Category: Forecast Models

Accumulating Snow Saturday Night?

In the short term, a wintry mix of sleet, freezing rain, and snow will transition to all rain across the entire region Saturday.  That said, if traveling early Saturday morning, please leave extra time to reach your destination and plan to take it slow on the roads as a mixed bag of wintry precipitation will fall on central Indiana tonight.  Most snow accumulations will range from 1″ or less.

After a cold and damp Saturday, we’ll have to pay close attention to the chance of snow mixing with the rain Saturday evening before possibly turning rather quickly to a heavy, wet snow Saturday night/ wee morning hours Sunday.  A cold front will slip south Saturday evening.  Additionally, a disturbance will move slowly northeast along the pressing front and result in widespread precipitation falling on the back side of the boundary (in the colder air) late Saturday night into Sunday morning.  As of Friday evening, guidance suggests a frontal passage in the city between 6-7 o’clock and cold air will begin to filter back into the region at that time period.

2

While we’ll have to keep a close eye on things during the afternoon Saturday, confidence is growing on the opportunity for a stripe of accumulating snow being laid down through central Indiana late Saturday night into the wee morning hours Sunday.  Just how much?  We wouldn’t be surprised if some amounts of 2-3″ are reported by daybreak Sunday, including in, and around, the greater Indianapolis region.  Most of this snow would accumulate within two-three hours so this will be what we call a “thumping” snow.  Stay tuned.

Permanent link to this article: https://indywx.com/accumulating-snow-saturday-night/

Complicated And Complex…

If you have travel plans across central Indiana Friday and Friday night, please make sure you leave plenty of time to get to your destination and prepare for a variety of precipitation types.  In fact, it’s entirely possible (depending on what time of day you’re traveling) that you have to deal with rain across south-central Indiana and snow by the time you arrive into the northern Indianapolis suburbs, complete with an icy mixture “in between.”

Digging through the weather playbook for Friday into Saturday:

A cold front is expected to move through the region Friday morning, allowing a wind shift out of the north to arrive into the city in the early to mid morning Friday. We’ll have to be in “nowcast” mode Friday to determine just exactly how far south the front makes it as this will go a long way into determining precipitation types across central Indiana.

Ultimately, a wave of low pressure will move along the front Saturday, which will help milder air push north and result in a changeover from a wintry mix to all rain during the majority of the day Saturday. In fact, there’s the chance portions of central Indiana may not have to deal with much, if any, precipitation through the majority of the day Saturday- especially south.  Before that, however, we’ll have to deal with a wide variety of wintry precipitation issues Friday and Friday night…  Warmer low level air will be drawn northward and overrun the colder air at the surface Friday and Friday night.  What will initially be a period of snow Friday will transition to an icy mixture of sleet and freezing rain Friday night and all rain Saturday.  That said, we note the milder push will be brief, and colder air will pour back into the region on gusty northwest winds Saturday night. This may result in a brief period of light snow Saturday night (not a big deal).

We think the latest high-resolution, short-term, NAM model (courtesy from the fine folks over at Weatherbell Analytics model suite) has a very good handle on accumulation ideas Friday and Saturday and is in best agreement with our analysis laid out above.  This is a look at forecast snow accumulation between now and Saturday night, but we also note there will be some light sleet and freezing rain accumulation on top of any snow that falls Friday. As far as that snow goes, we think a 1-2″ band is laid down from the city and points north, increasing further as you travel into north-central and northern Indiana.

hires_snow_acc_indy_18

 

 

Permanent link to this article: https://indywx.com/as-promised-complicated-and-complex/

A Word About Early Next Week…

We posted earlier this morning on the near term (below) and Friday and Saturday remain quite challenging and complicated.  Precipitation type and amounts will have to be resolved as we…

You must be logged in to view this content. Click Here to become a member of IndyWX.com for full access.  Already a member of IndyWx.com All-Access?  Log-in here.

Permanent link to this article: https://indywx.com/a-word-about-early-next-week/

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

 

 

 

 

 

23

 

 

 

 

 

 

 

 

 

 

 

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.

4

 

 

 

 

5

 

 

 

 

 

 

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/

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.

1011

 

 

 

 

 

 

 

 

 

 

 

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…

12

 

 

 

 

 

 

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/