• Category Archives HRRR
  • Showers, Thunderstorms Expand In Coverage Later Today.

    We’re eyeing a rather unsettled day across central Indiana, including numerous showers and thunderstorms that will likely develop across the region, especially from late morning into the evening hours.  So far, the majority of heavy rain and thunderstorms has remained off to our northwest, but that will likely change within the next few hours.

    We’re tracking upper level energy off to our southwest this morning and this piece of energy will track northeast as we move through the second half of the day.

    nam_z500_uv_vort_mc_4

    The latest visible satellite image also shows the spin associated with the upper level energy over southern Illinois this morning.

    20140624_1300_LIT_vis

    Note the heavy rain and embedded thunder currently to our southwest associated with this disturbance this morning.

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    As this energy moves northeast there’s no reason to think widespread showers and thunderstorms won’t be around the region this afternoon and evening.  We note a very humid air mass in place with dew points around 70.  Furthermore, precipitable water (PWAT) will approach 2″ this afternoon across the area.  The upper energy will provide the needed lift.  Needless to say, the ingredients are in place for another round of heavy rain.

    The HRRR simulated radar product has a pretty good handle on what the radar may look like this afternoon, valid at 3p.

    hrrr_ref_indy_9

    Widespread rainfall totals should fall within the 0.50″-1.00″ range on average today, but locally heavier totals closer to 2″ will certainly be possible under the heavier storms.

    Interested in personal weather forecasts or consulting for yourself or place of business?  Email us at bill@indywx.com.


  • Boone County, Central Indiana Flooding 6/19/14

    A rather rare flood event took place across localized areas of central Indiana between Wednesday, June 18th, 2014 and Thursday, June 19th, 2014.  (27) hour rainfall totals 4pm Wednesday, June 18th through 7pm Thursday, June 19th reached 5.5″ (5) miles northwest of Zionsville, IN in southeastern Boone County, IN.  2.9″ of that rain fell in less than a (3) hour period between 4pm and 7pm Thursday, June 19th.

    Local Agriculture impact:

    Numerous central and southern Boone County crops experienced some sort of damage from rapid run off of the torrential rainfall.  Communities and farmland impacted included Lebanon, Whitestown, and Zionsville.

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    Ground-truth reports taken at our IndyWx.com headquarters (5 miles northwest of Zionsville, just outside Whitestown, IN) recorded 5.5″ of rain within the (27) hour period mentioned above.

    Radar estimated data also shows the widespread 4-5″+ rainfall totals across Boone County over the past 24 hours- Wednesday, June 18th through Thursday, June 19th.

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    Forecast model data from as early as Thursday morning suggested that particular afternoon and evening could feature training of heavy rain producing thunderstorms through central Indiana, including some embedded strong to severe thunderstorms, despite the Storm Prediction Center including central Indiana in any sort of severe weather categorical outlook (Slight Risk, or above).  That said, it should also be noted that this wasn’t a major severe weather outbreak across central Indiana, though isolated severe weather reports did come in, including a brief tornado touchdown near Anderson Thursday afternoon, along with a couple of additional severe thunderstorm warnings.  That said, the purpose of this post will focus on the set-up for heavy, and in some cases excessive, rainfall “training” (moving repeatedly over the same locale) over central Indiana communities Thursday afternoon/ evening.

    First, let’s take a look at the broad scale pattern set-up.  Needless to say, it’s certainly easy to see why localized flash flooding developed.

    Thursday morning’s 06z model runs suggested CAPE values, or Convective Available Potential Energy, would reach 4800-5000 across central Indiana.  You can look at CAPE as the “umph,” or fuel, that basically will feed a thunderstorms it’s energy.  Anything over 2000 is considered plenty enough for strong thunderstorm potential.

    hires_cape_ky_13The overall upper air pattern and steering currents suggested portions of the Ohio Valley would be under the gun, so to speak, for potential training of heavy rain and associated thunderstorms.

    gfs_z500_uv_vort_east_5

    Rich tropical moisture was readily available across the area, indicative of 06z forecast dew points in the upper 60s and lower 70s across the Ohio Valley region.

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    Perhaps the more telling story had to do with the forecast PWAT, or Precipitable Water, values that exceeded 2″ to 2.4″ across portions of central Indiana from the 06z model run Thursday morning.  PWAT values are a good indication of heavy rainfall potential should there be something to trigger (lifting mechanism) showers and storms.  PWAT values of 2″ and above are considered extreme and rather rare, even for this time of year.

    We tip our hat to the 06z 4km NAM picking up on this early Thursday morning as it very closely matched where training thunderstorms and heavy rain initiated Thursday afternoon.  Take a look at the forecast PWAT levels and the afternoon radar on Thursday, June 19th, as storms began to develop:  Note rainfall rates exceeded 2″/ hr. across portions of central Indiana, including Boone County on the afternoon of June 19th.

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    Compare that to the forecast radar from another one of our short-term, high resolution, forecast models, the HRRR, valid 6pm:

    hrrr_ref_indy_2

    (We want to thank the fine folks at Weatherbell Analytics for some of the forecast model images.  Additionally, thanks to Radarscope for the radar storm rainfall totals).

