Category: Forecast Discussion

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/

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/

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/

Video Model Discussion On Upcoming Wintry Threat

  Tonight we discuss the various model solutions for the upcoming wintry pattern ahead Friday through Monday.  This is the data that helped us come to an official IndyWx.com forecast…

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Permanent link to this article: https://indywx.com/2013/12/03/video-model-discussion-on-upcoming-wintry-threat/

Potential Long Duration Winter Event Looming…

Your complete 7-Day IndyWx.com forecast can be found in the video player to the right of this post.

Before we begin to discuss the potential wintry mischief ahead for late week, it’s important to stress that there are still several unanswered questions out there that will have to be ironed out with time as we go through the next couple of days.  That said, the latest data continues to suggest the potential is there for a rather prolonged, multi-day, winter weather event looming.  This won’t come from some sort of powerhouse storm system, but instead multiple waves of energy (low pressure) moving along a pressing arctic boundary.  The continued “curious” item here is the interaction with the arctic boundary’s progress south and east and the resistance that will be put forth from the southeast ridge.

The latest 500mb pattern off the 0z run of the GFS forecast model has “trouble” written all over it and we must keep a close eye on things as we move forward the next couple of days.  Additional model data from the European forecast model and Canadian are also suggesting fun times ahead.

gfs_namer_144_500_vort_ht_s

This image is valid Saturday evening and shows a couple of important items- the southeast ridge and the associated fight it’ll put up with the pressing arctic front, as well as “renewed” energy organizing across the Four Corners region, organizing before a track northeast.

The way we currently see things panning out would suggest the threat of light accumulating snow is on the table late Thursday night through Friday followed by a dry and cold day Saturday. That said, as shown above, renewed energy will move northeast the second half of the weekend into early next week and be responsible for spreading moisture back over what will be an unseasonably cold air mass in place, certainly one conducive for wintry precipitation.

It’s important to note that this isn’t just a snow event, but some places of the immediate coverage area (central Indiana, in particular) could experience an icy mixture of sleet and freezing rain, as well.  It’s far too early to talk about any sort of storm total accumulations as these type “overrunning” events can surprise…  That said, we are gaining confidence on “part 1″ of this event providing light accumulating snow for most of central Indiana Friday- light meaning less than 3”.  Additional accumulation of wintry precipitation would occur with “part 2” of this event during the back half of the weekend.

Again, it’ll be crucial to keep up to date with the latest forecasts and developments as things become clearer as we move forward.  As of now, keep a mental note in the back of your mind that the possibility is there for accumulating snow late Thursday into Friday, as well as later in the weekend…

Permanent link to this article: https://indywx.com/2013/12/01/potential-long-duration-winter-event-looming/

Questions Around Next Week’s Arctic Front…

Your complete 7-Day forecast can be found in the video to the right of this article.

We continue to keep a close eye on the developing weather situation here late next week.  Many questions remain in regards to the track, timing, and strength of the cold air associated with an arctic cold front that will result in record-breaking cold for portions of the country next week.  How much fight will the southeast ridge put up as the front progresses east?  Will we have to deal with a wave of low pressure along the arctic boundary, potentially leading to some wintry “mischief” around these parts?  We hope to give some clarity around those questions by looking at some of the latest data below.

First, let’s take a look at the various model solutions for late next week.  It should be noted that the latest run of the National Weather Service’s GFS forecast model has taken a turn to look more like the overnight run of the European forecast model and suggests we have to deal with a wave of low pressure moving through here Friday into Saturday of next week, leading to the threat of wintry precipitation.  Taken at face value, this would suggest the threat of an accumulating snow event for central Indiana Friday night into Saturday morning of next week.  This is in stark contrast to the 0z GFS run signaling dry, cold weather during the aforementioned time frame.

Here’s a look at the latest GFS solution, valid next Friday evening:

gfs_namer_180_1000_500_thick_s

There’s relatively good agreement in the GFS ensembles, but, again, we’ll have to fine tune the details.  It’s encouraging to see the agreement in the pattern evolution, though, this far out.

f192

Here’s a look at the latest European forecast, again valid for next Friday evening.

As we spoke about above, the 0z ECMWF run suggests we have to deal with a wave of low pressure in the cold air here next Friday into Saturday.  Similar to the latest run of the GFS model, there would be the potential of accumulating snow here.  The ensembles are on the left and the operational run is on the right.  The precise details will have to be ironed out, but we note relative agreement here.

Geopotential32at32500hPa_North32America_192

The latest Canadian forecast model also sees the wave of low pressure along the pressing arctic front, but suggests the wave is too far south to result in any sort of significant snowfall accumulation for central Indiana.  (As of this post time, the 12z Canadian ensemble package hadn’t arrived).

cmc_precip_mslp_east_31

So, with all of that said, we still have plenty of time to watch things unfold in the coming days.  What are we confident in as of today?

  • Brutally cold arctic air invading the northwest early in the week before slowly spreading east and south as we progress through the week.
  • We’ll be in a much warmer (though very brief) pattern here Thursday as highs zoom into the middle 50s to near 60 with rain.
  • We target the arctic front to blow through here during the day Friday.
  • While we’ll turn MUCH colder than normal next weekend, we aren’t looking at the brutality of the cold that our friends out west will have to deal with.

What are the answers that have to be ironed out this week?

  • Strength and depth of the cold air coming east.
  • Strength of the upper ridge over the Southeast US.
  • The resistance of the ridge will be crucial into determining where the “wintry precip. zone” sets up shop.

