Our snow map remains unchanged from preliminary forecast, battle between warm air and cold air at the surface will determine low or high end totals, and duration of icing.
Timing: – 1pm to 4pm : Periods of snow begin from west to east
– 8pm to 2am : Snow mixes with sleet and freezing rain from SW to NE
– 2am to 8am Sunday: Wintry mix changes to plain rain in valley areas… Icing continues in Catskills and hill town west of Hudson River – 8am to 2pm : Period of icing possible in portions of Catskills, rain in the valley, freezing rain retreats from hill towns and lower elevations and persists across highest terrain.
– 2pm to 8pm : Rain may be heavy at times between 2-4pm, thunder possible, some freezing rain may persist across peaks and ridges of Catskills. Winds begin to increase out of the WNW 30-50mph, temps begin to drop back below freezing.
Impact:
– Period of light to moderate snow expected on front end of storm
– Snow covered & icy roads possible Saturday evening
– Transition to sleet and freezing rain results in ice accretion on top of snow
– worst icing expected in Catskills (up to 0.50? possible in isolated spots)
– Icy conditions should improve Sunday morning in valley areas
– High winds Sunday afternoon… Tree and utilization impacts possible
Snow Accumulations:
– Catskills: 3 to 6 inches of snow, followed by potential ice accretion up to 0.50?
– I-84 and points North: 2 to 4 inches of snow, followed by up to 0.20? ice accretion
– South of I-84: Coating to 2 inches followed by up to 0.10? ice accretion, then rain
Freezing Rain Discussion
Areas of concern for period of freezing rain or long duration icing event. Areas within the Purple Zones- Freezing rain can begin as early as 11PM Saturday from SW to NE, may remain freezing rain through 8am Sunday. If cold air trapped at surface is understated, a longer period of icing is possible here. As of current data, ice accretion of .10-.25” is possible within these areas, icing over .25” is possible and outages and tree impacts will increase with duration of icing.
Areas within the Red Zones- Freezing rain may fall between 4AM Sunday and persist through 4PM Sunday, ice accretion of .20”-.40” is possible across these regions. In addition the strongest potential wind gusts will occur in this zone. These locations have the highest probability of numerous impacts to trees and utilities.
Please realize the holding power of surface temps below 32° and just how much the warm air can erode this surface cold will determine the duration or severity of the icing that occurs and its impacts. Given the cold air that follows the system and potential for high winds, we wanted to follow up this mornings post with some greater detail around icing potential.
Remember, if the temp outside is 32° or less, liquid rain is likely freezing on contact with colder surfaces and icing is ongoing. Keep an eye on the latest updates and the thermometer tonight to keep a pulse on whether or not the icing potential is being realized.
High Winds and Power Outages
Want to expand the conversation around the risk for damaging winds across the region and share some of our concerns with this potential.
Timing- Sunday 12PM- Tuesday 6PM
Peak Wind Timing- Sunday 12PM- Monday 9PM
High End Gust Potential-
Lower Elevations- 35-50MPH
Higher Elevations 45-60MPH
Areas Sheltered from NW Winds- 15-30MPH
Why are we concerned? While outages and tree damage is possible/likely across lower elevations, our larger area of concern is the circled zone on the map.
If you look at the simulated radar image attached, you will see that the higher elevations of our region are expected to hold on to a longer duration of freezing rain even after the valley locations have turned to rain.
This also happens to be the region where we are expected to see the highest wind gusts. The combination of ice laden trees and wires will create additional surface area and drag against powerful NW wind gusts. If the winds do in fact reach their full forecasted potential as does the prolonged icing period. Tree damage and outages across this part of the region could be extensive.
In addition, for the entire region- temps will be dropping quickly in the wake of the storm, and any power outages that do occur will be coupled with highs on Monday in the teens in twenties.
With temps this low any outages of long duration could be a concern of holding temps inside homes in businesses. As of this morning it is hard to determine just how much of the highest gusts will mix down to the surface, but the combination of these factors is enough to cause us to want to give folks the opportunity to prepare for that potential. Before the peak period of wind, it might be best to turn home thermostats a bit higher than normal, be aware of any ice laden trees that could become a risk while at home or traveling.
This outcome will be very much tied to whether or not colder air holds the icing potential across these parts of the region, and is the modeled wind gusts are able to fully mix down to the surface. We will continue to monitor, in the meantime it’s best to be prepared for this possibility.
Street Flooding/Refreeze Risk
As the cold front crashes into the region Sunday afternoon, a period of heavy rainfall associated with an embedded squall line will push through the region. As this boundary pushes through we will see a period of heavy rainfall which may even be accompanied by a rumble of thunder as it passes. Thanks to previous snow and ice, existing snow banks, blocked storm drains and culverts and frozen ground, there will be enhanced runoff. The timing for this period of heavier rainfall is between 2-4pm Sunday.
This will lead to water traveling courses it may not usually follow and localized street flooding, colder air will crash in behind this boundary and water will refreeze overnight and will remain so through next week. As snow begins to end or even throughout the day today, might be a good idea to push back snow, clear culverts and preemptively allow room for runoff during the rainfall tomorrow. Any standing water will become a semi permanent fixture through next week.
