Ann Arbor is included in MD 903, which stretches from Nashville approximately up to Port Huron.
Within this area, thunderstorm activity is expected to increase throughout the afternoon, with organized clusters or lines of strong-to-severe storm are expected to form. These storms would bring strong winds and possibly damaging hail, along with the lightning and heavy rain that is expected with any strong storm system. We might (40% probability) see a severe thunderstorm watch for the area issued shortly.
MESOSCALE DISCUSSION 0903 NWS STORM PREDICTION CENTER NORMAN OK 1233 PM CDT FRI MAY 31 2013 AREAS AFFECTED...FAR SE MI...WRN OH...FAR SE IND...CNTRL/ERN KY...N CNTRL TN CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE VALID 311733Z - 311900Z CORRECTED FOR AFFECTED AREA PROBABILITY OF WATCH ISSUANCE...40 PERCENT SUMMARY...THUNDERSTORM COVERAGE WILL INCREASE THROUGH THE AFTERNOON. LOOSELY ORGANIZED STRONG TO SEVERE STORM CLUSTERS WILL BE CAPABLE OF PRODUCING STRONG WINDS AND MARGINALLY SEVERE HAIL. DISCUSSION...SCATTERED THUNDERSTORMS WERE DEVELOPING IN AREA OF INCREASING ASCENT AHEAD OF UPPER SHORTWAVE IMPULSE MOVING ACROSS THE MID-MS VALLEY EARLY THIS AFTERNOON. POCKETS OF STRONGER HEATING ACROSS SE MI/WRN OHIO INTO PARTS OF CNTRL AND ERN KY HAS ALLOWED FOR WEAK DESTABILIZATION WITH SBCAPE VALUES AROUND 1000 J/KG. BULK SHEAR VALUES AROUND 20-40 KTS SHOULD LEAD TO AT LEAST SOME ORGANIZED CLUSTERS/LINE SEGMENTS. THE BEST LOCATIONS FOR THIS TO OCCUR WOULD BE ACROSS FAR SW MI /WHERE STORMS ARE CURRENTLY ONGOING/ INTO PARTS OF IND AND OHIO WHERE DEEP LAYER SHEAR IS A BIT STRONGER THAN FURTHER SOUTH INTO KY/TN. HOWEVER...A REMNANT MCV EVIDENT IN SATELLITE IMAGERY MOVING ACROSS THE LOWER OHIO VALLEY MAY SERVE TO FOCUS STRONGER THUNDERSTORM DEVELOPMENT THIS AFTERNOON ACROSS KY DESPITE WEAKER DEEP LAYER SHEAR. STRONG WINDS AND MARGINALLY SEVERE HAIL WILL BE THE MAIN THREATS WITH ANY ORGANIZED STORMS THAT CAN DEVELOP TODAY. TRENDS WILL BE MONITORED FOR POSSIBLE WW ISSUANCE. ..LEITMAN/HART.. 05/31/2013 ATTN...WFO...RLX...CLE...MRX...JKL...ILN...DTX...LMK...IWX... GRR...OHX...IND...PAH... LAT...LON 35778565 35868653 36028704 36568743 37298738 37958704 40308554 42028418 43628266 43478203 42768135 41478167 39918246 37318371 36258449 35798517 35778565