Monday 5:30 AM Update

Good morning, here is your 5:30 AM update:

High impact Nor’easter still slated to slam the Washington Metropolitan Area this evening through Tuesday.  Thunder-Snow and sleet is possible overnight with gusty winds (40 mph +) and snowfall/sleet rates of one to two inches per hour during the overnight hours!

The exact snow/snow-sleet/sleet-rain line is still in question but it is important to remember that where this line sets up, one won’t have to travel too far to go from lighter accumulations to significant accumulations. This is why it is prudent to be prepared for this major high-impact winter storm (the potential loss of power) than to focus too much on any slight shifts back and forth between where this line sets up. Please continue to monitor the official forecast from the National Weather Service as those of you under Winter Weather Advisories could still be upgraded to a Winter Storm Warning later today.

As of 5AM No changes to my snowfall map:

  • After looking at the all-important European Model I am sticking with this for now. Any update to this map won’t be made until this afternoon.

 

  • The area of highest uncertainty in my opinion continues to be those of you located in the “4 to 8” and “1 to 4” zone in the map below.  I can see a situation where this zone gets shrunk very close together meaning the short west to east distance from Woodbridge, VA to Waldorf, MD could see a snowfall gradient of 10″ or more! 

This storm has a lot of moisture to work with:

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Preliminary DC Area Snowfall Accumulation Forecast for March 14th Blockbuster Nor’easter

  • Heaviest Snow should fall overnight Monday through Tuesday morning with snowfall rates of 1 to 2″ per hour; thunder-snow is possible, widespread snow showers likely Tuesday afternoon through Wednesday as upper level trough crosses the region (additional snowfall accumulation possible).

 

  • Winds will gust well over 45 mph Tuesday through Wednesday with scattered power outages likely especially in areas near 32 degrees (heavy, wet, snow).

 

  • Tricky forecast remains for the interstate 95 corridor as amounts may be much higher if mixing with sleet and or rain doesn’t occur.

 

  • Stay tuned for updates this afternoon & evening.

March Roars in like a Lion: Widespread Severe Thunderstorms Today; Snow Showers & Squalls Friday

Main threats with today’s storms (opinions are mine):

High Winds (80% chance of widespread damaging winds with initial squall line)
Hail (60% chance of individual super cells containing nickel to ping-pong sized hail)
Tornadoes (40% chance of a Tornado within any rotating super cell that develops)

030117_preliminary_severe_tstorm_risk_dcstorms-com

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Snow and Ice Map Posted for Major Winter Storm

I got my map templates back up and running. The first map is for how much snow I think will accumulate before the change over to sleet and then freezing rain.DCstorms_Snow_Accumulation_021516

The second map is how much ice accretion (trees, power lines, sidewalks, all untreated surfaces) from a pro-longed period of freezing rain. The time-frame of freezing rain is highlighted in yellow text on the map for the three zones.
DCstorms_Ice_Accumulation_021516

Bottom Line: Up to a quarter of an inch of ice could accumulate along the interstate 95 corridor before a change over to rain during the pre-dawn hours on Tuesday. The damage will have been done by the morning rush hour! What a mess!