Cincy ForecastDaily Weather Updates and Analysis

New Year’s Eve
Day: Rain/snow showers early, changing to snow showers during the afternoon with little to no accumulation. Highs in the upper 30s.
Night: A 40% chance of scattered snow showers, otherwise cloudy (and becoming windy late). Temps will rapidly fall through the 20s after midnight, so watch out for spotty slick spots on roads. Lows in the lower 20s.

New Year’s Day
Day: A 50% chance of snow showers, accumulating up to an inch. Breezy with wind chills in the single digits/teens. Highs in the middle 20s.
Night: A 30% chance of snow showers, with little additional accumulation. Breezy with wind chills dipping below zero at times. Lows in the middle teens.

Clouds are increasing across the tri-state ahead of a two stage storm system. Temps have begun to level off (were increasing at a steady pace earlier) due to evaporational cooling (cooling due to evaporating water droplets/ice crystals) and the increased cloud cover. However, even with marginal surface temps, the mid and upper levels of the atmosphere are still cold enough to support snow (850s below 0 and the 540 critical thickness line is south of the river). Given the slowed warming and colder column, most areas will start as all snow this afternoon/evening, with rain mixing in later tonight for areas inside and SSW of the 275 loop. Areas NNE of the loop look to stay mostly snow through the entire event, adding up to an inch or two in spots. Given the marginal surface temps, however, most paved surfaces will stay wet.

A week storm system will affect the tri-state through the rest of the week, providing chances for rain and snow showers, as well as ushering in much colder air by late Thursday.

Wed-Thu
The aforementioned storm system will continue to slowly slide through the Deep South, helping to throw moisture into the Ohio Valley. However, southerly winds will help surge in milder air, thus allowing the bulk of the precip (for Wed-Thu) to fall as rain showers. I wouldn’t rule out a bit of a rain/snow mix in the northern counties of the tri-state Wed afternoon, but it would be brief with no snow accumulation. Expect off-and-on showers from midday Wed through midday Thu, adding up to a quarter inch at most. By late Thu, a strong cold front will cross the area, ushering in the coldest air of the season thus far!

Fri-Tue
After the cold front passes through Thu night, we will be left with a very cold airmass in place. Highs through this period will struggle to make it out of the middle 20s, with lows in the lower to middle teens (single digits in spots)! Given the tight pressure gradient between the exiting storm and the high pressure area moving south from Canada, breezy conditions will be present through early next week. Wind chills will thus be very uncomfortable, with teens being the “warmest” they will get. Due to the strong NW flow, LES (Lake-Effect Snow) will be widespread to our north, with some of the stronger bands having the potential of making it into the tri-state. Otherwise, expect some CAA (Cold Air Advection) snow showers, some of which may be impressive. Given the very cold temperatures, all snow that falls (albeit light) will stick, resulting in an inch or less of accumulation each day. By early next week, it wouldn’t surprise me if some spots have a couple inches of snow on the ground…

I hope everyone has enjoyed the holiday season thus far! By now, we are all pretty used to this active weather pattern, which shows no signs of ending. Both the northern and southern jets have been working in tandem to provide constant bouts of precipitation and shots of cold air. This upcoming week features a very complex storm setup, as well as a grand finale of bitterly cold to end the week/send us into 2010!

Tue
High pressure will briefly gain control for Tuesday, allowing skies to clear a bit and temps to moderate slightly. Enjoy it, as changes are soon to follow!

Wed-Fri
Complexity in the forecast begins on Wednesday. A storm system, currently developing in Mexico, will begin to slowly slide ENE towards the Deep South (which will affect the tri-state in two rounds). This will allow for the development of rain/snow showers by Wednesday evening. Given that temps will be above freezing for a majority of round one, the snow will have a hard time accumulating. The precip will continue through midday Thursday (when I expect a brief lull). By Thursday night, the storm system will really begin to organize to our east, allowing for precip to resume across the tri-state (round two). Given the copious amount of model uncertainty regarding this stage of the storm’s development, the forecacast becomes rather blurry. For starters, the track of the low is crucial for what type of precip we will receive, as well as how heavy it will be. The “cone of uncertainty” for this storm’s track is rather large, ranging from off the east coast to the OH/PA border. The next vital aspect is how quickly, if at all, phasing occurs. Put simply, phasing occurs when the northern and southern branches of the jet stream converge. When this happens, cold air is able to spill into the storm, allowing for some areas to receive impressive wintry weather. Many of today’s models want to phase this storm well to our east, which means that we receive little in the way of wintry weather. However, the models have been trending westward with the track of the storm over the past several models runs. If this trend continues, the tri-state will be in a prime spot for accumulating snow, possibly heavy. I will definitely monitor the latest info regarding this storm, and will pass it onto you in a timely manner!

