The above surface weather chart is for 7am Tuesday.
SURFACE WEATHER CHART 7PM-1PM TUESDAY:
SURFACE WEATHER CHART 7PM TUESDAY:
As you can see the Polar Cold Front sweeps through fast. At most locations after light rain the snow will only last a couple hours or so. We could well see some sun before the day is done. The warmest part of Tuesday will be Midnight to 7am or so.
WINTER STORM WARNING IN PINK 3AM-7PM TUESDAY:
WINTER WEATHER ADVISORY FROM NATIONAL WEATHER SERVICE 3AM-7PM TUESDAY:
Rain moves in from NW to SE around 5am far NW, 8am central locations, 10am far SE suburbs... give or take a couple hours on each. Changing to snow 8am far NW, 10am central locations... give or take a couple hours for each. It may never turn to snow far SE suburbs, in places like Covington for example or just a mix of some flakes.
The highest risk for accumulation of a coating to 1 inch in spots is near and NW of the Chattahoochee River, especially far NW suburbs. LITTLE OR NONE expected near and East of a line from Gainesville to Griffin. 1-3 inches for parts of the Georgia mountains.
There are models that show 1-2 inches for much of the Atlanta area, but experience tells me fronts RARELY produce significant snow except mountains and far NW burbs. Obviously rarely doesn’t mean never but I have to lean on past history.
Temperatures fall to a range of 31-37 during the day, so there could be problems on some roads especially NW suburbs. Remember bridges and overpasses freeze first.
IF the snow falls at a gentle rate it will accumulate mostly on grass, trees, bushes, decks and rooftops. But if it falls at a fast rate then it will also accumulate on highways. But, IF we are right and temperatures in MOST of the area don’t fall BELOW 32 then the MAJORITY of the area highways will be OK.
I covered this in the past but new followers may not know. Our equations let us estimate how much snow will fall out of the clouds, but because we are meteorologists and not Civil Engineers. Our models do not tell us on what roads it will stick and which it will melt as we have no pavement input or output. Borderline situations like this one are a close call since just a few degrees will make all the difference in the world.
I’ve already explained since blogs last week and in years past that in ALL forecast parameters there is a RANGE of possible outcomes for both temperature and rain or snow amount. There is a normal and expected margin of error of at least a few degrees and a few inches. So logically you can see what that means for 32F and the CHANCE of 1 inch of snow. 27-37 and 0-4. Those are just the limitations of the current state of the art that we can’t change or control.
I’ve also repeatedly pointed out that the lines we give for accumulation are guidelines and best estimates, not red lines in the sky that nature must not and will not cross. What is more the normal and expected margin of error means the lines in reality may end up being some 30 miles further North or South than forecast.
Not everyone in the coating to 1 inch or so region will get 1 inch or a coating, yet some may get 2 and some a trace sometimes in the same county. No heavy snow is expected and no freezing rain so no power loss worry.
A HARD FREEZE tomorrow evening into Wednesday morning so any moisture then will turn to ice. But I am hopeful that the drying and gusty winds coming after the precip ends will dry most roads preventing widespread black ice.
NOAA WPC ODDS OF SNOW ACCUMULATION OF AT LEAST ONE INCH:
Obviously I can be wrong as I have in the past, forecast can and will change so check back for updates as things unfold. Download the WSB Radio APP and Follow me on Twitter @MellishMeterWSB.