Category: Forecast Models

Mar 27

Looking Ahead Into Early April…

Month-to-date, Indianapolis is running near seasonal norms from a temperature standpoint (0.50° above normal).  Chill has dominated the northern tier and eastern third of the country.

Precipitation is running above normal, locally, to the tune of nearly 1″ month-to-date.  Heaviest rains have fallen across southeastern Indiana over the past (30) days.

A look at precipitation anomalies across the mid west, month-to-date:

As we progress through the upcoming (10) days, a transient weather pattern will persist.  This will keep forecasters busy, but it should also be stressed it’s not all a “doom and gloom” type pattern, either.  There will be plenty of dry time over the upcoming period, including drier conditions building in tomorrow (Tuesday) into a good chunk of Wednesday.

By Wednesday night/ Thursday morning, shower chances will begin to increase and that will set the stage for a wet close to the work week as numerous showers and embedded thunder move across the region Thursday into Friday.  This is courtesy of a storm system “bowling” through to our south.  This won’t be a severe weather maker for our neck of the woods, but will serve to create a rather damp and gloomy regime during the aforementioned period.

However, timing is our friend this go around as upper ridging develops over the upcoming weekend.  Not only will we dry out, but we’ll also enjoy increasing sunshine as the weekend progresses.

That said, looking further down the pipe line, another (potentially more significant) storm system looms during the 8-10 day period.  This would fall in the April 3rd-4th time frame.  From this distance, models are bullish on hefty rainfall totals with this storm system and we’ll keep a close eye on things as time draws closer.

Speaking of April, our overall thoughts for the fourth month of the year (where does time go?) would imply a warmer than average month and active (wetter than average).  Relative to average, we feel we still may have some chill to traverse early month, but there’s also some indication we could bust into an early summer-like feel mid and late month.  With the mean trough position west and ridging east, we’ll have to also be mindful for the potential of an active severe weather month- especially mid and late month.  Overall, the CanSIPS idea below is one we would agree with from a mean 500mb perspective.

Permanent link to this article: https://indywx.com/looking-ahead-into-early-april/

Mar 16

Thursday Morning Weather Rambles…

1.)  All of a sudden what was a warm March has revered big time.  Officially, Indianapolis is running close to 1° below normal on the month and will continue to fall further once today’s data is factored in.  Always fun to see Mother Nature “balance” things out.

2.)  It’s another cold start to the day with many central Indiana neighborhoods in the teens and hard freezes extending south into Florida this morning.

3.)  Sunshine can be expected today and after the frigid beginning, a moderating trend will begin this afternoon that will send temperatures into the lower to middle 40s.  That’s still close to 10° below average for daytime highs, but will feel much better than what we’ve been dealing with over the past several days.  Add in that high March sun angle and it’ll actually be a very pleasant afternoon.

4.)  Unfortunately, we won’t hang on to the sunshine for St. Patrick’s Day.  A warm front will lift northeast through the region during the overnight and lead to an increase in clouds by evening.  A wintry mix of sleet and freezing rain will impact central IN predawn Friday morning before transitioning to showers mid-to-late morning.  “Light” is the key word here with models suggesting less than 0.20″ total.  By Friday afternoon we’re back to dry times.

5.)  We’ll turn a touch cooler Saturday and it’ll be a blustery day, as well.  A couple of early snow showers are possible across east and northeast portions of the state before afternoon sunshine returns.  High pressure settles in overhead Saturday evening and will set up a nice second half of the weekend- lots of sunshine and milder temperatures by Sunday (lower 50s).

6.)  Looking ahead, the quiet times will be hard to come by as we progress through the latter portions of the month.  Both the new JMA Weeklies (shown below) and other ensemble guidance is bullish on a wetter than average close to the month, and also one that features wild temperature swings.  Thoughts shift back to severe prospects, especially for our friends to our south and the potential of backlash wet snow showers in the colder air.  From a temperature perspective, it’s a pattern that will be very “transient” with no true long-lasting periods of significant warmth, or cold- relative to average.

Permanent link to this article: https://indywx.com/thursday-morning-weather-rambles-4/

Mar 10

Extended Period Of Unseasonably Cold Air…

Today will begin a rather extended period of unseasonably chilly air that will grip the region.  It’s not until the latter portions of next week that we should begin to see slowly moderating temperatures.

The reason for this is a persistent trough setting up over the Great Lakes and eastern portions of the country.  From time to time, individual disturbances will come racing along in the fast northwest flow aloft and help to reinforce the cold and also create snow potential.

