Category: European Model

Mar 05

“Trouble” Brewing Mid Month.

We continue to closely monitor the goings on towards the middle of the month- more specifically March 12th through the 14th.  There are indications a significant late season winter storm is brewing and the overall pattern is one that is aligning itself in a way that certainly has to raise an eye brow.  That said, it’s far too early for precise details.  Is a major storm possible?  Absolutely.  Is it okay to pin down a given area for heavy snow totals at this stage?  Absolutely not.

First, let’s take a look at the latest ensemble charts.

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European

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Canadian

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At this stage in the game (more than a week away from the expected event), we suggest investing much more in the ensembles as opposed to a single operational model run.  (Case in point just from today alone…the 0z run of the European suggested the interior northeast was ground zero for widespread 12″ type snowfall totals with little to nothing expected across central Indiana.  Flip ahead 12 hours later and the 12z European takes the heavy snow axis through the heart of central Indiana on into the Northeast region).

Wikipedia has a nice write up on ensemble forecasting:

Ensemble forecasting is a numerical prediction method that is used to attempt to generate a representative sample of the possible future states of a dynamical system. Ensemble forecasting is a form of Monte Carlo analysis: multiple numerical predictions are conducted using slightly different initial conditions that are all plausible given the past and current set of observations, or measurements. Sometimes the ensemble of forecasts may use different forecast models for different members, or different formulations of a forecast model. The multiple simulations are conducted to account for the two usual sources of uncertainty in forecast models: (1) the errors introduced by the use of imperfect initial conditions, amplified by thechaotic nature of the evolution equations of the dynamical system, which is often referred to as sensitive dependence on the initial conditions; and (2) errors introduced because of imperfections in the model formulation, such as the approximate mathematical methods to solve the equations. Ideally, the verified future dynamical system state should fall within the predicted ensemble spread, and the amount of spread should be related to the uncertainty (error) of the forecast.

Though this is an event set to take shape close to a week from now, confidence on a significant storm across the east is higher than normal due to:

1.)  Excellent agreement amongst the three primary mid range ensemble charts.

2.)  The significance of the trough depicted on each set of ensembles.

While there are some differences, it’s highly unusual to see such relative agreement at this stage in the game.  We continue to bracket March 12th through the 14th time period for potential impacts from this storm across central Indiana.  Many questions will remain unanswered for now concerning precipitation type or amount, but we’re leaning more towards a winter weather maker at this early juncture for the Ohio Valley region.  We stress this can, and likely will, change multiple times in the days ahead.

Regardless, we strongly agree with the week 2 temperature anomalies courtesy of the GFS.  Should this come to fruition then March 12th through the 18th would feel more like early February then early to mid March.  Again, we think the GFS is on to something with the return of the cold pattern.

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As we move ahead know that we’ll be here keeping a close eye on the goings on behind the scenes around the potential “trouble” brewing for mid month.  As we continue to dig into the details with this potential storm, you worry about finding ways to enjoy the spring like feel Friday and again Monday :-).  We forecast both days to certainly have many craving spring as temperatures zoom well into the 50s both days.  Get out there and enjoy it!

Permanent link to this article: https://indywx.com/2014/03/05/trouble-brewing-mid-month/

Mar 03

Cold Pattern Continues…

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Forecast Updated 03.04.14 @ 8:22a

Sunny, But Cold…Another day of bright sunshine will help temperatures rebound to the freezing mark Tuesday afternoon.  While this is still well below normal and closer to the normal low for this date of 29 degrees, it’ll be a full 14 degrees “milder” than Monday’s high.  You know it’s been a cold winter when you’re saying the freezing mark is milder for a high in March.

Weak Weather Maker…A weak clipper system will move towards the region Wednesday evening into Thursday.  While this will be an accumulating snow producer for areas to our west, current thinking still moves this moisture towards our region, but with a dry air mass in place we think precipitation starts to fall apart as it moves in.  All of that said, light snow and scattered snow showers will fall for parts of the region Wednesday night into early Thursday.  We still think most don’t deal with much, if any, accumulation, but a light coating is possible in spots.  We’ll continue to monitor.

