The National Weather Service Storm Prediction Center has issued “Mesoscale Discussion Number 814,” which indicates that parts of southeastern Missouri, southern Illinois, western and central Kentucky and southern Indiana (outlined in map graphic above) have an 80 percent probability of a weather watch by 3:30 p.m. EDT and possibly earlier. Large hail and damaging straight-line winds appear to be the greatest threats.

Green area: General (non-severe) thunderstorms between 8 a.m. EDT today and 8 a.m. EDT tomorrow. Yellow: Slight risk of severe thunderstorms.

Update: 12:30 p.m. EDT update to the Day 1 Convective Outlook did not change the categorical slight risk area boundaries significantly. The slight risk area remains south of I-70. The risk of significant damaging winds (75 mph or greater) that appeared in this morning’s original convective outlook has, however, disappeared. The next update is due by 4 p.m. EDT.

In contrast to yesterday’s outlook for today, forecasters now indicate that any risk of severe weather will remain much further south. The “Day 1 Convective Outlook” that the National Weather Service (NWS) Storm Prediction Center issued at 2 a.m. EDT indicates a slight risk of severe weather in less than half of Indiana, south of a line from approximately Vincennes to Bloomington to New Castle to Richmond.

The new slight risk area does not include any of the county warning area of the northern Indiana NWS office. Within that area, an isolated, non-severe thunderstorm is possible this morning through this afternoon, generally south of the U.S. 6 corridor, according to a “Hazardous Weather Outlook” that the northern Indiana NWS office issued at 4:25 a.m. EDT. South of a line from Winimac to Decatur, locally heavy rain is possible.

SKYWARN storm spotter activation will not be needed in the northern Indiana county warning area today or tonight, according to the Hazardous Weather Outlook.

Our next look at the outlook for severe weather today comes with an updated SPC Day 1 Convective Outlook, due out by 9 a.m. EDT.

Probabilities of severe weather within 25 miles of a point between 8 a.m. EDT tomorrow (June 4) and 8 a.m. EDT Thursday. Brown area: Five percent (below “slight risk” criteria). Yellow area: 15% (low end of “slight risk”). Red area: 30% (high end of slight risk). Inside black loop: 10 percent or greater probability of significant severe weather (EF2 or greater tornadoes, damaging winds greater than 65 knots (75 mph), or hail 2 inches or greater in diameter). Read more about severe weather probabilities. Highlighted counties: County warning area of the northern Indiana NWS office. Source: SPC “Day  2 Convective Outlook,” 2 a.m EDT June 3.

Approximately the southern three fourths of Indiana plus large areas of nearby states have a slight risk of severe weather between 8 a.m. EDT tomorrow and 8 a.m. EDT Thursday, according to the “Day 2 Convective Outlook” that the National Weather Service (NWS) Storm Prediction Center (SPC) issued at 2 a.m. EDT. In addition, the southern half of Indiana and parts of Illinois, Kentucky, Ohio and West Virginia (within the black loop on the map above) have a larger than normal chance of significant severe weather (EF2 or greater tornadoes, damaging winds greater than 65 knots (75 mph), or hail two inches or greater in diameter).

As you can see on the map above, the slight risk area (yellow and red areas) currently falls just south of Fort Wayne south of a forecast warm front. Forecasters were uncertain, however, how far north the warm front might move. If it moves farther north, the probabilities of severe weather could move north with it. Currently, the slight risk area includes all or parts of the following counties in IMO SKYWARN quadrant two: In Indiana, Huntington (very small part), Wells, Adams, Blackford and Jay. In Ohio, Van Wert, Allen and Putnam (very small part).

All types of severe weather will be possible in the slight risk area tomorrow, including damaging straight-line winds, large hail and tornadoes.

The threat will be greatest from late morning tomorrow through the early evening. SKYWARN storm spotters in and near the slight risk area should prepare for possible activation during that time. Anyone planning outdoor activities should have a way to be informed of developing severe weather and a plan for what to do if it occurs.

The SPC will update its Day 2 Outlook by 1:30 p.m. EDT. At that time, changes in both probabilities and areas are possible. When the updated outlook is published, this link will take you there.

Thunderstorms are likely today, especially this afternoon and evening, according to the “Hazardous Weather Outlook” that the northern Indiana office of the National Weather Service (NWS) issued at 5 a.m. EDT. Although forecasters do not expect widespread severe weather today, they cannot rule out isolated strong to severe thunderstorms this afternoon and early evening. Some localized areas could also receive heavy rain. The northern Indiana NWS office does not anticipate activating SKYWARN storm spotters today or tonight but the office will appreciate any reports of flooding.

