Wednesday, May 26, 2010

Rain chances going away, pollution moving in...


As high pressure builds above us in the next 24 hrs, rain chances will diminish and pollution will be on the increase. Our winds have switched to the East and NE, which during the summer months, brings in transported pollution (both man-made and natural) from the eastern parts of the United States. This added pollution, which normally does not exist in our area, may cause our ozone levels to rise to over 70 ppb. by Friday and Saturday. This is a perfect example of why our current system of penalizing cities like San Antonio for high ozone is wrong. Without the additional pollution, San Antonio never reaches high ozone levels. Last summer, despite our searing heat and cloudless days, we did not go above the EPA mandated 8hr. Ozone Average Maximum of 75 ppb.. And now, the EPA may act to lower the maximum 8hr. standard even lower, forcing almost ever small, medium and large cities into non-attainment.

Below are two links to follow the potential high ozone event. On the first link, look at the sulfates in the upper right hand corner. Sulfates signify where the pollution "blob" is in the country. On the second link, just go to the ozone forecast and check out forecast where high ozone will occur. Notice that high levels will be occurring out in the Gulf of Mexico, where there are no cars. Speaking of no cars, check out the past 10 days of ozone for Joshua Tree National Park, a desolate area in south central California. They have already had several high ozone events in the past 10 days.


Tuesday, May 25, 2010

"Pop-O-Matic" Storms!


Take an unstable atmosphere, add some heat and humidity and you get lots of afternoon "poppers". While we missed out on the record 7 inch rainfall in Del Rio last night, we still managed a developing cell around 11am this morning that dropped a half inch at my backyard. With a little luck, many of us will see some brief downpours of rain this afternoon. One of the computer models wants to make it flood around here this evening...

In case some of you are too young to catch my humor in the title of this blog:

Monday, May 17, 2010

An Exciting Afternoon Ahead!

Wow! Another exciting day around here...we've got another mesoscale convective system moving down from the north, which I've been following since this morning when it formed near Amarillo, and other storms forming to the east and west of San Antonio.

With an abundance of heat and humidity outside, it would not surprise me to see some severe weather in the San Antonio area by sunset. Right now the biggest threat is heavy rain, high winds and hail. No mention of tornadoes for us, but a slight chance to our west.

Saturday, May 15, 2010

Latest from NOAA


Most of south central Texas has enjoyed a beautiful day after the large thunderstorm cluster brought more flooding overnight. Late this afternoon, some strong thunderstorms are already forming over the far western hill country near Mason. These may stick together and bring an evening thunderstorm threat to areas generally west of Austin say across mainly Llano and Burnet counties. These storms will have to overcome some capping in the atmosphere to make it farther east however...so we will keep the chances of this happening at about 30-40%. Strong gusty winds in excess of 60 mph and large hail would be the primary threat. These may last well into the evening hours if they can hold together.

Also of concern is yet another upper level disturbance over southern NM which will be moving across west Texas later tonight and then likely triggering additional storms west of our area late tonight. Much like last night...these storms may organize into a large cluster of storms and move over south central Texas primarily after midnight. The main threat if this scenario plays out, would be locally heavy rains in the 3-5 inch range. There is a small severe threat later tonight over the SW near the Rio Grande as large storms fire over the Mexican mountains and move east of the Rio Grande.

Unfortunately there is still a lot of uncertainty about the scenarios. But everybody needs to be on the lookout. Many areas cant handle any additional rainfall. Many rivers, creeks, and rivers are already in Flood stage. A Flash Flood Watch may have to be considered later tonight.

I have attached the latest graphic. Please keep watch this afternoon and tonight as the system develops. Log onto our website for the latest watches and warnings. www.srh.noaa.gov/ewx

Paul Yura
National Weather Service Austin-San Antonio TX

More rain is on the way...

According to today's 5 day rainfall forecast from NOAA, we could see an additional 1-3 inches of rain in our area by the end of the week. A stationary cool front and a series of upper level disturbances will cause more thunderstorms to form over most of Texas in the next few days.

Last night's mesoscale convective system moved through the San Antonio from NW Texas and dropped an additional 1.83 inches of rain in my backyard, giving me a 24hr storm total of 5.88 inches of rain. Having gone almost a month without rain, it was very welcome.

The Storm Prediction Center is showing a slight chance for severe storms to our west on both Saturday and Sunday. My guess is that because of the storms last night cooling the atmosphere, Sunday afternoon will be a better day for potential tornadoes to our west and northwest.

For an update on our monthly and yearly rainfall totals go to my weather page.

