Daily Discussions

Daily Discussions

Note: From now on, daily discussions will appear as blog posts so that blog subscribers can get updates via RSS. This page will remain up (but hidden) for archive purposes.

Wednesday, February 15, 2017

Analysis: Morning surface analysis shows that the cold front that pushed through Texas yesterday is now well out over the Gulf of Mexico. High pressure is building in behind this cold front, with a 1032 mb high noted over southwest Wyoming. Weak cold air advection continues across the state. Visible satellite imagery shows clear skies (save for some high cirrus here and there) across most of Texas, except for the Southeast where clouds persist, but should be moving out later today.

Forecast: An upper-level low is forecast to move across Texas on Thursday and into Friday. While this forcing for ascent would lead to precipitation in many cases, dry air is abundant, which should keep rain chances low. Some rain chances may exist across Southeast Texas, but accumulations should be light. Ridging will build back in for Friday and Saturday, leading to pleasant conditions.

The weather will get active again by Sunday as another high-amplitude trough approaches the region. There is significant disagreement between the European and GFS models on timing however. The GFS is faster, bringing the trough axis to a Gallup, NM to Cabo San Lucas, Mexico line by Sunday evening. The ECMWF on the other hand has the trough axis still over Arizona. Based on the timing from the GFS, rain chances would increase from west to east across Texas beginning Sunday afternoon. The severe potential looks low at this time given the limited instability, and expected widespread nature of rainfall. A low-end severe threat could exist over portions of South Texas however where there will be some instability, as well as directional wind shear. The bigger concern will be for heavy rainfall. Precipitable water is forecast to be approaching 1.50 inches across much of Texas, which is about as high as it gets this time of year. The GFS shows a widespread area of 1-2 inches of rain roughly along the I-35 corridor, with a few pockets of more than 3 inches in some places.

A lot of uncertainty still exists on timing right now, but look for Sunday and/or Monday to be rainy, with locally heavy rainfall possible across portions of Central, North, and South Texas.

GFS forecast precipitable water, valid Monday, February 20 0600Z (12:00 AM CST). Image source: Pivotal Weather.
Precipitable water sounding climatology for Fort Worth, TX. Image source: NWS/Storm Prediction Center.

Tuesday, February 14, 2017

  • Analysis: A strong upper-level low near the New Mexico/Texas border is leading to large-scale ascent across much of the region. A surface low is noted in the vicinity of Houston. Rain and thunderstorms are occurring across much of the eastern third of the state, with severe thunderstorms occurring in the Houston area. A Tornado Watch is in effect for Southeast Texas until 1:00 PM CST this afternoon. Meanwhile, precipitation is wrapping around the northwest side of the low into the Texas Panhandle, where a few sites are reporting light snow.
  • Short Range (today and tonight): Most of the precipitation should push east and out of Texas by this evening, with snow showers continuing over the Texas Panhandle through about midnight tonight. Severe weather will remain possible across Southeast Texas through early afternoon, with damaging wind gusts likely to be the main hazard. In the Texas Panhandle, snowfall accumulations should be generally light.
  • Medium Range (Wednesday through Monday): Quiet weather is expected through at least mid-week as high pressure builds in over much of the interior United States. The weather may get active again by Sunday however as a potent, high-amplitude upper-level trough digs in over the Southwest. A severe weather potential may exist on Sunday, especially across Central Texas, but details remain uncertain at this time.
  • Long Range (next Tuesday and beyond): Above normal temperatures are forecast to persist through the next two weeks, with the pattern remaining active across much of the U.S. While it is difficult to say which days will be the most active next week, it does appear that there will be at least a few shots for rain across Texas next week as well.
February 14, 2017 1200Z 500 mb analysis
February 14, 2017 1200Z surface analysis

Monday, February 6, 2017

  • Analysis: An upper-level trough and associated vorticity maximum are noted at 500 mb near the Four Corners region. This approaching trough has led to the development of a weak surface low over Southeast Colorado. Strong southerly flow in place across much of Texas has led to temperatures in the upper 60s to lower 70s this morning, with dewpoints rising into the mid 60s across the eastern half of the state. Morning soundings across the region show a strong capping inversion in place, with a fairly robust elevated mixed layer noted from 800 to 650 mb on the Fort Worth sounding. This strong cap should prevent convective initiation.
  • Short Range (today & tonight): Despite some forcing for ascent from the upper-level cyclonic vorticity advection and strong warm air advection from the surface to 850 mb, the very strong cap should prevent convective development today. Even across the slight risk area highlighted by SPC to the northeast, the cap is strong, and the severe risk is considered to be “conditional”. That is, thunderstorm development is uncertain, but should thunderstorms develop, they could become severe. The convection-allowing 4km NAM and HRRR both show no convective development across the region today or tonight. Across West Texas, fire weather will be the main concern as strong southwesterly winds develop behind a dryline. Red Flag Warnings are in effect from the Texas Panhandle southward through Midland/Odessa and into Far West Texas.
  • Medium Range (Tuesday through Friday): Unseasonably warm weather will continue for another day on Tuesday. While the winds will be somewhat weaker across West Texas on Tuesday than on Monday, low relative humidity will lead to another day of enhanced wildfire potential. A cold front will push through the state late Wednesday, returning temperatures closer to seasonal values. Upper-level ridging through the rest of the week will maintain quiet weather conditions.
  • Long Range (Saturday and beyond): The GFS and ECMWF models both show an upper-level low cutting off over the Southwest early next week, with this low translating slowly eastward towards Texas by the middle of the week. While details remain uncertain at this time, this pattern would likely lead to increased rain chances across much of the state by the middle to end of next week.
02/06/2017 1200Z 500 mb analysis
02/06/2017 1200Z Fort Worth, TX sounding
02/06/2017 1500Z Surface Analysis