LCRA Weather Blog by Bob Rose http://www.lcra.org/water/conditions/weather/weather_column.html LCRA Weather Blog by Bob Rose <![CDATA[Summer Weather Has Arrived Early and Looks to Stick Around For Quite a While. ]]> http://www.lcra.org/water/conditions/weather/weather_column.html 17-MAY-13 06.15.06.068000 PM It would appear that over the past couple of days our weather pattern has quickly transitioned to summer. Thursday and again today, the temperature soared into the low and middle 90s across much of Central Texas while triple-digit temperatures were observed across the western Hill Country. Temperatures early this morning only dipped to the low and middle 70s. The combination of very warm temperatures and high relative humidity levels are certainly making it feel like the middle of summer. Unfortunately, this warm and sticky pattern looks like it’s going to be with us for some time now as the positions of the position of the Jet Stream is no longer allowing cool Canadian air to reach south into Texas. In fact, long-range forecast data indicates summer-like temperatures will likely continue across the region through the end of the month.
 
By the way, you may have noticed quite a bit of haze across the sky today. This haze is actually smoke from agricultural fires in Central America that is being pulled north into Texas by gusty south winds. Today’s polar orbiting satellite image covering the eastern half of Texas and the western Gulf of Mexico from the Aqua satellite showed this “haze” quite well:
 
 
 
Today’s analysis of the upper atmosphere across North America showed a broad ridge of high pressure covering the southern Gulf of Mexico and southern Mexico, extending north to the southern Plains states. This feature, combined with a bubble of hot air spreading into Texas out of Mexico is responsible for the recent spell of unseasonably hot temperatures:
 
 
 
Note how the Jet Stream is generally flowing from California to southern Canada and south into the northeastern US. With this type of configuration, the cooler air is now well to the north of Texas.
 
Late this afternoon, a cluster of thunderstorms developed across the northern Hill Country between Junction and San Saba. These storms developed along the Dry Line, in a small zone where a mid-level stable layer weakened enough to allow thunderstorms to develop. 100-degree temperatures across West Texas also aided in making the atmosphere more e unstable. This area of storms will continue into the evening hours and diminish after sunset. Across the rest of the region, a broad layer of warm air in the middle atmosphere will limit thunderstorm development. The sky will become cloudy overnight and low temperatures Saturday morning will again be mostly in the low 70s. A south wind of 10-15 mph will continue overnight.
 
A very similar weather setup is forecast Saturday. Overall, weather conditions will be mostly sunny, breezy and warm. High temperatures will range from the upper 90s across the western Hill Country to near 90 degrees towards the coast. Expect a south winds at 10-20 mph. There will again be a slight chance for some late afternoon thunderstorms across the northern and western Hill Country as the Dry Line pushes east out of West Texas. Should storms develop, they’ll have a strong potential to become severe. The chance for rain will be at 20 percent. These potential storms could possibly move as far east as the Interstate 35 corridor before diminishing in the late evening.
 
That small chance for thunderstorms is forecast to decrease on Sunday with the Dry Line holding across Far West Texas. Expect another sunny and breezy day with high temperatures ranging from the upper 90s out west to near 90 degrees towards the coast. Very similar weather and temperatures should continue into Monday.
 
Some slight changes in the pattern look to occur Tuesday afternoon into Wednesday when a weak cold front sags south out of North Texas and pulls up stationary somewhere over Central Texas. There will be a slight chance for scattered rain showers and thunderstorms between Tuesday afternoon and Wednesday evening across the entire region. Wednesday’s sky will likely stay mostly cloudy on Wednesday. High temperatures both days will be near 88-90 degrees. Rain amounts between late Tuesday and late Wednesday are not expected to be very heavy with most totals averaging between a quarter and a third of an inch.
 
Late next week into next weekend, high pressure in the upper atmosphere is forecast to re-strengthen across Texas. Dry and hot weather is forecast with high temperatures in the 90s and lows in the 70s. Unfortunately, today’s forecast data doesn’t call for any significant rain across Central Texas through the end of the month.
 
Have a good weekend and stay cool.
 
