Week One through Four Forecast

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Above are the CFSv2 through the 12th of January – keep in mind these are shown in metric units in regards to the anomalies using baseline data points over a 30 year period (K).  I am not going to get into the math used to assemble these maps as most of it is well above my pay grade (ha).  I could show you some of the formula but it is all alien to me – I can barely get through algebra and statistical math.

What the graphics are trying to tell us are we will have a period of warming over the next week before the next shot of Arctic air come pouring forth from Canada the week of Christmas.  It appears the cold air will try to retreat the second week of January.  These graphics have been changing daily so we have to take them with a grain of salt.

A temperature anomaly is the difference from an average, or baseline, temperature. The baseline temperature is typically computed by averaging 30 or more years of temperature data. A positive anomaly indicates the observed temperature was warmer than the baseline, while a negative anomaly indicates the observed temperature was cooler than the baseline.

When calculating an average of absolute temperatures, things like station location or elevation will have an effect on the data (ex. higher elevations tend to be cooler than lower elevations and urban areas tend to be warmer than rural areas). However, when looking at anomalies, those factors are less critical. For example, a summer month over an area may be cooler than average, both at a mountain top and in a nearby valley, but the absolute temperatures will be quite different at the two locations.

This is why the temperatures at my station may read lower due to my location in a valley where as the temperature at the Gerald Ford Airport  and downtown GR may read higher due to the concrete and buildings.  So, the formula for creating data in weather models for any one location would have a hard time assuming a correct forecast (long range)  using data for any one location over that period.  As I said the other day, a forecast generally goes out a few days using weather patterns while long range models are based on climatology using data over a 30 year base period.

Simply put, I think we will see a return to winter the week of Christmas/New Years – in the long term I believe we will continue with the up and down temperatures as the jet stream moves back and forth through the Midwest and Great lakes.

Milder air will spread north into the area. Light rain will be possible near I-94 tonight into early Monday, but temperatures should be warm enough to keep precipitation all liquid. Generally dry conditions are expected late Monday through Wednesday with highs around 40 both Monday and Tuesday. Unsettled weather returns towards the end of the week with cold temperatures making a return for the weekend right before Christmas.

We could be looking at an interesting storm at the end of this week as a low develops over the northern plains and upper Midwest – the track of the storm is unknown at this time, we should have a better idea on Wednesday.

A much colder airmass will move in on the back side of the system for next weekend. Longer range medium range guidance continues to show potential for an even colder arctic airmass to move in by Christmas Day.

Today: Mostly cloudy, with a high near 35. East wind 7 to 9 mph becoming south southeast in the afternoon.

Tonight: Cloudy, with a low around 33. South southeast wind around 6 mph becoming southwest after midnight.

Monday: A 20 percent chance of showers after 1pm. Cloudy, with a high near 40. Southwest wind 5 to 9 mph.

Monday Night: Mostly cloudy, with a low around 36. Southwest wind 9 to 14 mph, with gusts as high as 22 mph.

Tuesday: Partly sunny, with a high near 42. West southwest wind 11 to 14 mph.

Tuesday Night: Partly cloudy, with a low around 25.

Wednesday: Partly sunny, with a high near 34.

Wednesday Night: Mostly cloudy, with a low around 24.

Thursday: A slight chance of rain and snow after 1pm. Mostly cloudy, with a high near 38.

Thursday Night: A chance of snow, mainly after 1am. Cloudy, with a low around 29.

Friday: Rain and snow likely. Cloudy, with a high near 39.

Friday Night: A chance of snow showers. Mostly cloudy, with a low around 23.

Saturday: A chance of snow showers. Mostly cloudy, with a high near 30.