Category: Forecast Discussion

Late Night Update: Snow Storm Brewing…

Early forecast model data into the office tonight suggests we remain on track for a disruptive widespread snow storm this weekend. We note the timing is speeding up just a…

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Permanent link to this article: https://indywx.com/2015/01/29/late-night-update-snow-storm-brewing/

Weekend Snow Storm Brewing?

Forecast models for the most part have been much more aligned with this upcoming event, with the exception of a couple runs on Wednesday. Overnight and this morning modeling is…

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Wednesday Evening Thoughts…

Quick video update on our thinking tonight, as well as a look at the weekend…

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Permanent link to this article: https://indywx.com/2015/01/28/wednesday-evening-thoughts-2/

Weekend Thoughts…

The video goes into the detail around our weekend thoughts.  Is a winter storm brewing?

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Keeping An Eye On The Weekend…

Forecast models have been printing out wintry solutions for the upcoming weekend- particularly Saturday night through Super Bowl Sunday.

The GFS 500mb charts between 12z Monday and this morning show the key with this potential storm.  Note the difference between yesterday (top) and today (bottom).  The GFS model brings more energy out and the result is a stronger storm system.

SunGFS5001

 

GFSSun5002Timing between cold and moisture associated with storm systems has been the important missing link this winter with bigger storms.  Does that trend continue this weekend?  Snow lovers hope not…

A key ingredient that has been missing in the past is a big area of high pressure north of the region supplying cold air as surface low pressure tracks in a favorable position for wintry precipitation.  Models do suggest not only renewed arctic high pressure building down the Plains region Sunday into Monday, but also a 1040mb high over the northern Lakes region.  This would help go a long way in keeping cold air flowing into the region.

What about the sensible weather here?!  Keeping in mind that this is still an event 5 days out…..  The GFS model suggests mostly a snow event north-central, but also brings in a wintry mix of icy precipitation and rain across the southern half of the state.  The Canadian forecast model (not shown here) is more suppressed and leads to an accumulating weekend snow event across the region and targets southern portions of the state for heaviest snowfall.  The European model is the most “ideal” scenario for central Indiana snow lovers and leads to a significant snow event across the heart of the state.

Note the European forecast model track a wave of low pressure in an ideal location for heavy snow across central Indiana before intensifying and hammering the Northeast region.

ecm_mslp_east_7

 

ecm_mslp_east_8

We’ll continue to keep a close eye on this developing situation. Stay tuned….

Permanent link to this article: https://indywx.com/2015/01/27/keeping-an-eye-on-the-weekend/

Sunday Clipper: Various Model Solutions

Quick update this morning on the various model solutions for Sunday’s clipper system:

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Permanent link to this article: https://indywx.com/2015/01/23/sunday-clipper-various-model-solutions/

Step Down Process To Cold Before The Return Of Truly Frigid Times…

The past 5-7 days have featured a common “January thaw-” something typically seen in even the coldest Januarys.  The coming 5-7 days will see a “step down” process of colder weather, interrupted by a day or two of milder southwest breezes.  In the longer range, we hold firm on the idea of more sustained cold, and potentially frigid air, setting up shop to open February.

See the GFS track the clipper through the lower lakes this weekend.  This is a mild track for central Indiana and will keep the accumulating snows over the Lakes region, extending into northern portions of the state.  Some light snow will fly here late Sunday night/ early Monday, but accumulations should be minimal.

gfs_ptype_slp_conus2_12

gfs_ptype_slp_conus2_16A brief surge of arctic air will invade early next week and may be accompanied by light snow Tuesday.

gfs_ptype_slp_conus2_21A brief southwesterly flow will allow milder air into the region by the middle of next week, but we caution this will be brief.

gfs_ptype_slp_conus2_29Much colder times loom to open February, potentially with a winter storm.  Obviously with this being in the 8-10 day period, there will be a lot of time to watch the storm potential.  Models have struggled mightily with storms this winter so far.  We’re much more confident on the cold, and potentially downright frigid air at that (still don’t think we’ve seen the coldest air of the winter yet).  Note the GFS sees the arctic highs “lining up.”

gfs_ptype_slp_conus2_41The European ensembles and operational are also keying in on the cold and wintry pattern closing January and to open February:

Geopotential32at32500hPa_North32America_216Initially the cold attacks the northeastern portions of the country, but “backs” west with time in the longer range:

Days 5-10

1Days 10-15

2The NAEFS and CFSv2 see the colder pattern returning:

2015012212_054@007_E1_north@america_I_NAEFS@TEMPERATURE_anomaly@probability@combined@week2_186

wk1.wk2_20150122.NAsfcT

We still think there’s a lot of “winter” left in the coming months.  Many folks enjoy snow Christmas into January, but begin to crave spring in February and March.  This is the type pattern that can be quite “ugly” for spring lovers as colder and snowy weather can push well into the spring months…  (Noted that we still have a lot of catch up to do in the snow department, but we’re not ready to say we won’t make up for “lost time”).

