Category: Forecast Discussion

Jan 01

Things Progressing As Planned; Double Shot Of Snow Love…

It’s great to be back in the good ole weather office and craft a post about the upcoming weather pattern- a pattern that should be pointed out to be progressing along as planned.  Simply put, if you like winter weather, this is the pattern for you.

If you haven’t had a chance to read the posts from the past couple weeks, please be sure to do so as we laid the ground work as to why we were buying a cold, wintry pattern returning:

As we look ahead over the upcoming (7) days we’re tracking two accumulating snow opportunities and one big slug of downright bitter (and dangerously cold) air.

First things first and that’s the snow event ahead Wednesday night into Thursday.

We currently think snow overspreads central Indiana late Wednesday night into the wee morning hours Thursday.  Snowfall accumulations with system numero uno will likely be in the 2-4″ range for many neighborhoods across central Indiana.

The latest high-resolution NAM model shows the snow moving in and becoming moderate to briefly heavy during the wee morning hours Thursday:

hires_ref_indy_35

 

 

 

 

 

 

 

Heaviest snow with system #1 falls prior to noon Thursday with light snow and gusty winds lingering for the PM.

That said, we don’t have much down time as system #2 is set to arrive late Saturday night into the wee morning hours Sunday.  The weather situation is one that features an arctic boundary sinking south over the region Sunday morning with a wave of low pressure organizing along the middle Mississippi River Valley. The surface low is expected to move northeast Sunday and help spread precipitation into the greater Indianapolis and central Indiana region. With cold air in place, this precipitation is likely to fall in the form of snow.

While we have a couple of days to keep an eye on the Saturday night-Sunday time period, the likelihood of additional accumulating snow is growing with each and every model run.  The “ridiculously” early call on the Saturday night-Sunday time period, based on a variety of raw numbers, medium range models, and ensembles would suggest 3-6″ of additional snow is ahead during the aforementioned time period.  Again, we caution confidence ins’t as high as with system #1, due to the time period, but please be sure to stay tuned.

The GFS shows widespread snow falling across the region Sunday, with a favorable surface low track for accumulating snow across central Indiana:

gfs_ptype_slp_east_20

 

 

 

 

 

 

Following the second snow system, model data continues to suggest we have to deal with some downright dangerous air. In fact, this would be the coldest air in many a year across central Indiana and many other locations of the Mid West and even into the Deep South.  Forecast lows in the double digit below zero range are possible following the second snow maker and associated arctic front early next week….

Needless to say, I hope you like winter weather!

Permanent link to this article: https://indywx.com/2014/01/01/things-progressing-as-planned-double-shot-of-snow-love/

Dec 23

Impressive Cold Pattern Looming; Beware Of The Northwest Flow…

We continue to be very impressed with the cold pattern that’s looming.  Even before the warm up and thaw last week, we made mention that the seeds were being planted for a very cold close to December and open to 2014.  Latest data continues to back this idea up.  Additionally, in the longer term, there are some goings on that would suggest we better hunker down for a colder than average January.  While December will finished colder than average, a colder than average January can really hurt the pocket book as “average” temperatures are obviously even colder than December.

Today’s 12z ensembles are locking in on the pattern than can deliver one shot after the other of arctic air in the 8-10 day range.

test8

As for the snow, we still think we need to watch the models around the New Year for the threat of some southern stream energy interacting with the available cold air.  That said, even without the southern stream, one must remain abreast of the challenge that a northwest flow pattern can produce.

Forecast models have a difficult time handling clipper systems in these type of patterns until within 24-48 hours within an event.  Many times what appears to be a rather “harmless” clipper 4-7 days out can suddenly turn much more robust once the model catches onto the track and ability to literally squeeze out any and all available moisture from a cold air mass.  Furthermore, the “normal” 10:1 snow ratio, many like to use, doesn’t apply in the least to these type systems.  In cold environments you can easily get what’s called the “fluff effect” and snow ratios are more in the 20-30:1 range.  Needless to say, it’s a challenging pattern that will keep us on our toes over the coming couple of weeks.

