Jul 22
Busy times continue in the good ole forecast office! This morning’s video talks about the one-two punch of cool air inbound to close July and looks at our increasingly-needed rain…
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Permanent link to this article: https://indywx.com/tuesday-morning-video-update/
Jun 30
We spoke Sunday of a couple complexes of thunderstorms potentially impacting the region today. The first complex of thunderstorms is moving into northwestern portions of the state as we write this and short-term modeling is already struggling on the track of this complex. Note the forecast radar, via the HRRR and 4km NAM, valid 8am versus the actual radar snapped at 7:30am.
The first complex of thunderstorms will likely blow through north-central Indiana counties later this morning.
The Storm Prediction Center has outlined portions of the region under a slight risk of severe today, including a heightened moderate risk across Iowa, MO, and IL. All modes of severe weather are in play, including potential tornadoes, large hail, and damaging straight line winds.
The latest 4km NAM shows complex number 2 erupting over Iowa later this afternoon.
This is the complex of storms that could pose a rather active time of things across Indiana tonight.
Moisture and energy will be plentiful, meaning storms will likely remain strong to severe as they push into central Indiana. Additionally, locally heavy downpours are a good bet.
Forecast CAPE is to be around 3500-4500 J/kg tonight when complex number 2 is eyeing the region. In short, this means “energy” will be plentiful for storms to remain strong to severe as they blow into the region. Think of CAPE as fuel for storms.
Forecast PWAT, or precipitable water, shows a ribbon of 2″ streaking through the central portions of the state and suggests torrential downpours with any storm.
Bottom line, it’ll be important to have a means of getting your latest weather information and radar trends later this evening. The greatest severe threat to our immediate region appears to be with a straight line wind component, but as stated above, we’ll have to be on guard for all modes of severe weather.
Now casting will be key later tonight as we eye another round of potential severe weather impacting the state. While the first complex of storms will impact northern counties this morning, it’s complex number 2 late tonight that could pack a punch across a more widespread portion of the region. More later this afternoon!
Permanent link to this article: https://indywx.com/severe-threat-tonight-for-portions-of-the-region/
Jun 24
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.
The latest visible satellite image also shows the spin associated with the upper level energy over southern Illinois this morning.
Note the heavy rain and embedded thunder currently to our southwest associated with this disturbance this morning.
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.
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.
Permanent link to this article: https://indywx.com/showers-thunderstorms-expand-in-coverage-later-today/
Jun 19
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.
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.
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.
The 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.
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.
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.
Compare that to the forecast radar from another one of our short-term, high resolution, forecast models, the HRRR, valid 6pm:
(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.
Permanent link to this article: https://indywx.com/boone-county-central-indiana-flooding-61914/
Jun 18
Good evening friends! I hope this finds you having a nice Wednesday. Our video update this evening looks at a couple rounds of strong, to potentially severe, thunderstorms ahead.
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Permanent link to this article: https://indywx.com/two-rounds-of-storms-ahead/