Category: Forecast Discussion

Looking Ahead To Christmas Week And The Rest Of December…

Finally, it’s a cold start to the day, and feels like a mid December morning should!  Temperatures are running significantly behind where we were across the east this time yesterday.

t0Highs today will only climb to around freezing across central Indiana.  Add in a stiff NW breeze and wind chills will be colder.  Grab the coat before heading out to finalize that Christmas shopping.

SaturdayHighsThis cold is coming in the face of what’s been a very warm month.  Meteorological winter, as expected, has opened warmer than normal.

DecToDateBy the way, we think changes towards colder loom mid and late January on.  That likely carries us into spring this year with winter continuing.

Christmas week is coming into better focus now, and the “blend” of model solutions was, indeed, the best path to take.  The European’s blow torch 70 degree idea was laughable.  Still warmer than normal, Christmas morning should start in the middle 30s with highs in the upper 40s.

The lead up to Christmas will be an unsettled one after a dry weekend.  Moisture returns Monday.

MondayAnother surge of moisture comes in advance of a cold front and associated area of low pressure Christmas Eve before colder air oozes in.

ChristmasEveChristmas morning opens chilly, but dry, as high pressure is overhead.

ChristmasMorningLooking ahead, an active close to 2015 appears to be in the cards.  Model solutions at this distance have ranged from a major winter storm to a flooding rain threat.  We’re not confident on either idea at this point.  Without blocking, it’ll be mighty tough to get anything wintry from this storm, and we also note models have been overdoing rainfall totals in the 5-10 day range as of late.  That said, is this the storm that can begin to set us up for the expected overall pattern change to winter coming in January?

Note the wild differences between the GFS, GEM, and European for the storm leading up to New Years.

29th

cmc_pr6_slp_t850_conus2_36

ecm_mslpa_conus_11When we turn to the ensembles to attempt to gain a clearer picture of what we can expect, we see they are of no help either.

f228Are we confident of a storm coming to wrap up 2015?  Absolutely, but, again, far less confident on the specifics from this distance.  An overall wetter than average pattern is likely, however.

LateDecTo wrap things up this morning we still note a favorable SST profile for wintry conditions mid and late winter.  In other words, hang in there winter fans.  🙂

sst.anomBy the way, a major crash is coming that will send us into a La Nina by the second half of 2016.  The implications this can have are vast, and include an active severe season and big time Atlantic tropical season.

ps2png-atls20-95e2cf679cd58ee9b4db4dd119a05a8d-59vNMa

figure42

Permanent link to this article: https://indywx.com/2015/12/19/looking-ahead-to-christmas-week-and-the-rest-of-december/

Sweaters Or Shorts For Christmas?

Before we get into the thinking behind our set-up for Christmas, we want to be very clear in saying the overall warm pattern will continue as we head through the holiday season and into early parts of 2016.  We do see signs of changes brewing that could (and should) lead to a dramatic flip of the coin for the second half of winter.  With a weakening Nino, it’s also likely that the cold and wintry changes last deep into spring this year, but that’s for another discussion down the road.

In the grand scheme of things, mid and long range model data strongly suggests a very warm pattern remains across the eastern half of the nation, while cold dominates the west, through the end of 2015.

CFSv2

NAEFS

GEFSJust to be clear, we’re very confident on the medium range warmth to wrap up the year (and most likely open 2016).  Contrary to how confident we are on the overall warm pattern through the mid range, we’re much less confident with the shorter term pattern that encompasses the all-important Christmas Eve – Christmas Day forecast.  Getting right to the point, the American GFS forecast model suggests we’re dealing with a FROPA (frontal passage) Christmas Eve night that sets up a blustery, colder Christmas with morning snow flurries possible.  The GFS says we make it into the lower to middle 40s for highs Christmas.  On the flip side, the European model (usually, but not always, more accurate than the GFS) says we blow into early summer-like levels with highs around 70 degrees Christmas, including a mostly dry forecast with strong southwest winds.  How does an afternoon BBQ sound Christmas with that sort of idea?!

When we get down to the dirty details, the differences all have to do with the way the models handle the eastern (Bermuda) ridge.  A snap-shot of the 8-10 day ensemble composite (that shows the Euro, GFS, and Canadian) highlights small, but significant, differences with the ridge placement.

Source: Penn State e-wall

Source: Penn State e-wall

The GFS model (and Canadian, as well) suggests we’re dealing with a more progressive pattern Christmas that results in the cold “sloshing” it’s way east much quicker than its’ European counterpart.  Meanwhile, the European model says the eastern ridge flexes it’s muscle going into the Christmas period and results in the warmer, breezy solution as opined above.

When we dig in further, experience tells us we should “raise an eyebrow” to both solutions.  How many times have we seen the biases that both models have impact the mid to long range forecast?  The GFS has an eastern (more progressive) bias while the European has a western (slower)  bias.  Hint: It’ll be important to remember that as we rumble into more active cold and wintry times come mid and late in the season.

