Sunday, September 16, 2012

Forecast for Monday, September 17, 2012

Mostly cloudy skies this evening may give way to partly cloudy conditions, although a few clouds are anticipated to be around the region throughout the night. On Monday, the few sunny breaks will become less and less as increasing clouds develop ahead of our next weather system. By Monday Evening, some showers may be developing in response to the warmer air surging ahead of a strong cold front.

Tuesday is looking like it could be problematic from at least a wind and severe weather standpoint, but even poor drainage flooding could be an issue. A strong cold front will be to our west and this front will move east. Along that strong frontal boundary will be waves of low pressure enhancing precipitation. At this point, it appears the strongest waves of energy will move northward along the front when it is still positioned to our west. This means that the highest precipitation amounts should be to our west as well. Still, by the time this front moves through our region and out our door, we may see a widespread one to two inches of rain with localized locations observing perhaps three inches of rain.  Meanwhile, earlier on Tuesday, there could be some frequent showers associated with warmer air rushing ahead of the cold front in the morning. By Tuesday Afternoon, a lull in the action is very possible with a few sunny breaks.  Tuesday Evening and Night is when the cold front moves through and this is when we could have showers and thunderstorms. By early Wednesday Morning, there may be a few leftover showers, but decreasing clouds and breezy conditions will develop by afternoon. 

Our previous blog post addresses the wind potential in more detail. This set-up on Tuesday will favor a period of strong winds as strong winds will reside just above the surface, especially if there is a break in the action and sunshine mixes the winds to the surface or if the heavier rain can bring the stronger winds down to the surface. In addition to the wind, any thunderstorm will have the potential of creating an isolated tornado as the wind shear and helicity increases. It is still a question of whether the best instability will coincide with the increasing shear. Anyhow, we are now under a slight risk of severe weather from the Storm Prediction Center and this is a high-end (30% probability) slight risk of severe weather. Even if we don’t see severe thunderstorms, some strong synoptic winds are likely too for at least some portions of our region. 

Could an onshore flow bring in clouds and drizzle late this week into the weekend, before a passage of a front this weekend? I will tend to be more optimistic at this moment, but the latest trend is to at least add more clouds to the forecast.