1/12/15: Variability

Low temperatures this morning were in the -10s and -20s across the North Dakota Agricultural Weather Network.  This will likely be the coldest morning of the week as a slow warm up is expected.

January 12, 2015 Minimums
January 12, 2015 Minimums

 

High pressure is centered near Grand Forks this morning.   Surface pressure adjusted for sea level is around 30.80 inches of mercury near this center (near 1050 mb).  That high pressure center will move slowly to the south to southeast over the next 24 hours.

7:00 AM Surface Analysis
7:00 AM Surface Analysis

On Tuesday morning the high will have moved into Iowa and that in turn will gradually shift the surface wind flow over North Dakota and western Minnesota to a more southerly component.  The southerly wind will make Tuesday morning no where near as cold as it was this morning, yet, most locations will still record a low below zero.

Tuesday 6:00 AM surface projection
Tuesday 6:00 AM surface projection

As the Arctic high pressure center moves to the east, not only will the surface flow turning south help with warmer temperatures, the wind aloft will shift more west / northwest that will bring in modified Pacific Air into this area, meaning warmer temperatures.

cmc_z500a_c_exnamer_19
500 mb Flow and Anomalies for Friday, January 16, 2015 at 6:00 AM

 

At the moment it appears a weak surface cold front will move across the area on Friday, meaning, Thursday the warm day of the week, slight colder Friday and Saturday (although still well above average) then a bit warmer Sunday, then cooler early next week.

End of January Progged 500 mb flow and anomalies
End of January Progged 500 mb flow and anomalies

Although the short term flow is for warmer air to advect into this area, events currently occurring in Asia would suggest this warm up is only temporary and that colder air will move back into the region toward the end of January as presented in the graphic above.  That transitions may also trigger a snow event, but this week, the warm air moving in will likely only produce a dusting in the transition to warmer air.  This weekend a couple of clippers will move across southern Canada that will drop more than a dusting, but at the moment the main band of snow appears to be in southern Canada.

Therefore, this week, generally dry and a bit warmer with a few ups and downs, but the overall trend for January still looks to be for much of the upper Midwest to record more below average days than above.

Daryl Ritchison