Eyeing Another Wintry Weekend…Modeling is still far from in agreement on the evolution of things on the weekend, but the general idea is one that brings a cold front through here Friday night into early Saturday morning with a wave of low pressure moving northeast out of the middle Mississippi River Valley into the eastern Ohio Valley Saturday.  With fresh cold air oozing south, combined with the associated track of the low, this is a potentially wintry set up for the region and we’re officially calling for a wintry mixture of light snow and/ or sleet across central Indiana Saturday.  The key word is light, but it could still be enough to create a few slick spots across the region.

Briefly Milder; Tracking The Next Significant Storm…The GFS and Canadian forecast models keep our region dry during the early to middle part of next week as a surface low tracks out of the Gulf and well south and east of our region.  On the other hand, the European forecast model winds a storm up much farther north and west and presents a heavy rain and possible thunderstorm threat here by Tuesday and Wednesday of next week.  We still have time to watch this and think the European may be a little too aggressive at present, but stay tuned.

What we are confident on is a briefly milder push of air early next week that could send temperatures well into the 50s.  Don’t get used to it, however, as yet another polar plunge arrives by the mid week stretch.

Upcoming 7-Day Precipitation Forecast

  • 7-Day Snowfall Forecast: 1-2″
  • 7-Day Rainfall Forecast: Less than 0.10″

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For weather updates and more “behind the scenes” data on the go, be sure to Follow Us on Twitter @indywx or become a Friend of IndyWx.com on Facebook!

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Permanent link to this article: https://indywx.com/2014/03/03/a-record-cold-start-possible/

Feb 28

More On This Weekend’s Winter Storm…

As we’ve been discussing, a significant winter storm is developing this weekend.  The set up is one that will feature an arctic cold front sinking south and stalling out across southern and central Indiana Saturday night.  Low pressure will then organize over the Ark-la-tex region and head northeast, tracking into the northern Tennessee Valley Sunday and Sunday night.  The low will move off the southern Mid Atlantic coastline Monday evening.  This will be more of a prolonged event when compared to our last two winter storms as waves of moderate to heavy snow move into central Indiana beginning late Saturday night.

This is an ominous set up for more heavy snow across central Indiana- one that’s notorious for heavy snow events across central Indiana.  We hoisted our initial snowfall forecast Thursday morning and placed central Indiana under the threat for 6-8″.  As of this morning, we’re remaining firm on that idea.  It should be noted that the GFS remains very bullish on heavier totals (and consistent, as well), but it should also be pointed out it’s somewhat of an outlier as of this morning as the GEM and ECMWF are more suppressed with lighter totals.  All of that said, we lean more towards the GFS solution versus the more suppressed Canadian and, to some extent, European forecast model.  Should the other model data begin to trend towards the snowfall idea per the GFS then the initial 6-8″ forecast will have to be adjusted upward.  The storm is just now coming onshore and will be sampled better with model runs later today.

Any way you slice it, a significant and disruptive winter storm is brewing this weekend and could make an absolute mess of your Sunday and Monday.  A shot of bitterly cold air will flow in behind our departing storm early next week.

Our current accumulation idea and storm track can be found below:  We’ll have another update here late tonight and you can keep up-to-date with all of our thoughts on the go on Twitter (@indywx).

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Permanent link to this article: https://indywx.com/2014/02/28/more-on-this-weekends-winter-storm/

Feb 16

Sunday Afternoon Thoughts…

1.) A scan over the latest data continues to point towards an absolute mess of a Monday afternoon.  Our accumulation ideas remain relatively unchanged from this morning’s update, aside from “beefing” expected snow totals for Indy’s northern ‘burbs by 1″.  Most of this falls from noon to 6pm and will be followed by a dry, cold, and blustery Monday night.  After likely a white-nuckle evening commute Monday, the combination of sub-freezing temperatures and gusty northwest winds Monday night will likely lead to another rough commute for Tuesday morning.

