Big snow (probably) on the way

Tuesday afternoon (March 3)

Weather patterns remain pretty much the same as yesterday (see March 2 blog), but the NAM’s much slower evolution of the weather pattern has definitely been the way to go.  In fact, the GFS has slowed to about match yesterday’s NAM while the NAM has slowed even more.

That may not sound like a big deal, but it is huge concerning potential snowfall tomorrow and tomorrow night.  One other major point mentioned yesterday is the continued lack of any “kicker” out of the cut-off southwestern trough.  That allows it to send in one more big chunk of moisture WITHOUT any significant energy to form a strong surface low along the cold front.  (A strong low moving along the front would kept warmer air here much longer than now expected.  Thus, snow expectations would have been much lower.

But, the big picture hasn’t changed much – heavy rain expected tonight.  Rain totals could range as high as 2″ to 4″ before the changeover  to snow.  The NAM still keeps the axis right along the Ohio River while the GFS continues to place Louisville on the northern edge of  the heaviest rain area – with the heaviest rain axis about 60 miles south of the river.  Either way, we’ll probably have a major water mess for rush hour tomorrow.

Now, the snow potential.  In spite of the timing differences between the NAM and GFS, they are a lot closer together with the potential snowfall.  Without explaining all the different scenarios from the models, I’ll just go right to my  current “working theory.”

CURRENT FORECAST IDEAS:  Heavy rain and widespread moderate urban flooding tonight.  Temperatures begin falling after midnight and and reach the 30’s by 7 A.M.

Tomorrow morning  rain changes to sleet, which should continue until at least mid-afternoon.  A change to snow is likely by late afternoon.

Tomorrow night:  SNOW, probably heavy at times through the evening and early morning hours.  Any significant snow should be over by 8 A.M.  Light snow/flurries could continue Thursday.

TOTAL SNOW ACCUMULATION:  6″ to 10″ for the Louisville area.  lower totals north of Louisville and heavier snows south of Louisville.

NOTE:  My prediction is based on the expectation of at least several hours of sleet tomorrow.  If the change to snow occurs sooner, snow totals could reach 8″-12″.  (The most recent “new” GFS model says 7.6″.

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