Today, more isolated storms are possible over much of the same areas that saw rain yesterday afternoon. Most of the activity will form with peak daytime heating and die out around sunset. Severe weather is generally not expected out of these storms, but heavy rain, gusty winds, and small hail are certainly within the realm of possibilities. High temperatures will struggle to reach triple-digit levels due to slightly more moist grounds and from rain cooled air around the thunderstorms that develop.

The culprit for these storms is a weakness aloft that is allowing disturbances to propagate southward into South-Central Texas combined with rich tropical moisture, and an endless source of surface heating (our hot temperatures!!). By tomorrow, the weakness will fill in, so to speak, reducing the northerly flow aloft — thus cutting us off from the disturbances up north. That means means our rain chances are also cut off after tomorrow.

Looking at longer range models, by the end of the 8-day forecast period models indicate a return to a southeasterly flow from the Gulf of Mexico. This will open the door to any disturbance/tropical wave in the Gulf into South-Central Texas. Therefore, rain chances next weekend will hover around 10-20%.

The Edwards Aquifer is holding relatively steady, but should go up a bit the next couple of days thanks to some rainfall over the recharge zone yesterday. Additional showers and thunderstorms are possible today. The Stage 3 Water Restrictions Trigger at the J-17 Well in Bexar County is 640 feet above mean sea level. San Antonio has avoided the onset of Stage 3 restrictions at least 3 times so far this summer due to last minute rains. We will continue to monitor the latest levels. Stay tuned for further developments.

TROPICAL UPDATE:

Since the tropics are officially active, I will now divide the near daily discussions into two sections to reduce the clutter.

The National Hurricane Center is currently issuing advisories on Tropical Depression Two in the East Atlantic. The 11 PM ADT update, the storm was located at 14.0ºN, 36.3ºW with maximum sustained winds of 35 MPH moving west at 14 MPH. The minimum central pressure was 1006 mb.

Now yesterday, the storm looked rather impressive with intense, organized convection around the center of the storm. At one point, it may have reached Tropical Storm status. However, the National Hurricane Center rightfully postponed an upgrade as the system showed signs of weakening and was surrounded by an unfavorable environment for further development. The biggest issue is the overabundance of dry air in the mid and upper levels due to the residual Saharan dust in the Eastern Atlantic infiltrating the system. Tropical cyclones need a calm, moist environment to thrive — Tropical Depression Two lacks that. Overnight satellite presentations show further weakening in overall convective trends. Therefore, this storm risks becoming an open wave before regenerating later, if at all. Computer models are in general agreement that in time, Tropical Depression Two will reorganize and strengthen into a weak to moderate tropical storm as it progresses westward. If it does so, its name would become Ana.

However, in the meantime, what Tropical Depression Two is doing is mixing out the dry air in the East Atlantic making the general area fairly moist. The large area of dry air is shrinking rapidly and becoming increasingly negligent. This will leave the door open for the series of disturbances in Africa to head into a moist environment favorable for tropical cyclone formation. The limiting factors, however, are lukewarm, but sustainable sea surface temperatures, and several areas of wind shear. Right now, there is a narrow path of relatively low wind shear for these storms to travel unscathed. The synoptic pattern aloft favors storm movement along this path, therefore storm development is possible.

In fact, the tropical wave behind the Tropical Depression number 2 is of greatest interest right now in the Atlantic. Several global models have been consistent in developing this wave into an intense tropical cyclone within a week or so as it progresses westward. Like its predecessor, it too is performing dismal this morning with its convective activity. However, in time, this will more than likely change as it adjusts to an oceanic environment. This system bears close watching through the next 48 to 72 hours.

Elsewhere in the tropical Atlantic, the National Hurricane Center flagged a couple areas near the Lesser Antilles for possible development. Right now there is a disturbance producing several storms over the islands. A couple models hint that it might organize into a tropical cyclone and move into the Gulf of Mexico. At this time, there is a low probability of intense organization, but as always we’ll keep an eye on it.

A few isolated showers and thunderstorms are possible mainly to the south and east of San Antonio during peak afternoon heating. These storms are a result of a southerly flow aloft due to ridging over the Eastern United States. However, most of these storms will be small and few and far between. Rainfall totals should remain relatively light across an overwhelming majority of the region. Otherwise, expect generally partly cloudy skies with temperatures reaching 100º or greater across South-Central Texas.