** We caution that this will be another “now cast” situation when it comes to precipitation types and their respected precise zones tomorrow afternoon.  Stay tuned here or to your favorite local weather media for updates and potential changes.**

  • Indianapolis northern ‘burbs, including Zionsville: 2-4″ snow and sleet with less than 0.10 of freezing rain.
  • Indianapolis proper: 2″ snow and sleet with around 0.10 of freezing rain
  • Indianapolis southern ‘burbs, including Greenwood: 1″ snow and sleet with up to 0.25 freezing rain.

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2.) We continue to monitor what will be a brief thaw and associated flood risk mid week.  Even without rain, water rise would occur and urban flooding from the combination of melting snow and blocked (from all of the snow) drainage zones.  When you add 0.50-1″ of rain atop the melting then problems could arise Wednesday into Thursday.  Additionally, we’ll need to prepare for the likelihood of dense fog Wednesday as milder air surges north over a deep snow pack.

3.) For anyone thinking spring is setting in during our mid week thaw will need to think again. Latest model data continues to suggest we reverse things quickly later this week and for the upcoming weekend.  In fact, some model data, including the European, suggests central Indiana is under the gun for a weekend winter storm.  We’ll continue to monitor closely…

021614ECSatWinterStorm022214

4.)  Additionally, prospects continue to grow for another extended period of well below normal cold and renewed wintry precipitation chances in the long term (into March).  Both the GFS and European models are in agreement on the mid to long range pattern with a trough settling back into the eastern half of the country.

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Permanent link to this article: https://indywx.com/2014/02/16/sunday-afternoon-thoughts/

Feb 10

Watching The Pattern Turn Active Yet Again…

After a dry period through early to mid week, our weather pattern will begin to turn active yet again as we head into late week and this weekend.  Three of our more trusted mid range computer models handle the individual impulses of energy differently and the snow potential ranges anywhere from nothing more than 1″ to as much as 10″ in the Friday-Tuesday period.  Most likely, we’re looking at something somewhere in the middle.

Our first chance of accumulating snow arrives Friday.  Both the European forecast model and Canadian forecast model agree on this, while the latest GFS takes the same energy through the Great Lakes, missing our region entirely.  We feel the GFS may be in error mode here.  While it’s possible the GFS may lead the way (anything is possible this far off), we feel the EC and Canadian have a better handle on things and we’ve based our forecast (post below) off a blend of these two models for Friday, including accumulating snow.

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Our next shot of accumulating snow blows in Saturday.  All three models agree on this, but handle the track of the low, another clipper system, differently.  The Canadian tracks the low south of IND, strengthens it on it’s journey east and results in a full blown snow storm here Saturday.  The GFS and EC remain weaker and track the low across central or northern parts of the state, with much lighter snow amounts here.

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You can find your completed 7-Day forecast in the post below this one.  Finally, there are some signs the pattern may begin to relax and allow a milder brand of air into the region around the 20th.  We caution though that this won’t be a “suddenly it’s spring” pattern, but rather a tease of sorts as longer term signals suggest a wintry regime returns late February into March…

Permanent link to this article: https://indywx.com/2014/02/10/watching-the-pattern-turn-active-yet-again/

Feb 02

More Thoughts On Our Next Winter Storm…

As we continue to draw ever closer to our next significant winter storm, we wanted to provide some of our latest thoughts.  This isn’t a post that will hash out snowfall accumulation ideas or precipitation types, but instead will provide details on our expected track and potential liquid equivalent precipitation amounts.  With so much hype and hoopla around this storm for the past couple weeks, lets just sit back and look at the “bigger” picture, as opposed to trying to sort out details that, quite frankly, are still too early to lay out with any certainty as I write this late Friday night

Here’s our (IndyWx.com) expected track of the low Tuesday afternoon to Wednesday afternoon.  We used a blend of the GFS, European, and Canadian operational model data, as well as the GFS and European ensemble data sets.  We think surface low pressure tracks out of northeastern Mississippi (Tuesday evening) through north-central Kentucky (Wednesday morning), and into Pennsylvania (Wednesday night) before a secondary low forms off the northeast coastline.

