Sunday, January 08, 2012

Forecast for Monday, January 9, 2012

On Monday Evening, a wave of energy will slide to the south of our region. The computer model guidance has trended northward over the past few runs with the system and now bring measurable precipitation into the southern half of our forecast area. The 12z European model brings measurable snow into a good part of Southern New Jersey and Delaware. The GFS from 12z and 18z brush the area with a period of snow. The NAM from 12z and 18z is further south and holds the precipitation into the Delmarva. The EURO did quite well with the clipping of snow we received this past week. In addition, we tend to see a northward inching with these southern sliders as the event approaches on our model guidance. This is going to have to be watched carefully. Now we are not talking about a moisture loaded system, but the potential is there for a coating to an inch of snow in some areas Monday Evening and Monday Night.

We also have to consider possible sleet and or rain mixing in, especially close to the coast and in Southern Delaware. Temperatures will probably drop as precipitation begins due to evaporative cooling; assuming it does precipitate and we will also lose a few degrees with darkness settling in. It may take sometime for the column to moisten up, especially with high pressure trying to hold firm. We will have snowfall forecasts and updates, if needed, in the future. We will include a chance of snow for southern areas Monday P.M.

The big event this week will be a roughly 996 MB low pressure area and associated fronts approaching on Wednesday, perhaps lingering into early Thursday. We expect rain to expand into our area Wednesday with the heaviest rain Wednesday Afternoon into Wednesday Night. It will turn windy in the region, with the strongest gusts in open fields and along the coastal communities. Mild air will come in, especially south and east of Philadelphia. Philadelphia may observe a late day high on Wednesday and an early high on Thursday of around 56 degrees. There is also some indication that as the low swings through with an accompanying cold front…some low-topped thunderstorms may develop. There could be a period of strong gusts of wind with this line. It will become windy and cooler on Thursday in the wake of this intensifying low pressure area.

A secondary cold front could approach late Thursday into Friday, bringing a chance of snow and rain showers. I wouldn’t be surprised to see spotty coatings with this event as well. Lake Effect snow showers may also impact us on Friday.

I will also include a chance for snow showers on Sunday.