Remnants Of Karen To Cause Issues On East Coast, More Rockies Snow!

Written by on October 8, 2013 in United States of America with 0 Comments

We enter a new week and potentially a new set of problems with another storm system entering the West and driving wind, rain and mountain snow all the way to Southern California but the remnants or the ghost of Karen will ride up the East Coast and looks poised to drive a fair amount of rain and wind into the Mid-Atlantic region mid to late week.

More snow for the Rockies and quite likely the Dakotas will be followed by at least one other system with yet more snow within the next 10 days as the active western pattern continues but interestingly the GFS is now coming around to the ECMWF idea of the NAO and AO flipping back negative after a brief spurt into positive. What’s also been interesting is the fact that despite the -NAO we’ve seen, this did not reflect an eastern trough but quite the opposite. The reason for warmth and ridging over the Midwest and East was of course the -PNA which by the way will continue through the next 7-10 days but is projected to go positive and therefore I suspect modelling will begin to show more western ridging sometime after the 20th. In conjunction with a -NAO, one must consider colder times ahead for the East (finally) while the West should be in for a break. That will be well earned given the fact that by the 20-25th, up to 5 systems will have brought wind, rain, heavy snow and cold to the Rockies. The -AO could mean a shock to the system for Easterners as it’s been so mild of late.

Here’s the 500mb ECMWF by Wednesday and note the newly carved trough digging all the way into SOCAL. Unsettled and much cooler days around LA and San Diego. Don’t be surprised to hear of high base t-storms and offshore water spouts. Heavy snow in the Sierra. Also note the remains of Karen bringing wind and rain to the Carolinas up towards DC and Baltimore.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

By Thursday the trough is centred over Las Vegas. Wind, rain and cool temps will be a factor.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

As for Thursday’s surface chart notice the rains in the West but more importantly note the wind and rain affecting the Mid-Atlantic. We could see flooding problems as this low winds up with the high to the north enhancing the tightening. Coastal gales along with heavy rain could lead to coastal flooding. Big wave action and increased rip currents will also play a role as strong east winds blow from a few hundred miles onshore.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

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The ECMWF rain totals are high from the eastern Carolinas up into the DC-Baltimore area on up to New York and southern New England.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

By Friday and western system up moving northeast and crossing the Rockies, likely tapping enough cold air from Canada and producing enough of it’s own to bring another batch of heavy snow to the Wasatch Range, Colorado and Wyoming Rockies and quite possibly the Black Hills of South Dakota BUT there is not as much cold with this as the last so there will be a fine line between rain and snow I think. The jet is splitting once it enters North America with the northern branch streaming across Canada and this will stop any real cold with dropping south over the US. Snows won’t be a plentiful either but there should still see some snow, especially above 7 or 8,000ft.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

By 204 hours or a week from Wednesday, the model shows another western system while this week’s pushes up into Ontario. That means yet another round of wet, windy, snowy and cool weather for the West, more Rockies snow. There could be more cold comes down with this as I suspect there’s less split from the jet and the AO starts going back negative.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

As you can see, this trough digs pretty far south and also there’s a trough digging into the Northeast. A sign of things to come with the onset of a +PNA, -NAO? The western system around this period could be the last as I suspect heights begin to rise over the east Pacific and western US once this system kicks ENE.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

Mountain snows are plentiful according to the ECMWF over the next 240 hours or 10 days.

Courtesy/Owned by AccuWeather Pro

Courtesy/Owned by AccuWeather Pro

Here’s the latest GFS indexes and note they all support a colder second half of October in the East.

Will be interesting to see whether we get a sharp turnaround from the abnormally warm first 10 days to perhaps an abnormally cold last 10 given the AO is heading back negative.

pna_fcst

nao_fcst

ao_fcst

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