Winter Storm — Jackson, Texas

2009-12-04 · Jackson, Texas

Event narrative

Snow accumulations of between 1 to near 2 inches occurred across the interior portions of the county. Edna reported the highest snow accumulation of around 2 inches.

Wider weather episode

Moderate, to locally heavy, snow fell across portions of southeast Texas. This resulted in the region's earliest recorded snow fall.

Preceding this event, a strong upper level storm system moved across Texas. In the wake of this system, a very cold Canadian air mass descended as far south as the coastal regions of southern Texas. A shortwave disturbance, rounding the base of a southwestern Texas upper trough, is what provided the lift needed to generate precipitation that fell within this arctic air mass.

Light rain developed over the coastal bend region that expanded northeast into the Houston-Galveston County Warning Area. This light rain, falling though a deep sub-freezing thermal layer, turned to snow and sleet over the southwestern counties of Jackson, Matagorda, Fort Bend, northern Brazoria and western Harris on the morning of the 4th.

Evaporative cooling and efficient cold air advection, in tandem with the nearing shortwave disturbance, formed a 1 to 3 inch total snow accumulation band parallel to, and near, the Highway 59 corridor. North and west of a line from Columbus to Conroe experienced snow accumulations generally less than 1 inch. The heaviest snow banding of between 3 to 5 inches fell along a southwest-to-northeast orientated line across Wharton, Fort Bend, and northern Brazoria counties.

Due to the fact that there was most likely significant melting upon surface contact, and snow was partially melting through a near surface above-freezing layer, a 5:1 liquid equivalent-to-snow ratio was a good approximation.

Source: NOAA Storm Events Database, event_id 205849. Narrative written by the NWS forecast office that issued the report.