    In closing, a combination of ingredients came together to present a localized, yet very significant flood event, for central Indiana.  The upper air pattern promoted movement of abnormally moist air to stream north into the Ohio Valley region.  At the same time, the same pattern resulted in a steering current that was relatively weak across our immediate region- adding to the potential of training.  The storms actually initiated (formed) along an old outflow boundary from the previous night, Wednesday, June 18th/ early morning Thursday, June 19th.

    The days ahead will continue the unsettled theme across the region and we’ll have to remain on our toes for potential additional significant weather impacts as we move forward Friday, and even into the weekend.  Much more later.


  • Tuesday Evening Video Update!

    Good evening and thank you for logging onto IndyWx.com!  Tonight’s video covers the unsettled time of things tonight into Wednesday morning as low pressure continues to have a hold on our area’s weather.  Also, we talk long range weather and give you an idea of what you can expect for the rest of the month of June, temperature-wise!  While we didn’t get into the precipitation side of things in tonight’s video for late month, I will say it continues to look very unsettled with above average rainfall anticipated to wrap up the month of June.  Anywhere from an additional 3-5″ of rain is possible as we go through the rest of the month here across central Indiana.

    While the CFSv2 can be a bit erratic at times, we feel the model has a good handle on the way the overall pattern will evolve late June into July.
    While the CFSv2 can be a bit erratic at times, we feel the model has a good handle on the way the overall pattern will evolve late June into July.


  • Wet Day Ahead…

    Widespread light to moderate rain moved into central Indiana during the predawn hours.  Most communities picked up .20″-.30″ since midnight.  Some of asked if this is it for the rain today?  Unfortunately not.  The large low pressure system that’s sitting and spinning to our southwest will continue to pump copious amounts of moisture north through the afternoon and into Wednesday.  Heavy showers and embedded thunderstorms (non-severe) will redevelop this afternoon and evening and be responsible for locally heavy rainfall.

    Forecast radar through the afternoon and heading into the evening hours.

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    We still anticipate widespread rainfall totals of 1-2″ across central Indiana when you look at the 48 hour period- 12a Tuesday through 12a Thursday.

    Grab a good book and settle in for a wet day!


  • Wednesday Severe Threat Far From Etched In Stone…

    Many central Indiana neighborhoods picked up copious amounts of rainfall within a short time period this afternoon and evening.  We received 2″ here at the IndyWx.com HQ within just under 90 minutes.

    Forecast radar 5am Tue
    Forecast radar 5am Tue

    The rest of the evening will feature a drier theme as the axis of slow moving, torrential, downpours presses east.  That said, a couple of “rumblers” may be present during the early Tuesday morning period as a boundary slowly sinks south. We’re not talking about widespread heavy rain and storms, such as this evening, but a couple of thunderstorms may rumble across central Indiana early Tuesday morning before we dry things out and introduce sunshine for the majority of your Tuesday.

    Our attention will then shift to another round of heavy rain and thunderstorms Wednesday.  A severe weather outbreak will unfold to our northwest late Tuesday afternoon.  While this severe weather episode is likely to begin with individual severe thunderstorms (including potentially tornadic super cells), the activity should eventually morph into a mesoscale convective complex (otherwise referred to as a MCC in the wonderful meteorological world) during the night Tuesday as the storms roll towards our neck of the woods.

    The Storm Prediction Center (SPC) highlights the region for a Slight Risk of severe weather Wednesday.

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    We want to stress that this particular severe weather episode is far from etched in stone.  Diving into our short to mid term forecast models would suggest the initial round of heavy rain and thunderstorms rumble into the state around 4-6am Wednesday- potentially in a weakened state when compared to what our friends and neighbors off to our north and west will experience Tuesday night.  Now it’s important that we insert the timing disclaimer to the equation as similar events in the past have been known to accelerate forward motion and arrive “ahead of schedule.”  (We’ll keep a close eye on the timing side of things and update Tuesday).

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    We’re confident we’ll be dealing with heavy rain around these parts Wednesday morning along with plenty of thunder and lightning.  That said, there are many more questions than answers at the moment around whether or not severe levels will be reached, at least in our humble opinion.  Should severe weather be an issue, it would most likely come from the following two impacts- damaging straight line winds and large hail.  Again, we’re leaning more towards this initial round of showers and thunderstorms blowing into town in a weakening state.

    Finally, there will be one more opportunity for strong to severe thunderstorms Wednesday afternoon, but this will be fueled by just how quickly the local air mass can warm and destabilize.  There are, again, questions around heating potential across the local area (central Indiana) and our thinking currently places a greater concern for damaging severe weather across southern Indiana into Kentucky (folks traveling to Louisville Wednesday afternoon would need to prepare for damaging severe potential).  Should we recover quicker than currently expected from Wednesday morning’s convection then we would need to hit the severe threat harder across central Indiana Wednesday afternoon.  Stay tuned for updates!

    Storms will likely strengthen yet again Wednesday afternoon, especially across southern Indiana.
    Storms will likely strengthen yet again Wednesday afternoon, especially across southern Indiana.