8:45pm
Overview
There is a low pressure system to our North (over Saskatchewan, Canada). This developing low has a trough stretched into Montana. This system is slowly moving toward the Dakotas. Elsewhere, a broad ridge of high pressure is anchored Mississippi & Ohio River Valleys and effecting a large area from the Gulf Coast, up the Atlantic coastline.
There is a low pressure system to our North (over Saskatchewan, Canada). This developing low has a trough stretched into Montana. This system is slowly moving toward the Dakotas. Elsewhere, a broad ridge of high pressure is anchored Mississippi & Ohio River Valleys and effecting a large area from the Gulf Coast, up the Atlantic coastline.
Discussion
The trough that is stretched across parts of Montana will continue to move toward our area. Normally, this time of the year we would be seeing snow with small accumulation totals. However tonight's setup will paint a different picture. Surface temperatures across the area will fall through the 30s and bottom out just below the freezing mark (32F degrees) and soil temps are near the freezing mark (31 bare/ 35 turf). This means that any precip that falls will freeze before the end of the night.
Just above the surface, our vertical profile does show a slot of warm air that is near or more than 5,000 feet thick. This is more than enough warm air to completely melt a snowflake.
After complete melting, the water will not re-crystalize until it makes contact with a solid surface (no matter how far below freezing it gets) If there was not a thick enough slot of warm air (1,200-1,600 feet with temps at least 3-5 degrees above freezing) we would only see partial melting. Once the water got back into a slot of air that was below freezing, it could refreeze and form sleet.
As the rain falls back into air that is below freezing, the water droplet will become super-cooled and instantly freeze after making contact with any solid object. This process is how freezing rain forms.
For our area, there will be several hours when this freezing rain is possible. 2am-9am. However the showers that will pass through our area will be light and patchy. So, not everyone will see freezing rain, but most of our area (Western & South-Central ND) are in the zone where it is possible. Where the freezing rain occurs, expect little to no accumulation. Surface temps will be at or below the freezing mark until the late morning 8-10am. Use caution during the morning commute. Watch out for black ice. Any accumulation that sticks will quickly melt off after temps climb above freezing and well above average again on Tuesday (and even more on Wednesday). Some parts of our area may see slightly more rain than others resulting in ice accumulations up to a tenth of an inch (.10"). It all depends on how long surface temps stay below freezing and shouldn't significantly affect roadways that have been pretreated for icy weather.
Just above the surface, our vertical profile does show a slot of warm air that is near or more than 5,000 feet thick. This is more than enough warm air to completely melt a snowflake.
After complete melting, the water will not re-crystalize until it makes contact with a solid surface (no matter how far below freezing it gets) If there was not a thick enough slot of warm air (1,200-1,600 feet with temps at least 3-5 degrees above freezing) we would only see partial melting. Once the water got back into a slot of air that was below freezing, it could refreeze and form sleet.
As the rain falls back into air that is below freezing, the water droplet will become super-cooled and instantly freeze after making contact with any solid object. This process is how freezing rain forms.
For our area, there will be several hours when this freezing rain is possible. 2am-9am. However the showers that will pass through our area will be light and patchy. So, not everyone will see freezing rain, but most of our area (Western & South-Central ND) are in the zone where it is possible. Where the freezing rain occurs, expect little to no accumulation. Surface temps will be at or below the freezing mark until the late morning 8-10am. Use caution during the morning commute. Watch out for black ice. Any accumulation that sticks will quickly melt off after temps climb above freezing and well above average again on Tuesday (and even more on Wednesday). Some parts of our area may see slightly more rain than others resulting in ice accumulations up to a tenth of an inch (.10"). It all depends on how long surface temps stay below freezing and shouldn't significantly affect roadways that have been pretreated for icy weather.
The latest model runs (for this evening) have significantly backed off on rainfall. However, I will still leave the possibility of some light freezing rain in our planner.
Through the rest of tonight & Tuesday
Overnight, temps will fall to near freezing with continued increasing clouds. After midnight, a surface trough (extended south from a low pressure system in Canada) will move into our area. This system will move through ND tomorrow morning and afternoon. Affected parts of Western and Central, North Dakota will mostly see a glazing (trace/thin sheet of ice) on drivable surfaces that will melt off quickly. Locally up to .10" is possible for some.
Tuesday after sunrise, expect any accumulated ice to quickly melt as temps climb well above average again. Highs will climb into the upper 40s by the afternoon hours. Tomorrow the headlines include very mild temps and very gusty winds with some seeing peak gusts at or higher than 30mph.
Overnight, temps will fall to near freezing with continued increasing clouds. After midnight, a surface trough (extended south from a low pressure system in Canada) will move into our area. This system will move through ND tomorrow morning and afternoon. Affected parts of Western and Central, North Dakota will mostly see a glazing (trace/thin sheet of ice) on drivable surfaces that will melt off quickly. Locally up to .10" is possible for some.
Tuesday after sunrise, expect any accumulated ice to quickly melt as temps climb well above average again. Highs will climb into the upper 40s by the afternoon hours. Tomorrow the headlines include very mild temps and very gusty winds with some seeing peak gusts at or higher than 30mph.
7day planner The rest of the 7day will bring a roller-coaster of conditions. Through the work week we will see a series of short waves(troughs) that will pass through and cause in & out clouds and a wintry mix tonight & Wednesday night. Temps will keep well above average (BIS avg. 8/28) and in the 40s & 50s for highs (20s & 30s for lows) . A front on Friday will bring our next significant chance for snow followed by temperatures falling well into a more seasonable range. It will be time to pull the jackets back out as lows will be in the teens and highs will be in the lower to mid 30s
TONIGHT...Increasing clouds before Midnight. Chance for freezing rain after 1pm until 9pm, followed by clearing skies. Lows 26-34. SW wind 2-10mph. Little to no accumulation is expect. A glaze is possible through the morning. Chills 20s & Teens. 50% chance for FRZ rain.
TUESDAY...Tapering rain chances followed by clearing skies revealing mostly sunny to partly cloudy conditions. Highs 46-52. W/NW wind 10-22mph G30. 40% chance for AM FRZrain/rain.
TUESDAY NIGHT...Fair to partly cloudy skies with temps below freezing. Lows 26-33. W/SW wind 2-10mph. Chills in the 20s.
WEDNESDAY...Partly to mostly cloudy skies with increasing cover and temps well above average and mild. Highs 51-57. SW wind 5-15mph.
WEDNESDAY NIGHT...Mostly cloudy skies with a chance for rain /mix/snow after midnight. Lows 39-35. Little to no accumulation.
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