Much of Indiana — including all of IMO SKYWARN quadrant two — continues to have a slight risk of severe weather between 4 p.m. EDT today and 8 a.m. EDT tomorrow, according to an updated “Day 1 Convective Outlook” that the National Weather Service Storm Prediction Center issued at 4:05 p.m. EDT.

The highest probabilities remain at 15 percent for either damaging straight-line thunderstorm winds of 58 mph or greater or large hail of one inch or more in diameter. The 15 percent hail probability, however, no longer includes an Ohio counties.

Factors that are limiting atmospheric instability should mitigate the potential for severe weather this afternoon and early evening, according to an “Area Forecast Discussion” that the northern Indiana office of the National Weather Service issued at 3:10 p.m. EDT. Meteorologists indicated, however, that coverage of showers and non-severe thunderstorms will increase over the next few hours.

I wrote yesterday that the National Weather Service (NWS) Storm Prediction Center (SPC) had issued convective outlooks for the following eight days that indicated no expectation of severe weather in Indiana.

Conditions changed since then.

As of 8:35 a.m. EDT, approximately the northern three fourths of Indiana and large parts of nearby states have a slight risk of severe weather between 9 a.m. EDT today and 8 a.m. EDT tomorrow, according to a “Day 1 Convective Outlook” that the SPC issued.

The entire slight risk area has a 15 percent probability of either of the following types of severe weather within 25 miles of a point:

• Damaging straight-line thunderstorm winds of 58 mph or greater.
• Large hail of one inch or more in diameter.

In addition, a large part of Indiana — primarily in the northwestern and north central regions — have a 2 percent probability of a tornado within 25 miles of a point.

If these probability numbers (15 percent and 2 percent) seem insignificant, have a look at the SPC’s explanation of what they mean.

Any severe weather that does occur is most likely this afternoon and evening. Showers and thunderstorms are forecast in the area this morning, but a second round of storms later today is mostly likely to contain severe weather.

SKYWARN storm spotter activation might be needed this afternoon and evening, according to the “Hazardous Weather Outlook” that the northern Indiana NWS office issued at 4:39 a.m. The slight risk area includes all of IMO SKYWARN quadrants two, three and four and nearly all of quadrant 1, with only the northeastern halves of Hillsdale and Fulton Counties excluded.

Anyone in the slight risk area — especially anyone involved in outdoor activities — should be sure they have a way of knowing about any weather watches or warnings that NWS might issue today.

As always, as time permits, I’ll update this blog with more information as it becomes available. Any updates will appear on the blog’s home page.

Meteorologists do  not expect any severe weather in or near Indiana through Wednesday, August 27, according to convective outlooks issued by the National Weather Service Storm Prediction Center.

Thunderstorms are possible for the next several days and some might be strong, especially Thursday. But meteorologists do not expect widespread severe weather.

Meteorologists indicated a 40 percent probability that they will issue a weather watch for northern Indiana this afternoon, in a “Mesoscale Discussion” the National Weather Service Storm Prediction Center issued at 2:03 p.m. EDT.

The area covered by Mesoscale Discussion 1580 includes all or part of the following counties in IMO SKYWARN quadrant two: Allen (Ind.), Whitley, Huntington, Wells, Adams, Blackford, Paulding and perhaps other nearby counties.

Slightly more of northwestern Indiana now has a slight risk of severe weather, along with all of the rest of Indiana and parts of nearby states, according to an updated “Day 1 Convective Outlook” that the National Weather Service (NWS) Storm Prediction Center (SPC) issued at 12:29 p.m. EDT.

The only parts of Indiana not in the updated slight risk area are extreme northwestern Porter County and approximately the northern half of Lake County.

The threats are still damaging straight-line thunderstorm winds and large hair, with probabilities of both remaining at 15 percent within 25 miles of a point.

Meteorologists expect the northern portion of a cluster of thunderstorms that were in Illinois and east-central Missouri at midday to develop northeastward and merge with another band of thunderstorms that was developing over southeastern Lake Michigan. That conglomeration of storms is forecast to move eastward across southern Lower Michigan, Indiana and Illinois through the afternoon. Atmospheric conditions should support organized multi-cell thunderstorm systems with accompanying risks for a few damaging wind gusts and large hail.

Meteorologists at the northern Indiana office of the National Weather Service have slightly less confidence in the extent and/or coverage of severe weather in its 37-county warning area this afternoon and evening. An updated “Hazardous Weather Outlook” that the northern Indiana office issued at 10:57 a.m. EDT reflects this change. It reads, “Spotter activation may be needed this afternoon.” The outlook that the office issued early this morning (4:47 a.m. EDT) reads, “Spotter activation will be likely by this afternoon.” The change from “will be likely” to “may be needed” reflects the change in confidence in the extent and/or coverage of today’s severe weather.

Strong to severe thunderstorms possible this afternoon and evening. http://t.co/5wd51Ex0bU

— NWS Northern Indiana (@NWSIWX) August 19, 2014

Above is an example of the the kind of information you can get from the Twitter feed of the northern Indiana National Weather Service Office.

Almost all of Indiana has a slight risk of severe storms between 9 a.m. EDT today and 8 a.m. EDT tomorrow, according to the “Day 1 Convective Outlook” that the National Weather Service Storm Prediction Center issued at 8:16 a.m. EDT.

Threats

The primary threats are damaging straight-line thunderstorm winds of 58 mph or greater and large hail of one inch or more in diameter, both of which have a 15 percent probability within 25 miles of a point anywhere in the slight risk area. Read more about the significance of outlook probabilities.  The tornado risk today is negligible, with less than a 2 percent probability.

Timing

The severe storms are most likely late this afternoon into early this evening.

Geography

The slight risk area includes all of Indiana except Lake County, most of Porter County and northern LaPorte County of northwestern Indiana. The slight risk area includes the entirety of IMO SKYWARN quadrant two.

Preparation

Everyone who is in the slight risk area — especially those involved in outdoor activities this afternoon and evening — should ensure they have a way to know if the NWS issues a storm watch or warning.

SKYWARN storm spotters should make sure they and their gear are ready for activation, which is likely by this afternoon, according to the “Hazardous Weather Outlook” that the northern Indiana NWS office issued at 4:47 a.m. EDT.

Updates

The SPC will issue an updated convective outlook by 12:30 p.m. EDT, which will be our next chance to know if the storm risk for today has changed.

As time permits, I will “live blog” the weather situation as it develops, but this is a work day for me and I have client expectations to meet, so do not rely on this blog as a primary information source.

The northern Indiana NWS office will use Twitter ( @NWSIWX ) and Facebook to keep residents updated.

To become immediately aware of watches and warnings, I recommend a weather alert radio or monitoring a local radio or TV station.