Sat-Mon
The potentially major storm will continue to slide away and deepen on Saturday, leaving the begginings of a nasty cold outbreak in its wake. A strong area of high pressure is progged to slide south from Canada on Saturday, allowing temps to really tumble. Additionally, the pressure gradient between the deepening Nor’Easter and the strong high will allow for very breezy conditions to develop (likely wind advisory criteria or higher). With temps rapidly falling through the 20s, wind chills will be in the single digits or lower, creating unpleasant and potentially dangerous conditions. If the storm does indeed lay down some snowcover, expect those values to be even lower. Given the strong winds, the typical LES (Lake-Effect Snow) belts will be cranking. I expect some of those bands to make their way into the tri-state (esp northern sections), along with general CAA (Cold Air Advection) snow showers, which may produce some additional light accumulations. Winds will begin to subside a bit for Sunday/Monday, though temps will still be very cold (highs not making it out of the lower-middle 20s).

A clipper system is in the process of moving through the tri-state, bringing with it a burst of wintry weather.

After a brief period of mild air, our first accumulating snow of the season is on the way for late Friday night-Saturday. Our snow will result from a combination of several factors. First, a vigorous storm system is in the process of developing across the western Gulf of Mexico. It is forecast to slide ENE at first, then NE along the east coast. At the same time, a disturbance will slide southeast out of Canada, towards the tri-state. This clipper-type system will be our main source of lift, and consequently help provide us with most of our snow. However, the stronger storm system traveling up the east coast will help stream extra moisture into our system, thus giving it a bit more of a punch. Both systems will work in tandem to develop widespread light to moderate snow across the entire tri-state area late Friday night-Saturday. I expect scattered snow showers to develop late tomorrow (around midnight or so), becoming widespread by late Saturday morning. I expect most areas to pick up anywhere from 1-3″, with isolated spots picking up 4″ (especially east of I-71). This forecast is still fluid. There is still quite a bit of model uncertainty at this time, thus a small shift in the track of the systems will greatly influence the forecast. After this evening’s model package, I will have a good idea as to what we should expect (including my updated snowfall forecast graphic). Stay tuned!

The cold front that crossed the tri-state last night will help to usher in much colder air than what we saw yesterday (highs around 60). Look for high temps to only make it into the middle to upper 30s today. With a stiff breeze, wind chill values will be in the 20s or lower, so bundle up before heading out!

Tue
High pressure remains in control for Tuesday, allowing skies to remain mostly sunny and temps to climb into the lower 50s!

Wed-Thu
High pressure slides east during the day on Wed, which will allow clouds to thicken and showers to develop. A vigorous area of low pressure will really begin to intensify shortly after developing in the Gulf of Mexico. After formation, the low will begin sliding NNE towards the Ohio Valley. Given its origin, the storm will have a lot of moisture to work with. Consequently, expect widespread rain to develop by Wed afternoon/evening, continuing through the night. Some of the rain may be heavy, so take it slow when driving, and watch out for ponding. Temps on Wed will only climb into the 40s before falling into the middle 30s overnight. For Thu, temps will really begin the drop, with highs only topping out in the upper 30s. I wouldn’t rule out a few flurries or snow showers, though they will be isolated and light. Temps really fall off Thu night with most areas expected to bottom out in the middle 20s.

Fri-Mon
The chill really sets in for Fri, Sat, and Sun. The strong cold front associated with the Wed/Thu system will really help usher in the cold air, which will easily be the coldest we’ve seen since last winter. The setup for LES (Lake-Effect Snow) will also be very favorable, so areas to our north (in the classic belts) look to receive their first significant accumulating snow of the season! As is always the case, if the fetch is favorable, we may see a scattered flurry or snow shower in portions of the tri-state, though they will be few and far between (especially for areas south of I-70). Most of the LES will fall on Fri, though some of the belts will still be cranking on Sat as well. Expect temps to struggle to make it to the freezing mark for both Fri and Sat, with lows both nights falling into the middle/upper TEENS! Temps begin to moderate a bit for Sunday with highs topping out in the middle 30s. The moderation continues for Monday with high temps topping out around 40.