UPDATE ON NOV 17-18 SIGNIFICANT EASTERN US LOW Over the last few days Ive been talking about the potential for significant eastern U.S. low pressure areas to develop in the second half the month . The first of these events is the system for November 17-18... the 2dn one is NOV 20-21 and the third is NOV 25-26 Despite what you may have read or seen another weather blogs ... weather FB pages or forums let me tell you with high degree of confidence in certainty that the event for November 17 - 18 is a pure rain event for almost everybody on the East Coast . Over the Appalachians it maybe more of snow/ rain mix going to snow type of event. Unfortunately and as is typically the case ... the early Wednesday morning G FS model continued to show its appallingly bad forecast bias and giving a false sense of hope to weather weenies and snow fanatics up and down the East Coast. The early Wednesday morning (0z run) GFS continues to show the low tracking too close to the coast and then passing to the south and east of Cape Cod on the 18th. This implies rain for most of the big cities of I-95 but the potential for the rain ending as a period of snow and even some snow accumulations over the interior coastal areas well to the north and west of I- 95. IMAGE 1 The European model (IMAGE 2) however is correct in depicting the low that forms on the next cold front as a system which is going to track significantly further inland. It is imperative that those who enjoy and love winter weather realize that the November 17 - 18 event for the East Coast is a rain storm. And nothing more. Simply because the GFS model produces the more favorable snow storm track than any other model does not mean that the bias the Model has in placing Coastal Low pressure areas to far to the south and east... has ended. Not only is the upper air pattern very unfavorable for a East Coast snowstorm of any kind... but having the cold area of HIGH pressure slighting east off the Middle Atlantic Coast into the Western Atlantic Ocean and producing southerly winds ...is a kiss of death. You simply cannot get a East Coast snowstorm with this sort a configuration. However for the western portions of the Appalachians as well as the Ohio Valley this system on November 17 and 18 had a good chance to bring that area significant early season snowfall---- this could be for Western PA mUch of OH maybe far nw WVA ,uch of IND and perhaps Northern KY and southeast ILL. The overall pattern becomes even more unfavorable for East Coast snowstorm with the next event sometime around November 21-22. This event looks to be fairly significant but also a Midwest snowstorm... The AO (arctic oscillation) turns neutral and so does the NAO (North American oscillation) by November 20.
Posted on: Wed, 12 Nov 2014 18:18:29 +0000