DAYTON, Ohio (WDTN) – The Miami Valley will see a little bit of everything Wednesday. Snow will start south and move north across the Miami Valley from 1-4 a.m. After 4 a.m., from south to north we will start to see sleet, then freezing rain and eventually just rain by 8 a.m.
Precipitation starts in the cloud as ice crystals form to make snowflakes. When the snowflake becomes too heavy it begins to fall to the ground.
The precipitation type when it hits the road varies based on temperature. Not just at the surface, but throughout the entire atmosphere.
If the temperature is above freezing all the way to the ground, the snowflake will hit your windshield.
The atmosphere is rarely perfect. On Wednesday, warm air will be moving into the cold air. Warm air rises. Cold air is dense. The cold air at the surface won’t move as fast and a layer of warm air aloft develops.
As the snowflake travels through the warm layer of air, it will begin to melt. The melted snowflake then encounters the cold air at the surface. If there is enough cold air the melting snowflake will refreeze as a small ball of ice known as sleet.
Freezing rain happens when the cold air layer at the surface is very shallow. The melted snowflake does not have time to refreeze. Instead the supercooled water droplet freezes on contact creating a glaze of ice.
If the warm layer reaches the ground, all we get is rain.
The warm air moving into the Miami Valley tomorrow will give us the chance to see snow, sleet, freezing rain and rain over a period of six hours.
To forecast winter precipitation Meteorologist use data that come from a weather balloon. Every morning at 7 a.m. and evening at 7 p.m. National Weather Service offices across the country launch weather balloons to find the upper air temperature and dew point.
The data is read on a Skew-T Log-P Diagram. The temperature is skewed to the right so we can view the entire atmosphere on one sheet.
At the time this article was written, Oklahoma was seeing, snow and sleet. This is the same storm system that will impact Ohio on Wednesday. Oklahoma City saw sleet during the lunch hour.
On a sounding profile from Norman, Oklahoma there is an inversion. The temperature warms with height instead of cools with height. This inversion inparticular is warmer than 32 degrees between 850 and 700 mb in the atmosphere.
A little bit further north in Oklahoma, there was no inversion and snow is on the radar.
The temperature and dew point reading is key to forecasting precipitation type. Forecast models use these readings to predict precipitation and cloud coverage.