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This is an ideal track for a winter storm across central Indiana, but specifics such as strength and depth of the cold air, potential southern convection, and forward motion of the storm will have to be sorted out over the next day, or so.  Early indications are that while this storm will take a “good” track for winter weather lovers here across central Indiana, the speed in which the system will be moving may reduce snow and ice accumulations from what they otherwise could be.  That said…early raw numbers suggest .50″ to .80″ amounts (liquid equivalent) could fall in the Tuesday-Wednesday time frame which is significant.  Case in point, a standard 10:1 ratio that would suggest 5 to 8 inches of snow- assuming the form of precipitation fell as snow through the entire duration.  Again, that is far from a certainty at this point.

Ignoring items such as model snowfall forecasts and precipitation types, just looking at the expected track would suggest central Indiana is very much in the game for a potentially significant and disruptive winter storm Tuesday into Wednesday.  We’ll have to fine tune precise amounts and precipitation types in the next day or two.  Additionally, much colder air (below zero once again at night) may blow into the state behind this storm for mid and late week before we gear up for yet another winter weather maker heading into next weekend.  We still have a long way to go in this pattern…

Permanent link to this article: https://indywx.com/2014/02/02/more-thoughts-on-our-next-winter-storm/

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/2014/01/27/big-fight-late-week-into-the-weekend/

Jan 21

Historic Snow Season Keeps Rolling Along…

The winter of 2013-2014 is off to a rip-roaring start and, as we’ve discussed in previous posts, the mid to long range data suggests we remain locked in an exceptionally cold and snowy pattern.  Officially, as of this evening, the Indianapolis National Weather Service has posted some impressive stats (the full report can be found here), including:

  • Through Jan. 21st, the 24.4″ of snow ranks as the 3rd snowiest January on record.
  • Through Jan. 21st, the season-to-date snowfall of 33.2″ ranks as the 2nd highest on record in the period Dec. 1st through Jan. 21st.
  • Through Jan. 21st, the season-to-date snowfall of 33.2″ ranks as the 8th snowiest on record for an entire winter season.

As we look ahead to the upcoming 7-10 day period, we note a continuation of arctic reinforcements- each which will be plenty capable of adding to the snowfall total.  Additionally, our cold air mass will only grow even more severe and bitter over time, including multiple days during the aforementioned period where central Indiana will go below zero.  Finally, there have been many questions concerning a potential big storm centered on early February.  I’m not sure where this rumor started, but it’s far too early to say with any sort of confidence any specifics around a possible big winter storm early February.  That said, as we’ll get into briefly below, the pattern does appear to be aligning itself in a way where a widespread winter storm is possible somewhere across the eastern half of the country.

Okay, okay, back to the near term…  Let’s start with tomorrow!  After a cold and dry start to the day, our next arctic front will blow into the region during the evening.  Arctic fronts are notorious for having bursts of heavy snow rates in a scattered fashion and this appears to be the case as the next arctic front moves through Wednesday evening.  We bracket the hours of 5p-8p for the possibility of heavy snow bursts racing through central Indiana.  While these won’t last long, they’ll likely be intense- capable of depositing a quick 1″-2″ of new snow on a gusty northwest wind within 30-60 minutes.  White-out conditions and extremely heavy snowfall rates will accompany the heavier bursts of snow.  Latest high-resolution model data shows the heavy snow bursts accompanying the arctic front tomorrow evening:

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Thursday will be mostly dry and frigid, but all eyes will then begin to turn to our next significant winter event Friday into Saturday.  The pressure gradient between high pressure across the Mississippi River Valley and the next approaching arctic front (and associated low pressure) will really being to kick up the wind across our region Friday.  We’re afraid we deal with another round of severe blowing and drifting snow Friday, especially Friday afternoon and night.  Areas most suspect to drifting and blowing snow will be central Indiana’s open country and may not be too different from the problems our region dealt with Sunday into Monday morning from blowing and drifting.