To summarize, we’re extremely confident on a colder than average close to December and open to January.  We’ll have to monitor fast moving clipper systems that modeling will struggle with until right up to the event.  Finally, we’ll keep a close eye on the potential interaction of the southern stream and cold air around the New Year time period for the possibility of a storm of “more significance.” Stay tuned!

Permanent link to this article: https://indywx.com/2013/12/23/impressive-cold-pattern-looming-beware-of-the-northwest-flow/

Dec 20

Colder Than Normal Pattern Set To Return

Before we go into the cold pattern that is looming, our current forecast of severe flooding developing across central Indiana this weekend remains.  Our projected precipitation numbers remain in the 3-4″ range for most of central Indiana, but there will be some higher totals reported.  Combine that with the recent snow melt and the stage is set for potentially a severe and dangerous flooding event.

As we look ahead to the next weather “challenge,” it has to do with temperatures.  As we’ve talked about in previous posts, our weather pattern flipped to one that has been predominantly colder than normal back in the middle of October.  Despite a handful of days, cold has dominated the pattern.  Before our current thaw temperatures were averaging 5 degrees below normal for the month of December.  While the recent thaw is certain to reduce the anomalous cold, the last week of December could send us right back to readings much colder than average, helping put the exclamation point on the month as far as cold goes.

The latest 8-10 day ensemble plots showcase a very cold pattern to end December.  Cross polar flow gets involved, helping lead to some bitterly cold air around these parts.  We note excellent agreement between the GFS and European forecast models, helping to further increase our confidence in the cold pattern ahead.

test8

But it doesn’t stop there…  We note long range data suggesting this cold pattern continues well into January.

The latest European forecast ensembles showcase the cold continuing to reload into the first week of the month.  This is an impressively cold look, considering we’re still a couple weeks out and that these are a multitude of individual computer model runs averaged together to come up with this solution.

eps_t2min_anom_east_61

As we watch the evolution of the cold pattern, it’s important to turn to the “goings-on” with the upper air pattern.  Note the reorganization of the polar vortex and, equally as important, the placement of the polar vortex.  For the purpose of giving you a couple of different viewpoints of the evolution of the pattern we’ve pasted a Northern Hemisphere and North America perspective.

Note how the polar vortex reorganizes itself and decides to set up shop over Hudson Bay and Baffin Island by early January.  This is significant in that it promotes multiple reinforcing shots of arctic air into the eastern half of the country and backs up what the data above would suggest in the cold pattern that appears to be looming as we move forward…

Sunday, December 22nd

12

Friday, January 3rd

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What does all of this mean?  That the current “thaw” is very brief.  The seeds were being planted for a return of the cold pattern earlier this week and it all begins Sunday night.  As the data above would suggest, the arctic cold appears to reinforce itself as we go through time and an overall prolonged colder than normal pattern appears to be setting itself up.

Additionally, we’ll have to handle winter storm systems as they come (and they will), but the pattern is one that very well may promote fast-moving clipper systems moving southeast out of Canada.  While most of these clipper systems don’t drop tremendous snowfall totals, the more potent clippers can deposit several inches of snow and serve to “feed back” and turn what’s initially a cold, dry pattern into one that’s suddenly snowy.  We’ll keep an eye on that.  Furthermore, the southern stream may also decide to add a little “excitement” into our forecast late December or early January.

Needless to say, there’s a lot of weather to talk about in the days ahead…

Permanent link to this article: https://indywx.com/2013/12/20/colder-than-normal-pattern-set-to-return/

Dec 18

A Lot Of Weather To Talk About…

Mother Nature seems determined to put us weather forecasters to hard work as we get set to head into the Christmas season and welcome in 2014.  We’re tracking a major flood situation that will unfold across central Indiana over the upcoming weekend, followed by a reload of the cold and potentially a storm with a more wintry component as we get closer to the New Year.

