Morning briefing from Jeff: Multiple impact Winter Storm heading for Texas. Cold rain expected for all of SE TX with ice likely over portions of SW, WC, and N TX this afternoon-early Friday. Winter Storm Warnings for ice accumulation in effect from Del Rio to west of Fort Worth. Travel west of I-35 to the New Mexico border is strongly discouraged due to ongoing roadway icing…conditions will worsen this evening into New Year’s Day. Cold arctic cold is entrenched over the state this morning with temperatures ranging from 4 at Amarillo to 32 at Dallas and 39 at Houston. Upstream temperature at Denver fell to a recorded low of -19 this morning shattering the previous 116 year old record of -11. Cold air will continue to funnel southward across TX today with temperatures showing very little recovery under a thickening cloud deck and continued cold air advection. Radar is showing echoes approaching Houston from the WSW, but surface observation show none of this is reaching the ground due to the dry sub cloud layer. Moist advection above the surface cold dome will continue as a strong storm system moves into the SW US resulting in SW upper level flow across TX. Freezing drizzle and freezing rain will continue all day across west and northwest TX resulting in significant surface travel concerns. Tonight: Coastal trough begins to sharpen along the lower TX coast in association with incoming slow moving SW US storm. Lead short wave ejects out of this system late tonight with increasing lift over the surface cold air. Expect an increase in light rain and drizzle after midnight across SE TX in association with isentropic processes and gradual saturation of the dry surface layer. Surface temperatures will remain above freezing and do not expect any freezing drizzle/rain over any portion of SE TX tonight. There is some debate on how quickly the surface layer moistens allowing drizzle to reach the ground…given the radar trends this morning will lean toward a slightly faster onset of drizzle and light rain overnight…but mainly think this will be after midnight. For areas west of I-35 onset of precipitation will fall into a cold sub-freezing layer resulting in freezing rain/drizzle. Overnight model guidance has come in with higher QPF over portions of N TX resulting in an upgrade of the winter weather products to winter storm warnings for ice accumulation. Travel to these areas is strongly discouraged after dark tonight until about noon on Thursday. Icing of roadways will make travel extremely dangerous. Thursday: Lift increases over the region with scattered showers moving northward off the western Gulf of Mexico. Surface cold dome will remain anchored in place with temperatures holding steady in the upper 30’s to near 40 for most of the day. NE surface winds will begin to increase as coastal low develops east of Brownsville in association with downstream height falls spreading over TX from the storm system to our west. Rain, clouds, and increasing winds along with cold temperatures will result in a raw first day of 2015. Friday-Saturday: Main upper level storm moves across the area with widespread rainfall and some thunderstorms likely. Coastal low will move from near KBRO toward KLCH over this period allowing the warm sector to back toward the coast on Friday. Do not expect the warm front to penetrate inland with the exception being possibly from Galveston Bay to Beaumont late Friday. This will keep much of the area in the cold sector with temperatures held in the 40’s with widespread rainfall. With the warm front being held near the coast or offshore, will not be concerned with any severe threat for coastal or inland sections…again will need to watch the narrow corridor from Galveston Bay to Beaumont where the warm front might push inland. Main impacts will be widespread and prolonged light to moderate rainfall. Rainfall amounts Thurs-Sat will average 1-2 inches with isolated amounts upwards of 3 inches. Not expecting any flooding due to the slow nature of the rainfall but overall run-off into mainstem rivers is likely due to the widespread prolonged nature of the event. Latest guidance wants to slow the ejection of the upper system down some and this may result in rain chances lingering into late Saturday evening. Marine: Coastal waters will feel strong impacts from this system with warm front cutting across this area. Additionally, NE to ENE winds ahead of the lower TX coast surface low will promote tidal increase along the upper TX and SW LA coast. Expect tides to run .5-1.0 ft above normal by early Friday and could reach 1.5 ft by late Friday. Strong to severe thunderstorms will be possible over the nearshore and offshore waters Friday and Friday night as strong dynamics overspread the unstable offshore warm sector. Aviation: Poor flying conditions expected at all SE TX terminals for the next 72 hours as low clouds, fog, light rain, and reduced visibilities are all likely. All liquid at all SE TX terminals, but upstream airports at DFW, Waco, Austin, Lubbock, Midland, Amarillo, and Oklahoma City will likely see varying degrees of freezing/frozen precipitation resulting in de-icing protocol and delays. Should see I-35 terminals improve to all liquid by noon on Thursday, but not expecting much improvement at the other locations. Expect both departure and arrival delays locally and across the southern plains.
Posted on: Wed, 31 Dec 2014 15:42:31 +0000