Weather Discussion for 02/23/2017

Weather Discussion for 02/23/2017

Analysis: A strong surface low continues to develop over the Southern Plains in response to an upper-level trough digging into the Central Rockies. This has led to strong southerly to southwesterly flow across Texas this afternoon. As a result, temperatures have soared into the mid 80s across much of North, Central, and West Texas. As of this writing, it is already 86 F at both Stephenville and Graham, and with several hours of solar heating still to go, it is likely that some spots will breach 90 F for their highs today. This very warm and dry weather has lead to extreme wildfire conditions across the Texas Panhandle, with critical conditions west of a Wichita Falls to San Angelo line. The NWS has posted Red Flag Warnings for these areas. To make matters worse in the Texas Panhandle, strong winds are also occurring, with sustained winds over 35 MPH occurring at most of the Panhandle sites. This means that any wildfires that develop in these areas will likely spread very rapidly.

500 mb analysis valid 1200Z 02/23/2017.
Surface analysis valid 1900Z 02/23/2017.
Day 1 Fire Weather Outlook for February 23, 2017. Image source: NWS/Storm Prediction Center.

Forecast: The aforementioned surface low will track northeast into the Midwest by tomorrow, bringing a chance for severe weather. Winter weather is expected north of the low, with a wide swath of Winter Storm or Blizzard Warnings in effect from western Wyoming to Wisconsin. Here in Texas, the weather should remain dry as the best lift passes well north of us. The cold front will move through most areas by Friday evening. Cooler temperatures are expected on Saturday, with highs forecast to be in the 50s and 60s across most of the state (much closer to seasonal norms).

The next upper-level trough will approach late Sunday. This trough will result in the development of a surface low over the High Plains of West Texas, which will then track east-northeast across North Texas. The strong lift should lead to rain and thunderstorm development across most of the eastern half of Texas. Unlike last weekend’s severe weather, where there was plenty of instability, but unfavorable wind shear profiles, this time, the wind shear profiles look good, but instability is lacking. The forecast sounding for Olney (Young County) shows MUCAPE of only 494 J/kg, but effective bulk shear of about 50 knots. It’s also worth noting that the equilibrium level is quite low: at about 450 mb (this is typically much higher in severe weather episodes). This suggests that while the overall severe potential should be low, perhaps there would be an outside chance for a low-topped supercell if an updraft became established.

Forecast sounding for Olney, TX (Young County) valid 02/27/2017 at 00Z (6 PM Sunday). Image source: Pivotal Weather.
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