Tomorrow, the upper level ridge will shift westward over Texas and eliminate any probability for precipitation. Temperatures will again soar into triple-digit territory. However, by Wednesday, the ridge will shift far enough to the west to allow for a return to the Northerly/Northwesterly flow aloft. This will allow for isolated afternoon storms with overnight storm complexes traveling south/southeastward across South-Central Texas. At this time, it appears most of the activity should pass east of San Antonio, but current rain chances in the city remain at 20%. A frontal boundary may pass through South-Central Texas Wednesday night into Thursday ushering in a slightly drier and cooler air mass. Temperatures, however, should hover near the century mark.

So far in 2009 there have been no named tropical cyclones in the North Atlantic. This should change soon as activity in the tropics is on the increase and at a rapid rate. The National Hurricane Center has flagged a region off the coast of Africa just south of the Cape Verde islands for a moderate risk of tropical cyclone formation. This storm has shown signs of organization through the past 24 hours and has continued to organize through the overnight and morning hours. Satellite and microwave imagery indicate a clear and well defined low-level circulation with most of the convection located symmetrically near the storm center. Several computer models develop this system into a tropical storm fairly soon and move it west-northwest through the Atlantic. Behind this storm are several disturbances over Central Africa, which will eventually make their way into the Atlantic. Models also develop a few of these disturbances into tropical cyclones.

The Edwards Aquifer is holding relatively steady, but should be on a downward trend the next few days unless rain falls this afternoon. The Stage 3 Water Restrictions Trigger at the J-17 Well in Bexar County is 640 feet above mean sea level. San Antonio has avoided the onset of Stage 3 restrictions at least 3 times so far this summer due to last minute rains. We will continue to monitor the latest levels. Stay tuned for further developments.

Showers scathed the airport in San Antonio for the most part, with the exception of an early morning shower that dropped 0.03″ of rain between 3:00 and 4:00 AM. In the afternoon, a complex of thunderstorms developed along the Mexican border before fizzling out just to the west of San Antonio in Medina, Frio, and Atascosa counties. These storms released an outflow boundary which originates from downdrafts brought down from the the tops of dying thunderstorms. The outflow boundary moved northward through San Antonio around 4 and 5:00 PM dropping temperatures from the upper 90’s down to the mid 80’s. Another outflow boundary from storms over East-Central Texas moved southwestward through the Austin area; that later converged with the outflow boundary that moved through San Antonio between San Marcos and Kyle. The collision of the two boundaries ignited a couple area of thunderstorms later in the evening that moved through southern Travis County, dying out by the time it reached Downtown Austin. Additional storm development occurred in Comal and Guadalupe counties near New Braunfels, providing a lightning show for San Antonio and other surrounding communities. Since then, activity has waned tremendously and only scattered clouds remain.

There is at least one more chance for additional shower and thunderstorm development across South-Central Texas this afternoon, particularly in the Hill Country north of San Antonio. The rainfall across parts of the region the past couple days has left a slight weakness in the upper levels of the atmosphere preventing the full reinstatement of the subtropical ridge that has prevailed most of the summer. The residual energy will allow for at least a few storms to develop with peak daytime heating. Widespread severe weather is not expected, however isolated pockets strong gusty winds and small hail is possible. Most of the activity should diminish after sunset.

The question remains of whether or not we break the record for most 100º days in a year remains unanswered. Again, the record was set back in 1998 with 36 days. This year holds a very close second place spot with the present count at 35. The MyTexasWeather 8-Day Forecast predicts a high of exactly 100º today, but it will be a very close call. If storms stay far enough away from San Antonio, the record will be broken with certainty. Otherwise, the wait continues at least one more day.

Looking ahead into next week, dry and hot weather will gradually work its way back into South-Central Texas as the summertime subtropical ridge dominates the weather pattern. Expect daytime highs to hover at or above 100º with morning lows bottoming out around 80º with little to no rainfall expected through the next 8 days.

The Edwards Aquifer went up yesterday and should continue to do so as some rain did fall over the Recharge Zone on Thursday. Hopefully more rain falls again this afternoon. The Stage 3 Water Restrictions Trigger at the J-17 Well in Bexar County is 640 feet above mean sea level. San Antonio has avoided the onset of Stage 3 restrictions at least 3 times so far this summer due to last minute rains. We will continue to monitor the latest levels. Stay tuned for further developments.

