Wednesday, November 24, 2010

Bad Timing: 1-3" Later Today (travel gets worse as the day goes on)

Doppler Update: 8:35 am. Radar shows snow (mostly aloft) - evaporating before reaching the ground. Snow should reach the ground over western MN later this morning, reaching the St. Cloud area by 1 pm, getting heavier/steadier as the afternoon goes on. Strong upward motion overhead may spark a period of freezing drizzle by midday. With surface temperatures below freezing some secondary roads/bridges may become very icy between 10 am and 2 pm.

How Much? This seems like a reasonable solution: most of the metro area in the 1-3" range (more north/east metro, less south of St. Cloud). As much as 6-10" will accumulate along the North Shore of Lake Superior. South of the metro this will be more of an icing event, a period of freezing rain/sleet likely this afternoon. With ice in the mix travel may actually be worse SOUTH of St. Cloud than north (where precipitation will fall as all-snow).



Latest NAM Output. Hot off the wire - the latest amounts are less than the computer runs last night (which were predicting closer to .40 to .50" liquid). The latest model is printing out .23" of liquid. With a 10:1 ratio in place (temperatures in the lowest mile of the atmosphere just below freezing) that should translate into 2, possibly 3" of snow.

Reasonable Continuity. Our blood pressure drops (a bit) when all the models converge on a single solution, when all models are reasonably close in their snowfall outlook. Not sure how we see less than 1-2" across most of the metro, a few spots may pick up 3 or 4", especially from Foley to Crosby, Aitkin and Hinckley. Yes, it still looks (barely) "plowable". It's not so much the amount - it's the TIMING of the snow & ice.

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