ST. LOUIS, MO (KTVI) - To say this is a complex forecast would be an understatement. Temperatures hovering just below or very near freezing are key to this forecast, along with where and when the most substantial icing will occur. Please consult this map so you can get an idea of what I'm thinking for this event. First, none of this is for Thursday. I don't expect anything anywhere until early Friday morning.
Let's go by zones:
Zone #1: They are the first to see any problems. It looks like a pretty quick hit south of Festus. Expect a brief burst of sleet then it is all freezing rain. It starts around sunrise Friday morning with the band lifting slowly south to north through the zone. Minimal sleet accumulation is expected, but icing from freezing rain could range from 1/4" to 1/3". Once this band lifts to the north late Friday afternoon, most of the action will be done here.
Zone #2: A band of sleet and some freezing rain will lift into this zone Friday afternoon and continue into the evening before diminishing to freezing drizzle. Pockets of light freezing rain and drizzle will continue through the night into Saturday morning. I do expect a ramp up in activity for a few hours just before sunrise Saturday morning before precipitation diminishes again. There is some potential for light sleet accumulations of 1/2" or less in this zone by Friday evening with a glaze ice accumulation of 1/4" to 1/3". Most of the icy mix will be over in this zone by late Saturday.
Zone #3: This zone will be the last to see any precipitation. I expect little if anything this far north Friday. Friday night could bring some light freezing drizzle at times, which will continue into Saturday. Temperatures here will be much slower to warm and will remain below freezing all day Saturday. A surge of moisture will cut across this zone late Saturday night into Sunday morning. That is the period that concerns me the most in this zone. It is possible they could see 1/4" to 1/3" of glaze ice in Zone #3 from Saturday night into Sunday morning.
POSSIBLE IMPACTS (ALL ZONES):
- Where sleet falls, roads will become slick fast as the ice will cause road temps to drop rapidly. Areas that are all freezing rain may take a bit more time, but are still expected to get slick.
- Ice accumulation will be most noticeable in trees and on elevated surfaces. However, winds are expected to remain mostly below 15 mph which should reduce the amount of tree/power line damage. That's not to say there will not be any, it just will not be what it could be if the winds were a somewhat stronger.
By Monday we are all well above freezing. In fact,we could reach to near 60 degrees with scattered thunderstorms possible by Monday afternoon.
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