Wednesday, December 2, 2009

Latest Snow Forecast Update (Wednesday PM)

As we’ve discussed for several days now, a cold arctic blast will punch down to the coast Friday and setup the opportunity for wintry precipitation. Computer models are slowly coming around to picking up on variables to align for snow development.

During my last look at the most recent atmospheric forecast, I detailed a noticeable amount of moisture available in the snow growth region 14,000 ft above the surface to induce the creation of snow. And the evolution of the snow as it falls will maintain a temperature below freezing till about 800 feet above the surface. Slight melting will occur as the precipitation falls in the small layer at the surface (ground), but the warmer layer should be thin enough to meet the threshold for maintaining snowfall. I do expect the warm layer to become increasingly thin as any melting of precipitation will cause the atmosphere to cool, which will help see more white stuff.

In other words, the latest computer models show snow falling after 9pm on Friday and going into the early hours on Saturday morning. A big difference at this point is the location. WRF computer model has the main snow line tracking through Jackson, but the GFS has the snow line tracking right through Hattiesburg. Similar to our snow event back in December 2008, a line of snow will stretch across the state perpendicular to Hwy 49 in a SW to NE direction. Last December, Hattiesburg barely saw any snow while Collins had nearly 3 inches. So location is very important.

How much snow? Well, considering the models are still varying on the location of the snow (see previous paragraph) the amount is still uncertain. Some models depict slightly more than a dusting, but others (GFS) show over an inch. My opinion, I would say some isolated areas will see up to 2 inches, but many folks will experience less than an inch.

The only definite forecast I can give is the potential snow event's snowflake size will be big and wet. After forming in the snow growth region in the atmosphere, the snow parcel will continue to have a wealth of moisture at its disposal. Also, knowing the surface temperature will be above freezing makes me note the snow parcel will slightly melt to give it a “wet” feeling.

Much can change in the next 48 hours going into Friday evening, but hopefully we can all wake up Saturday morning with a beautiful white landscape. I’m sticking with saying “light snow” for Friday night’s forecast until we get closer to the event to help distinguish the exact location of the snow line through the state. But the snow line is still capable of missing our region all together.

Interesting note…The Houston, Texas, area could see a rich snowfall before it reaches Mississippi on Friday.

No comments: