Here comes the "F" word
The "F" word -- freezing rain -- is in the forecast for Friday the 13th, but right now it appears that Cape Girardeau will just miss most of the ice. Areas to the north and west, however, might see another story.
The probabilities from the Weather Prediction Center, based on a consensus of the computer models, put Cape right on the southeast edge of the ice blob. Central Missouri, particularly around Rolla, appears to be in the bullseye. The map below shows the probability of seeing a total freezing rain accumulation of at least one-tenth of an inch:
Or, put another way, here is a table showing the latest percentages for local towns of receiving one-tenth, one-quarter, and one-half of an inch. You'll notice that you don't have to travel far to the northwest for the forecast to be considerably worse. Even the difference between Cape and Jackson is noticeable:
Location 0.10 in 0.25 in 0.50 in
Cape Girardeau 20-30% - -
Jackson 30-40% 1-5% -
Oak Ridge 50-60% 5-10% -
Altenburg 50-60% 5-10% -
Perryville 70-80% 30-40% -
Ste. Genevieve 80-90% 50-60% 5-10%
Farmington 80-90% 70-80% 20-30%
Rolla 95% 90-95% 60-70%
For Cape, the temperature is expected to plunge and then hang around freezing for a few hours on Friday before climbing above freezing again. The good news is that this doesn't provide much time for ice to develop. Indeed, some of the computer models suggest that the temperature will never actually drop below freezing, so the ice storm could be a total bust. Nevertheless, it doesn't take much ice at all to cause big problems.
Here is an interesting plot from the "Plume Viewer" tool that shows the temperature that some of the computer models are predicting every three hours at Cape Girardeau. The black line is the average of the models -- and it just barely touches the 32°F mark (the blue horizontal line).
The more ugly models show the temperature dropping to 30°F, while others show that we don't even get below 35°. That, of course, represents a massive difference, and explains why forecasting winter storms is such an exercise in hair-pulling insanity.
Even in a worst case scenario where the temperature drops below freezing for longer than expected, warmer weather is on the way for Saturday (high 42°F). By Monday and Tuesday we'll be in the upper 50s -- with a chance for thunderstorms.
For now, the National Weather Service in Paducah has refrained from issuing a Winter Storm Watch, although their afternoon forecast discussion does suggest they will issue a Freezing Rain Advisory later where appropriate. To the north and west, much of Missouri is facing a Winter Storm Watch which will likely be upgraded to an Ice Storm Warning.
Of course, there's always the outside chance that this could be much worse than expected (at this point somebody always mentions the "Blizzard of '79" that defied all forecasts). But I doubt it.
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