Category: Forecast Discussion

Dec 14

Period Of Heavy Snow Coming

Latest short-term, high resolution, models are showing what’s taking shape nicely this morning. We think the city and points north will undergo a period of moderate to heavy snow from late morning into the early afternoon hours.

Within the highlighted area, we think snowfall rates will approach 1″ per hour between 10a-2p.  Yes, within that (4) hour time period, don’t be surprised if a few reports come in with 3-4 additional inches of snow atop what’s already fallen, particularly across the northern half of the highlighted area.

HVYSnow

Here’s a look at the latest HRRR model simulated radar showing the swath of moderate to heavy snow coming over the next few hours.  Again, high snowfall rates will make plowing duties difficult so if you must travel, please take things slow.

hrrr_ref_ne_8

South-central Indiana will see dramatically less snow due to mixing issues (as forecast) and the dry slot that is arriving now.  The track of the upper low should lock moderate to heavy snow into central and north-central Indiana into the early to mid afternoon.  All of the snow will then begin to diminish and move northeast during the early to mid afternoon, as our storm system departs.  This will then allow northwest winds to strengthen and become gusty this evening, with cold air pouring back into the region.

Permanent link to this article: https://indywx.com/period-of-heavy-snow-coming/

Dec 12

Old Man Winter Jabbing Now, But Is The Knock-Out Punch Coming?

Before we discuss what may lie ahead closer to Christmas, our going forecast for Friday night and Saturday’s snow storm hasn’t change…4-5″ for the greater Indianapolis region by late Saturday morning.

Since really back in the middle of October we noted a distinct pattern change that has resulted in a colder than normal regime around these parts ever since.  As we look ahead, there really aren’t any indicators that would suggest we’ll deal with warmer than normal air for any period of significant time through the remainder of the year.  Furthermore, there are multiple computer models hinting that we’ll have to deal with a significant winter storm and potentially a shot of brutal cold as we rumble closer to the busy Christmas week.

It’s very important to note that we still have several days to watch the goings on for Christmas week, but the stage has at least been set for the possibility of a storm of “importance” being around the region as we near that particular time period.

Confidence is growing on brutal cold (most likely record-breaking) initially dumping into the Plains states towards the latter portion of next week.  With time, we think this cold slugs it’s way east.  Before the arctic intrusion gains control of the Mid West and Ohio Valley, we think this is the area that stands the greatest chance of dealing with a major winter storm.  We have strong ensemble support (pictured below) of the evolution of the overall pattern, but we caution that the precise details will have to be ironed out.

Ensemble1Ensemble2Ensemble3

The “sensible” weather that would ensue here across central Indiana could vary wildly from a significant full-blown winter storm with all of the precipitation falling in the form of a wintry variety (i.e. snow, sleet, freezing rain) to a situation that features a western track with briefly milder air surging north into portions of the region and leading to a rain-to-snow situation.  The accumulation ideas would swing from a significant, plowable, snow storm to as little as a coating with arctic air blowing in behind the rain to snow scenario.

At the end of the day right now we’re confident on two things: 1.) a major winter storm around the Mid West/ Ohio Valley as we near Christmas week and 2.) brutal arctic air swinging into the area around Christmas.  Questions will have to be answered as we move ahead to determine the precise precipitation amounts and type.

In closing, just for fun, we thought we’d provide a look at the latest European forecast model data.  Here’s a look at the upcoming 10 day European model snowfall forecast.  Of course, these amounts account for the 4-5″ expected here tomorrow night and Saturday,  but (2) additional systems also add to the potential growing snow pack…a clipper system Monday and the “more important” system next weekend.  Stay tuned.

