Now we will take a closer look at analyzed hourly surface weather maps and really focus on the synoptic and mesoscale features over the Great Lakes region from 8 a.m. through 4 p.m. (when the Kalamazoo tornado developed).
8 a.m. E.D.T. 5/13/80
Note that there were numerous observation sites reporting fog and mist north of the quasi-stationary frontal boundary across southern Lower Michigan. Fog and low ceilings obviously imply abundant low-level moisture. This is also an indication of an environment the supports low LCL heights. Another important feature to note is the weak low-pressure area over eastern Iowa. This 8 a.m. surface weather map is also almost identical to the composite surface weather map we generated for all “Type One” tornado events from the Significant Tornado Climatology for Lower Michigan (see next page).
9 a.m. E.D.T.
There was very little change in surface observations between 8 and 9 a.m. The visibility in Kalamazoo increased from one-half to one mile.
10 a.m. E.D.T.
There still was not too much change in the surface observations, although the low-pressure wave had progressed into northwest Illinois. Temperatures were slowly rising, especially near and south of the quasi-stationary boundary. Reduced visibility in mist was still being reported at all stations across southern Lower Michigan.
11 a.m. E.D.T.
By 11 a.m. the surface weather map began to show considerable changes. Of greatest importance, please note that the quasi-stationary front had begun to lift north as a warm front. The temperature at South Bend climbed to 61 degrees and winds backed from the NW to the SW south of the boundary. The temperature in Kalamazoo had risen to 63 degrees and the dew point jumped up three degrees, to 57°. Also, note several observations from across central IL east through IN and OH, which indicate that surface winds were increasing and already up to around 20 knots.
12 p.m. E.D.T.
The warm front had not made any progress farther north in the past hour, and the boundary became quasi stationary once again. Just south of the boundary, surface based instability continued to rise slowly, where the temperature in Kalamazoo had climbed four more degrees to 67. Light and variable winds were reported in Kalamazoo most of the morning, but now southerly winds of around 10 knots had developed. This mixing allowed visibility to increase to six miles, though haze was still being reported.
1 p.m. E.D.T.
The temperature continued to moderate slowly in Kalamazoo, now up to 70 degrees. This was very strong boundary as evidenced by the 16 degree F difference between Kalamazoo and Lansing and the 25 degree F difference over the 75 mile distance from Kalamazoo to Muskegon. The 1002-millibar surface low continued to move ever so slowly east northeast.
2 p.m. E.D.T.
This was one and a half hours before the first tornado touched down (in Van Buren county). The boundary was still nearly stationary just north of Kalamazoo and the I-94 corridor. The low had continued to proceed slowly east-northeast to near Chicago. An important question that day may have been; will the quasi-stationary boundary tend to kink a little farther north as a warm front as the surface low moves closer to Lower Michigan? Lake Michigan water temperatures in mid May were likely only in the 40’s. Another concern may have been exactly what would the impact of the colder, denser air over Lake Michigan be on the movement of the boundary and the track of the area of low pressure.
3 p.m. E.D.T. – 30 minutes before tornado develops in Van Buren county
The surface low had deepened slightly to 1001 mb and moved out over extreme southern Lake Michigan. The boundary lifted back north and actually moved just north of the Kent County airport at 3 p.m. It is apparent that the boundary is north of Grand Rapids as the temperature jumped up 9 degrees in the past hour to 64° F, and light southeast winds were reported. Visibility there was still reduced to 3 miles in mist.
Also, note that the temperature had risen to 76F degrees in South Bend and 74F in Kalamazoo. Kalamazoo still reported reduced visibility (6 miles) in haze. Note how strong surface wind field directional shear was, looking from Grand Rapids and Kalamazoo to the west. Over a relatively short distance, Grand Rapids had south-southeast winds at 5 knots, Kalamazoo reported south winds at 8 knots, South Bend had west-southwest sustained winds at 18 knots, and Chicago had west-southwest sustained winds of 25 knots with gusts to 36 knots.
Here are a few observations from across the area to provide detail on 3 p.m. surface conditions:
North of warm front, restricted visibility in haze/mist and very low ceilings:
KFNT 131858Z 07004KT 6SM HZ OVC009 13/10 A2967 RMK SLP053 T01330100
Just south of warm front, the temperature had jumped up 9 nine degrees in one hour in Grand Rapids, to 64 degrees:
KGRR 131855Z 16005KT 3SM BR BKN009 OVC100 18/14 A2966 RMK SLP041 T01780139
South of the warm front, temperatures continued to rise. Numerous locations in Indiana were getting wind gusts over 30 m.p.h.:
KAZO 131850Z 19008KT 6SM HZ BKN020 23/13 A2962 RMK T02330128 KSBN 131853Z 24018KT 7SM SCT020 BKN035 24/13 A2958 RMK SLP012 T02440133 KFWA 131850Z 24012KT 8SM OVC035 22/13 RMK SLP048 T02220128 KLAF 131849Z 25020G27KT 7SM -SHRA SCT010 BKN025 24/16 A2971 RMK SLP057 T02390156 KIND 131855Z 22019G27KT 12SM BKN040 28/16 A2975 RMK T02780156 KORD 131853Z 25025G36KT 10SM 20/10 A2963 RMK SLP028 T02000100
4 p.m. E.D.T. – tornado strikes downtown Kalamazoo
The position of the boundary across southern lower Michigan is critical. Note that it meandered back to the south of Grand Rapids, as evidenced by the temperature and northeast surface winds there. The temperature at the airport in Kalamazoo (7 miles south of downtown Kalamazoo) was cooled one degree by a rain shower. Visibility was reduced to 6 miles by mist and rain and the broken cloud deck was only 1,800 feet above ground level (AGL). The low had continued to track very slowly east northeast to near South Haven. Note how abruptly wind direction changes were taking place in the vicinity of the quasi-stationary frontal boundary and in the vicinity of the low pressure area.
Here is the Kalamazoo observation taken at the airport in Portage (7 miles south of “downtown” Kalamazoo) at 3:50 p.m., 10 minutes before tornado touchdown in Kalamazoo:
KAZO 131950Z 19008KT 6SM –SHRA BKN018 23/13 A2952 RMK T02280128
Grand Rapids observation taken at 3:55 p.m.
KGRR 131955Z 05012KT 3SM BR SCT009 OVC044 17/14 A2961 RMK SLP025 T01670139
Noting the position of the boundary near Kalamazoo and “splitting the difference” in
wind direction between the Kalamazoo and Grand Rapids airports, we can make a reasonable
assumption that the wind direction in downtown Kalamazoo at the time the tornado
developed was out of the southeast or east. This is an important point because this
would have contributed to higher 0-1 km and 0-3 km storm relative helicity values.