To sum things up, while we’re supremely confident in the long term warm pattern to wrap up the year, we remain very cautious with either solution currently being portrayed by either *normally* more-trusted mid range models.  Lets give it a couple more days and see where things go.  I wish we could be more certain with that all-important Christmas forecast, but we simply can’t at this juncture.  Both solutions have been very consistent with their respected idea for the past couple days.  One thing’s for sure and that’s that we’ll be looking at a major model bust sooner rather than later…

Permanent link to this article: https://indywx.com/2015/12/16/sweaters-or-shorts-for-christmas/

Wednesday Morning Video Update…

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Permanent link to this article: https://indywx.com/2015/12/16/wednesday-morning-video-update/

Monday Morning: Transient Pattern…

Wow, the warmth of the weekend was simply amazing. We were even able to take our Christmas party outside Saturday night and enjoy the warm weather in the back yard.…

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Permanent link to this article: https://indywx.com/2015/12/14/monday-morning-transient-pattern/

Weekend Warmth…

I had this set to post Friday evening, and apologize it’s just getting on now.

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Warm, Warm, Warm…

The huge story this weekend will be the record warm weather. We’ll likely set records both Saturday and Sunday in the mid to upper 60s.         The balance of…

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Changes Are Brewing Friends…

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Record Warmth Coming; Rain And Storms As Well…

Screen Shot 2015-12-09 at 7.13.26 AMHighlights:

  • Warmth is the big story now
  • Showers and t-storms increase

Relatively quiet weather remains in the near-term period.  A fast moving disturbance will cross the state this morning and could spark a light shower or sprinkle, but we’ll get back to increasingly sunny conditions this afternoon and evening.

Moisture will begin to return as we close the week and head into the weekend, but it’s really not until the second half of the weekend that we begin looking at more widespread rain.

As a SW flow begins to transport Gulf of Mexico (GoM) moisture north, a light passing shower is possible Friday evening and Saturday.

Friday

Saturday

Despite the increase in cloudiness and threat of a passing shower, it won’t keep us away from flirting with records Saturday, and note the widespread portion of the Tennessee and Ohio Valley that will also be in jeopardy of setting new records.

Source: Weatherbell.com

Source: Weatherbell.com

Much better rain and storm chances ramp up Sunday afternoon into Monday.

PWATs (precipitable water values) increase dramatically during the aforementioned time period and could help fuel locally heavy rains during that time period, particularly with embedded thunderstorms.

PWAT

Cooler air will arrive early next week, but remain significantly above normal.  We’ll discuss the longer range a bit later…

Permanent link to this article: https://indywx.com/2015/12/09/record-warmth-coming-rain-and-storms-as-well/

Patience Required…

Ironically, the only area of normal to below normal air (with the exception of the Rockies and southern Plains) is located over our region, month-to-date.

ncep_cfsr_noram_t2m_anomFrom a winter lover’s perspective, this December has been one to forget this far, and it’ll only grow more frustrating in the days ahead (we still forecast mid to upper 60s over the weekend).

The basic drivers of our pattern remain generally unchanged from ideas in October when we posted our Winter Outlook.  Our complete Winter Outlook can be found here.  We feel the need to remind some that we thought we would get off to warmer than normal and relatively quiet start:

  • “We feel this model best represents the likely milder than average start to winter before colder conditions mid and late winter.”
  • “We think the winter opens warmer than normal and relatively dry before shifting towards a colder than average pattern for mid and late winter.”
  • “The word “volatile” comes to mind at times.”

In short, there’s nothing out there that would suggest any reasons we should deviate from our current winter outlook that’s out there.  Despite the warm start, we still feel the winter, when all totaled up, will end up slightly colder than normal.  Additionally, though still falling short of normal snowfall, we also feel there will be plenty of winter weather potential come mid and late winter.

That leads us to the shorter term and what happens after the near record warmth of the upcoming weekend.

To sum it up:

  • A very active pattern develops this weekend with storms to track every 3-4 days.
  • Despite a storm or two that may have a favorable storm track for winter potential, it’s important to note sufficient cold air is tough to come by in the more immediate term.
  • Last week’s crashing SOI (Southern Oscillation Index) will lead to poor run-to-run consistency.
  • We do see a way the pattern could get cold enough for more interesting times the closer we get to Christmas.  Does this mean we’re guaranteeing a snow storm?  No, but, as mentioned this morning, the teleconnections will at least make an attempt to transition closer towards a state that could offer up wintry mischief at some point during the last (10) days of the month.

Bottom line is that the overall pattern is one that favors more in the way of warmer than average conditions through the next couple weeks before we begin transitioning towards more sustained wintry conditions mid and late winter.  The idea here is that with each successive storm that comes through, it’ll cut into the mean ridge position and the heights will continue to lift further and further north with time over the upcoming 10-14 days.  The GFS ensembles show this.

RidgepositionIs it an ideal set up for “lock and load” winter?  Not at all.  Is it an improvement that can at least offer up a couple attempts of wintry potential around Christmas?  Yes.

As stated above, in the longer term, based off current data and seasonal modeling, there’s no reason to walk away from the idea the slow start to winter continues for the duration.  Patience friends. 🙂

Permanent link to this article: https://indywx.com/2015/12/07/patience-required/

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/

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