Euro1

Permanent link to this article: https://indywx.com/old-man-winter-jabbing-now-but-is-the-knock-out-punch-coming/

Dec 10

Snowy Pattern Continues…

Considering we’re only a third of the way through December, we’re certainly running “snowier” than normal at this very early stage in the game.  As we look ahead at the upcoming 10 days, or so, we see this snowier than normal pattern continuing with multiple systems to contend with over the course of the upcoming couple weeks.  Up next will be the threat of some light snow showers and flurries with reinforcing arctic air Wednesday PM.  Nothing significant is anticipated here on Wednesday, accumulation-wise, but snow showers will blow through the area Wednesday afternoon.  The latest high-resolution NAM shows this well.

hires_ref_indy_37

 

 

 

 

 

 

Then our attention turns to a developing winter storm for the weekend. We think clouds increase Friday and snow develops Friday night into early Saturday.  Here’s a look at the latest GFS forecast model, valid Friday night.

gfs_ptype_slp_east_17

 

 

 

 

 

 

Fast forward that to Saturday morning and snow grows heavier…

gfs_ptype_slp_east_18

 

 

 

 

 

 

The GFS suggests a weak surface low tracks into eastern Ohio with backlash snow showers and embedded squalls continuing here Saturday night into Sunday.

gfs_ptype_slp_east_20

 

 

 

 

 

 

It’s important to remember that we’re still a few days out from this event and I can guarantee you things will change as we go through the course of the upcoming few days that will require us to do some adjusting to our forecast Friday-Sunday.  That said, at this early stage in the game, unlike with our last storm, I’d favor areas from IND and points north as the place where heavier snow falls this go around.

Latest GFS ensembles suggest something similar to the operational run shown above with one low tracking into the eastern Ohio Valley as another coastal low develops.

f120

The European ensembles provide an “intriguing” look for an Ohio Valley winter weather event this weekend, as well.

Geopotential32at32500hPa_North32America_96

 

 

 

 

A couple of additional items to consider at this early juncture- this will be a fast moving winter storm so that will have an impact on snowfall accumulation.  Additionally, there’s also the chance enough warm air aloft advects (WAA or warm air advection) into the southern portions of the region to result in “mixing” issues (i.e. sleet and freezing rain).  In the primarily “snow zone” Friday night-Saturday (again, we’re currently targeting IND and points north for the snow zone) several inches of snow could accumulate.

Here’s an early look at what the latest mid-range forecast models are seeing in terms of potential accumulations with this event.  Top to bottom: ECMWF, GFS, and Canadian.  Stay tuned, we’ll have another update later!  Enjoy your day!

ECMWFGFScmc_snow_acc_east_24

Permanent link to this article: https://indywx.com/snowy-pattern-continues/

Dec 09

Monday Morning Weather Rambles…

1.)  Light freezing rain and freezing drizzle led to numerous reports of a light glaze and associated very hazardous travel across central Indiana overnight.  With temperatures remaining below freezing today,…

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Dec 05

Heavy Snow Warnings Ahead?

Good evening, Indy.  As of late morning, we began spreading the word, via our social media accounts, of the need to “beef up” snow totals.  Sure enough, latest data continues to point towards a snowier solution as of this update.  We now think widespread 5″-8″ snow totals will be common across most of central Indiana, but there will be heavier amounts where localized banding sets up.  As expected last night, the transition from sleet to snow was a rather rapid one this evening and we now think this will be an all-snow event for the majority of central Indiana through the duration of the storm.

While it won’t snow the entire upcoming 24 hours, waves of moderate to heavy precipitation will move in from the southwest and result in a widespread heavy snow event Friday.  There’s the chance the National Weather Service will transition Winter Storm Warnings over to Heavy Snow Warnings to account for the all-snow event ahead.

Latest raw data breaks down like this for Indianapolis:

  • GFS:  0.68″ (equates to nearly 7″ of snow on a 10:1 ratio)
  • NAM:  1.00″ (equates to 10″ of snow on a 10:1 ratio)
  • ECMWF: 0.58″ (equates to nearly 6″ of snow on a 10:1 ratio)

We’ll have your updated, custom-built, 7-Day forecast video posted shortly.  For now, here’s a look at what the local radar may look like tomorrow morning when we think another wave of moderate to heavy snow moves back into the region from the southwest:

NAM

Permanent link to this article: https://indywx.com/heavy-snow-warnings-ahead/