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Wintry Winter Storm Dec 7-10

First time poster, but long-time lurker. Just wanted to take a minute to commend everyone on the discussions and model postings over the past few days. It has been very informative to amateur weather-lovers like myself. Anyway, let's all take a minute and appreciate what we're seeing, which is historic in a lot of ways: IT IS SNOWING IN THE DEEP SOUTH IN EARLY DECEMBER. Let that sink in. Carry on.
 
Webberweather53 said:
Once again, the models completely botched the northward extent and intensity of the precipitation shield in an overrunning event in the SE US. NWP verification was probably made worse by the fact that most of us were in an incredible right entrance region of the upper level jet... Most of the lift here seemed to be generated by large-scale upper level divergence forced by this jet streak rather than broad isentropic upglide and concomitant warm air advection that we more often see in an event like this.
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I'm glad NWS Birmingham picked up on that the overrunning precip being further north than models projected on Wednesday. This is from their Wednesday afternoon AFD:

"THE BIGGEST CHANGE FROM THE OVERNIGHT FORECAST IS THE PERSISTENT
TREND OF THE PRECIPITATION FIELD TO BE FURTHER NORTH EARLY ON
FRIDAY THANKS TO INCREASING AMPLIFICATION OF THE TROUGH AXIS.
THIS IS OBVIOUSLY PROBLEMATIC BECAUSE THE COLDER AIR ALSO RESIDES
FURTHER NORTH. SO, WHILE AREAS LIKE THE I-20 CORRIDOR WERE
ORIGINALLY NOT IN THE IMPACT ZONE, THEY WILL NOW BE INCLUDED.
METRO AREAS FROM TUSCALOOSA...TO BIRMINGHAM...TO ANNISTON SHOULD
PAY PARTICULAR ATTENTION NOW FOR THE FRIDAY COMMUTE. THESE
OVERRUNNING SITUATIONS TYPICALLY BIAS THE MODEL 'ACCUMULATED
PRECIPITATION' TOO FAR TO THE SOUTH AS IS, AND THEY ALSO STRUGGLE
WITH THE TIMING - OFTEN PREDICTING A LATER TIMING THAN REALITY.
SO, I WOULD CERTAINLY SUGGEST TO PAY PARTICULAR ATTENTION BEFORE
VENTURING OUT ON FRIDAY, AS A CHANGE FROM RAIN TO SNOW WILL BE
LIKELY THROUGH THE EARLY MORNING TO EARLY AFTERNOON FROM WEST TO
EAST AND NORTH TO SOUTH."

They may have been low on the accumulation totals, but they have done a really good job with this event overall.
 
Can someone explain to me how it can be pouring snow in N GA and over state lines its not even coming a flurry. The air must be real dry have had returns over me for a while and still no snow southeast TN
 
MotoWeatherman said:
Not only that but the NAM sniffed out the deeper 500mb trough before the globals. Good call on the jet streak!!
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Yeah I noticed, good call by the NAM on that front for sure... Certainly a little head scratching when different mechanisms are at play for forcing ascent in this particular overrunning event yet we end up with the same model biases. Maybe they just can't handle the secondary ageostrophic frontal circulation, thermal contrast, and/or intensifying frontogenesis on the northern flank of the event that's enhanced by latent heating which we know they really can't forecast to begin with even inside 12-24 hours.
 
Mets are saying this sticks around until 3-4 PM, and its gonna be heavy at times. I honestly believe that there will be widespread 3-5 inch totals....easily! Cheaha is probably getting SMOKED!
 
Look at that Wake Co. line cut-off. I barely made the cut. I still expect 0 inches.
 
stormcentral said:
Can someone explain to me how it can be pouring snow in N GA and over state lines its not even coming a flurry. The air must be real dry have had returns over me for a while and still no snow southeast TN
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Not enough moisture yet to overcome the dry mid levels. Unfortunately that will probably be the rule over your area today for the most part.
 
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