Category: Forecast Models

Aug 04

Still Some Question On Northward Extent Of Heavy Rain…

The morning is off to a beautiful start as drier air oozed into central IN overnight.  Many reporting sites are returning numbers in the middle 50s this morning!  Anyone else craving fall?

While a beautiful day is in store locally, we note clouds associated with a storm complex off to our northwest this morning.  Some of these clouds could blow into central IN at some point this afternoon or evening.

As we fast forward to mid week the cold front that’s currently to our south will lift back north as a warm front.  This will be in response to surface low pressure tracking in west to east fashion through the central Plains and into the Ohio Valley.  That said, there’s precise details still not etched in stone that can, and will, have a large impact on our weather (locally) Wednesday night though Thursday.  Note some of the differences with just a few of our forecast models in regards to heavy rainfall placement:

High-resolution NAM

1GFS (interestingly the 6z GFS shunted the rain farther south):

5Canadian:

3* The European most closely resembles the 0z GFS run.

We still have time to sort through the details in regards to the precise placement of heaviest rain, but for now we’re keeping widespread rain and embedded thunder in the forecast Wednesday night through Thursday.

Note precipitable water values exceeding 2″ in spots Thursday.  This will certainly support locally heavy rain and a flash flood threat for portions of the state during the aforementioned time period.  Much more later this evening!

2

Permanent link to this article: https://indywx.com/2015/08/04/still-some-question-on-northward-extent-of-heavy-rain/

Jul 27

August Outlook

Before we dive into what we expect for the month of August, here’s a look at where we stand so far for July (with 4 days left as of this post).

This was our July forecast upper air pattern, issued 6.29:

July2015UAHere’s a look at temperature anomalies through 7.27:

ncep_cfsr_noram_t2m_anomWhile overnight lows have been running warm with all of the clouds and moisture, daytime highs have been significantly below average:

tmax30dydevWith four days left in the month, it’s already been the wettest month on record at IND.  The Corn Belt, as a whole, has been quite wet month-to-date.

nws_precip_conus2_mtd nws_precip_indy_mtd precip30dydevAs we progress into August (where does time go) we think we continue in an active pattern, locally, biased cooler than normal and wetter than normal.

AugustUA2015While modeling disagrees with the specifics in regards to the timing, most mid to long range modeling does agree on the overall idea of the hot dome (ridge) backing west and setting up shop over the southwest portion of the country early August which will put our region in (you guessed it) the favorable northwest flow for active weather.  Similar to July, disturbances will ride the periphery of the hot dome to our southwest and offer up plenty of chances for showers and thunderstorms.  That’s not to say we’re looking at setting another record for greatest amount of rain within a month, but it is saying precipitation should be above average yet again.

From time to time the ridge will attempt to expand northeast, but we don’t think it’s potentially until the last portion of the month before the ridge has much chance to encompass our region for any staying power more than a few days.  We suggest getting used to this 500mb look:

EarlyAugThe latest NAEFS and CFSv2 highlights the cooler than normal period we should undergo early August (especially after the 5th).

wk1.wk2_20150726.NAsfcT2015072712_054@007_E1_north@america_I_NAEFS@TEMPERATURE_anomaly@probability@combined@week2_186The latest European Weeklies suggest there may be a window for a “calmer” regime after the 25th.  That said, it’s a rather volatile pattern.

Yet another tool we’ve been keeping a close eye on the past few months has been the SOI (Southern Oscillation Index) as it’s been a big help in tipping us off for prolonged wet weather.  Note the consistent negative SOI:

Screen Shot 2015-07-27 at 11.22.11 PM

 

 

 

 

 

 

World

Not to sound like a broken record, but we continue to think the relentless wet weather pattern “keeps on keepin’ on” as we progress through August.  It’s very interesting to note the dynamics at play between the strengthening El Nino and warm northeast PAC waters… More on that, and the implications we feel for fall and winter, in the weeks and months ahead. 🙂

July2015SST

Permanent link to this article: https://indywx.com/2015/07/27/august-outlook-2/

Jul 23

Needed Break From The Rain…

It’s been a very wet July across these parts. Specifically talking about Indianapolis, we’re running a whopping 8.5″ above normal, month-to-date!     Cool and wet has been the theme across…

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Jul 20

Needed Dry Time After One More Round Of Storms…

We’re looking ahead to another round of showers and thunderstorms this evening/ tonight, particularly along and south of I-70. Locally heavy rain and embedded strong to severe thunderstorms are a…

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Jul 19

Oppressive Feel; Periods Of Storms…

A cold front will limp into the region to open the new week. A wave of low pressure will press east along the boundary Monday before the front pushes far…

