15 May - 15 July 1988
(Revised, 19 June 1998)
Initialization (assumed 00 UTC 15 May 1988) fields are relatively zonal, with weak 500 mb High in SW US and weak Low in SE US. Only modest precip at Canadian border, Montana to Great Lakes over first 12 hr after initialization.
| Julian Day | Date | Synoptic pattern |
| 137-144 | May 16-23 | Well organized synoptic precipitation with centers on both coasts followed by large precipitation regions migrating across US. Peak precipitation from stationary Low in central MO giving heavy precipitation through central states. |
| 145-146 | May 24-25 | Dry period. Rain moves to E US. |
| 147-150 | May 26-29 | Persistent High in S US with light discontiguous precipitation in northern US to Canadian border. |
| 151-155 | May 30 – June 3 |
Closed 500 mb low moves across US, exiting Gulf coast; large organized precipitation patterns. |
| 156-159 | June 4-7 | High dominates US, very little precipitation. |
| 160 | June 8 | Brief breakdown of High in E and SE US, with brief period of precipitation. |
| 161-163 | June 9-11 | Re-establishment of High over whole US, little precipitation. |
| 164-166 | June 12-14 | Brief, moderate precipitation central US into Canada. |
| 167-180 | June 15-28 | 500 mb jet zonal at Canadian border. High across lower US, very spotty (mesoscale) precipitation patterns dominated by mesoscale processes. |
| 181-182 | June 29–30 | Transition to omega block with more organized precipitation. Weak High in Gulf supports LLJ, mesoscale precipitation over broad area of central US. |
| 183 | July 1 | Transition to weak and spotty precipitation. |
| 184-186 | July 2-4 | Return to dominance by High in south US; spotty precipitation. |
| 187-190 | July 5-8 | Scattered areas of light precipitation. |
| 191-196 | July 9-14 | Weakened High, return to organized precipitation. |
Additional notes on Day 160 (June 8)
Day 160 (June 8) may offer a unique opportunity to test the capabilities of a regional climate model to simulate significant isolated precipitation events at scales well below those resolvable by GCMs.
The Higgins precipitation for this day over the analysis subdomain had a spike, with no rain on adjacent days. The FIFE data (the FIFE region is near the western boundary of the analysis subdomain) also had a spike, but on June 7. Des Moines had a thunderstorm at midnight (6/7-8) followed by more rain until about sunrise on the 8th. The daily weather map showed a system with precip footprint about the size of the state of Iowa with center tracking west to east along the IA/MO border. This event was quite isolated in both space (everywhere else in the Midwest was dry) and time (2 or more days ahead and a day or two after were dry).
There is a brief switch to southerly winds on the morning of the 8th at the surface with the emergence of a weak Hi in the Gulf. This could have supported a jet with sufficient moisture to fuel the system into an MCC.
If, in fact, this it is generally possible to capture such an event and get it in the right place at the right time and produce substantial precip because of a timely but brief switch of the low-level winds, this could be a very supportive demonstration of the utility of a regional climate model.
Several models reporting at the St. Louis meeting may have captured the timing as well as the spatial and temporal extent of this event. Participants are encouraged to further investigate representation of this event in their model results.
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