Precipitation:
OVERVIEW: The month of November had a bit of a reprieve in the overall abnormally dry conditions this past week with much needed rainfall in the form of a pre-Thanksgiving area-wide soaker. Despite the plentiful rainfall from that system, most areas are still on the drier side of average for the month as a whole. With minimal prospects for rain for the remainder of the month sans a system that brings showers Sunday evening and overnight, we are confident that the month will finish with at least slightly below average precipitation by month’s end. November typically doesn’t yield much in the snowfall department on average, so it is of course relative…but outside of very far northwestern areas, no snow is expected for the remainder of the month…at least not measurable. December projections were maintained this week for near to slightly above average precipitation, and a +0.0″ to +0.5″ precipitation departure overall for the month. With an El Niño background state, we can expect an uptick in precipitation departures heading into winter with a more active subtropical jet stream despite the overall dry Fall months prior. With temperatures very close to average in December, combined with the near to slightly above average precipitation expectation, the projected snowfall has been maintained this week at near average.
Shorter term, a weak coastal low will develop on Sunday near the Carolinas and quickly move northward along the coast ahead of an incoming trough. This will draw in just enough milder air to keep the precipitation type primarily rain showers Sunday evening and part of the overnight, but snow can mix in with the trailing trough/cold front in far northwestern areas Sunday evening. A more active pattern takes shape in the first week to 10 days of December, with a system cutting to our west dragging a warm front (and milder air, rain showers) through our region in the December 3rd/4th time frame…followed by a cold front around December 6th. With a blocking pattern (west-based -NAO) well established by this point and rising toward neutral in the December 7th-9th period, a storm signal was introduced this week which is common when there is a relaxation of an existing blocking pattern. Whether this (1) materializes and (2) has enough cold air in place to make this a wintry event is still unknown, but this can certainly transition from storm signal to winter storm signal in subsequent outlooks if the right conditions are met. A storm signal indicates a favorable period for a storm to occur, but is not a guarantee for rain (or snow) at any given location. Just a period of interest at present time, which will be monitored going forward.
Our projection for the month of November as a whole is for a slightly below average (-0.5″ to -1.5″) precipitation departure, and below average snowfall. For most of the region, no measurable snow will occur. Our projection for the month of December was maintained this week for a near to slightly above average (+0.0″ to +0.5″) precipitation departure for the month as a whole, along with near average snowfall using collective long range ensembles and global observation trends.
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EPAWA Facebook: https://www.facebook.com/epawawx/
Meteorologist Bobby Martrich [EPAWA] on Twitter: https://twitter.com/epawawx
YouTube channel/daily forecast video: https://www.youtube.com/user/eastpaweather
Breakdown of precipitation departures from normal over the next several weeks:
November 25th – December 1st: Slightly below average
December 2nd – December 8th: Near to slightly above average
December 9th – December 15th: Near to slightly above average
December 16th – December 22nd: Near average
December 23rd – December 29th: Near average
December 30th – January 5th: Near to slightly below average
Public/free available maps will be updated when a threat is imminent for significant weather on the weather alerts page throughout the year: http://epawaweather.com/weather-alerts/
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