Category: Forecast Discussion

Jan 29

Wintry Mix Issues Late Week/ Weekend

We’re going to enjoy another day of sunshine, but moderating temperatures (finally) will help being outdoors become a little more tolerable (we think we “warm” into the middle 20s today).  That said, another winter weather maker is brewing and will result in an active Friday-Sunday ahead.

A cold front will sink south Thursday night and could result in a little light snow (not a big deal).  As we move into Friday and Saturday, model data handles our sensible weather differently.  Precipitation type will be highly dependent upon exactly where the cold front stalls.  We want to show you the GFS as it depicts the variety of precipitation types. It should be important to note that the GFS, European, and Canadian, though different in their respected solutions this weekend, are close enough to go with a “blend” of all three models for our official forecast.

We think snow overspreads the region Friday morning and could deposit a quick couple inches across the metro area Friday. It’s as we get into Friday night and Saturday that we’ll note another (stronger) wave moving along the front. In response to this wave of low pressure, warmer air (both at the surface and aloft) will push north.  Exactly how far north is still up for debate as a battle will be established with push back being provided from an area of high pressure across the upper Mississippi River Valley. We feel as if south-central Indiana will get in on some mixing issues with sleet and perhaps a cold rain Friday night into Saturday.  Depending on how strong the wave of low pressure is will determine exactly how far north the rain line makes it.  For now, we think Indianapolis and northern suburbs remain in a wintry mix of snow, sleet, and possible freezing rain through the majority of the day Saturday.  That said, we do note this will warrant tight focus in the days ahead as any deviation from the track of the low or strength of the cold high to our north could greatly impact our weekend weather.1

 

 

 

 

 

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Finally, precipitation will begin to taper late Saturday night as the cold high to our north eventually wins out. It’s possible all of central Indiana deals with a quick pop of accumulating snow as precipitation ends Saturday night/ wee morning hours Sunday.

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We stress that this is still a highly changing weather situation and most likely will require some “fine tuning” as we move forward.  This morning we think heaviest snow (potentially approaching half a foot) falls across north-central Indiana, including Kokomo, Marion, and Lafayette.  A wintry mix of all precipitation types will fall south of there, including the Indianapolis metro.  South of I-70, we think rain will be the predominant precipitation type, with only a light accumulation of snow as precipitation ends.

As stated above, stay tuned…

Permanent link to this article: https://indywx.com/wintry-mix-issues-late-week-weekend/

Jan 27

Big Fight Late Week Into The Weekend….

A major battle is taking shape between two of the more respected mid range forecast models for the late week period, including Super Bowl weekend.  The differences range from yet another wintry weekend, with a couple shots of accumulating snow to one that’s much milder and includes some rain.  Operational guidance today has remained consistent with what each particular model has been saying for the past 24-48 hours, adding further complexity to the upcoming late week period.  Usually we’d give a slight nudge towards the European output (warmer solution), but here in a bit we’ll tell you why we’re really not ready to hedge more towards one particular model over the other at this time frame.  Instead, we want to give it a couple more days and see which model “gives in” to the other.

Let’s dive into the European output first.

We note both models in relative good agreement on Thursday night into Friday as light snow overspreads the region (not a huge deal, but potentially enough to make for a slippery Friday morning commute).

As we move into Saturday the European tracks a developing surface low much further north than the GFS, resulting in a milder solution across central Indiana and a forecast that would produce a rain to snow solution Saturday as cold air quickly pours back into our region, with enough snow, perhaps, to produce a light accumulation Saturday night. However, it’s important to note, most European ensemble members are colder than the operational run and this is something we’ll need to continue to monitor.

As we head into early early next week, the European forecast model remains bullish on a potential major winter storm, with a favorable storm track for heavy amounts of wintry precipitation across central Indiana.  The time we’re eyeing for this next storm falls in the Monday night-Tuesday time period so we have plenty of time to monitor things and iron out the details…

Now, as we look at the GFS forecast model, we note a colder solution from start to finish.  We have to raise an eye brow here as the track record of the GFS in the mid range is one that has been known to be biased too “flat” and too cold in handling similar patterns.  Is that saying the GFS is wrong here?  Absolutely not…nobody knows that at this juncture.  It is saying we have to rely on experience and remember similar patterns of the past, including the way the model “corrected” itself with time as we drew closer to the particular event in most cases…

Nonetheless, similar to the European, the GFS delivers a round of accumulating snow Friday morning, but is flatter (colder) with the initial wave and also leads to quite the overrunning event through the Ohio Valley.  As a matter of fact, we deal with two rounds of accumulating snow…Friday morning into the early afternoon and again Saturday morning, associated with yet another wave of low pressure.

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Of interest, the GFS also sees the potential strong winter storm that could impact our neck of the woods early next week.  Needless to say, the surface map next Tuesday morning would have snow lovers smiling in a big way should this come to fruition…

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While we have many details to iron out late week and on into early next week, the overall weather pattern is one that we remain confident on and the results are cold and stormy (i.e. snowy) over the upcoming 10-14 day period.  As a matter of fact, long range teleconnections suggest we remain colder than normal and stormy through the majority of February. In short, there’s really no let up in sight from the overall cold and wintry time of things Hoosiers have grown oh so accustomed to this winter…

Permanent link to this article: https://indywx.com/big-fight-late-week-into-the-weekend/

Jan 24

1st of 3 Rounds Of Wind-Whipped Snow This Weekend!

