The above surface weather chart is valid 7am Tuesday. The sharp cold front represents the leading edge of a polar air mass.

It’s coming in from the NW so precipitation will start earliest in the far NW suburbs and sweep across the rest of the Metro area, it’s a fast moving system so rain and snow will only last 3 or 4 hours give or take an hour with most of it falling before 2pm, except 4pm far SE suburbs.

Rain starts by 7am give or take a few hours changing to snow between 10am and 1pm from NW to SE.

Temperatures will be warmest between Midnight Monday and sunrise Tuesday for most areas. Temperatures fall to near freezing West and North Suburbs by afternoon, elsewhere by 6pm give or take a couple hours. A HARD FREEZE all areas by 8pm give or take, with lows by Wednesday morning AROUND 20 so any moisture on the ground will be ice by then.

Remember, there is no winter storm low pressure system. It’s a cold front, there can always be an exception but past history shows cold fronts rarely produce even an inch or snow, and most places just get a coating, mainly on trees, bushes, grassy areas, decks and rooftops.

Areas from around downtown South and East get the least, the far South and East suburbs may only get rain followed by a few flurries.

IF the snow falls at a fast enough rate or for a long enough time then it can stick on the highways. At least for now I think for most of us the majority of roads will be OK with the exception of the far West and North suburbs. However, that changes as temperatures fall. We’ll be able to fine-tune these kind of details as we get closer to it. Please read prior blog posts because I can’t repeat every point every time I post.

The greatest risk for significant accumulation including roads as of now anyway, looks to be near and North of a line from Rome to Gainesville. Remember, these are not magic lines or walls in the sky, it’s really a transition zone that could be 20-30 miles further South or North.

The next levels risk for a coating to an inch is near and NW of a line from Lake Rabun Southwest to Alpharetta and Marietta to Franklin Georgia, a dusting or less far South and East Suburbs.

WPC ODDS OF AT LEAST ONE INCH SNOW ACCUMULATION:

MY CURRENT SNOWFALL ESTIMATE:

NEAR AND NORTH OF BLUE LINE IS 32F OR COLDER BY 1PM TUESDAY ECMWF MODEL:

BLUE 32F OR COLDER LINE 7PM TUESDAY ECMWF MODEL:

Note that my forecast is currently on the low end, many models and National Weather Service outfits have at least one inch for a good part of the Metro. All forecast as always are subject to change including mine.

Keep in mind the normal and expected margin of error for ANY snow forecast ANYWHERE in the country is a few inches in either direction, so when we are talking about low amounts the normal and expected range includes zero.

NOAA WEATHER PREDICTION CENTER SNOW FORECAST:

You should expect changes in the forecast going forward so check back. Always read text don't just look at maps. 

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