February 2015 Monthly Forecast: Cold Air Rules the East, Snow Blitz to Ease | NECN
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February 2015 Monthly Forecast: Cold Air Rules the East, Snow Blitz to Ease

Air will be exceptionally cold, challenging the coldest of the season for New England

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    NEWSLETTERS

    Each month, on the first weekday of the month, I air my monthly forecast for the upcoming weather pattern.  This week was so busy with active weather, that it finally made air today and, admittedly, in a short month, airing it on the 6th is like cheating, but...so many have asked for it in the last day or two, and I've had it prepared, so it seemed pertinent.  Besides, with a 6-day cheating period in a 28 day month, you can really give me heck if it doesn't work out!!

    For those of you who follow my forecasts closely, you may remember at the start of our winter special back in December, I referred to a messy December, then a cold and relatively dry January leading into a snowy February as a transition to an early spring.  So far, so good, but confidence is rarely more than moderate in monthly forecasting, and rarely more than low in seasonal forecasting, so humility is always essential when constructing these.  That said, I think February is fairly clear-cut - after our recent "snow-blitz" that started at January's end and continues through early February comes to an end, it will be immediately followed by a huge dump of cold air directly from the North Pole that will charge into New England in the mid-month period.  This air will be exceptionally cold, challenging the coldest of the season for New England, and occurring in response to a southward shift in the jet stream winds aloft.  Remember that the jet stream winds are the fast river of air, high in the sky, that steer our storm systems and separate cold air to the north from milder air to the south.  So...with the jet stream dipping far south, cold air will also spread deep into the Southeast, but the storm track also should deviate. More on the storm track below, but here's the expectation for temperature, which reflects not only the deep jet stream trough in the east, but also the offsetting "ridge" - or bump - in the jet stream over the Western half of the nation, which will allow for building warmth.  That's the warmth that I think could end up our warmer-than-normal March, but we shouldn't get ahead of ourselves!

    February 2015 Temperature Forecast:

    30_DAY_FORECAST_TEMPS
     

    As for precipitation, the "amplification" of the jet stream - a building ridge in the west and a digging trough in the east, should have some major implications - 1) The early-month feed of moisture with heavy rain into the Pacific Northwest will taper somewhat mid to late month, though by then, above normal precipitation for the month will already have been recorded there; 2) Dry conditions will likely take over for much of the Central and Western United States as the storm track (jet stream) shifts north; 3) Frequent incursions of Gulf of Mexico moisture will cross Florida and the deep Southeast; 4) The Northeast should end up cold...and drier than we've been...for much of mid to late month as the jet stream trough axis looks to set up just a bit too far east for more big storm development, which is the reason I'm expecting a break in the recent snow-blitz for mid-month, and I'm not convinced there'll be another blitz to get through on the other side.  It's really important for me to make the distinction between precipitation and snowfall - Boston, for example, is already above normal snowfall for February as of this posting!  But that's melted down to only .88" of liquid equivalent, and with the normal value for the month just over 3" of melted precipitation, it's that value I look for as "precipitation" - clearly, snowfall is a lock above normal for most of New England.

    30_DAY_FORECAST_PRECIP

    Where could the forecast go wrong?  With regard to temperature, there's not a lot of room for error, given the significant mid-month arctic blast, unless we get some unforeseen big warmth at the end of the month, but even that will likely be insufficient to offset colder than normal temperatures.  The precipitation forecast is definitely a bit more tenuous, and very well could end up above normal if additional precipitation events occur on the backside of the mid-month cold.  That is, right now I'm expecting the jet stream pattern to remain sufficiently amplified that, even as cold air eases toward month's end, new snow would not be enough to push us significantly above the normal precipitation amounts for the month - though a reminder that doesn't mean normal snowfall...we've already bested that.

    Hopefully, if all goes as planned, I'll be here advising of a warmer-than-normal March, but again...that's just a tease...I won't lose that humility and overstep my bounds yet!

    Matt

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