Friday, May 14, 2010

NOAA Statement and Storm chances this weekend

Here's the latest from NOAA on today's rain event and what we can expect this weekend:

NOAA: Sorry for the delayed posting, the weather situation is
not being handled well at all by the models or from our
expectations based on climatology and how heavy rain
events develop. We wanted to have the best information
possible for you.

A series of upper level ripples will move across Texas over
the weekend. The computer models have a hard time telling
which of these ripples will ignite thunderstorms. Obviously,
the ripple early this morning was at a very unusual time of day,
and produced over 8 inches of rain in northern Medina County,
and significant rain for nearly everywhere along and east of I-35.

The ripples tend to come along every 12-18 hours, but since our
coverage area is oriented east to west, we could have one in the
coastal plains and another just coming across the Rio Grande
further west at the same time.

The bottom line is we expect severe storms mainly over the
Rio Grande Plains and Edwards Plateau tonight and Saturday,
then over the Hill Country and Metro Austin on Sunday.
We expect the heaviest rain to be south of I-10 and east of
I-35 tonight. There will be scattered thunderstorms Saturday
and Sunday, and some locations could receive 3 to 5 inches
of rain in two hours, producing localized flash flooding. However,
we do not expect a widespread flood event, and most rivers
should not rise above bankfull.

Obviously, this is a graduation weekend and many of our summer
recreation spots are getting in full gear. The main safety concerns
are for lightning (When thunder roars, go indoors) and for low
water crossings (Turn around, don't drown). Please stress with
your staff and anyone planning outdoor events to keep safety
first in mind and have a way to get weather information from
local media, the Internet, or a weather radio.

The latest and most complete information is always at our
website: http://weather.gov/austin or http://weather.gov/sanantonio
whichever is better for you to use. I have attached our latest
graphics.

-Jon

Good Grief! Over 4 inches and still raining!

A quick update at 1pm.

We've had 4.05 inches of rain at my place in Helotes this morning and more is trying to form to the west of us as I type this update.

Now there's a tornado watch for areas to our west and northwest! Follow me on Facebook for quicker updates...

Wednesday, May 12, 2010

5-12-10 Back in SA


Well, as I expected, I ended up at the birthing zone for the terrible storms that hit the Oklahoma City area later in the afternoon on Monday. If the system had come through 24 hrs earlier, I would have been able to be in the Oklahoma City area to chase the storms, but I had to be in Lubbock to help my youngest daughter move back for the summer from Texas Tech on Tuesday. After seeing all of the destruction, I won't lose much sleep not having been in the areas where the storms hit. Some of the storms were moving at over 50 mph, so chasing was very difficult and dangerous for those that attempted it. I much prefer a stationary dry line and slowly moving supercells. The conditions were very creepy, with surface winds in western OK gusting to over 50mph.

Rain chances are still looking good for San Antonio, from Thursday night through the weekend. I have attached the latest NOAA graphics above.

Monday, May 10, 2010

Waiting in Lawton, Oklahoma


It's 11am in Lawton, Oklahoma and I'm still trying to make a decision on an afternoon storm chase. Models are showing most of the sever storms will form in Central and Eastern parts of Oklahoma and Kansas. Since I have to be in Lubbock tonight, I won't be able to go eastward this afternoon. Even if I had the time, I'm not much into storm chasing where there are an abundance of trees. I like very open areas.

For San Antonio, models continue to show that our almost 30 days of dry weather, may be over. Starting on Thursday, we should see at least 5 days of good rain chances, with the best chances coming over next weekend. The latest rainfall estimates are very promising!

Thursday, May 6, 2010

Not much to talk about this week...



Not a lot to talk about this week, except for Saharan conditions in May. It's very odd to have dew points in the 40's this late in the season and our highs on Wednesday reflected this. At my place in Helotes, it started off in the 50's and ended up in the 90's!

A wimpy cool front will try to move through our area on Friday, but will return as a warm front on Saturday. If the front goes stationary for a while, we might see a slight chance for some thunderstorms on Friday night. Right now, computer models show the rain staying to the NE of San Antonio.

On Monday, there is a slight chance that thunderstorms will develop along a dry line in West Texas and some of them might drift far enough south to give San Antonio a chance of rain. At this time, most of the activity will stay far to the north of us. Hopefully, I'll have a chance to shoot some severe storms in the northern parts of Texas or western Oklahoma on Sunday and Monday, as I work my way up to Lubbock to pick up my daughter's dorm stuff on Tuesday. Right now, chances are looking pretty good for a scattered, but severe outbreak of super cells in the areas that I will be in.

Later next week, models are finally hinting at a change in our weather, giving San Antonio several days of good rain chances. I certainly hope it pans out...things are really getting dry again.