Forecast models continue to show an eastern trough into the middle parts of next week.

 

This is an impressively cold pattern for so late in the season.

This is the type pattern that will promote multiple nights in the teens over the upcoming week.  We forecast coldest nights to be Saturday night, Sunday night, Wednesday night, and Thursday night.  Each has the potential to send neighborhoods into the middle-upper teens.

As far as snow goes, we still are keeping an eye on the early stages of the work week.  We’ll fine tune things this weekend, but models continue to show energy diving southeast Monday that would help snow overspread the region during the day, continuing into Tuesday morning.  This time of year, snowfall rates and time of day means a world of difference between snow flying in the air, versus accumulating.  The potential is there for light accumulation Monday night as reinforcing cold air pours in.

Stay tuned!  Much more later!

Permanent link to this article: https://indywx.com/extended-period-of-unseasonably-cold-air/

Mar 06

Thoughts Shift From Storms To Snow…

Before we discuss the weekend winter storm threat, we still have to get through the overnight period-morning hours Tuesday with embedded heavy rain and storms.  Some of these storms could offer up gusty winds and a few could be strong as they rumble across central Indiana Tuesday morning.

Most of the storms should push through west-central Indiana well before the morning rush hour.

Forecast radar 4am Tuesday.

Forecast radar 6am Tuesday.

Attention will then shift to the winter storm threat this weekend- particularly Friday night through early Sunday morning.  We still have to fine tune the all-important specifics, but confidence is rising on the possibility of a significant wintry event impacting at least portions of the region this weekend.  March snow events provide added headaches of dealing with the impacts of marginal temperatures, higher sun angle/ time of day, etc.  Conversely, the tight thermal gradients noted with most late season, spring snow events can be impressive, as they can quickly feedback, ultimately leading to swaths of thumping wet, heavy snow.  Hoosiers don’t have to think back too terribly far to some impressive and impactful March snow events.  Modeling today is in relatively good and surprising agreement, especially considering the lack of agreement models have dealt us weather ‘folk for the past few months.  🙂

GFS ensemble members are focusing in on a snow event this weekend.

It’s still early in the game and a lot can (and likely will) change with model runs over the next few days.  It’s wise not to make knee-jerk reactions to the operational model solutions, but instead understand the overall pattern driving the potential of this memorable March wintry event.  Anomalously cold air in southern Canada will spill south this weekend and help aid in the “fun and games” ahead.  At the same time, given the time of year, “suppression depression” isn’t likely as their will be resistance from the south-central Plains and southeast ridging in place.  As of now, we think the I-70 corridor could be the “sweet spot” for snow totals, understanding fine-tuning will be required moving forward.  Where a snowpack accumulates this weekend, expect temperatures Sunday night/ Monday morning to fall into the 10s.

Much more later!

Permanent link to this article: https://indywx.com/thoughts-shift-from-storms-to-snow/

Mar 05

Sunday Afternoon Rambles…

1.)  It’s another unseasonably pleasant afternoon across central Indiana.  Despite a gusty SW breeze (open county is approaching 40 MPH throughout central IN Sunday afternoon), the sunshine and warm temperatures are providing a phenomenal second half of the weekend.

Temperatures are running 20+ degrees above normal this afternoon.

2.)  Clouds will begin to increase tonight and give way to showers as we open the work week.  There will be plenty of dry time Monday morning into the afternoon, but a passing shower will remain in our forecast.  Heavier rain and embedded thunderstorms will arrive on the scene Monday night into the wee morning hours Tuesday.  As a whole, we expect between 0.50-1″ of rain, overall, by Tuesday morning.

Greatest rainfall coverage will arrive overnight Monday night.

3.)  We’ll trend cooler for the mid week stretch, but nothing “cold” for this time of year.  In fact, temperatures will remain above average as high pressure provides dry conditions.

Weak high pressure builds in for mid week.

4.)  Confidence is high on an active period of weather arriving for the weekend into potentially early parts of next week.  That said, despite overall high confidence on a busy time of things, the specifics remain “murky,” at best.  It’ll be important to check back for updates on the weekend forecast as we progress through the upcoming week.  Solutions range anywhere from a period of rain and storms to possibly some wintry “mischief.”  One thing seems certain and that’s for a period of colder air (below normal) arriving in the 8-10 day period.  In fact, the latest European model suggests overnight low in the 10s late next weekend.

The weather turns active next weekend.

Permanent link to this article: https://indywx.com/sunday-afternoon-rambles-3/