CENTRAL ILLINOIS (WMBD) — You don’t need a crystal ball to forecast the impacts from the remnants of Tropical Storm Cristobal on our weather Tuesday into Wednesday.
Cristobal will move northward through the Mississippi River Valley Tuesday morning and afternoon, bringing widespread moderate-to-heavy rainfall through parts of the mid-west including here in Central Illinois.
So far the track of the low-pressure associated with the system will remain just west of our region. This projection will take the bulk of the heavy rainfall into eastern Iowa and northwest Illinois, where multiple inches of rain will be likely.
We should remain on the eastern side of the low where rainfall amounts will be less, ranging from 0.75″ to 1.50″ with pockets of heavier rainfall not out of the realm of possibility. At this point, most of our reliable weather models are taking the slightly higher amounts west of the Illinois River from.
Rainfall will not be the only issue from Cristobal, a few breaks in the clouds during the afternoon could increase instability enough and allow a few strong-to-severe storms to develop on the eastern side of the low pressure center. Strong non-thunderstorm wind gusts (45-55 miles per hour) from the south could develop from the tight pressure gradient surrounding the east side of the low.
This will aid in the turning of the winds (winds moving in different directions from the ground, up toward the top of the atmosphere) and possibly create a window for brief, isolated spin-up tornadoes, however the threat remains low at this time. The time frame for severe storms will range from Tuesday afternoon through early evening.
One thing to note about Tuesday afternoon and early evening is instability is lacking and depends on breaks in the clouds to allow sunshine to destabilize the atmosphere. Sunshine easily adds energy to the atmosphere which storms then feed on. An eastward jog in the track of Cristobal and we could be looking at higher rainfall amounts. As we get into Wednesday, the front pushing Cristobal out of the way has a chance to spark additional showers along with very gusty winds. Conditions will generally clear up heading through Wednesday afternoon and night.
Central Illinois experiences remnants of tropical systems and tropical depressions, however wind gusts rarely exceed 50 miles per hour from these circulations.