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Jul 18

Watching For More Evening Storms…

The heat & humidity is the story currently, but short term models develop showers and strong to severe thunderstorms over the northern half of the state this evening.  Futurecast valid…

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Jul 16

At Odds With Some Of The Modeling In The Mid/ Long Range…

Right off the bat, we tend to lean more in the direction of the 12z GFS and its’ associated cooler look next week, rather than the warm European. It’s a…

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Jul 15

Wednesday Morning Rambles…

July so far has been unseasonably wet and unseasonably cool for our part of the country (what’s new this summer)?!      As we progress through the next couple days, refreshingly…

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Jul 12

Sunday Evening Update On Monday’s Weather Situation…

6psatAn update this evening shows severe thunderstorms beginning to ignite over the northern Plains.  This is all associated with the first in a series of upper disturbances that will move southeast and provide multiple waves of severe weather around our neck of the woods over the upcoming 24-48 hours.

Data this evening really hasn’t changed from what we think will be a potentially dangerous day of severe weather and flooding across central Indiana.  It’ll be highly important to remain weather-aware tomorrow and have a means of getting the latest weather information.  Please take all warnings seriously.  Conditions are highly favorable for numerous damaging wind reports tomorrow and we suggest taking severe thunderstorm warnings as if they were tornado warnings tomorrow because of this.

* Please understand that though some of the data below includes time stamps for reference of what the radar may look like that these storm complexes often take a mind of their own and can accelerate off to the southeast sometimes quicker than what modeled radar may project 12+ hours out.  Tomorrow will certainly be a nowcast situation, beginning early in the morning.

With that said, we forecast multiple waves of severe weather tomorrow, beginning in the morning.  With high PWAT values, or precipitable water values, thunderstorms will be capable of producing torrential rainfall and flash flooding.  It should be noted that with precipitable water values of over 2″ tomorrow (photo below) combined with recent saturated soils, flash flooding is a major concern.

1Speaking of flash flooding, latest data suggests rainfall of only 0.8″-1.5″ within a (3) hr. time period will lead to flash flooding.

ffg_IN_3Again, keeping in mind with the disclaimer prior, here’s what the radar may look like late morning, mid afternoon, and tomorrow night.

11a

3p

11pIn addition to the aforementioned flash flood concerns, we’re also supremely concerned with the potential of damaging straight line winds, particularly with the 3rd complex of storms Monday evening/ night.  Earlier in the day, and depending on how the atmosphere “recovers” with the 1st round of storms Monday morning, conditions are favorable for discrete super cells to develop during the mid afternoon (radar image #2 above).  While there are questions, early to mid afternoon would be the most likely time frame for potential tornadic activity and large hail.

To close, please ensure you have a means of getting the latest weather information Monday- beginning early in the morning.  Go ahead and charge your phones, tablets, and other electronics.  We suggest reviewing your severe weather safety plan with your family this evening  to provide a peace of mind, and to ensure you and your loved ones are prepared in the event severe weather and flooding develops.

Permanent link to this article: https://indywx.com/2015/07/12/sunday-evening-update-on-mondays-weather-situation/

Jul 11

Multiple Rounds Of Severe Weather Beginning Sunday…

Good morning and happy Saturday, friends!  After a prolonged stretch of clouds, rain, drizzle, and fog, today will feature a good deal of sunshine and very pleasant conditions.  Unfortunately, the sunshine and pleasant weather won’t last long as storms and severe weather chances ramp up beginning Sunday, and continues through Monday.

A hot dome (high pressure ridge) will be centered over Texas and this will place our immediate region under a rather busy northwest flow.  Multiple disturbances (highlighted in blue below) will rotate northwest to southeast around the periphery of the Texas ridge.  Each disturbance will be capable of producing heavy rain and thunderstorms, including severe weather.

Sunday morning

1Monday morning

2Tuesday morning

3The Storm Prediction Center has outlined the region for a risk of severe weather both Sunday and Monday, and they mention large hail, widespread damaging wind potential, and isolated tornadoes- particularly with Monday’s event.

Day Two Outlook (Sunday)

SundayDay Three Outlook (Monday)

MondayWe’ll begin the action late tonight/ Sunday morning (forecast radar below is a time stamp series from 7a to 12p Sunday) with the first in the expected series of thunderstorms rumbling in from the northwest.  

Moral of the story? Enjoy today’s sunshine, but get ready for more active weather in the coming days!
   

  

  

Permanent link to this article: https://indywx.com/2015/07/11/multiple-rounds-of-severe-weather-beginning-sunday/

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