March Grades

March 2012 was a record-breaking month. Portland saw its latest snowfall ever when 0.04" fell on March 22nd. Nine days later, Portland set the all-time rainfall record for the month of March, breaking a 55 year old mark. Portland ended March with 7.89" of rainfall, average is 3.68"!

While Portland set the record, other Northwest cities came close to their rainfall records. March was Salem's 2nd wettest with 9.98", Vancouver's 3rd wettest with 7.81" and Astoria saw its 4th wettest March with 14.13". Hillsboro and Eugene both saw the 5th wettest March on record with 6.59" and 9.94", respectively.

No records were broken with my forecasting grades this month. That doesn't mean it was an off month, however. Accurately forecasting 86% of temperatures and 95% of the conditions, I'd say it was a successful March. The average temperature in the 3rd month jumps by five degrees from the March 1st to the 31st. Couple that with the unpredictability of the spring weather and you wind up with some fairly respectable marks.

There were two "snow" events last month. One at the beginning of March and the bigger event on the 22nd. The first event totaled no snow accumulation even though flakes were falling. One March 1st, I called for a snow/rain mix transitioning into spotty showers during the afternoon with a high of 45 degrees. The forecast worked out perfectly, with a high of 45 degrees and snow turned to rain showers later in the day. I just missed the high temperature by a degree on our second snow day (March 22nd). While working during snow events is stressful, it really gives me the best opportunity to prove my forecasting skills. I never thought that winter weather forecasting would be something I'd enjoy but it is rewarding when an accurate forecast plays out.

For the month of April, I will throw in a new wrinkle to the forecast accuracy. Given the high rain totals last month, I have decided to implement rain amounts into my daily forecast. I will grade the daily totals with a +/- 0.05". Not too many folks notice a difference between 0.25" and 0.30", it just seems like one wet day! I'll consider the rain totals separate from conditions, so there will be a third category for the April totals. Quantitative Precipitation Forecasting (QPF) is a bit challenging so make sure to check back in next month to see how the totals impact accuracy!

La Nina Returns?

NOAA has put out a La Nina Advisory for the 2011 winter season. That's right folks, La Nina appears to have re-developed and is here to stay a bit longer than first thought.

What exactly does La Nina mean, you may be asking? It essentially is a cooling of Sea Surface Temperatures (SST) in the central and eastern portions of the tropical Pacific Ocean. The set up has warmer than average SST's over the western Pacific and cooler than average SST's in the central and eastern Pacific. La Nina typically occurs ever 3-5 years but consecutive episodes occur nearly 50% of the time, according to the NOAA Climate Prediction Center. While La Nina stems from the anomalies of SST's, its impacts go way beyond ocean temperatures.

Sea Surface Temperatures showing a cooler eastern Pacific which signals a La Nina return. Via NOAA CPC.

Winter of 2010 in the United States was a record-setting one. High snowfall totals lead to record Spring flooding and severe weather that was off the charts! The exceptional drought that is on-going in the South...yup, put that one on La Nina. Wichita Falls, TX became the first location with 100 days at or above 100 degrees this year! So the news that La Nina has reformed does not offer much in the way of relief.

What can we expect for winter 2011? Average La Nina winters cause wetter than normal conditions here in the Pacific Northwest and can often expect cooler than average temperatures, too. La Nina doesn't offer much drought relief during the winter months either for those in the South and Southwest,

“This means drought is likely to continue in the drought-stricken states of Texas, Oklahoma and New Mexico,” said Mike Halpert, deputy director of the Climate Prediction Center.  

 

Typical La Nina setup

Beyond the upcoming winter, it is tough to tell just how long and strong La Nina will be. Should it last into next Summer, it could mean another active hurricane season. During the 2010-11 La Nina conditions, forecasters predicted a very active tropics with 14-19 named tropical storms. As of today, we are sitting at 14 named storms this season. Pretty good, huh? With those cold waters in the Pacific, oceans try to balance out by warming up the tropical Atlantic waters to above average temperatures. So, if La Nina lingers around for another Summer, things could be active again.


With La Nina's anticipated return, records could fall again this winter. That would not be welcome news to most.