The northern Indiana office of the National Weather Service published the above infographic today regarding the slight risk of severe weather tomorrow.

Probability of severe weather within 25 miles of a point between 8 a.m. Friday and 8 a.m Saturday.

Update: The risks for tomorrow are pretty much the same in the updated convective outlook that the SPC issued at 1:30 p.m. EDT. In the new version, the 30 percent probability area dips just south of the Indiana-Michigan state line. The next outlook for tomorrow will be the first Day 1 Outlook of the day, scheduled for about 2 a.m. EDT.

The northern third of Indiana, as well as all of lower Michigan and parts of Illinois and Wisconsin have a slight risk of severe weather between 8 a.m. EDT tomorrow and 8 a.m. EDT Saturday, according to the Day 2 Convective Outlook that the National Weather Service (NWS) Storm Prediction Center (SPC) issued this morning. The slight risk area includes all 37 Indiana, Michigan and Ohio counties that receive warnings from the northern Indiana NWS office. All of those counties have at least a 15 percent probability of severe weather within 25 miles of any point (see an explanation of outlook probability numbers). But as you can see on the map at left, the probability is twice as high (30 percent) in the Chicago and Milwaukee areas, as well as in much of lower Michigan.

In the area covered by the northern Indiana NWS office, thunderstorms are most likely late Friday into Saturday, according to the Hazardous Weather Outlook that the office issued this morning.

According to the convective outlook, numerous episodes of strong to severe storms seem possible in the Great Lakes region through the day Friday. The greatest severe weather potential is damaging wind around the time of maximum daytime heating (i.e. around 3 p.m. EDT). Conditions such as high atmospheric instability and strong changes in wind speed with altitude could support relatively fast-moving and longer-lived linear storm segments. We could see some line echo wave patterns (bulges in thunderstorm lines that produce wave-shaped “kinks” in the lines) and bowing lines of storms. These could result in a greater potential for damaging winds and perhaps a brief tornado or two in any areas where they occur.

Later in the evening, especially in the eastern Great Lakes region, conditions should support one or two longer-lived lines of thunderstorm complexes. Damaging winds might accompany these storms into early Saturday morning.

Our next look at the risk of severe weather tomorrow comes when the SPC issues an updated Day 2 Convective Outlook at around 1:30 p.m. EDT.

Yellow area: Slight risk of severe weather between 8 a.m. EDT Saturday and 8 a.m. EDT Sunday. Green area: non-severe thunderstorms.

Also, much of Indiana has a slight risk of severe weather between 8 a.m. Saturday and 8 a.m. Sunday, according to today’s Day 3 Convective Outlook. As you can see on the map at left, the slight risk area includes the Indiana Counties of Allen and Whitley, as well as counties to the south and west and Ohio Counties to the east (Van Wert and Allen). In those areas, there’s a 15 percent probability of severe weather within 25 miles of a point on Saturday.

Feed line damage high above northwestern Fort Wayne. (NWS Northern Indiana photo)

Technicians have discovered damage to the coaxial feed line that connects the Fort Wayne NOAA Weather Radio transmitter to its antenna approximately 700 feet above the ground on the WFWA-TV tower on Butler Road. In addition, they discovered water in that feed line, which means all 700 feet of feed line must be removed from the tower and replaced. Feed line with water in it doesn’t work well and there’s no reliable way to drain all the water from a feed line.

According to an NWS meteorologist, the tower crew discovered the feed line damage after they installed a new power divider and feed line jumpers for the four-bay antenna.

It is unknown at this time how long it will take to receive and install the replacement feed line. In the interim, the Fort Wayne NOAA Weather Radio transmitter will continue to operate at lower than usual power, which means some weather radios that normally pick up the signal will be unable to do so.

In addition, expect the transmitter to go off the air completely during the feed line replacement work, whenever that happens.

View of the bottom two bays of the NOAA Weather Radio four-bay antenna, side-mounted near the top of the WFWA-TV tower on Butler Road. Fort Wayne’s animal control facility appears in the lower right-hand corner. (NWS Northern Indiana photo)

Probability of severe weather within 25 miles of a point.

Remember yesterday, when I suggested that the Day 4 Convective Outlook wasn’t the last word on Indiana’s risk of severe weather Friday? As of this morning, there’s a slight risk of severe weather over the northern third of Indiana, all of lower Michigan and the northwest quarter of Ohio, among other ares (see may at left), according to the Day 3 Convective Outlook that the National Weather Service (NWS) Storm Prediction Center (SPC) issued.

While the greatest probability of severe weather between 8 a.m. EDT Friday and 8 a.m. EDT Saturday remains in Michigan (30 percent), the entire 37-county warning area of the northern Indiana NWS office has at least a 15 percent probability of severe weather within 25 miles of any point. (See an explanation of these probabilities.)

The focus of attention is a sharp cold front — currently running from Canada across northern Minnesota — that’s forecast to move across the Great Lakes region Friday. In today’s Hazardous Weather Outlook, the northern Indiana NWS office forecasts storms in its coverage area Friday night, during which severe weather and heavy rainfall are possible. The timing of the storms, however, depends on how fast the cold front moves to and across the area.

Our next outlook on Friday’s severe weather risk comes early tomorrow morning, when the SPC issues the first Day 2 Convective Outlook of the day.

Meanwhile, the northern Indiana NWS office issued another Special Weather Statement this morning, advising that high temperatures in the lower 90s and high humidity will result in peak afternoon heat indices from the upper 90s to around 100 until the cold front arrives Friday. The statement includes the standard caution for anyone who must be outside during high heat indices: Take frequent breaks and drink copious fluids.

We apologize for any inconvenience this may cause. This statement will be updated when further information becomes available.

Red area: 30 percent or higher probability of severe thunderstorms within 25 miles of any point between 8 a.m. EDT Friday and 8 a.m. EDT Saturday.

Indiana and Ohio are no longer at risk for severe weather this week, according to convective outlooks that the National Weather Service (NWS) Storm Prediction Center (SPC) issued today. For the past few days, SPC outlooks indicated a slight risk of severe thunderstorms between 8 a.m. Friday and 8 a.m. Saturday. As of today’s outlooks, that risk has moved north and no longer includes Indiana or Ohio.

The Hazardous Weather Outlook that the northern Indiana NWS office issued this morning indicates that thunderstorms are likely in the office’s 37-county area Friday night into Saturday. The outlook does not, however, mention severe thunderstorms. 

These outlooks often change from day to day, however, so it would be wise to check back tomorrow for a look at tomorrow’s Day 3 Convective Outlook to see if the forecast has changed again.

The northern Indiana office of the National Weather Service published the above infographic today to explain the heat index that will appear in forecasts and advisories this week.