damaging thunderstorms and flooding rain.

The Setup

High pressure will setup to the east of Uruguay this week while low pressure will establish itself over the Gran Chaco region located just east of the Andes Mountains. Additionally, a second low pressure system will move into Chile later in the week.

Satellite imagery from Sunday shows low pressure off of the Chilean coast. This storm will move into Chile and eventually aid in heavy rain and severe thunderstorms across Argentina and Uruguay later Wednesday through Thursday.

The flow around the pressure systems will draw tropical moisture southward. The result will be numerous rounds of showers and heavy thunderstorms, some of which will be severe.

Initially, the heaviest rain and best chance for severe thunderstorms will exist across Paraguay and central Argentina through Tuesday. However, this threat area will shift toward eastern Argentina, Uruguay, and southern Brazil during the middle and end of the week.

The Impacts

Damaging winds, large hail, and torrential downpours capable of flash flooding are likely in the heaviest storms.

5-day rainfall totals of 100-200 mm are likely in a corridor from northern Argentina into parts of Paraguay. Outside of this area, widespread rainfall amounts of 25-100 mm are likely.

Weather models trends this weekend suggest that the period from Wednesday evening through Thursday and Thursday night may bring the greatest risk for severe thunderstorms and flash flooding.

Capital cities such as Asuncion, Buenos Aires, and Montevideo are within the threat area for heavy rain and severe storms, mainly from Tuesday through Thursday night. Other cities such as Cordoba and Rosario are also at risk for severe weather and flash flooding.

By the upcoming weekend, the risk for severe weather will end as a more tranquil fall air mass moves into the region.

Wild Week Of Severe Weather

Written by Meteo Expert Josef Lukas

The month of May got off to an active start with severe thunderstorms across the US.

The National Weather Service (NWS) recorded over 500 reports of severe weather from Colorado to New York state. The majority of the severe weather occurred across the central Plains from Texas to Iowa.

The most active day for severe thunderstorms in term of reports was on Wednesday when the Storm Prediction Center (SPC) reported a total of 232 severe weather reports.

One of the more impressive individual storms occurred on May 1st from a severe thunderstorm that produced a large tornado in Kansas. This particular tornado was captured by a storm chaser’s dash cam.


In addition to the severe storms, heavy rain and flash flooding was observed across portions of the Plains and Midwest. In just the first 3 days of May, a swath of 3-6 inches (75-150 mm) of rain fell from Iowa to Wisconsin.

The system responsible for the severe thunderstorms will be moving off of the East Coast this weekend giving a much need break from severe weather to the Central US.

Tornadoes, 100-mph Winds, and Baseball-Size Hail Ravage the Plains

Written by Team Morecast

 

A slow-moving trough has been pumping dynamic mid to upper level energy across the Plains (see water vapor imagery below) over the last several days. Meanwhile, juicy Gulf moisture and warmth have fed in from the south. The combination of upper level energy and surface instability has led to multiple rounds of severe storms. Almost 400 reports of severe weather were received on 1-2 May (Tuesday and Wednesday), including 32 tornadoes.

 

 

One of the largest tornadoes of the outbreak rolled across northern Kansas on Tuesday evening (see tweeted video below). The twister had a lifespan of about 30 minutes, covering almost 15 miles in that time, and was at one point almost 1,000 yards wide! After post-storm damage analysis, the tornado was rated EF-3 on the Enhanced Fujita scale. Elsewhere, large hail up to four inches in diameter was recorded with storms in Nebraska and Kansas. A wind gust to 106 mph was recorded with a severe cell in Oklahoma.

 

 

 

Another Round of Severe Storms on Thursday in the Plains!

Written by Team Morecast

 

Tornadoes and destructive straight-line wind gusts exceeding 100 mph have slammed the Plains today. The system responsible for severe weather today isn’t going anywhere in a hurry! More high winds, large hail, and isolated tornadoes are expected for Thursday.

 

 

Wednesday night’s storms will weaken into early Thursday morning, but could still produce some locally heavy rain and lightning from central Texas into the Ozarks and the Mid-Mississippi Valley. Daytime heating will help build instability by early afternoon. Upper-level winds will remain quite strong. The combination of instability and shear will lead to severe storms building by mid-afternoon.

The greatest risk for severe storms is expected from northeast Oklahoma into eastern Kansas, Missouri, southeast Iowa, and northwest Illinois. A more isolated or marginal risk of severe storms will extend down into north Texas and north and east into the Midwest. Large hail up to three inches in diameter, destructive wind gusts to 80 mph, and isolated tornadoes will occur well into Thursday night.