9/3/15: Trending to Autumn

Yesterday, the high temperature at the North Dakota Agricultural Weather Network (NDAWN) station in Williston reached a maximum of 100° at 5:03 CDT.  Other readings in the western one-third of North Dakota were not much cooler with several maximums at 98° or 99°.

9/2/15 Maximums
9/2/15 Maximums

Western North Dakota will likely be cooler today as a cold front will transition cooler air into that region later today.  Also with the front will come a threat of thunderstorms later today as well.

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

The NAM-WRF Guidance maximum projections places the warmest maximum temperatures in central North Dakota which seems likely based on where the cold front is situated as well as some low clouds/fog in eastern North Dakota that will need to “burn” off before temperatures there will begin the daily climb.

9/3/15: Maximums
9/3/15: Maximums

 

That low cloudiness can be clearly seen on visible satellite imagery this morning.  Because the wind is already blowing in the 15-30 mph from the south to southeast, surface fog was unable to form in most locations, but just above the surface, there is widespread clouds (stratus) that will take time to fully evaporate.

Early Morning Satellite Image
Early Morning Satellite Image

That low level cloudiness is a visible sign of the high moisture content in the lower atmosphere,  Dew points a measure of that low level moisture will likely remain around 70° for the entire day in the eastern one-half of North Dakota through western Minnesota.

7:10 AM Dew Point Temperatures
7:10 AM Dew Point Temperatures

Thunderstorms today should confine themselves to western North Dakota today.  Central North Dakota tonight.  It will be Central and eastern North Dakota with the threat on Friday with the Red River Valley probably not having much of a chance until evening or overnight on Friday.  Eastern North Dakota and Minnesota will have higher probabilities of rain on Saturday PM into Saturday Night with perhaps just some popcorn showers developing Sunday afternoon behind the cold front that should be in Minnesota by Sunday afternoon.  Rain amounts average in the 0.25 inches to 0.75 inches expected, but there will very likely be localized higher totals in excess of 1.5 inches with northern North Dakota being the most favored areas for those higher totals.

That cold front will reduce temperatures into the 70s on Sunday for most areas and even Saturday, the western part of North Dakota should record 70s for highs.  So the trend to more “typical” September weather will be coming, it will just take a few days to get the front to move across the region.

Daryl Ritchison