The first of three rounds of accumulating, wind-whipped, snow is blowing into central Indiana as I type this.  We still think widespread 2-3″ totals fall across many central Indiana neighborhoods during the overnight, with snow ending from north to south between 6-8am.  Additionally, blowing and drifting snow will be a huge concern and local white-outs/ near blizzard conditions will develop into the morning Saturday.  Needless to say, if you don’t have to travel tonight or Saturday, it would be a great time to hunker down at home, start a fire, and enjoy friends and family!

Here’s a look at forecast radar during the “height” of the storm, most likely between 2-4a for most areas:

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Snow will end Saturday morning, but we’ll have to contend with continued severe blowing and drifting, especially in central Indiana’s open country.  Remain cautious if you must venture out.  Winds will back around from the southwest during the wee morning hours Saturday to a colder (yet again) northwest direction late Saturday morning, resulting in another bitter feel to the air Saturday afternoon.

We’ll enjoy a brief calm period Saturday evening (despite continued gusty winds), but our meteorological eyes will already be poised to the northwest, focused on our next round of accumulating snow Sunday morning. We call this “warm advection” snow as it’ll fall on milder southwest winds ahead of yet another arctic front due in here Sunday night.  This will likely be a  “thumper” snow as additional accumulation Sunday of 1-3″ is a solid bet at this point- most of which falls within a 2-3 hour time period.

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Sunday afternoon will likely turn drier (and briefly milder) before that “famous” arctic front slams into the region Sunday night. We think additional snow showers and embedded heavier squalls will accompany the frontal passage (FROPA) and could easily lay down yet another half inch to one inch of accumulation Sunday night/ early Monday.

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All of this additional weekend snow will be capped off with some of the most brutally bitter air so far this season (and that’s obviously saying something, considering how cold it’s been). Gusty northwest winds will lead to continued blowing and drifting issues in the open country early next week, but produce dangerous wind chill values, colder than 30 degrees below zero from time to time.  Additionally, overnight lows Monday night into Tuesday morning will likely fall to between 15 and 20 degrees below zero and highs on Tuesday will likely struggle just to make it to the 0 degree mark for a high…

Permanent link to this article: https://indywx.com/1st-of-3-rounds-of-wind-whipped-snow-this-weekend/

Jan 23

Combo Of Snow & Wind Likely To Cause Problems…

We wanted to take some time to focus solely on our next shot of accumulating snow due in here late Friday night into early Saturday morning.  This will be a quick-hitter, but with snow ratios much higher than normal (thanks to the arctic air mass in place), it won’t take much moisture to fluff up a few inches of powder.

Before we get into the next snow, we can’t ignore what will be a growing concern as morning progresses into afternoon Friday.  The pressure gradient will really begin to tighten between arctic high pressure to our south and the next cold front and associated low pressure to our north.  West winds will increase and gust in excess of 30 MPH by early to mid afternoon.  This will lead to concerns for blowing and drifting in the open country from the existing snow pack in place.  Otherwise, mostly sunny skies will begin to cloud up later in the afternoon and evening.

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A continued very windy evening will be coupled with light to moderate snow spreading south over the region late Friday night into Saturday morning.  We note the heaviest snow likely to fall in the pre dawn hours Saturday and may become briefly heavy at times.  We forecast 2-3″ of new snow with this system across all of central Indiana, but when you combine a strong west wind, shifting to the northwest Saturday morning, trouble will result.  Significant blowing and drifting snow can be expected through the night and into Saturday.  Travel will likely be very tough late Friday night into Saturday morning.  Not only will we have to contend with severe blowing and drifting, but we’ll also have to deal with local white-out conditions.

The latest high resolution model data shows widespread snow across the region Saturday morning before snow tapers by mid morning from north to south.

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As mentioned in posts from earlier this week, we’ll also deal with yet another round of accumulating snow for the second half of the weekend and we’ll have more on this tomorrow and Saturday…

Permanent link to this article: https://indywx.com/combo-of-snow-wind-likely-to-cause-problems/

Jan 22

Quick Remark On Sunday.

We have enough to worry ourselves with tonight and again Friday night-Saturday, but many are wondering about what Sunday holds.  The consensus of operational model data today is for a north track Sunday, keeping most of the heavy snowfall across northern Indiana.  That said, is it the correct idea?  We’re not ready to buy the extreme north trend just yet…

While anything is possible, the northward trend in operational runs today has me scratching my head a bit given the overall pattern.  Current thinking here would suggest operational models  “correct” south with time over the next couple days, but time will tell.  The GFS ensembles help illustrate the wide variance with the track of Sunday’s snow storm (below).  While the track of the system is still up for debate, confidence is growing on amounts just north of the low’s track that approach half a foot Sunday.  Much more later!

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Permanent link to this article: https://indywx.com/quick-remark-on-sunday/