Winter Outlook 2011-2012
Issue Date: October 17, 2011
Forecaster: Trevor Cole

Introduction:
Winter is right around the corner, so it’s time to take a look at what we’ll expect across the Ohio Valley. We are in times of major change in the weather world, with colder air becoming dominant over warmer air globally. Widespread records have been shattered each and every winter for the last several years across the US and beyond, including the Ohio Valley. December 2010 went down as the fourth snowiest on record with 16.6” (or over 70% of our average yearly total in one month) in Cincinnati. In addition to being very snowy, last winter was also fairly cold overall. This upcoming winter season looks to bring much of the same.

La Nina:
One of the most important factors in long range forecasting is the current ENSO state. This refers to whether the equatorial Pacific is warmer (El Nino) or colder (La Nina) than normal. The state of the ocean has major implications on North American weather. We are headed towards another La Nina winter (similar to last year), with some forecast models dropping the SSTs (sea-surface temperatures) across the Nino 3.4 region to record cold levels. As of the latest reading, La Nina is fairly weak with around a -0.5 degree temperature anomaly. At this point in time, I do not see this episode cooling to strong levels, but more-so a moderate event. It is very rare for a second-year Nina to be stronger than the first, which is one reason why the current CFS (Climate Forecast System) projection seems unlikely (though not impossible).

The image below depicts a typical La Nina winter:

A typical La Nina winter across the Ohio Valley features above average precipitation and above average temperatures. However, the overall setup is not typical, and is why the above graphic needs to be edited this time around. Let’s take a look as to why…

NAO (North Atlantic Oscillation):
The NAO is another important factor when making long-range forecasts. It is essentially a relationship or fluctuation between the two major pressure systems over the Atlantic—the Azores High (subtropical) and the Icelandic Low (subpolar). The way they are set up distinguishes a positive or negative phase. A positive phase can be described as having a stronger than normal Azores High, thus leading to a more northerly storm track across the US and milder temperatures across the Eastern US. A negative phase is just the opposite with a stronger Icelandic Low leading to a more southerly storm track and colder temperatures. The NAO has been in an overall negative phase for the past several months, with brief positive spikes. The NAO is known for frequent fluctuations, which provides for changing weather as opposed to static conditions. I expect this to remain the same through the winter, which will allow for periods of bitter cold, along with periods of milder air.

From the above description, a –NAO favors increased cold and snowy weather across the Ohio Valley and Eastern US during the winter months.

Below is an image of the last few months of NAO readings, along with the CPC (Climate Prediction Center) forecast:

PDO (Pacific Decadal Oscillation):
The PDO, like the NAO, is yet another factor to take into account. The PDO is described as a warming or cooling of Pacific waters around and north of 20 degrees north latitude (which helps distinguish it from the ENSO zone). In a +PDO, the waters across the West Pacific warm while the East Pacific cools. A –PDO is just the opposite. Unlike the NAO, the PDO tends to be multi-decadal. In other words, one phase will typically last over 20 years. Currently, the Pacific is in a –PDO state. One reason why I believe this is an important tidbit is that the storms entering the Western US will be tracking over these colder waters and thus, not bringing a ton of mild air with them. When adding in the fact that the Gulf of Mexico continues to run cooler as well, it will be harder for periods of milder air to hang on this winter.

Clipper Train vs. Major Storms
One thing to begin to think about when forecasting for an upcoming winter season is the main storm type or mode. There are usually two types of storms to choose from, which are either clipper systems or a storm originating in the Pacific or Gulf. This is when things begin to get pretty tricky. If we wind up being around average or slightly below temperature-wise for the season, that’ll mean that we run a higher risk of bigger storms (capable of producing rain, a mix, and/or). This is mainly due to the fact that in this scenario, the persistence of major blasts of bitter air will be lessened, which will allow for storms to track further north rather than suppression occurring. If cold is the rule, then we have a decreased risk for bigger storms and an enhanced risk for clipper-type systems. The NAO plays a significant role in this.

