La Nina is officially here

HOUSTON (KTRK) -- Last week, Chief Meteorologist Tim Heller explained how a developing La Nina could impact Houston's winter. Now we have confirmation from NOAA that La Nina is officially here.

While this La Nina is expected to remain weak, it is already influencing the jet stream wind pattern that pushes storms systems around the globe. So far this fall, the jet stream has largely stayed over Canada, flooding much of north America with milder Pacific air.

This northern shift in the jet stream has prevented the North American snowpack from developing into the United States, which is one reason our cold fronts so far this fall haven't been all that cold.

Does this mean we are doomed to a winter without any significant cold spells? Not necessarily.

While the snowpack today is lower than normal across North America, it is well above normal through much of Eurasia, generating a large pool of colder than normal air across Siberia. This cold Siberian air will eventually blow into North America, helping to build the snowpack over Canada and the northern United States.

Once that happens we'll have a better chance of getting a REAL cold front along with our first freeze. We just might need to wait a few more weeks for that process to unfold. Houston's first freeze doesn't typically occur until the first week of December anyway.