As the troublesome “Christmas Plus” storm pulls away from Texas (and into the record books for its biggest late December tornado outbreak ever as well as its array of blizzard and ice storm conditions), it is apparent that weather will remain unsettled for Houston through the first week of the New Year. At issue is how the active storm sequence from the northern Pacific Ocean interacts with the abundant cold air and snow cover across North America. The numerical models are having a tough time figuring the forward speed of the storms as well as the generalized temperature display. Since the CFS and NAEFS programs support a colder outcome over much of the U.S., I will lean toward lower temperatures and lower latitude track scenario (northern California to Texas Gulf Coast, then to the Virginia Capes to Nova Scotia. You can expect at least two more significant disturbances to progress through the Lone Star State in this series.
After a very cold Wednesday night, the next storm in the group arrives on Thursday night and Friday. While some locally heavy rain and thunder is possible before the low leaves the Bayou City on Friday evening, I suspect its biggest impacts will be to our north (ice storm in Arklatex vicinity) and east (potential for major snow and wind event from Virginia Tidewater into New England). Much of the weekend following this feature should be nice with fair skies, but prone to chilly nights.
The next area of low pressure to affect southeastern Texas will be (commence sighing….) will be on New Year’s Eve and New Year’s Day. Starting out as a giant cut-off 500MB gyre near Baja California, the disturbance will migrate across northern Mexico and begin to phase with a digging shortwave from Alberta and Montana by December 30. Overrunning of moist tropical values from the Bay of Campeche will slowly establish cloud cover, fog and drizzle from the Rio Grande Valley north and east. Since the storm will be blocked by a strong subtropical high to its east over Cuba, high dewpoints will pour into the Texas Gulf Coast and be forced up and over a frontal structure. Thunderstorms will start to pop up, but the air temperature should be warm enough around Houston for all rain. North Texas may not be so lucky, and I suspect the potential for ice accumulations will be very near the Dallas/Fort Worth metroplex as we ring in 2013.
I am inclined to believe the operational GFS version take on the slow emergence of what will be a major winter storm. Rain, possibly heavy, may continue through much of New Year’s Day in Houston. A surge of very cold air will take place in the north and east sectors of the cyclone, and there will be the potential for widespread heavy snow, sleet and freezing rain from northeastern Texas through the Mid-South, Appalachia, and the Northeast before January 4. For most of Texas, the new year will get off on a wintry note.
Rapid Refresh (RAP)
NAEFS – Ensemble Forecasts – Environment Canada
Wednesday: Clear, breezy and cool. Highs 55 Madisonville to 59 Hitchcock
Wednesday Night: Fair to partly cloudy and cold. Hard frost or freeze possible northern half of Houston metro. Lows 28 Huntsville to 32 Santa Fe
Thursday: Increasing cloudiness with light rain and drizzle developing in late afternoon. Breezy. Highs 61 New Waverly to 65 Alvin
Thursday Night: Cloudy with drizzle, light rain and locally dense fog. Lows 50 Willis to 54 Friendswood
Friday: Cloudy with rain, ending in late afternoon. A thunderstorm is possible during the morning hours. Highs 63 Conroe to 67 Fresno
Holiday Weekend Forecast
Saturday: Sunny, breezy and cool. High 61, Low 37
Sunday: Mostly sunny and milder after a cold start. Increasing cloudiness likely late in the day. High 69, Low 32
Monday, New Year’s Eve: Cloudy with heavy rain and thunderstorms. Thunderstorms could be strong as the New Year arrives. High 70, Low 54
Tuesday: New Year’s Day: Cloudy, windy and colder with periods of rain. High 62, Low 44