Bob
   
]]> 20130517 <![CDATA[A Suumer-Like Weather Pattern Will Continue into Next Week.]]> http://www.lcra.org/water/conditions/weather/weather_column.html 16-MAY-13 06.41.09.201000 PM Summer-like heat set up quickly across Central and South Texas as a bubble of hot air spread northeast out of Mexico. Southwesterly breezes in the wake of Wednesday’s large area of low pressure help pull this hot air northeast. With a strong sun and relatively dry soils, temperatures heated up quickly. For many locations, Thursday temperature was the hottest so far this year. A check of LCRA’s Hydromet showed readings reached or exceeded 100 degrees across the western Hill Country, reaching the low and middle 90s across much of the rest of the Hill Country:
 
Max Temperatures Thursday:
 
In Austin, the temperature peaked at 93 degrees at Camp Mabry and at 91 degrees at Austin-Bergstrom International Airport. Interestingly, the temperature only reached the low and middle 80s across the coastal plains region. These relatively “cooler temperatures” are generally the result of cool sea surface temperatures in the low and middle 70s across the western Gulf of Mexico and a few more clouds compared to inland locations.
 
A ridge of high pressure in the upper atmosphere located over northern Mexico and the southwestern US will spread east across Texas on Friday, causing a sunny, dry and hot weather pattern. High temperatures will be near 100 degrees across the western Hill Country, in the mid and upper 90s across the rest of the Hill Country, the low and middle 90s across Central Texas and the upper 80s across the coastal plains. Breezy south winds of 10-20 mph will be in place.
 
Only minor changes in the “summer-like” pattern are expected this weekend and Monday . The large ridge of high pressure is forecast to move east of Texas on Sunday as a large trough of low pressure develops over the southern Rockies and the southwestern US. A few isolated thunderstorms will be possible across the western Hill Country Saturday and Sunday afternoons as the Dry Line pushes east from the Rio Grande Plains. No significant rain is forecast. A mostly sunny and warm pattern will continue. Daily high temperatures will range from the mid 90s across the western Hill Country to the low 90s across Central Texas to around 90 degrees near the coast. Low temperatures will be in the low 70s.
 
The trough of low pressure over the southern Rockies is forecast to lift northeast to the Plains states on Tuesday, dragging a weak cold front into Texas. Today’s forecast data indicates the front will be weaker than forecast Wednesday. It should sag south toward Central Texas late Tuesday and pull up stationary. The front will cause a slight chance for thunderstorms across the Hill Country and Central Texas regions late Tuesday into Tuesday night. Actual rain totals will be low. A weak ridge of high pressure is forecast to build across Texas next Wednesday through Friday, causing more dry and warm weather. High temperatures will remain near 90 degrees.  Long-range forecast solutions continue to call for a mostly dry and warm pattern lasting through the end of the month.
 
National Weather Service Summer Forecast: Today, the National Weather Service issued its monthly seasonal outlook of temperature and precipitation. Unfortunately, the outlook is not all very promising for wet weather. For the months of June-July and August, the outlook calls for above normal temperatures and equal chances for above, below or near normal rainfall:
 
 
                   Temperature                                             Precipitation
Climate Prediction Center forecasters indicated there was little trend for precipitation across Texas this summer. Dry soils across the region will likely play a role in warmer than normal temperatures and near to below normal rainfall. Of course, tropical weather could change things significantly.
 
Bob
]]> 20130516 <![CDATA[Say Hello to 90-Degree Temperatures. Little to No Rain Expected through Next Week.]]> http://www.lcra.org/water/conditions/weather/weather_column.html 15-MAY-13 06.44.34.975000 PM After an unusually cool start to the month of May, our weather pattern is now transitioning to a warm, more spring-like pattern that is typical of late May. Over the next few days, a ridge of high pressure in the upper atmosphere will strengthen over Texas as the Jet Stream shifts north towards the Canadian border. This ridge will cause generally stable weather and somewhat noticeably warmer temperatures. I expect a fairly widespread coverage of 90-degree temperatures across most of Central Texas and the Hill Country with middle and upper 90s across the western and northern Hill Country. A weak cold front looks to bring some slightly cooler temperatures for the middle of next week with more 90-degree heat returning late week. Let’s face it; it’s the middle of May in Central Texas and summer is just around the corner. There will be very few cool mornings in the weeks ahead.
 
Some spring-like thunderstorms will be possible across parts of the Hill Country and Central Texas this evening as a wave of low pressure swings southeast out of New Mexico and Far West Texas. This wave of low pressure is circulating around a broad area of low pressure in the upper atmosphere that lifted northeast out of Mexico early this morning. As of low Wednesday afternoon, the low was centered over central Oklahoma, moving to the northeast. An afternoon visible satellite image shows the swirl of clouds associated with low very nicely:
 
 
 
Thunderstorm clouds can be seen developing across northwest Texas and these are moving to the southeast. As of late this afternoon, the atmosphere over the Hill Country and Central Texas was slightly unstable and it’s possible these thunderstorms could build south across the region through the evening hours. Some of these storms may be severe, possibly producing large hail and damaging winds. The Storm Prediction Center has placed all of the Hill Country and the Interstate 35 corridor extending south to San Antonio under a Slight Risk for severe thunderstorms overnight. Potential rain amounts will average around a half inch with isolated heavier totals. The chance for rain tonight will range from 50 percent across the western Hill Country to the 30 percent across Central Texas to 20 percent towards the coast. This potential thunderstorm activity should diminish late tonight as the temperature cools. Lows Thursday morning will generally be in the upper 60s.
 
