#684 Postby vbhoutex » Wed Dec 06, 2017 2:49 am
Me thinks Winter is here!
This is the latest from Jeff Linder:
Winter Storm will move into Texas Wednesday…accumulating snow likely over far SW TX into the extreme NW Hill Country, and NE MX.
Snow may mix with rain across the far northern portions of SE TX Wednesday night.
Snow may mix with rainfall across the coastal bend Thursday night/Friday morning.
Strong 110kt jet core approaching the Mexican border this evening with large area of lift starting to develop over TX. Radars show enhancing returns both near the coast and across central TX and this will increase in coverage and intensity overnight. Models have becoming much more aggressive in rainfall trends today with both the GFS and ECMWF showing widespread light to at times moderate rainfall and also extending rainfall into Thursday. Temperatures will continue to fall tonight and through much of the day on Wednesday given strong cold air advection along with rainfall and advecting drier air which will help lower wet bulb temperatures. Will go with temperatures steady in the mid 40’s on Wednesday.
Wednesday night:
Profiles start to become a bit more favorable for snow production across our northern counties Wednesday night as more dry air enters the region helping to cool the air column through precipitation evaporating. Expect surface temperatures north of a College Station to Livingston line to remain above freezing, but the air column above may locally cool enough to allow a rain/snow mix along and north of that line. Think most areas will stay as a very cold rain, but trends have been for both greater moisture and a slightly cooler air column and will need to monitor this on Wednesday for any additional cooling trends. Current thermal profiles are just a bit too warm to get much excitement over those northern counties on Wednesday night. Southward over the rest of SE TX, wet bulb temperatures are in the mid to upper 30’s which should preclude any significant cooling of the air column. Both NAM and GFS show the freezing level falling early Thursday morning, but it looks like rain will be ending by the time the thermal profile would support a rain/snow mix further southward over a larger portion of SE TX. Would not totally rule out some sleet Thursday morning, but thermal profiles really do not support it, but I have seen stranger things happen
Thursday night/Friday morning:
A cold upper level trough will move across south Texas and there appears to be just enough moisture in the atmosphere to potentially result in a rain/snow mix or even change to snow across portions of the middle TX into the Rio Grande plains and possible as far east as Corpus Christi. Think the local air mass over SE TX will have dried out enough by this time to prevent any precipitation this far north and without any evaporative cooling the thermal profile actuals warms some away from Matagorda Bay. While surface temperatures are expected to remain above freezing…if a full changeover to snow were to occur and any sort of meso banding develops snowfall rates could overcome the ground warmth and allow for some minor accumulations.
Uncertainty over the next 48 hours is large given the changing factors at play and the potential for locally enhanced cooling which could yield P-type changes over a large portion of the state. Additionally, advection of drier air surges from the NNE and overrunning moisture from the SW will compete allowing differences in where precipitation falls and how much.
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Skywarn, C.E.R.T.
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