We now have a new record-longest wait for the first tornado of the year in Oklahoma.

The previous record for the latest start to tornado season in Oklahoma was April 26 , which occurred in 1962. This record was broken after no tornadoes were reported in the Sooner State on Thursday.

Overall for the U.S., fewer tornadoes than average have occurred so far in 2018, and portions of the Plains that would typically expect at least a few tornadoes by now have not seen any of these dangerous twisters thanks to an unfavorable upper-level jet stream pattern.

Through April 26, NOAA's Storm Prediction Center estimates 229 tornadoes have been reported this year in the U.S., well below the 10-year average of more than 400 tornadoes from 2005 through 2015 , according to NOAA.

(MORE: Tornado Central )

The fact that Oklahoma has not seen any tornadoes reported so far in 2018 is remarkable, given that Oklahoma is usually a favorable area for tornado development in March and April.

In April, Oklahoma experiences about 11.7 tornadoes on average , based on data since 1950. There have been two other years – 1987 and 1988 – when no tornadoes were reported in April.

Since 1950, however, there has never been a year with zero tornadoes recorded from January through April in Oklahoma.

(MORE: April, May and June are Most Active and Dangerous Months of Year )

One reason for the lack of tornadoes and severe weather this year has been the persistent upper-level pattern in place. This pattern has brought a southward dip in the jet stream to much of the central U.S., which has allowed colder-than-average conditions to dominate these regions.

The combination of colder temperatures, less moisture and a more northerly storm track has resulted in fewer severe thunderstorms and tornadoes through April.

In April, the corridor that typically has the greatest risk of tornadoes is from southern Kansas into Oklahoma, northern Texas, southwestern Missouri, Arkansas, northern Louisiana, northern Mississippi and central Alabama.

Tornado reports so far in 2018 have been more common in many areas that are typically expected. This includes Texas into Arkansas, Louisiana, Mississippi, Alabama and Kentucky.

(MORE: Tornado Risk By Month )

Kansas also has not reported any tornadoes in 2018. In April, Kansas typically sees about 12 tornadoes , based on data from 1991 to 2010.

According to the National Weather Service offices in Topeka and Wichita, a tornado-less January through April in the Sunflower State has only happened three other times, most recently in 1980.

The higher risk of tornadoes in Oklahoma and Kansas continues through June, so this streak will likely come to an end at some point this spring, likely next week.

What Does a Slow Start to Tornado Season Mean?

Just because no tornadoes have touched down in Oklahoma yet this year, you can't let your guard down.

2010 featured another slow start to the Oklahoma tornado season, with only three tornadoes confirmed in the state through mid-afternoon on May 10.

Over the next five hours, 56 tornadoes ripped through the Sooner State, bringing the total to 59 by 8:45 p.m. local time.

This doesn't mean a similar scenario will necessarily occur this year, but next week's weather pattern is expected to become more favorable for severe thunderstorms in the Plains .

Remember, it only takes one. Deadly tornadoes don't just occur in large severe weather outbreaks.

(MORE: It Only Takes One: Why You Should Be Prepared )