A mostly sunny to partly cloudy sky will develop Thursday as the upper low exits to the middle Mississippi Valley and a ridge of high pressure begins to strengthen over Texas out of Mexico. Thursday’s temperature looks to warm to the upper 80s at most locations with some low 90s across the western and northern Country. This ridge of high pressure is forecast to hold in place across Texas Friday through Sunday, causing a warm, summer-like temperature pattern. Daily high temperatures will be near 90 degrees across Central Texas and the coastal plains region. Across the Hill Country, highs will be in the low 90s with some middle and upper 90s occurring across the western and northern Hill Country. Some thunderstorms may develop across parts of the Hill Country Sunday afternoon and Sunday evening when a disturbance moving out of the southern Rockies pushes the Dry Line east out of West Texas. While conditions are not expected to be all that favorable, some thunderstorms may develop.
 
Partly cloudy, warm and breezy weather is forecast Monday as a strong trough of low pressure in the upper atmosphere pushes east out of the Rockies. Expect south winds of 15-25 mph. High temperatures will be mostly in the low 90s with mid and upper 90s across the western Hill Country.
 
That trough of low pressure moving across the Plains states is forecast to push a weak cold front into Texas next Tuesday. The front is forecast to push south into Central Texas late Tuesday and push off the coast Tuesday night. The front may cause a few rain showers and thunderstorms but the atmosphere is shaping up to be fairly warm and stable. As of now, rain totals are only forecast to be around a quarter inch.  Dry and slightly cooler air is expected to follow the cold front Wednesday through Friday as a weak bubble of Canadian high pressure builds south into Texas. High temperatures will be mostly in the low and middle 80s with lows in the 60s. Dry and warmer weather looks to return late next week into next weekend. Unfortunately, today’s long-range data is not calling for any significant rainfall developing over the next couple of weeks.
 
Eastern Pacific Tropical Weather Season Opens with a Bang:  Today marks the official start to the 2013 Eastern Pacific Tropical weather season.  And coincidentally, the first tropical storm of the season developed earlier today. Tropical Storm Alvin was centered late this afternoon about 665 miles south-southwest of Acapulco, Mexico, moving to the west-northwest at 13 mph. It shows up nicely as that large swirl of clouds south of Mexico:
 
 
 
Maximum sustained winds are near 40 mph and additional strengthening is forecast. Alvin could become a hurricane in a couple of days. Alvin is forecast to move to the west-northwest over the next few days, having no effect on any land areas. The development of a tropical storm on the first day of hurricane season might indicate this could be an active season for the eastern Pacific basin. By the way, the Atlantic hurricane season officially begins June 1st.
 
Bob
]]> 20130515 <![CDATA[Quick Tuesday Weather Update]]> http://www.lcra.org/water/conditions/weather/weather_column.html 14-MAY-13 04.40.45.741000 PM After a few mild and quiet weather days, some changes will begin to take place this evening and overnight when an area of low pressure in the upper atmosphere currently located near southern Baja, California starts moving to the northeast.  Clouds and moisture will increase off the Pacific and Gulf of Mexico, resulting in a mostly cloudy sky.  At the same time, the atmosphere over the area looks to become increasingly unstable.
 
This evening, attention will be focused across Far West Texas, the Rio Grande Plains and the western Hill Country where thunderstorms are forecast to develop along the Dry Line as the atmosphere becomes unstable.  Thunderstorms look to develop near the Rio Grande River and track to the east-northeast.  These storms are forecast to potentially reach the western Hill Country late this evening, moving across the rest of the Hill Country and possibly as far east as the Interstate 35 corridor between 10 pm and midnight.  Forecast data suggests some of these thunderstorms may be strong to severe, producing large hail, dangerous lightning and damaging downburst winds.  The Storm Prediction Center has placed the far western Hill Country under a Slight Risk for severe thunderstorms late this afternoon and tonight.  The threat for severe weather is forecast to decrease by midnight.  The area of thunderstorms is also forecast to decrease around or shortly after midnight.
 
