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...There will be a brief potential for a taste of snow across the Hill Country and the northern counties of Central Texas late Thursday night into Friday morning…

A active period of weather is expected to unfold across Central Texas tonight through Friday when two troughs of low pressure track across the state.  The first trough was located this afternoon across northern Mexico.   This system is forecast to move east northeast and track across Central Texas late tonight into Thursday morning.  Gulf moisture will increase this afternoon and tonight in advance of the approaching trough.  There will be a 30 to 40 percent chance for the development of light rain showers from the Hill Country to the middle Texas coast beginning around midnight, continuing till about mid-morning Thursday.  Rain amounts will generally average less than a quarter inch.

The second and more energetic trough of low pressure was located this afternoon across the central Rockies.  This system is forecast to dive southeast, reaching Northwest Texas around midday Thursday.  The trough is forecast to sink southeast and move over North Central Texas Thursday night into Friday morning.  Strong atmospheric lift generated by the trough is forecast to produce an area of precipitation across the northern Hill Country and the northern counties of Central Texas beginning late Thursday evening, continuing through early Friday morning.  The precipitation is forecast to start off as a light rain, but there is some potential the precipitation may become mixed with snow flurries when the precipitation begins to fall through a dry layer in the middle atmosphere.  The potential for this rain/snow mix will generally be for areas north of a line from Kerrville to Blanco, to Lakeway, Georgetown and Temple.  Snow accumulations in this area are forecast to be very light.  Do note that temperatures at the surface are predicted to be above freezing, so any snow that falls will melt fairly quickly.  Scattered light rain showers are expected across Central Texas Thursday night.

The National Weather Service has posted a Winter Storm Watch for the Big Country, including Brown and Coleman counties from late Thursday night through early Friday morning.  Here, accumulations of 1 to 3 inches will be possible.  To the south, little to no snow accumulation is forecast.  The potential for snow flurries in the Austin area and areas to the south appears to be very low.  The chance for snow is forecast to end around sunrise Friday morning as the upper trough exits to the northeast.

Very windy conditions are forecast to develop across the entire region beginning late Thursday morning, continuing Thursday afternoon, Thursday night and Friday as the trough moves over the region.  The National Weather Service has posted a Wind Advisory for the region from 10 am Thursday through midnight Thursday night.

• Westerly winds of 10-20 mph are forecast Thursday morning. 
  Northwesterly winds of 20-30 mph with gusts to 45 mph are forecast Thursday afternoon and Thursday night.  Some gusts to 50 mph will be possible.
• Northwesterly winds of 20-25 mph with gusts to 35 mph are forecast Friday.
• Wind speeds should decrease to around 10-15 mph Friday night.

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Forecasters continue to keep a close eye on weather developments for Friday and Friday night.  Tuesday's forecast data didn't show a significant change from Monday, although forecasted rain totals have increased a bit.

The combination of a trough of low pressure pushing east out of the Desert Southwest, a slow-moving cold front out of North Texas and a very moist flow off the Gulf of Mexico is expected to produce widespread soaking rains beginning Thursday night, continuing through Friday night.

Moderate to occasionally heavy rain is predicted through the period.  Some training of the rain may occur along the cold front as it slowly moves to the southeast.  The rain is expected to taper off from west to east late Friday night into Saturday morning.

The National Weather Service's rainfall forecasts from Tuesday calls for widespread multi-inch totals across the region.  The forecast calls for the highest totals of rain to occur across North Central Texas, with slightly lower totals to the south.  Totals of 3-4 inches are predicted for areas generally to the north of US Highway 290, with totals of 2-3 inches to the south.

NWS rainfall forecast for the period 6 pm Tuesday through 6 pm next Tuesday:

 
In general, totals of 2-4 inches are forecast, with isolated totals of 4-6 inches possible.  This amount of rain will have the potential to cause flash flooding on area creeks, streams and roads.

Bob

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A persistent flow off the Gulf of Mexico has brought an unseasonably mild and humid air mass to Central and South Texas.  Friday morning's low temperature was in the mid and upper 60s for most locations along and east of Interstate 35.  Overnight temperatures were a bit cooler across the Hill Country, with most lows in the mid-50s to low 60s.  Widespread low clouds developed across the region late Thursday night and have persisted into midday Friday.  These clouds are forecast to thin early this afternoon, allowing the sky to become mostly sunny.   Breezy and warm conditions will develop, with the temperature climbing close to 80 degrees. Expect a south breeze at 10-15 mph.  With low-level moisture levels increasing, there will be a 20 percent chance for the development of a few widely scattered rain showers for areas east of Interstate 35 this afternoon.  Rainfall, if any, should total less than a tenth of an inch.

Forecasters are monitoring a vigorous trough of low pressure in the upper atmosphere that was located Friday morning over the Four Corners region.  The trough is moving to the east and is forecast to reach the Texas Panhandle late this evening, turning northeast into Oklahoma and the southern Plains late tonight into Saturday morning.  While this system is expected to pass well north of our region, it will help drag a Pacific cold front across the area overnight.  The front is forecast to track across the Hill Country late this evening, reaching the Austin area around midnight and pushing off the coast before daybreak Saturday.  Atmospheric conditions appear somewhat favorable for a thin line of rain showers and thunderstorms to develop along the cold front about the time it reaches the Interstate 35 corrido.  The probability for rain will be around 30 percent for locations along and to the east of Interstate 35.  Should thunderstorms develop, there is a small chance for a few of the storms to become severe, mainly for the area between Austin and La Grange.  The Storm Prediction Center has placed this area under a Marginal Risk for severe thunderstorms through Saturday morning.  Severe weather threats will primarily be strong and damaging winds along with large hail.   The rain and storms are forecast to quickly push to the east and exit the entire region before sunrise Saturday.  Rain amounts are forecast to average around a quarter inch or less.  Drier and slightly cooler air will funnel into the region behind the cold front.  Low temperatures Saturday morning will be in the low and mid-50s across the Hill Country and Central Texas regions and be close to 60 degrees towards the coast.

