Thunderstorms are expected to increase in coverage through the afternoon as a pre-frontal air mass gradually destabilizes. Though a few marginally severe hail or wind events will be possible with stronger cells, a watch is not anticipated, according to a mesoscale discussion the National Weather Service Storm Prediction Center issued at 12:37 a.m. EDT.

Radar showed thunderstorms gradually increasing in a band from southern lower Michigan south-southwestward into southwestern Indiana, along a slowly advancing surface cold front. Ahead of the front and storms, the atmosphere is becoming moderately unstable and sunshine is heating moist air, with dew points are in the upper 60s.

Although the thermodynamic environment will support additional increases in storm coverage and/or intensity, the high-altitude winds will limit widespread severe potential. As such, somewhat weakly organized storms are expected. Thus, with only an isolated severe risk expected, a watch will likely remain unnecessary across the region.

Yellow area: Slight risk of severe thunderstorms today and tonight. Green area: Non-severe thunderstorms.

Portions of northern Indiana, southern Lower Michigan and northwestern Ohio have a slight risk of severe thunderstorms this afternoon and evening, according to the “Day 1 Convective Outlook” that the National Weather Service (NWS) Storm Prediction Center issued at 8:39 a.m. EDT. The main threats from these storms will be damaging straight-line winds and hail. In addition to these, torrential rain is possible, according to the “Hazardous Weather Outlook” that the northern Indiana NWS office issued at 8:58 a.m. EDT.

That outlook also indicates that SKYWARN spotter activation might be needed later this afternoon and this evening.

The slight risk area includes Allen and Whitley Counties of Indiana and counties to the west and north of them. It also includes Paulding and Putnam Counties of Ohio and counties to the north.

FLOOD ADVISORY
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1045 PM EDT SUN MAY 11 2014

ALLEN IN-WHITLEY IN-HUNTINGTON IN-
1045 PM EDT SUN MAY 11 2014

THE NATIONAL WEATHER SERVICE IN NORTHERN INDIANA HAS ISSUED AN

* URBAN AND SMALL STREAM FLOOD ADVISORY FOR...
  SOUTHWESTERN ALLEN COUNTY IN NORTHEAST INDIANA
  NORTHERN HUNTINGTON COUNTY IN NORTHEAST INDIANA
  WHITLEY COUNTY IN NORTHEAST INDIANA

* UNTIL 145 AM EDT

* AT 1041 PM EDT NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED    
  SLOW MOVING THUNDERSTORMS WITH VERY HEAVY RAIN OVER THE WARNED     
  AREA. RAINFALL RATES OF 1 TO 2 INCHES PER HOUR WILL BE POSSIBLE    
  THROUGH THE EARLY OVERNIGHT WHICH MAY CREATE LOCALIZED FLOODING. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM THESE STORMS WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...HIGHWAYS AND UNDERPASSES. ADDITIONALLY...
COUNTRY ROADS AND FARMLANDS ALONG THE BANKS OF CREEKS AND STREAMS AND
OTHER LOW LYING AREAS ARE SUBJECT TO FLOODING.

Almost all of Indiana has a slight risk of severe thunderstorms late this afternoon and this evening, according to the Day 1 Convective Outlook the National Weather Service Storm Prediction Center issued at 12:22 p.m. EDT.