Chances for additional showers and thunderstorms will progressively decline throughout the next 24 to 48 hours as the weather pattern evolves. The past few days, the setup was a steady northerly flow aloft in the upper levels of the atmosphere as a result of an unseasonably deep trough positioned east of the Mississippi. Models continue to “flatten” the trough, which would then in turn reduce the flow aloft thus limiting the propagation of these disturbances southward into our region. This means that dry and hot weather return to South-Central Texas throughout the next several days.

The good news, however, is that the upper level ridge that plagued the region with record heat shows no indication of redeveloping, at least in the short-term. Instead, we remain in a relatively stagnant pattern with weak to nonexistent upper level dynamics. Thus, there is at least the outside chance for a shower or thunderstorm on any given day with peak daytime heating along the daily sea breeze boundary.

In the longer range extending next week, computer models show a resurgence of the Eastern US trough. This solution is certainly plausible as this pattern has dominated most of the summer. That would, again, bring back the same general setup that we experience now; looking to the north for isolated rounds of showers and thunderstorms to reach South-Central Texas with some reaching severe limits.

The Edwards Aquifer is back on the way down, however this trend should eventually reverse as it did rain over the recharge zone yesterday. Hopefully more rain develops this afternoon. The Stage 3 Water Restrictions Trigger at the J-17 Well in Bexar County is 640 feet above mean sea level. We will continue to monitor the latest levels. Stay tuned for further developments.

There are also two tropical systems we are monitoring: One located to southeast; the other is Hurricane Andres in the Pacific.   Neither system will affect our forecast.

The aquifer level is still dropping at a fast rate.  Stage 3 water restrictions will be possible by next week.

Now back to reality:  this streak of hot and dry weather does not look like it is going to end anytime in the foreseeable future.  The culprit?  A powerful and incredibly stubborn ridge of high pressure that will not go away.  Storm systems keep riding around the high to our north and to our south.  But, unfortunately for our friends up north, many of the systems are providing plenty of severe weather.  Large hail, damaging winds, and tornadoes have been occuring nearly daily in the upper midwest, and today will not be an exception.  More storms are expected to fire up in the upper midwest and head towards the Ohio Valley. However, again for us, we will remain hot and dry.  Did I say that already?

The problem is… we need rain BADLY.  The Edwards Aquifer is dropping at a rapid rate.  Here is information regarding the Aquifer elevation at the J-17 Well here in Bexar County obtained from the Edwards Aquifer Authority since Saturday when we entered Stage 2 Water Restrictions Criteria:

June 13 - 649.6′
June 14 - 648.2′
June 15 - 648.7′
June 16 - 647.2′
June 17 - 646.0

and right now at 4:00 AM, the aquifer stands at 644.91′ where it’s been sitting since 1:45 AM.

The trigger for Stage 3 Water Restrictions is 640 feet above sea level.  At this rate, we’ll be there in a matter of a few days.  The water rules then are much stricter, and you can find out more about them at the SAWS webpage linked on MyTexasWeather.com.  The biggest change once Stage 3 is implemented will be the fact that you can only water with a sprinkler once every other week, instead of weekly.

It is imperative that we as a community conserve our water, it’s a precious resource.  And in droughts like these, you cannot save enough.

Looking in the long-range, I’m not overly optimistic, but I am seeing some possible changes.  One of the models wants to push the ridge further north, which will help bring us in the path of the easterly trade winds.  Under such scenarios, any disturbance in the Gulf will be pushed up in our direction bringing us nice and healthy tropical downpours.  Right now the model indicates any such chance for storms around the first week of July… which is still quite a ways away.   But, at this rate, mentioning anything is a good thing and something we can keep our fingers crossed to see verify.

Other than that, keep cool and conserve as much water as possible to slow the drop of the aquifer.

Unfortunately the Aquifer continues to be taking continuous hits from this latest dry and hot spell.  Yesterday’s reading was 647.2 ft at the J-17 well in Bexar County.  Today is shaping up to hang around 645 or 646 based on latest trends I’ve been monitoring all night.  The trigger for rigorous Stage 3 watering restrictions is at 640 ft.  We may approach that critical level by next week if the trend holds.  CONSERVE WATER!

Our 8-day forecast is calling for 100º+ temperatures everyday.  Exercise caution when performing outdoor activities and avoid strenuous workouts during peak heating hours. Also remember to keep hydrated at all times.