Sunny, breezy and mild weather conditions will develop Saturday in the wake of Friday night's cold front.  Very dry air spreading into the region will allow the temperature to warm to the low and middle 70s.  Expect a westerly breeze at 10-15 mph throughout the day.  Wind speeds should decrease by Saturday night.  Lows Sunday morning will include the mid-40s across the Hill Country, the upper 40s across Central Texas and be around 50-52 degrees towards the coast.

With afternoon relative humidity values slated to plummet into the 20-30 percent range Saturday afternoon, the combination of very dry air and breezy conditions will causeelevated fire weather conditions across the entire region from late Saturday morning through late Saturday afternoon.

Sunday's weather is shaping up to be sunny, mild and very pleasant.  High temperatures will be in the low and mid-70s.  Expect a southwesterly breeze at 5-10 mph.  Lows Sunday morning will range from the low 40s across the Hill Country to around 50 degrees towards the coast.

Forecast solutions call for a large trough of low pressure to push east out of the Rockies late Sunday.  This will allow a Canadian cold front to plummet south into Texas out of the western US Sunday night into Monday morning.  With very little moisture in place, no rain is expected with the front.  Sunny, breezy and noticeably cooler conditions are forecast to develop Monday as the cold front pushes southeast into the Gulf.  Monday's temperature is forecast to warm only to around 58-62 degrees across the Hill Country and Central Texas regions with  mid-60s towards the coast.

Sunny, dry and cool weather conditions are forecast Tuesday through Wednesday as a large dome of Canadian high pressure settles south across Texas.  A light freeze is expected across the Hill Country and parts of Central Texas Tuesday and Wednesday mornings.  Lows both mornings are forecast to be around 28-30 degrees across the Hill Country and around 31-34 degrees across Central Texas.  Lows across the coastal plains region will be near 36-40 degrees.  High temperatures Tuesday and Wednesday will be mostly in the mid-50s.

There will be change in the weather pattern beginning next Thursday when a large trough of low pressure off the coast of southern California begins to track to the east.  Forecast solutions call for the trough to move across Texas next Friday, turning northeast into the Plains states Friday night into Saturday.  Moisture will increase off the Gulf of Mexico on Thursday, leading to the development of scattered rain showers and thunderstorms.  There will be an increasing chance for rain showers and thunderstorms Friday and Friday night as the trough moves across the state.  Weather conditions appear favorable for the development of widespread rain and thunderstorms, with the rain tapering off next Saturday.  Forecast solutions suggest totals of 1-2 inches will be possible across the region Thursday through Saturday morning as the trough moves over the area.  In addition, some strong storms will be possible.  Dry weather looks to follow next weekend.

NWS Rainfall Forecast for the Period 7 pm Wednesday through 7 pm Friday:

Forecasts call for chilly air to spread south into Texas beginning next Saturday as the large trough of low pressure exits to the northeast.  This chilly air may bring a freeze to the Hill Country and parts of Central Texas next Sunday and Monday mornings.  High temperatures next weekend look to be in the low and mid-50s, with low temperatures in the 30s.  The chilly weather is predicted to last into the early part of the week of December 10th.

Tropical Weather Update

Today marks the last official day of the 2018 Atlantic Hurricane Season.  Conditions are currently quiet across the tropical Atlantic and there are no systems in place which pose a threat for tropical development over the next several days.

In total, this year's hurricane season produced 15 named storms, including 8 hurricanes, of which 2 were "major" hurricanes (Category 3, 4 or 5).  An average season has 12 named storms, 6 hurricanes, and 3 major hurricanes.  This year's season will be remembered most for hurricanes Florence and Michael, which caused significant damage in the southeastern US.

Fortunately unlike 2017, no storms visited the western Gulf of Mexico or the Texas coast.


Venus Shining at its Brightest in Early December

In early December, 2018, the dazzling planet Venus will be shining at its greatest brilliancy in the morning sky.   Venus is always the third-brightest celestial object, after the sun and moon.  Even so, Venus' brightness, now at maximum, is some 2 1/2 times greater than Venus at minimum brightness.

Because Venus is an inferior planet – orbiting the sun inside Earth's orbit, this world shows the whole range of phases, much like Earth's moon.   Perhaps  it'll surprise you that Venus shines most brightly when its disk is only about 25 percent illuminated by sunshine, as viewed from Earth.  Venus' disk will become 100 percent illuminated in sunshine some 8 1/2 months from now (August 14, 2019).  But at that time, Venus will be nearly five times farther from Earth than it is right now.  Hence, the illuminated portion of Venus' disk will actually cover less square area of sky, and Venus will be less bright when seen as fully illuminated next August.

Thus you might see that greater brilliancy for Venus is a trade-off between the apparent size of the planet's disk, and the extent to which we see the disk illuminated by sunlight.

You can't miss spotting Venus blazing away in the eastern sky in the period just before sunrise.  (courtesy Earthsky.org) 

Have a good weekend.

Bob