Spring Outlook

90-day March-April-May average

A record high of 79 yesterday (Sunday) 22 degrees lower today and 29 degrees colder than that tomorrow.

March, “in like a lamb out like a lion, in like a lion out like a lamb” is the old saying. We have an active sub-tropical jet stream persisting with storm systems from China-Asia to the U.S. so unsettled and changeable weather will keep our temperature see-saw pattern going this month much like February keeping us sunshine challenged.

La Nina is projected by model consensus to weaken gradually heading into Summer but the CFSv2 model disagrees, near-neutral in most models by July, but look for an update in March after the February data is processed:

TEMPERATURE AND PRECIPITATION OUTLOOK 6-14 DAY (average for the period not every day):

MARCH OUTLOOK CONSENSUS OF US/CANADA MODELS:

INTERNATIONAL MODELS ENSEMBLE MARCH:

INTERNATIONAL MODELS ENSEMBLE MARCH-MAY:

The NOAA/NWS/CPC outlooks for these periods are not drastically different.

Looking away from models and at observations, post 1950 La Nina Springs have shown a tendency for above-normal temperatures in the Southwest and Southern Great Plains with below-normal for the Northern Rockies and Northern Plains. The greatest dry trends in recent La Nina Springs have been in the central Plains and Southeast:

Remember these are the averages over a 90-day period, not every day or every week would be as depicted. That is covered in 5-7 day forecasts which use entirely different models and analogs.

The models do not depict the kind of temperature pattern one would expect if there was going to be a huge tornado season with the clashing air masses absent. That would suggest a normal or average severe weather season IF they are correct.

However, as I posted in the Feb 22nd blog RESEARCH has shown severe weather trends MORE ACTIVE with an increase in hail and tornadoes in La Nina Springs (right hand panels), especially just to the North and West of Atlanta as shown in the purple shading in the map:

It is best to monitor severe weather threats on a weekly and daily basis. But remember what I’ve pointed out a dozen times now, we are STILL in a period of poor model performance beyond about 4 days.

So despite a lot of the numerical variants yelling “a mostly warm and dry March and Spring”. I am not ready to go all-in on that for this month, seems more likely to happen in April and May this year.

March will have its thermometer ups and downs as this yo-yo ride continues. I’ll wait for any serious planting until between Easter and tax deadline day.

ANALOGS (past weather history projected forward) are opposite of the models with a cooler than average March with rainfall liable to swing either way. For the Spring as a whole though the models and the analog system are in better agreement.

ANALOGS MARCH TEMP/RAIN AVERAGE:

ANALOGS MARCH-MAY TEMP/RAIN AVERAGE:

Some of the best Oceanic Nino Index analog years are 1955, 1965, 71, 72, 96, 99, 08, 11, 12, 17, and 2018

Remember, no two La Nina seasons are ever exactly alike. As they say in the investment stock market world: past performance is no guarantee of future results.

For daily updates follow me on Twitter @MellishMeterWSB.

Kirk Mellish

Meteorologist

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