Snow Forecast for Great Lakes and Northern New England; Wet Weather continues across California

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
359 PM EST Wed Dec 17 2014

Valid 00Z Thu Dec 18 2014 - 00Z Sat Dec 20 2014

...A slow-moving storm is expected to deliver up to a foot of snow in northern New England...

...Fine weather prevails in the northern and eastern U.S. while a new storm will begin to form in the southern Plains...

...Occasional mountain snow and coastal rain showers are expected in the western U.S....

The short-term forecast period begins with an intensifying coastal storm over the Gulf of Maine. The storm center is forecast to pass just east of New England, moving slowly into the Canadian Maritimes over the next couple of days. Snow is expected to accumulate to the north and west of the storm track, bringing up to a foot of snow in northern New England. The snow should taper off early on Friday and should end later in the day as the storm moves far enough to the east.

A high pressure system is providing fine weather with milder than normal temperatures across the northern U.S., the Ohio Valley and into the eastern U.S. Meanwhile moisture is gathering in the central and southern Plains ahead of an upper-level trough. Some snow and mixed precipitation can be expected across the central Plains and mid-Mississippi Valley tonight into early Thursday. However, the entire batch of precipitation is forecast to collapse during the day on Thursday as the upper-level trough loses support and de-amplifies. Farther to the south, moisture from the Gulf of Mexico will begin to gather along a stationary front near the Texas coast where a new low pressure center is forecast to develop. The development will begin to accelerate as upper-level energy coming from the southern Rockies is injected into the system. It appears that showers and thunderstorms will become heavier and more widespread in southern Texas Thursday night which will be spreading eastward into the central Gulf States on Friday.

Over the western U.S., pieces of energy associated with weakening lows and frontal systems from the Pacific will bring occasional snow showers over the interior mountains, particularly the southern Rockies and Intermountain West through Friday. Moderate amounts of rainfall can be expected in coastal northern California tonight as well as the Pacific Northwest Thursday night into Friday with the arrival of a new Pacific front.

No real cold air is in sight for the entire continental U.S. through Friday. In fact, temperatures are forecast to be more than 10 degrees above normal in the northern Rockies, northern Plains as well as the western Gulf Coast.

Reference Link: http://www.wpc.ncep.noaa.gov/discussions/hpcdiscussions.php?disc=pmdspd