The weather on Wednesday is shaping up to be cloudy and wet.  There will be an increasing chance for rain and thunderstorms across the entire region beginning Wednesday morning, continuing through Wednesday afternoon as the area of low pressure tracks from northern Mexico into West Texas.  Scattered to numerous showers and thunderstorms are forecast.  But note that today’s forecast data suggests severe thunderstorms are not likely.  The chance for rain will decrease from west to east late Wednesday afternoon into Wednesday evening as the area of low pressure exits to the northeast.   Today’s forecast data indicates rain totals between this evening and Tuesday evening will generally average between a half and one inch.  However, a couple of isolated totals of 1-2 inches will be possible across parts of the Hill Country and Central Texas.  Wednesday’s high temperature will generally be in the upper 70s.
 
Partly cloudy and dry weather will return Thursday as a  weak ridge of high pressure begins to spread over the region from the west.  Thursday’s temperature will generally warm to the middle 80s.  Mostly sunny and warm weather looks to continue Friday through Sunday as the ridge remains over Texas.  Daily high temperatures will be near 88-90 degrees across Central Texas and the coastal plains region and near 90-92 degrees across the western and northern Hill Country.  Breezy south winds of 10-20 mph are forecast to develop Saturday and continue through Monday.
 
Looking ahead to next week, partly cloudy and warm weather will continue Monday with a high temperature near 88-90 degrees.  A chance for rain showers and thunderstorms is forecast Tuesday when a weak Canadian cold front pushes south across the region.  Rain amounts are not expected to be very high.  Dry and just slightly cooler air will follow next Wednesday with much warmer temperatures expected late next week.
 
Bob
]]> 20130514 <![CDATA[Rain and Storms Friday Night Into Saturday but Sunny and Pleasant on Sunday]]> http://www.lcra.org/water/conditions/weather/weather_column.html 10-MAY-13 06.01.02.857000 PM Late this afternoon, scattered thunderstorms were developing across the Hill Country as another wave of low pressure tracks east out of Mexico.   This wave of low pressure has rotated around a broad trough of low pressure in the upper atmosphere located over southern New Mexico and Far West Texas. The storms are forecast to track to the east across the Hill Country and Central Texas region late this afternoon and evening. The atmosphere across the Hill Country is still moist and moderately unstable, so some of these storms are expected to be strong to severe. Very large hail and damaging winds will be the primary severe weather threats. However, an isolated tornado or two cannot be ruled out. 
 
Atmospheric conditions appear favorable for this area of thunderstorms storms to track east-southeast across Central Texas and the coastal plains region late this evening and overnight. These storms will still have the potential to be severe, producing very large hail, damaging downburst winds and locally heavy rain. The chance for additional thunderstorms will decrease across the Hill Country and Central Texas region late tonight into Saturday morning as a more stable air mass spreads in behind a weak Canadian cold front. The sky on Saturday will be mostly cloudy and there will be a slight chance for a few scattered rain showers or thunderstorms. The focus for rain and thunderstorms will shift the coastal plains region on Saturday as the cold front slowly moves towards the coast. Here, a good chance for rain will continue through early afternoon with the rain tapering off Saturday night.   Rain amounts from the storms tonight and Saturday will generally average between 0.5 and 1 inch with a few isolated heavier totals. The high temperature Saturday will generally be in the upper 70s. Lows Sunday morning will be in the mid and upper 50s.
 
Sunday’s weather is shaping up to be mostly sunny, dry and quite pleasant with a high temperature near 78-80 degrees. A partly cloudy sky is forecast Monday and Tuesday with high temperatures in the low 80s. Lows Monday and Tuesday mornings will generally be near 58-60 degrees.
 
A chance for rain and thunderstorms is forecast to develop Tuesday night through night when a wave that same area of low pressure which is currently sinking south into Mexico lifts northeast and moves across Texas. As of now, it appears rain totals will be less than a half inch. Dry and warm weather looks to return next Thursday and Friday when a ridge of high pressure strengthens over Texas. Today’s long-range solutions indicate the next widespread chance for rain will occur around the 15th or 16th when another large trough of low pressure moves southeast out of the Rockies.
 
Planets Aligning in the Sunset Sky:  Mercury, Venus and Jupiter are lining up for a beautiful sunset conjunction at the end of May. Check out the full story from NASA Science News: http://science.nasa.gov/science-news/science-at-nasa/2013/10may_sunsettriangle
 
Have a good weekend.
 

Bob

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