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Clouds and sun duke it out for control of the sky

Approaching rain to end the week gives clouds the upper hand.
Credit: WHAS

Clouds, clouds go away, come again another day...it feels like it's been a while since we've seen the sun, hasn't it? Well we might see a few peaks of it now and again through the end of the week, but clouds will have a firm grip in the sky through Saturday. Rain is also on way the way for consecutive days, and some of us could see some very healthy amounts.

Credit: WHAS

The weather setup: Despite being under the influence of an upper level ridge, we are cloudy and cool thanks to trapped moisture behind yesterday's rain event. This is a common occurrence for us this time of year. Those clouds will struggle to clear out Wednesday, but where the sun does peak through you can enjoy some sunshine to briefly warm you up. The ridge will be pushed east thanks to a storm currently sitting near the CO/KS/OK borders. That storm is responsible for bringing our region the first round of rain beginning Thursday (Figure 1). Also note that big low pressure system in California. That will be our rain maker for Friday and Saturday.

Credit: WHAS
Fig. 1: Upper ridge over central U.S. Wednesday will move east, but it's unlikely we see any additional sunshine. Where the sun appears, warmer temps.

The storm near the Oklahoma panhandle will quickly move into the Great Lakes region Thursday and interact with a shortwave trough that will be moving southeast from portions of Canada. As these two interact, the low will develop warm and cold fronts and set the staging ground for some light precipitation during the day Thursday.Thursday's cold front isn't the strongest, so precipitation will be somewhat spotty and light in nature. Most of the rain and snow will stay to our north in the Great Lakes. As the cold front approaches Thursday night, we'll see another round of light rain across the area. Rain accumulations up to 1/4" are possible through Thursday night. (Figures 2 and 2a). 

Credit: WHAS
Fig. 2: By Thursday a surface low over Wisconsin will feature a cold front through Missouri and a warm front through Ohio. Notice only the light rain near Louisville.
Credit: WHAS
Figure 2a: by Thursday night the cold front will move across Kentuckiana, but only light to moderate rain is forecast.

Temperatures: Clouds and wind Thursday will play a huge factor in how warm we get. What works in our favor are forecast southwest winds between 10 and 15 miles per hour. A southwest wind brings us warmer air and usually allows temperatures to somewhat overachieve model guidance. Will the wind be enough to counteract cloud cover? Possibly. We believe we'll see a bit more sunshine Thursday, which would help warming. With strong enough winds and enough sunshine, temps could easily warm into the lower-to-middle 60s! Our average high is now in the middle 50s, so it would be a rare day this month that temps were warmer than normal.

The next round of rain: A more significant round of rain is forecast for Friday into Saturday. This is the upper level storm mentioned earlier churning over southern California and it will progress through the Rockies. The surface low for this storm will enter the lower Mississippi River Valley Friday afternoon. There is actually good agreement among models that the center of this low pressure system will track through the Ohio Valley Friday night into Saturday which would mean ample rainfall for almost everyone, but particularly those in central and southern Kentucky (Figure 3).

Credit: WHAS
Figure 3: Friday and Saturday's storm will take a path through the Ohio Valley and should bring a good amount of rain for everyone.

I haven't mentioned the "S" word yet. That's because we're not expecting any snow of significance. Like last time, temperatures are going to be too warm to support snow. That being said it is possible that we'll see enough cold air on the backside of the storm Saturday that a few snowflakes may make show themselves. The Indiana side of the Ohio River is the most favorable area to see some of the falling white stuff. Elsewhere temperatures will be at or slightly above freezing.

How much rain? Heavier rain is expected south of Louisville through Saturday, with lighter amounts north of it. One to two inches possible from about Louisville  to Columbia, KY. Southern Indiana will have lighter totals of 1/2" to 3/4" of rain, with maybe a couple towns making a run at one inch on the high end (Figure 4). Again, despite some possible snowflakes late Saturday night, we will not see any accumulating snow.

Credit: WHAS
Figure 4: Potential rainfall amounts by Sunday morning.

A few days of calmer weather will begin starting Sunday. Temperatures will moderate and we might end up above average, but that would be more a result of our average high temperature continuing to decline while temps stay relatively consistent. Average highs through Thanksgiving (November 28) dip to 52° from 56° today (November 20). We're currently forecasting high temperatures early next week in the middle-to-upper 50s and perhaps trying to make another run at 60°.

Thanksgiving: This is the forecast we're all wanting to know. While still a week away, there are signs of a significant storm around Thanksgiving moving through the heartland and affecting us during its journey. This could mean a soggy and slow travel day to grandma's house Wednesday. While models agree about a storm around Thanksgiving, they disagree is on timing and temperatures. GFS is a bit slower and warmer than the Euro, which is quicker and much cooler. Figure 5 shows the GFS solution for Wednesday, November 27. All long-term guidance suggests calmer weather for Thanksgiving day, but another storm looks to be on its heels for that weekend.

Credit: WHAS
Figure 5: One week out, the GFS paints a sizable storm entering the Great Lakes and affecting the country down to the Gulf of Mexico. Should this verify, it could mean a wet day of travel for Thanksgiving.

A busy end to the month in the weather center it would seem.

Meteorologist Alden German
Facebook: Facebook.com/AldenGermanWX 
Twitter: @WXAlden

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