This from the NWS this morning:
Severe WX Briefing – NWS 211215 @ 1030
NWS Des Moines – National Storm Prediction Center (Norman OK)
“Extremely Rare and Historic Event Likely!”
Likely damage to trees, power lines… power outages likely….
Travel – likely incidents with trucks / busses – tip-overs
Line of fast-moving thunderstorms… threat of tornadoes has increased… strong tornadoes possible
Any fires that would start from electrical system failures would be difficult to control in these winds….
Blowing dust and debris likely !!!
30-40 mph winds from 11 am to noon…. Increasing intensity to max after ~ 4 pm
High wind warning goes into effect at 12 noon…. Ramp-up time 3-4 hours
Convective risk for severe thunderstorms increases during the afternoon…
Post-convective wind peaks may be as strong as 70 to 100 mph… time gap after storm passes to strongest sustained winds
Movement extremely fast from 4-9 pm
Uncharted territory…. VERY rare…. fast moving storms… timing could be trigger at sunset when you can’t see much… take warning seriously when issued…
Peak of thunderstorm winds will arrive after thunderstorms pass…,,. non-convective post-thunderstorm winds may peak an hour or more post thunderstorms….
If widespread power loss…. for recovery considerations, realize that temps will fall into the 30s after the system passes…
Not planning another briefing unless something changes….
Wind chart is the NON-THUNDERSTORM winds w/maximum sustained gust… not reflective of potential straight-line gusts post-convection….
Would not want to be on the roads with 60-70+ mph winds…. stay off the road unless absolutely necessary….
Rainfall…. with speed of storms, not expecting flooding…. system moving too fast… wind is primary concern….
Wind should be diminishing tomorrow morning ref school busing… should be OK tomorrow….
More than dozen active tornado warnings in western Iowa
We had bad predictions in western Colorado. It was a flop here.
“Extremely Rare”= Has Happened Before.