November 30th Long Range Forecast
Forecast Updated 3:00 PM EST 30 November 2011
December comes in with a major drop in temperatures for much the US and a heavy rain producer that will need to continue to be monitored for a potential flooding risk along the Ohio River Valley and Kentucky and Tennessee. December 3 1200 UTC has a cold front approaching Illinois which should keep much of the precipitation to the west of Indiana, but that is dependent on the timing of the front. The dominant high pressure sitting along the East Coast will keep much of the eastern US dry and warm so Indiana can expect mild high temps in the mid 50's for Saturday. A dying cold front extending into the Great Lakes shouldn't be much of a threat for precipitation.
Saturday night into Sunday morning increases the chances for precipitation as a low pressure system moves northeastward out of the Great Plains into the the Straights of Mackinaw with a cold front stretching south to provide precipitation from the moisture being brought up from the Gulf of Mexico. Sunday night lows for much of the Midwest will be bordering freezing, so depending on the arrival of the precipitation, some areas could see light snow flurries Sunday morning with a better chance coming Sunday night as low temperatures drop near freezing so a wintry mix is possible.
Sunday night has the cold front begins to push eastward slowly according to recent GFS model runs which could result in Tennessee, Kentcuky, and northern Mississippi seeing 5 or 6 inches of rain. Dry Arctic air from very strong cold air advection arrives for much of Great Plains and into the Great Lakes region for Monday and Tuesday as an upper level low descends into Minnesota greatly limiting high temperatures.
The cold front continues to slowly work its way off the east coast, bringing more rain along with it. High pressure starts to establish itself over the Gulf of Mexico and warm air advection takes hold allowing for the Midwest to see a slight increase in temperatures. Some warming is expected along the West Coast as well, as winds pul moisture in off the coast of Washington to fuel some snow showers for December 7 as a new low pressure system drops in from Canada bringing a very strong Arctic air with it.
Today's long range graphic was produced by Chris Ward.