To further complicate things, a snowier than normal winter can occur in either scenario. If the cold wins out and we have clipper after clipper tracking through with high snow to liquid ratios (like last winter), it can really add up. If the opposite occurs, we can have less in the way of frequent snow, but rather two or three bigger events that take us to or above normal by season’s end. For this upcoming winter, I believe we’ll have a mix of the two. I expect frequent, intense cold blasts which bring a favorable setup for high ratio clippers. On the flip-side, I also expect periods of milder conditions to be mixed in as well which either give us risks for rain (and even severe t-storms) or a rain changing to heavy snow event with big accumulations. Heck, if the NAO is just right, we could even run the risk for a massive snow event or potential blizzard with this kind of setup.

Conclusion:
So now let’s get past all of the jargon and get to the point. Overall, I’m expecting below average temperatures and above average snowfall for this upcoming winter. In a typical winter, Cincinnati receives around 23.5” of snow. I’m expecting anywhere between 25-35” for the upcoming winter season. Some areas could see more, some less. It all just depends on the storm track and precipitation type. However, I believe 25-35” is a nice average to represent the entire tri-state area. We’ll have a variety of jet stream setups that should allow for us to see the potential for frequent clipper snows, along with some rain events, ice events, and potentially a large snowstorm or two. I know some forecasters like to go month by month, but I feel that the situation and setup is just too unpredictable to do so. Thus, I’ll keep things simple with a general overview.

10:00am, October 12, 2011

After an absence over the last several months, I am finally getting things in order for new updates. I’ll be tinkering with things over the next few days to get the site back in full working order. Expect a return of daily seven day outlook updates, weather analysis, video updates, and storm (both severe weather and winter weather) coverage. Additionally, I’m in the process of putting together my outlook for the upcoming winter, which will be released this coming Sunday (October 16th). Fun times are ahead in both the weather world and for this site, so stay tuned!

If you have any suggestions for the future of CincyForecast.com, don’t hesitate to place it in a comment under this post or email me at trevor@cincyforecast.com

-Trevor Cole, Forecaster

After a rather hot, humid, and dry day yesterday, rain chances are once again back in the picture. A cold front will continue to sag south towards the tri-state through the afternoon-evening hours. Ahead of the boundary, our atmosphere is expected to become moderately to highly unstable (strong amounts of lift and energy). This will lead to the development of scattered showers and thunderstorms through the afternoon, some of which may be strong to severe with damaging winds and large hail being the main threats. If the storms are able to organize into a larger complex (which is a possible scenario), then our severe threat will be increased (both in probability and coverage). Additionally, that sort of situation would also increase the risk for potential spin-ups.

Some of the models are hinting at some spotty action during the morning hours, though that should be scattered and in the process of weakening (remnants of the large storm complex that raked WI yesterday). If the storms are able to maintain strength, spotty areas of gusty winds and small hail are possible before things clear out through early afternoon.

Expect highs to stay in the middle to upper 80s today given increased cloud development and potential storm activity.

For a look at the weekend forecast, check out my latest five day outlook below!

After a brief break, a rather unsettled pattern is yet again in the making. The ridge of high pressure that has been dominating our weather over the past few days will begin to slide to the east today, allowing for a strong SW flow to commence. This will really help usher in copious amounts of moisture, which will then set the stage for an impressively active pattern.

There is an outside chance of an afternoon shower or thundershower today, though most areas will remain dry and hot. Expect highs to top out in the lower 90s area-wide, with middle 90s possible south of the river. Combined with the humidity, it’ll feel rather uncomfortable outside (especially if you’re out there for long periods of time). This isn’t dangerous heat by any means, though it will likely be the warmest we’ve been this year.

Activity really begins to pick up starting tomorrow. Waves/impulses of energy will begin tracking through the Ohio Valley, which will provide daily shower/t’storm chances. Strong to severe thunderstorms and locally heavy rainfall are threats pretty much each day through the middle of next week. The main threats with the storms will be gusty winds and hail. This type of a pattern, especially with the amount of moisture shown on the models, is also notorious for impressive rainfall totals. By the middle of next week, I fully expect widespread 2-4″ totals, with some areas picking up near 6″. There will be dry periods mixed in, though each day at least some portions of the tri-state will likely see rain.

