Category: Forecast Models

What Season Is This? Active Pattern Develops…

Screen Shot 2015-12-07 at 7.31.39 AMHighlights:

  • AM fog gives way to sunshine
  • Another fast moving disturbance moves through Tuesday night-Wednesday
  • Major warmth
  • Stormy finish

A quick glance at the updated 7-day shows two things, a lack of cold air and a rather active time of things.  In the near term, it remains a relatively quiet period.  We’ll deal with morning fog in spots this morning (especially north-central IN) and another fast moving disturbance in the Tuesday night-Wednesday time frame.

The big story as we move into the back half of the week is the unseasonably warm regime that will have many asking “What season are we in?”  We’ll aim for the upper 50s Thursday, around 60 Friday, and upper 60s Saturday as a strong SW flow develops in advance of our next storm system

Warmth will reach it's peak Saturday. Source: Weatherbell

Warmth will reach it’s peak Saturday. Source: Weatherbell

While a scattered, fast moving, shower is possible Saturday, the big story will be the warmth and a gusty SW breeze.

Our storm system will grow closer Sunday and we’ll ramp up rain and storm chances accordingly during that period.  Our two most trusted global models handle things differently as we progress into the Sunday-Monday time frame (strength, track, and timing), and we’ll need to continue to fine tune that particular period as we move forward.  As it stands now we’ll forecast rain and thunderstorms to become widespread Sunday before colder air arrives on the backside of the storm. Stay tuned.

SundayMap

MondayMap

Permanent link to this article: https://indywx.com/2015/12/07/what-season-is-this-active-pattern-develops/

Major Warmth Ahead Of Storm Next Weekend…

The near term period is about as quiet as you’ll get it this time of year so that gives us an opportunity to search for the next “trouble maker.”  Out…

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Permanent link to this article: https://indywx.com/2015/12/06/major-warmth-ahead-of-storm-next-weekend/

Warm Late Next Week; Active Times Loom For The 2nd Half Of December…

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Permanent link to this article: https://indywx.com/2015/12/05/warm-late-next-week-active-times-loom-for-the-2nd-half-of-december/

Constructed Analog Model Holds Steady…

The updated constructed analog model is in the house and holds steady with the on-going idea from previous months.

Upper air pattern for Jan., Feb., and March

Screen Shot 2015-12-03 at 9.11.29 PMTemperature anomalies for Jan., Feb., and March

Screen Shot 2015-12-03 at 9.11.50 PMPrecipitation anomalies for Jan., Feb., and March

Screen Shot 2015-12-03 at 9.11.15 PMBased on this update, we really don’t see anything that would suggest we need to change our ongoing thinking this winter.

While the mainstream national media seems to continue to push the warmth this winter, we just don’t see it that way.  It doesn’t mean that we’re guaranteed to be correct, but at least we’ve outlined our reasoning behind why we disagree with that idea in countless previous posts (that can be found in the archives).

As it stands now, we are really becoming bullish on the possibility we turn much more active for mid and late month.  This will come after a relatively quiet and mild first two weeks of December.  The SOI has been tanking for several days, but has gone into an all-out tail spin today.

Screen Shot 2015-12-03 at 7.01.56 AMA couple things that come to mind right off the bat with that kind of daily negative value?  Poor model performance in the mid range, and an active pattern 10-14 days out.  Let’s see how things unfold.

Additionally, latest model data suggests our teleconnections may begin to align in a better fashion for central and eastern cold.  Latest runs take the AO slightly negative, the NAO neutral, and trend the PNA back positive towards late month.  Not perfect, but we’ll take it.

I heard one prominent national weather source today say December looks warm, quiet, and feature reduced chances of a White Christmas for most compared to normal.  Perhaps that will, indeed, be the case.  We’re, however, in the camp (small as it may be :-)) that believes a colder and more active period looms leading up to Christmas.  We shall see what we shall see…

Permanent link to this article: https://indywx.com/2015/12/03/constructed-analog-model-holds-steady/

Hang In There You Lovers Of Winter…

As I sit here in the good ole weather office, snow is falling and the Christmas lights are shining at the McMillan household.  Just doesn’t get any better!  Unfortunately, for winter lovers out there, the overall weather pattern over the upcoming couple weeks won’t offer up much in the way of wintry precipitation, as strong ridging results in a rather prolonged period of uneventful and mild weather across these parts (at least compared to normals).

The GFS ensembles show ridging expanding over our region this weekend into early next week. Source: Weatherbell.com

The GFS ensembles show ridging expanding over our region this weekend into early next week. Source: Weatherbell.com

That said, there are indications that our weather pattern may be changing enough to at least put us on the playing field for wintry potential as we rumble into the back half of the month, including the all-important Christmas period.

The SOI continues to tank and while the impacts (storminess) of a tanking SOI are delayed, we’re in the time frame now where this may result in busy times, or an active storm track, come mid and late December.

