The most likely area for heavier snow accumulations will be just North of interstate 10 where a winter storm warning has been issued. Cities like Brenham, Conroe and North to Livingston could get anywhere from 2" to 4" of snowfall. The real danger will come Tuesday night as some of this snow sticks to elevated roadways and bridges. The Texas Department of Transportation (TxDOT) has begun to apply magnesium chloride to most overpasses to help prevent ice buildup as temperatures start to drop off to near freezing Wednesday night.
For the Houston area the main threat could be a slushy wet mix falling from the sky to create slippery roads during the evening rush hour Tuesday and again Wednesday morning for the graveyard shift. Snow accumulations will be much lighter below a half inch mostly to grassy areas. The bay area and Galveston will see just a very cold rain. I don't expect any school closers or cancellations to the South of the metro Houston area. Although this is a rare event, according to the Weather Research Center Houston has not seen snow three times in a season in over thirty seven years. The last time this happened was during the winter of 1973. Houston had an impressive snow total of 4.8" that winter.
As skies begin to clear Wednesday Houston could wake up to a frosty wonderland, so have your cameras ready. You may have to wait another thirty seven years to get a cold snowy season like the one we are about to have. The temperatures will allow the snow and ice to last a few hours before readings climb to near 50. The weekend Houston Rodeo parade weather will range from near 48-52 under mostly cloudy skies.