This is also a pattern that favors MCSs, or Mesoscale Convective Systems. An MCS is basically a large complex of thunderstorms that usually maintains organization for hours on end along its track. Most of the time, they are accompanied by strong winds/hail and heavy rain.

I’ll keep an eye on this developing active pattern. For a look at the next few days, check out my latest extended outlook!

Have a great Wednesday!

-Trevor Cole

I’m bringing this site back to life this summer. Expect daily forecasts/analyses to commence over the next week, and I’ll do my best to keep it updated frequently over the summer. It’s been quite a while since I’ve done anything with it, though I’m very excited to resurrect it over the coming days. Stay tuned!

After a rather chilly week, temperatures are finally on the rebound thanks to the beginnings of a WSW flow. A weak disturbance passing through the OV will continue to bring shower chances through tonight before things begin to clear out. Expect an outside chance for a shower on Saturday, though most will stay dry under partly cloudy skies. Highs should once again top out in the lower to middle 50s before falling into the upper 30s Saturday night. A warm front will approach the tri-state on Sunday, bringing with it warmer temperatures and a chance of showers/thunderstorms. Expect highs to top out in the lower to middle 60s Sunday afternoon.

As a deepening area of low pressure approaches from the west on Monday, strong SWerly winds will really help pump in the warmth and allow for temperatures to spike up to around 70 or so ahead of the strong cold front. This setup, which includes lift, strong winds aloft, and enhanced shear values will lead to the development of strong to severe thunderstorms ahead of the front. The latest model runs show a very impressive setup, one of which is similar to the bigger events we’ve had in the past. The risk for a widespread severe weather outbreak is becoming more and more likely, including the threat for damaging winds, large hail, and isolated tornadoes. Stay with CincyForecast.com for future updates regarding this potentially large-scale severe weather event!

A winter storm is headed for the tri-state! Expect light snow to commence Thu AM between 4-6am, becoming steady to heavy by noon. Snow, heavy at times, will continue through early evening before tapering to flurries. In total, I’m expecting 4-6″ of accumulation area-wide. After the snow winds down Thu night, a new threat will become the main player…wind. Expect gusty winds due to the nice gradient setting up between the exiting low and the area of high pressure sliding in from the west. Blowing/drifting of the fallen snow will likely lead to continued slick spots on roads through the first part of Friday.

Passing snow showers continue across the tri-state thanks to lake-enhancement (from Lake Michigan). While they won’t last long, expect quick additional accumulations of up to a half inch in the heavier bursts. The bigger threat today is blowing snow as winds occassionally gust up to 25mph. Watch out for slick spots, especially in areas that receive heavier snow showers or where there is snow blown onto the road. The NWS in Wilmington has extended our Winter Weather Advisory until 7pm to account for these threats.

Below is the official storm total map through 6am today from the NWS (which is made by compiling reports from around the tri-state). My 3-5″ forecast from several days ago looks to have verified nicely.

Models continue to hint at several more storm chances through January, so stay tuned!

After a day filled with bouts of heavy snow and significant accumulations, things are starting to wind down. The best energy and lift (for the development of widespread snow) has shifted to our ENE, but now we are presented with a new problem…winds. There is a nice pressure gradient between our exiting low and an area of high pressure sliding through the Plains. This is creating a prime setup for blowing/drifting snow, which will likely lead to slick spots on area roadways Wed AM (when combined with temps in the low 20s and passing snow showers). I expect widespread delays and even some closings for the more rural districts tomorrow. Take it slow when venturing out, and allow for some extra time to get to your destination. For the extended outlook, check out the 7-day forecast page.

Storm Totals (not final as snow is still falling in many areas):
-Cincinnati: 3.1″
-Centerville: 4.0″
-Wilmington: 3.5″
-Dayton: 2.0″
-Lebanon: 3.6″

After a rather delightful weekend, the reality of summer is about to make a comeback. An area of high pressure to our east and developing low to the west will work in tandem to bring in a SSW flow, which will once again enhance the heat and humidity. It won’t be oppressive, but it sure won’t feel comfortable when outdoors. For the rest of my forecast, including upcoming rain chances, check out the 7-day forecast page!