Screen Shot 2015-12-02 at 6.28.52 PMRight on schedule, we see the GFS ensembles going towards a much different look around mid month.  Note the heights (ridging) pulling further and further north while the southern stream energizes.  This is likely a byproduct of that tanking SOI that we see now.

GFS ensembles. It's a "night and day" difference out at mid month. Source: Weatherbell.com

GFS ensembles. It’s a “night and day” difference out at mid month. Source: Weatherbell.com

We also note the AO, or Arctic Oscillation, trending more in a negative to neutral direction.  While still not significantly negative, this is an improvement from a winter lover’s perspective from the positive values we’ve seen of late.

AOWe’re only two days into meteorological winter and still feel very confident about our winter outlook, focusing on the back half of winter for the worst conditions, relative to averages.  That said, even though the first couple of weeks of December, as a whole, may not be as cold or snowy as you’d like, it doesn’t mean we can’t reverse things enough to put us in a position to make for more “interesting” times around these parts leading up to Christmas….

Could this be the scene this Christmas across central IN?  Much more later!Christmas

Permanent link to this article: https://indywx.com/2015/12/02/hang-in-there-you-lovers-of-winter/

Considerable Cloudiness Remain; Mid Week Snow Flakes…

Screen Shot 2015-11-30 at 7.27.36 AMHighlights:

  • Showers/ drizzle return tonight
  • Scattered snow showers Wednesday
  • Dry and mild to close the week

We’re getting the work week kicked off with weather conditions that have been common over the Thanksgiving weekend- cloudy and cold.  Moisture will return slowly this evening and overnight with showers and drizzle moving back in.  We’re not looking at significant rains by any stretch of the imagination, but this is what the radar could look like during the overnight, courtesy of Weatherbell.com.

OvernightShowers will exit Tuesday morning and most of the day will be rain-free.  Colder air will slowly move back into the state Wednesday morning and as wrap-around moisture pivots through central and northern IN Wednesday scattered snow showers will result.  We’re not looking at any accumulations, but it’ll be nice to see a little of the white stuff falling.

WednesdayMorningOnce our Wednesday snow showers exit we’ll get back to dry skies and mild temperatures to wrap up the work week and head into the weekend.

Permanent link to this article: https://indywx.com/2015/11/30/considerable-cloudiness-remain-mid-week-snow-flakes/

Iron Bowl Saturday: December Rambles…

This is a special day in the McMillan house.  Iron Bowl Saturday only comes around one day a year… Needless to say, the Auburn flags have been on the vehicles since Wednesday, we’re decked out in our orange and blue, and game faces are on for this evening’s matchup.  WAR EAGLE!

As we get set to flip the calendar to December, we wanted to post some latest thinking.

Let’s take a look at the latest teleconnections.  As we’ve been talking, there’s a lot of “noise” in model land, including conflicting signals.  The positive NAO and AO argue for warmer than average conditions, while the positive PNA suggests chillier than normal times should prevail.

We wanted to post the latest model predictions of each teleconnections, courtesy of Weatherbell.com.  Additionally, courtesy of madusweather.com, here’s what each teleconnection “phase” would normally lead to in December.

NAO

Screen Shot 2015-11-28 at 10.55.21 AMNAOpos_12dec

AO

Screen Shot 2015-11-28 at 10.55.07 AMAOpos_12dec

PNA

Screen Shot 2015-11-28 at 10.55.34 AMPNApos_12decSimply based on the teleconnections, you would build a December forecast that would lean more warm than cold, as the short term positive AO and NAO should trump the positive PNA.  As we look at the month, as a whole, the AO and NAO are forecast to trend more neutral, while the PNA remains solidly positive.  Does this suggest colder air, relative to normal, would invade mid and late month?  – Certainly something to watch.

Additionally, the latest Southern Oscillation Index (SOI), has begun to take a negative hit.  This is after weeks of positive SOI values- relative to the base state.

Screen Shot 2015-11-28 at 10.47.52 AM

 

 

 

 

While it takes a while to impact the pattern, locally, this negative hit does suggest mid and late month could be a bit more interesting from a wintry perspective.  We shall see.

The CFSv2 remains very consistent on a warm month, relative to normal, particularly across the northern tier.

cfs_anom_z500_noram_201512_w3cfs_anom_t2m_noram_201512_w3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

While we can’t post the European weeklies here, the latest run suggests colder, and stormy times around Christmas week.  Now, we should also note the overall performance of the Weeklies hasn’t been as accurate compared to normal over the past few months, but it’s another interesting trend to keep an eye on.

The MJO will begin the month in Phase 3 before going into the “wheel house.”  All-in-all, we don’t get a “hat tip” from the expected monthly MJO forecast, with the exception of Phase 3 to begin (warm phase).

