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Taste Of Winter This Weekend…

A rather pleasant, benign week of weather will transition to a rude feel by the weekend.

A cold front will sweep through the state Saturday morning and will help the season’s first blast of true, winter-like air plunge southward over the weekend, into early next week.  Ahead of the cold front, a band of showers and perhaps a clap of thunder will track east.  As of now, rainfall totals don’t look particularly impressive (0.10″-0.25″).

Shower chances will increase Friday evening. Courtesy of weatherbell.com
Shower chances will increase Friday evening. Courtesy of weatherbell.com

Ahead of the front, winds will gust out of the southwest Thursday afternoon and Friday (in the 30-40 MPH range), but will shift around to the northwest Saturday (same 30-40 MPH potential) and drive a much colder air mass southeast.  Temperatures will fall through the day Saturday and temperatures will grow cold enough Saturday evening into Sunday to allow “backlash” moisture to fall as scattered snow showers and snow flurries.  Further north, in the snowbelt regions, heavier lake-generated snow bands and squalls will develop over the second half of the weekend.

The season's first true lake effect snow outbreak will occur this weekend. Courtesy of weatherbell.com
The season’s first true lake effect snow outbreak will occur this weekend. Courtesy of weatherbell.com

Wind chills will fall into the teens Sunday night into Monday morning.

gfs_windchill_indy_30

Longer term, data continues to suggest we continue to transition, overall, towards a colder and stormy pattern in the targeted Thanksgiving to Christmas period.  More on that later this week…

Arctic Cold, Autumn, Christmas/ Thanksgiving, Forecast, Forecast Discussion, Rain, snow, T-storms, Unseasonably Cool Weather, Windy

Frosty Mornings; Late Week Storm System…

screen-shot-2016-11-13-at-10-19-07-amHighlights:

  • Dry stretch of weather remains
  • Late week storm system offers up rain; t-storm chances
  • Much colder next weekend

Frosty Mornings To Start The Week…High pressure will dominate our weather pattern to open the new week.  As such, skies will remain mostly sunny and temperatures will be very pleasant.  Monday morning will feature the third morning in a row with sub-freezing air.  Expect another frosty start to the day, including outlying neighborhoods into the 20s yet again.

Looking ahead, our weather will remain rather uneventful until Thursday.  Dry conditions will remain, but southwest winds will become increasingly gusty by the afternoon.  This is in advance of an approaching storm system that will deliver showers, and perhaps a clap of thunder, Friday evening.  Timing will have to be fine tuned as we progress through the week.  Behind the boundary, much colder air will pour into the region on gusty northwest winds next weekend.  In fact, the air will grow cold enough to potentially lead to scattered snow showers Saturday night into Sunday in the left over “back lash” moisture.

Upcoming 7-Day Precipitation Forecast:

  • Snowfall: 0.00″
  • Rainfall: 0.25″ – 0.50″
7-Day Outlook, Autumn, Forecast, Rain, snow, T-storms, Unseasonably Cool Weather, Unseasonably Warm, Windy

Chilly Weekend Ahead…

screen-shot-2016-11-11-at-6-58-12-amHighlights:

  • Dry and chilly weekend
  • First freeze of the season
  • Dry skies remain next week

Cold Air Blows In This Evening…We’ll wrap up the work week with plentiful sunshine, but reinforcing cold air will blow into town this evening.  After a high in the middle 50s, temperatures will begin to fall rather quickly by late afternoon into the early evening. Temperatures will grow cold enough to allow the first freeze of the season to greet many Hoosiers Saturday and Sunday mornings (many neighborhoods away from the city will drop into the middle/ upper 20s).

Dry skies will remain next week, but by the middle parts of next week, all eyes will be on our next fall storm system.  It’s still early, but the next best chances of rain appear to be slated for a late week arrival next week.  Colder air will follow.

Upcoming 7-Day Precipitation Forecast:

Snowfall: 0.00″

Rainfall: 0.00″

7-Day Outlook, Autumn, First Freeze, Forecast, Rain, Unseasonably Cool Weather

A Word (Or Two) On Where We Think This Pattern Is Going…

Before we get into the updated thinking on the pattern, lets review what we have out:

  • Step-down process to cooler/ colder weather begins in mid-November.
  • Thanksgiving-Christmas period, as a whole, turns wintry and is snowier than average.
  • Our complete 2016-2017 Winter Outlook can be found here.

The first week of November has featured an incredibly warm start to the month. (Image courtesy of MRCC).

month-tdevSpeaking of warmth, 2016 has been a very warm year.

ncep_cfsr_t2m_anom_ytd(The cold of 2014 seems so long ago…)

ncep_cfsr_t2m_anom_2014Back to present.  We’ve targeted the middle part of November to finally beginning “bucking” the recent warm trend.  This won’t happen overnight and will be a battle of back and forth, initially.  Thus, the “step-down” label.  To be clear, November, as a whole, will finish much warmer than average.  It’s virtually impossible to counter the incredibly warm start.  That said, we do anticipate “jabs” of colder air working in here over the next couple weeks. For instance, this weekend will feature lows in the 20s for most and highs not making it out of the 40s Saturday afternoon.  (The average low and high at IND Saturday are 37 and 54).

Despite being in a weak La Nina, the pattern is taking a while to respond.  Remember, we’re coming off one of the strongest El Ninos on record.  Until we slow the PAC jet, significant, long-lasting, changes won’t occur.  We can lean on the AAM (Atmospheric Angular Momentum) forecast for clues as to when this may occur.  You can read more about the AAM here.  My fellow local weather compadres, Michael Clark, Ed Valley, and Kirk Hinz have also written/ blogged extensively about the AAM and resulting impacts.

gfsgwo_1

gfs1When we look at the AAM forecast (above), we note the westerlies may begin to slow (indicative of the negative values) in the 8-10 day period.  This is crucial and, simply put, has to happen for the pattern to begin shifting into more of a position to allow sustained cold to enter the equation.  We want to reiterate that this, in and of itself, doesn’t create the cold, but instead allows the pattern to begin shifting away from the Nino-like (warm) regime into more of a La Nina pattern, as a whole.  – Hey, you have to start somewhere.

If we can finally get the westerlies to slow, other elements are in play that could (and should) lead to a colder pattern as we move forward.  Our (3) big teleconnections are in a position favorable for cold for mid/ late November, into early Dec.

cw5yrrsxaaefhiy-jpg-largeAdditionally, the EPO is forecast negative off the GEFS and EPS. (Images courtesy of Weatherbell.com).

eps_epo_bias

gefs_epo_12Again, this is a cold signal. (Image courtesy of Madusweather.com).

eponew_neg_11novThe ensemble data is also beginning to key-in on higher heights (blocking) developing over the top.  Notice the significant changes in the overall look to the pattern between now and days 11-16. (Images courtesy of Weatherbell.com).

cw5qrw0wgaaphxr-jpg-largeIn summary, and in the face of *most* seasonal data that is screaming warm, warm, warm, we still don’t have any significant changes to our overall thinking of “step-down” mid-November giving way to more sustained wintry-like conditions in the overall sense from the Thanksgiving-Christmas period.  Time will tell and only the Good Lord knows what the future holds, but we’ve done far too much work and research to throw the “game plan” in the trash before the game even begins…

AAM, AO, Autumn, Christmas/ Thanksgiving, El Niño, Ensemble Discussion, EPO, Forecast Discussion, Forecast Models, Jet Stream Discussion, La Nina, NAO, PNA, Unseasonably Cool Weather, Unseasonably Warm