Permanent link to this article: https://indywx.com/2013/11/29/questions-around-next-weeks-arctic-front/

Tuesday Night Video Update: Lake Enhanced Snow Showers

Tonight’s Video Highlights: Lake Effect Snow Showers And Squalls Set To Impact Central Indiana Coldest Thanksgiving In Years On Deck Eyeing The Potential Of An Arctic Invasion Next Week

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Permanent link to this article: https://indywx.com/2013/11/26/tuesday-night-video-update-lake-enhanced-snow-showers/

Data Suggests Cold Pattern Keeps On Keepin’ On…

As we approach the all-important holiday travel season, I thought it would be nice to review what some of the data suggests in the long range sense.  While nothing is “set in stone” talking about weather 2-3 weeks out, we feel pretty confident in the overall idea of a colder than normal pattern and one that’s also potentially wintry- from a precipitation perspective.  The specifics with each storm will have to be handled as they come.

Let’s look at some of the data.  BTW, I want to give full credit to the awesome model suite that can be found at Weatherbell Analytics for some of these images.  Be sure to check them out at weather bell.com.

First, we’ll take a look at the Canadian ensembles, centered on the 8-16 day period.  Note the tongue of cold coming out of western Canada, extending southeast and encompassing the Ohio Valley region.  Folks, this is significant cold forecast off the Canadian ensembles as temperatures are suggested to average 5-7 degrees (C) below normal.

can_t2m_mean_conus_d8_16

 

 

 

 

 

 

The latest GFS ensembles also suggest widespread colder than normal temperatures over the upcoming couple weeks.  Similar to the Canadian (above), the GFS suggests temperatures average 5-7 degrees celsius below normal.

gefs_t2m_mean_noram_d0_16

 

 

 

 

 

 

Latest European ensemble data suggests a cold look as well, but one that also may feature a day or two above normal (over the next couple weeks). The latest ensemble control run highlights the threat of some bitterly cold arctic air plunging south towards the second week of December (posted below).  We’ll continue to monitor this in the days to come.

eps_t850a_c_nh_57

 

 

 

 

 

 

Here’s a look at the latest CFSv2. While it’s in stark contrast to only a couple of weeks ago (in its December forecast), the model is now onboard with most other data in forecasting a colder than normal December for our region.

CFSv2.NaT2m.20131124.201312

 

 

 

 

 

 

It has to be pointed out that all of the cold data is forecast during a time where the three “major” teleconnections really aren’t in the most ideal spots for eastern cold.  Typically, cold lovers across the eastern United States want a negative AO and NAO with a positive PNA. The NAO and AO are forecast to be very “sporadic” over the course of the upcoming 7-10 days while the PNA is forecast to go back negative.  That said, the NAO has the biggest influence on our weather from January through March (we’ve covered this in posts in the archives).  The expansive early season snow and ice pack through western Canada is having it’s say with a couple of early season “brutal” cold shots here (it’s very rare to get this kind of cold so early in the season).  We’ll continue to monitor these teleconnections moving forward for any sort of a more defined signal that may begin to come to fruition.

Speaking of snow and ice cover; look at how much more territory across the Lower 48 is covered with snow and ice compared to this date (November 24th) last year.  Impressive, huh?

November 24, 2012 (11.8% covered in snow)

nsm_depth_2012112405_National

November 24, 2013 (37.8% covered in snow)

nsm_depth_2013112405_National

As we look closer at the near term, there’s a chance of some light snow moving in Monday evening (not a huge deal, but some light accumulations of a dusting to half an inch are possible).  Scattered snow showers will also blow into central Indiana Wednesday as a reinforcing shot of fresh arctic air blows in prior to Thanksgiving.

In the mid range, both the GFS and European ensembles (below) suggest an “intriguing” look for the first 10 days of December for the potential of a more widespread winter weather maker.  It’s far too early for details, but with arctic air being supplied into a pattern that looks to have a southern branch beginning to flex it’s muscle, we’ll have to remain on our toes as we go into December…  Here’s wishing you a very happy and healthy Thanksgiving, complete with safe travels!

Geopotential32at32500hPa_North32America_240gefs_z500anom_nh_65

Permanent link to this article: https://indywx.com/2013/11/24/data-suggests-cold-pattern-keeps-on-keepin-on/

A Closer Look At Thanksgiving Week

Today’s model data continues the theme of a southern and eastern storm for the days surrounding Thanksgiving.  We’ll continue to monitor for any potential shift northwest, but as of now, the trend remains for a “suppressed” storm track.  Here’s a look at the individual GFS ensemble members, off today’s 12z run.  Taken at face value, 3 out of 10 members show some light snow in the air.

f132

For now, the big story still appears to be the unseasonably cold air around for Thanksgiving.  The ECMWF, Canadian, and American models (GFS and NAM) continue to hammer home the idea of a frigid Thanksgiving ahead (relative to the time of year, of course).  I’m not convinced we won’t have to deal with some light snow next week at some point, but for now, the bigger story still appears to be  impressive early season cold, and this cold pattern isn’t going away anytime soon.

The latest European forecast data illustrates this well.  Note each and every day is well below normal, aside from tomorrow (cold air pushes in tomorrow PM).  This is a snap shot of the average temperature (in degrees C) over the upcoming 10 day period.  The blues, greens, and purples showcase the cold, relative to average.

tavg_anom_ecmwf_mc_1

 

 

 

 

 

 

Permanent link to this article: https://indywx.com/2013/11/21/a-closer-look-at-thanksgiving-week/

Wednesday Evening Video Update: Rain Moving In; Arctic Blast This Weekend

http:/ Tonight’s Video Highlights: We talk rain and amounts for Thursday and Friday. The coldest air of the season and coldest November day in some 13 years is ahead! A…

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Permanent link to this article: https://indywx.com/2013/11/20/wednesday-evening-video-update-rain-moving-in-arctic-blast-this-weekend/

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