EMON_phase_MANOM_51m_full

Screen Shot 2015-11-28 at 11.53.45 AMTo sum up:  Long range forecasting is always a gamble.  Only the good Lord knows what the future holds.  That said, there are times when we feel more confident about our long range, monthly outlooks, more so than normal.

We’ll lean warmer than normal for December (+ 1.5 at IND), and this really plays into our Winter Outlook (slow start expected with the emphasis on the cold and snow mid and late winter), but that doesn’t mean we’re expecting a “boring” month.  Keep in mind November has been both warmer AND snowier than normal, with a very busy 2nd half of the month.

We’ll have plenty of challenges to handle as we rumble through the month no doubt, but we expect the positive AO and NAO to trump the positive PNA to start to the month.  As we progress into mid and late month, we’ll have to be on alert for potential impacts of that significant SOI hit to open the month.  We’ll also keep the Weeklies in check to see if the colder, stormy look Christmas week remains.  It’ll be fun, as always.

To close, here’s one more emphatic WAR EAGLE from our home to yours! 🙂

Permanent link to this article: https://indywx.com/2015/11/28/iron-bowl-saturday-december-rambles/

Extended Stretch Of Raw Conditions…

Screen Shot 2015-11-27 at 7.13.46 AMHighlights:

  • Periods of rain
  • Turning colder
  • Finally begin to dry things out

We sure hope you enjoyed those pleasant conditions on Thanksgiving Day, as rain (and eventually colder air) is settling in for the long haul.

The overall set-up shows a cold front slicing it’s way through the mid section this morning.  This front will continue to slowly settle southeast and much colder air will “ooze” into the area directly behind the boundary later tonight and Saturday.  Unfortunately, once the front passes to our south, additional disturbances will move along the front and enhance rain across our area from time to time over the weekend.

Here’s a snap shot, courtesy of Weatherbell.com, of what we the surface map/ simulated radar may look like as we rumble through the Thanksgiving weekend.

FridayMap

SaturdayMap

SundayMapAs mentioned above, the temperature story will also be a focal point later tonight.  Notice the incredible difference within just a matter of miles as we go deeper into the weekend.  While central IN will be in the “transition” period tonight, all of the area will be on the cold side of the boundary Saturday.  That forecast high in the upper 40s that you see above in our 7-day will be at midnight as most of tomorrow will be in the upper 30s/lower 40s.

8pFriTemp

Sat4pTempWe’ll continue to deal with unsettled and rather “raw” conditions into the early portions of next week, but we should finally be able to shake the damp conditions by Wednesday.  We’ll continue to keep a close eye on yet another system late next week, but models keep this storm to our south as of now.  Stay tuned.

Permanent link to this article: https://indywx.com/2015/11/27/5767/

Rain Moving In Late Thanksgiving…

First, I apologize for the lack of posts today. I had my first (and hopefully only) encounter with food poison yesterday evening and it’s taken most of the day to…

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Permanent link to this article: https://indywx.com/2015/11/23/rain-moving-in-late-thanksgiving/

Frigid Start; Looking Ahead To Thanksgiving…

Screen Shot 2015-11-22 at 9.27.08 AMHighlights:

  • Arctic air begins to moderate
  • Next storm system arrives late Thanksgiving
  • Another punch of cold air next weekend

Before we discuss what lies ahead, let’s look back at yesterday’s snow event that “overachieved” for many.  Particularly just northwest of the city where 2″-4″ fell.  Snowfall rates were heavy enough to overcome the initially warm surface temperatures, and it was very impressive to see the way the snow accumulated considering this was a November event that took place from late morning into the early afternoon (when the sun angle does the majority of it’s work).  This was an impressive first snow of the season and this morning’s snowpack is widespread throughout the Mid West.

nsm_depth_2015112205_MidwestThe visible satellite this morning shows the snow cover across the central and northern portions of the state, where single digits and teens were common.

SnowpackThe next few days will feature dry and cold conditions.  While we’ll remain below average, temperatures will slowly begin to moderate from the arctic intrusion of today.

We’ll get into a SW (milder air flow) regime for a brief period of time Thanksgiving Day out ahead of our next storm system that will move in Thanksgiving Night and Black Friday.  Clouds will increase and moisture will spread into the region during the aforementioned time period.  Most of the rain will fall Friday, so plan on taking the rain gear with you as you venture out to begin that Christmas shopping.

Thanksgiving

BlackFridayMuch colder air will pour into the region Thanksgiving weekend and we’ll have to maintain a close eye on the evolution of things late next weekend into early December.  Models will continue to waiver on specific solutions over the next few days, but there will be an attempt of a southern stream storm system coming out and “attacking” the cold air in place…

Permanent link to this article: https://indywx.com/2015/11/22/frigid-start-looking-ahead-to-thanksgiving/

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