Permanent link to this article: https://indywx.com/2015/01/22/step-down-process-to-cold-before-the-return-of-truly-frigid-times/

Facts Are Facts…

I’m hearing rumblings out there that you can’t get sustained cold across Indiana without a negative Arctic Oscillation (AO) and/ or negative North Atlantic Oscillation (NAO).  I would ask those with that belief to please explain the following:

January temperature anomalies month-to-date show widespread cold (even accounting for the January thaw the past week).

ncep_cfsr_noram_t2m_anom

 

The first two weeks of the month were downright frigid and this was in the face of an AO that was not just positive, but strongly positive.

AO

To take this a step farther, the recent relative warmth has come with a negative AO.

Bottom line is that a ton of drivers are trying to take the wheel this winter.  Admittedly, that makes things incredibly difficult for forecasting- short-term or longer range.  That said, coming out with a “blanket statement” that you can’t have sustained cold without a negative AO or NAO is a flat-out lie and we wanted to address it.  Teleconnections can help many times with coming weather patterns, but not always.  This winter is a prime example of that.

Quick note on the clipper system- all forecast models today have taken the primary impacts (at least from a snow standpoint) north of the immediate region (central Indiana). Heaviest snows are favored across the Great Lakes, extending down into northern IN. We’ll continue to keep a close eye on things…

Permanent link to this article: https://indywx.com/2015/01/21/facts-are-facts/

Light Rain And Snow Showers Around This Afternoon/ Evening…

Scattered light rain and snow showers will dot the central Indiana landscape this afternoon and evening as colder air moves into the region.

hrrr_ref_indy_14

Thursday and Friday will be colder than what we’ve been used to the past few days, but nothing out of the ordinary and actually more seasonal.

We’re still eyeing a late weekend clipper system, but the precise track will determine who sees “several” inches of snow, versus little to nothing. Feast or famine, we’ll call it!  Overnight computer model guidance would place the heavier snow totals across northern portions of the state, but we still have a ways to go before anything is set in stone.

Back later this evening with a complete 7-day update!

Permanent link to this article: https://indywx.com/2015/01/21/light-rain-and-snow-showers-around-this-afternoon-evening/

A Word On The Longer Range; Steady As She Goes…

We wanted to touch briefly on the longer range weather pattern as we’ve been answering questions this weekend out there concerning what lies ahead. Ultimately, the good Lord above is the only one who knows tomorrow and this idea we have very well may be the wrong one. However; we still see a lot of winter in this weather pattern. The combination of below average snowfall to date, combined with milder air the past 24 hours has led some winter lovers into a panic. Despite the past 24 hours, let’s remember where we are for the month of January through the first half:

image

Now let’s compare this to the infamous January 2014:

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So far, this January the cold is more widespread across the nation. Additionally, through the first half of January, IND is actually running colder than last January. Many remember the brutal cold following the major winter storm early last January. Let’s also remember that a few days after that snow and cold we were dealing with much milder air and rain- a bonafide January thaw.

That brings us back to the present and our current January thaw. Looking back through the record books indicate even the coldest Januarys on record have “thaws.” What’s perhaps more impressive is that the end of this year’s thaw appears to be seen really before it even begins.

There are so many different drivers trying to take the wheel this winter it, admittedly, makes for an incredibly challenging time of things forecasting. That said, should we see the “stars align” (negative AO, negative NAO, positive PNA) in the coming weeks, this is the type scenario that could carry winter deep into spring.

In the shorter term, as of now we see no reason to abandon the idea the cold reloads to close January and open February. It’s possible that some weather outlets lean heavily on particular model runs and base their mid to long range forecast accordingly. While we agree you have to supplement some of that data into your mid and long range forecast, this is the type pattern than can make for risky business putting all the eggs in one basket.  (We also suggest any outlets leaning solely on operational and ensemble output are in need for a serious dose of dramamine). Instead, we prefer a blend of the above with the foundation being a combination of a nearly ideal SST profile for wintry times continuing and big-hitter analogs. It must also be noted that we have to keep the current AO/ PNA state in the back of our mind.

Speaking of those teleconnections… The current AO and PNA leave a lot to be desired for winter lovers in the longer range:

image image

That said, it should be noted the first two weeks of January cold was in the face of teleconnections that screamed of a warm pattern and a MJO phase that was also mild.

Perhaps the bigger driver here is the surface temperature profile in the PAC and ATL. Also note the modoki El Niño.

IMG_2167.PNG

That warmer water sitting across the northeast Pacific Ocean promotes ridging into the PAC NW and AK.  In return the upper level winds tap available arctic air and send it southeast (see the first two weeks of January).

In the mid range, ensemble data is bullish on this aforementioned pattern returning after the very brief January thaw.

1

2

The sensible weather that should result the upcoming 10-12 days?  An active pattern and one that’s very challenging with that northwest flow (we’ll be on clipper watch), biased colder than average.  In fact, the GFS ensembles aren’t too shy about eastern cold week 2.

gefs_t2m_mean_noram_d8_16

Let’s watch things unfold in the coming couple of weeks.  Make it a great day and GO COLTS!

Permanent link to this article: https://indywx.com/2015/01/18/a-word-on-the-longer-range-steady-as-she-goes/

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