** * SNOW FOR TUESDAY IN THE NORTHEAST ? *** ...Most of the forecast are way over done and Too Bullish about this event and this is especially True for DCA BWI PHL and NYC. I have seen some posts from several meteorologists and Washington, DC Baltimore area as well as Philadelphia who are talking up this next weather system. For those of you that do not know ...this type of fast moving moisture starved weather system which dives out of the Great Lakes towards the Middle Atlantic Coast or the New England Coast is refer to as a **CLIPPER LOW**. These systems can be pretty strong at the middle and upper levels of the atmosphere but because of the fast speed and the movement into a arctic air mass or seasonally cold air mass... they are starved of moisture. However if you take a look at a map of the northeastern US... You will see that the geography of the New England region often becomes a factor with CLIPPER LOWS ( The New England region sticks out much further into the Atlantic ocean when compared to the New Jersey or Maryland or Virginia coastline). The result is that when these CLIPPER LOWS reached the coast they t begin to develop and grab some the Atlantic moisture and slinging back it into the New England region. This can result in a interval of moderate snow for some areas of New England and occasionally for portions of New Jersey New York City AND Philly. It is extremely rare for any sort of CLIPPER Low to affect Maryland or Virginia with moderate or even light snow. If there is a blocking pattern in Eastern Canada and Greenland... That is to say if the NAO is in the negative phase...IF there is Ocean low stalled over southeastern Canada (refer to as a 50/50 Low in the wx Biz) AND ... IF ..IF the clipper Low slows down it can result in explosive development and a surprise a snowstorm for somebody in the Northeast US. In this case none of those features are present and this CLIPPER LOW will be moving at warp 7.... and it is not going to slow down in any way whatsoever. That being said the 0z Monday NAM Model has just come out and it is much wetter than ANY other model . Taken verbatim it shows a significant snow event for portions of New York City Long Island Connecticut Long Island and Eastern Massachusetts on Tuesday. It puts down a nice band of 2 to 6 of snow with the heaviest snow over southeastern Mass and central and eastern Long Island but there are also are few inches of snow across Central Pennsylvania and New York City as well as Northern New Jersey But again it is still almost 48 hrs to the event and the track record of the NAM with respect to how much moisture it produces shows a clear serious bias of being too wet. A very good rule of thumb is that unless the CLIPPER LOW slows down or is extremely powerful... to always go with the weaker precipitation output of whenever model it is. The 0z GFS has just come The GFS out and it has very little precipitation on the coast from this clipper system. The 0z GFS Has a few inches of snow over the mountains of western PA and southern NY but nothing over 1 inch over the coast New York City New Jersey Long Island or Connecticut . SUMMARY any and all talk from forecasters south of NYC / N NJ about snow should be treated with a a TON of skepticism. and over NYC N NJ LI CT ... better hope that the NAM is only 50% too wet.
Posted on: Mon, 16 Dec 2013 04:13:26 +0000
Recently Viewed Topics
© 2015