As we approach Friday night into Saturday, snow will overspread the region and will likely accumulate to the tune of a “few inches” during this time period.  Strong winds will remain, shifting from the west to the northwest and eventually north.  Open country will remain the prime place for continued severe blowing and drifting problems.

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Just as soon as Saturday’s snow systems exits stage right, we turn our attention to potentially another significant snow maker for the second half of the weekend.  Latest model data remains consistent on moving another potent clipper system into our region Sunday, including the GFS and Canadian forecast models.  We still have time to fine tune the precise track of the storm, but just north of the low’s track an additional 3-5″ type snow is possible Sunday.  Note the GFS and Euro in relative agreement on the track of the low, with the Canadian currently a touch further north. We’ll fine tune in the days ahead…  Experience with similar patterns from the past suggests central Indiana should brace for more accumulating snow Sunday.

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As for the brutal cold, we note multiple pushes of fresh arctic air behind each snow maker.  We currently target Thursday morning, Friday morning, Tuesday morning, next Wednesday morning, and next Friday morning as having the most likely shot at dipping below zero. The “coldest of the cold” likely means Tuesday morning takes the crown, with lows potentially dipping into the double-digit below zero range for central Indiana.  The European forecast model (below) even shows sub-zero temperatures making it as far south as the southern Appalachians.

As we look even longer term, there have been many questions centered on the potential of a big winter storm for early February.  Before we go any further, we want to stress it’s far too early to make any claim of certainty to the above.  That said, there are items we can pick up on to a least “raise an eyebrow” that something of significance may be brewing… Do we mean for anyone to take that verbatim and to the bank?  Absolutely not.

The European Weeklies suggest we need to keep an eye on the first week of February.  They show a potential phasing of the jet (where the northern and southern streams of the jet stream phase together- often times resulting in a big storm)… That said, we want to again stress this is far too early to be discussing with any sort of certainty.  Heh, the next week will keep us busy enough!

Keep the shovel handy!  Snow removal companies, thank you for your service and hard work…hopefully you have plenty of coffee on hand!

Permanent link to this article: https://indywx.com/2014/01/21/historic-snow-season-keeps-rolling-along/

Jan 19

Locked In The Freezer…

We’ve talked a lot about the relentless weather pattern that has kept our immediate region in what seems like a snow globe since mid December.  Of course we’re on pace…

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Permanent link to this article: https://indywx.com/2014/01/19/locked-in-the-freezer/

Jan 13

Cold, Snowy Pattern Reloading…

I sure hope you’ve taken time to get out and enjoy a couple of days of milder air (temperatures have run 10-12 degrees above seasonal levels the past couple days) and even some sunshine.  Given what I see coming down the road, the trend that looks to take a colder turn this week may really go into the tank week two.

Here’s an overview of the latest GFS and ECMWF ensemble data out at Days 8 through 10 (January 21st-23rd).  Both of these, more trusted, mid to long range computer models suggest a cold pattern locks itself into the East once again, and spells for colder than average temperatures and potentially a snowier than normal regime.

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We’ll now dive a little deeper into the forecast model vault, courtesy of the unbelievable Weatherbell Analytics model suite (can’t brag on that company enough).  We’re looking at the Northern Hemisphere Upper Air Pattern, courtesy of the European ensemble control run from this afternoon.

Note the mid week trough set to deliver a return of arctic air into the region.  That’s reinforced with a late week trough and renewed arctic air.  Both cold air masses will be capable of producing light accumulating snow across the area.

Per yesterday’s post, as we get into the early to middle portion of next week, we’ll have to keep a close eye on the potential of the southern and northern branches of the jet stream phasing, which would lead to a significant winter storm across some parts of the eastern half of the country (far too early for specifics or details).

We then note the Polar Vortex recharges itself and threatens to turn the last week to 10 days of January very cold.  How cold is yet to be determined, but I think it’s a safe bet sub-zero temperatures aren’t finished with our area just yet.

Intrusions of very cold arctic air will “pinwheel” around the Polar Vortex and likely lead to a bitterly cold end of January and open to February…

Permanent link to this article: https://indywx.com/2014/01/13/cold-snowy-pattern-reloading/

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