First things first and that’s the significant flood threat in the short-term period.  Without trying to go into scare tactic mode, current model data would result in a downright dangerous flooding event for many low lying and flood prone areas this weekend.  Rainfall numbers are extremely impressive with this event and with a deep tropical connection, widespread 3-4″ totals are certainly likely, including some localized higher amounts.  Note the latest European chart, courtesy of the model suite off Weatherbell Analytics.  Needless to say, the Gulf of Mexico is officially “open for business” and will help contribute to excessive rainfall totals and, as stated above, potentially a dangerous flooding event this weekend across central Indiana.

ecmwf_uvz850_noram_16

Latest numbers averaged off a variety of computer models would place just under 4″ of rainfall down by noon Sunday, most of which falls between Friday and Sunday morning.  We note (2) waves of enhanced rainfall intensity set to impact the region.  As of now we’re targeting Saturday afternoon and again late Saturday night/ Sunday morning for extremely heavy rain, shown below.

ecmwf_slp_precip_mc_14ecmwf_slp_precip_mc_17

We still have time to watch the data and monitor the track of the storm.  It’s possible the “heaviest of the heavy” axis of rain shifts somewhat in the days ahead,  but it’s also important to note that even a light to moderate rain event combined with a frozen ground and a solid snow pack still in place will lead to flooding problems here across central Indiana.  The question of whether or not we’ll deal with flooding here this weekend shouldn’t be asked, but instead the question that remains is just how severe will the flooding be?  Stay tuned and if you live or work in a flood prone area, we would recommend preparing now for flooding.

Now, as we look ahead and focus on the Christmas to New Years period our thoughts will shift from a flood threat in the near term to one that’s more wintry.  We’ll turn dramatically colder Sunday afternoon behind the big rain storm and that will set the stage for a colder-than-average run up to Christmas. In fact, latest raw numbers off some forecast model guidance has some frigid readings ahead next week (upper single digits not ruled out for lows).

The upcoming 10 days off the European forecast model charts show an interesting scenario with the coming thaw, but the key word is brief.  Note days 6-10 are back into a colder-than-normal regime.

tavg_anom_ecmwf_conus_1

Additionally, we think we’ll have to deal with another storm prior to the New Year period and with the colder air back in place, there’s the threat we could have to contend with a wintry side to the next storm.  The details with storm number two will have to wait until we finish dealing with the first storm and associated serious flood threat it’s presenting.

Permanent link to this article: https://indywx.com/2013/12/18/a-lot-of-weather-to-talk-about/

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/2013/12/14/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/2013/12/12/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/2013/12/10/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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Permanent link to this article: https://indywx.com/2013/12/09/monday-morning-weather-rambles/

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/2013/12/05/heavy-snow-warnings-ahead/

Dec 05

A Closer Look At Two Winter Weather Events.

Your updated, custom-built, Thursday video forecast can be found to the right of this post in the video player.  We typically update our video forecast during the evening.

Good Morning and happy Thursday!  We continue to monitor the latest data for our upcoming winter weather events.  It’s a busy time of things and by the looks of the overall pattern, I’ll have to stock up on the coffee for the weeks ahead.  Quite honestly, a very cold and snowy pattern appears to be setting up shop now through the end of the month.  Anyone dreaming of a white Christmas? 😉

Here are some quick bullet points for the upcoming few days:

  • Snow/ sleet overspreads the region this evening
  • (2) waves of snow/ sleet move through the region between this evening and Friday
  • Saturday will be a very cold and dry day
  • Renewed snow and potentially freezing drizzle move in Sunday
  • We continue to forecast a total of 3-6″ of snow between tonight and Monday morning

Latest forecast models continue to suggest temperatures fall through the day with a mixture of snow and sleet overspreading the region as early as 3-5pm from southwest to northeast.  We anticipate a rather rapid transition from sleet to snow, especially from IND and points north.  Here’s a look at the latest HRRR simulated radar data, valid tonight at 6 o’clock:

hrrr_ref_indy_15

Here’s a look at the GFS model.  (We think this particular model has a much better handle on things now that we’re closer to the event).  Note the “waves” of wintry precipitation forecast and we agree with this.  Wave #1 arrives for the evening rush with wave #2 arriving Friday morning into the afternoon.

GFS1GFS2GFS3

Additionally, after a very cold and dry Saturday, renewed accumulating snow will overspread the region Sunday, potentially ending as a mixture of light freezing rain or freezing drizzle atop the fresh snow Sunday afternoon.

GFS4GFS5

Permanent link to this article: https://indywx.com/2013/12/05/a-closer-look-at-two-winter-weather-events/

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