What does this mean for today’s forecast?  It is actually a no-brainer — more of the same.  This morning’s Doppler radar and infrared satellite imagery continue to indicate several impulses activating in West Texas and Northern Mexico pushing eastward into the region.  The next line of storms has already developed and should cross the border into western portions of South-Central Texas fairly shortly.  These storms will probably make it to the San Antonio-Metropolitan area/ IH-35 corridor around lunch time. Again with these storms the main threats will be heavy rainfall, strong winds, and large hail.  An isolated tornado cannot be ruled out.  I do not expect a widespread outbeak of severe storms due to the lack of upper-level dynamics, but there is certainly more than enough instability to get these storms going strong.  And behind this?  Another round of storms will move through the region yet again later this evening into the overnight hours.

Thunderstorms remain again in the forecast on Thursday and Friday, albiet less organized than last night and today.  Most of the storms will be the product of daytime heating and will fizzle out after sunset.  A late season cold front may move through by Friday ending our rain chances at least temporarily.

Another series of disturbances is forecast to approach South-Central Texas by Sunday and continue through at least the early portions of next week. As a result of all the precipitation, high temperatures should be much more moderate than previously anticipated.  We will not see nearly as much sunshine so I have reduced highs to hover between the mid 80s and low 90s the next 8 days.  Overnight lows will be in the mid 60s to about 70 accounting for the possibility of rain-cooled air.

Quite an amazing shift in our weather pattern considering how long and brutal our drought, which began in September 2007, has been.  And as always, we will surely keep a very close eye on each and every storm system that moves through the region.

Should inclimate weather affect our region, we will do our best to notify you immediately.  Check our Twitter, frontpag e, and Live Streams on MyTexasWeather.com for the latest updates.

Stay tuned.

Luckily, the storms have moved out just in time for Memorial Day across the region.  Most of the storms will remain across East Texas and the northern Gulf Coast states.  This means that we will enjoy excellent barbecue/pincic weather here in South-Central Texas.  That is, if you can handle the heat and humidity.  Highs should top out in the low to mid 90s today under generally clear skies, with a few clouds here and there. Pack the cold beverages if you are going to stay outside.

Tomorrow will be another warm day, but not looking nearly as warm as previously anticipated.  If you remember in earlier discussions, the mitigating factor to how hot it would get was how much rain we saw this weekend.  And since many locations recieved healthy rainfall totals, I think that the moisture in the soil and vegetation will help inhibit high temperatures and keep most areas in the eastern 2/3 of South-Central Texas below the century mark.

By Tuesday Night, another disturbance will enter the area bringing the chance for more showers and thudnerstorms.  The probability for more storms will be on the increase Wednesday and Thursday as a front approaches the region.  In fact, some models are bringing the late-season front through here by Friday or Saturday.  This should buy us a couple of dry days as models bring in yet another system by early next week.

Happy Memorial Day and we solute the soldiers who make this country what it is.

Stay tuned.

Should “Ana” be declared, MyTexasWeather will keep you updated. Check out our Tropics page for the latest information.  I don’t think that this storm will have much of an effect here on South-Central Texas as the upper level jet should push most of the energy out east.

Meanwhile back out here, we are tracking a weakening ridge and numerous storms that develop with the help of daytime heating.   The capping inversion I briefly discussed last time eroded much quicker than anticipated, which is why many of you reported rain yesterday and why we say so much lightning overnight.  The same general setup should persist through the weekend with scattered hit and miss thunderstorms.  I do think these storms will be slightly more numerous this weekend than they were Friday.  Due to the lack of upper level winds, these storms will move very slowly if at all.  However, the good news is that the lack of sufficient wind shear will prevent these storms from reaching severe limits. But, I would not be surprised if a couple of these storms get strong enough to drop small hail here and there.

By Monday and Tuesday the winds will shift to the South and Southwest.  This will help reduce the humidity but also increase the temperatures drastically. You may want to limit the amount of heat you add to the barbecues on Memorial Day as the outdoor air temperature should suffice.  Highs on Monday should hover in the mid 90s under partly cloudy skies.  Tuesday, however, may top out near 100 degrees.

Beyond Tuesday, a series of shortwave troughs will move through the region allowing for storms to develop on a nearly daily basis beginning Wednesday.  As the event(s) near, I will be able to get more specific on what to expect out of these storms.  However at this time, a severe weather outbreak is not anticipated.

Stay tuned.