The picture looks different, however, for Wednesday afternoon and evening, when much of Indiana, Illinois and Ohio have a 15 percent to 30 percent probability of a severe thunderstorm within 25 miles of a point, according to the “Day 3 Convective Outlook” that the NWS Storm Prediction Center (SPC) issued at 3:39 a.m. Damaging wind, large hail and a few tornadoes will be possible in the risk area Wednesday, especially in the afternoon and early evening.

As you can see on the map below, the current forecast puts the slight risk area just south of Allen County, Ind. and includes the following counties in the NWS northern Indiana county warning area:

Parts of Grant, Blackford and Jay Counties have a 30 percent probability (the high end of “slight risk”) of severe storms within 25 miles of a point. The remainder of the slight risk area has a 15 percent probability, as of the day three outlook.

The risk areas might change between now and Wednesday. Our next look at SPC thinking comes at about 2 a.m. EDT tomorrow (Tuesday), when the Center will issue its “Day 2 Convective Outlook” for the period (the link at left will not work until the SPC issues the outlook).

Meanwhile, if you are a SKYWARN storm spotter in the slight risk area, prepare for the possibility of activation Wednesday. If you are planning any outdoor activities (e.g. a summer festival), plan to have a way to remain aware of and respond to severe weather threats.

Probabilities of severe weather within 25 miles of a point between 8 a.m. EDT Wednesday, June 4 and 8 a.m. EDT Thursday, June 5, according to the SPC’s “Day 3 Convective Outlook” issued early June 2. Brown area: five percent. Yellow area: 15 percent (slight risk). Red area: 30 percent (slight risk). Read more about the probability figures. Highlighted counties: NWS northern Indiana office’s county warning area.

Red area: 30% or higher probability of severe thunderstorms within 25 miles of a point between 8 a.m. EDT June 4 and 8 a.m. EDT June 5

Most of Indiana, all of Ohio and parts of Illinois, Pennsylvania and West Virginia have a 30 percent or higher probability of severe thunderstorms within 25 miles of a point between 8 a.m. EDT Wednesday, June 4 and 8 a.m. EDT Thursday, June 5, according to the “Day 4-8 Severe Weather Outlook” that the National Weather Service Storm Prediction Center issued at 5 a.m. EDT today.

The potential for large hail and widespread, damaging straight-line winds exists during the period.

As Wednesday draws closer, keep an eye on subsequent convective outlooks and forecasts to know whether SKYWARN storm spotter activation become likely for Wednesday.

A now stationary front hanging along the Indiana-Michigan line is forecast to slowly move south today. As daytime heating occurs, thunderstorms should form and mature along and south of the front, according to the “Day 1 Convective Outlook” that the National Weather Service (NWS) Storm Prediction Center issued at 1:59 a.m. EDT.

Available moisture (dew points in the 60s) and atmospheric instability (forecast to be above 1,000 j/kg by 1 p.m. EDT) might allow for pulse-type storms and perhaps some multicell storms capable of locally damaging winds and perhaps marginal hail. Wind shear today, however, is insufficient to support even a slight risk of severe thunderstorms in the convective outlook.

The northern Indiana NWS office agrees that an isolated strong to severe storm and heavy rainfall are possible this afternoon and evening anywhere in its 37-county warning area, according to the “Hazardous Weather Outlook” the office issued at 5:40 a.m. EDT. The outlook indicates, however, that spotter activation is not anticipated.

Much of Indiana and Ohio, as well as parts of other nearby states, have a slight risk of severe weather between 9 a.m. EDT today and 8 a.m. EDT tomorrow, according to the “Day 1 Convective Outlook” that the National Weather Service (NWS) Storm Prediction Center (SPC) issued at 8:40 a.m. today.

The main threats are isolated damaging strait-line wind gusts and hail. In south central Indiana, hail stones could be larger than two inches in diameter.

The slight risk area includes includes parts or all of the following counties in IMO SKYWARN quadrant two:

• Huntington
• Wells
• Adams
• Van Wert
• Allen (Ohio)
• Blackford
• Jay

The slight risk area does not currently include any part of Allen County, Indiana or any Indiana counties to the north or west of Allen County.
 
Scattered thunderstorms should begin developing by late afternoon and storms might continue into the evening. SKYWARN spotter activation might be needed this afternoon, according to the “Hazardous Weather Outlook” that the northern Indiana NWS office issued at 4:47 a.m. EDT.

We’ll get our next look at the severe weather risks for today when the SPC issues an updated convective outlook by 12:30 p.m. EDT.