I'm asking on this forum because a lot of you seem to be hanging out over here, so excuse the interruption.

I have several questions about the current weather that most of Texas is experiencing. I've lived in Oregon (it was my FAVORITE weather in the world), and I've lived in Central Texas most of my life, so these are my observations on what's going on.

(1) The jet stream seems to be heading over the pacific Northwest, drenching them more than usual in rain. Obviously, it's missing us, somehow. Can you tell me why? What is causing the jet stream to deviate from, say, last year?

(2) Is this related to a weak La Nina? I've done some reading on this, and the the NWS climate folks say it's because we're possibly in a weak "La Nina" year. True, or not?

(3) Is there some Bermuda High causing this travesty? WHY is the moisture all going to the southeast, and totally bypassing us? I know that the high clouds have moisture, but the lower level clouds don't, which is why we have no rain.

(4) Any hope for rain past March? The Drought index says no. This is too depressing for words to a girl who loves rain.

Thanks for your answers ahead of time.

Unfortunately, I've really not been able to monitor what's going on with the larger scale of things lately....I've been out of the state and have had a lot of things going on. As far as your question about the climatological things that are causing us to be so dry in Texas...the Climate Prediction Center is indeed attributing dry conditions to a very weak La Nina event in the Pacific. It's actually bordering on neutral (between El Nino and La Nina).

What happened yesterday was on a smaller scale...a low pressure system (or cyclone) brought a shortwave trough through the area, which hit Texas with strong westerly winds bringing in extremely dry air (giving us relative humidities of less than 15%). This, along with excessive daytime heating and drought conditions basically turned the state of Texas into a big heap of kindling.

I wish I were able to answer your questions more throughly...maybe someone reading this that is currently an actual operational meteorologist can answer her better?

Janag81,

Sorry to take a little bit to get back to you. Saw your post yesterday and got side tracked. Anyway, here’s a shot to answer your questions, although your questions can are quite technical to some degree.

1&2) The jet stream pattern can be tricky at times. I’ll try not to get to technical on this stuff, but the jet pattern is quite normal for winter time. Usually meteorologists look at dips or troughs in the jet stream and humps or ridges in the jet stream. When the dips and humps are big, meteorologists call the jet pattern amplified or meridional. Jet flow is more north to south as it moves from west to east. A good example of this was earlier in December. TX had a strong arctic airmass come from Canada as a result of this pattern. Several record low temps were broken. Lately the jet pattern is not as amplified or zonal. Jet flow may have some troughs and ridges, but not as big as a meridional or amplified pattern. Jet flow will have less flow from north to south and tends to be even more west to east. Sometimes there are smaller troughs called shortwave troughs that move through the jet pattern. Theses shortwave troughs or upper disturbances move through to create areas of low pressure at the surface. We’ll get to this later in answering #3. Anyway, the jet stream is not necessarily missing us, but is not as amplified as it had been and so we are not seeing as many low pressure systems impacting TX directly. Is this part of La Nina? La Nina is where equatorial Pacific sea surface temperatures are colder than normal. While this is certainly occurring, I don’t think it is strong enough to really cause any shifts in jet patterns as a strong El Nino would. I would think that during the winter we will see shifts between the more and less amplified jet pattern. Last year the jet pattern didn’t change as much and stuck with a typical winter time pattern.

3) No rain and fire danger – As AndyMac said, basically with the jet pattern we are in, shortwave troughs in the jet stream move across the southern plains. Low pressure at the surface results due to upward motions associated with the trough. With counterclock-wise flow around the low pressure, winds turn from southeast to west as the system moves by the region. Usually the southerly winds are prolonged enough to draw moisture northwards from the Gulf, but this has not been happening as much. Right now seems the gulf coast and E TX will get moisture back, but not enough for W and Cen TX. Usually what happens is that as the low moves by, west winds develop ahead of a cold front. These winds are strong and bring dry air in to the area usually behind a dryline. This happened on Monday/Tuesday and as a result you had high fire danger due to strong winds and low relative humidity. Meteorologist will also call this a dry slot as it is a slot of dry air between moisture to the east and a cold airmass behind a cold front to the north. So, when these types of things happen, no rain, high fire danger. Looks like we’ll see these same type of conditions on Saturday and Sunday for the New Year.

4) Long term forecasts are tricky, but right now, CPC has a good handle on the situation. I would think that towards spring we might tap the Gulf moisture better and have better rain chances, but for now, looks like warmer than normal and dry.

Hope this helps and sorry for the long post. Good questions, and if you have any more, fire away and I’ll do my best.

weatheag

That was great! I completely understood what you were saying, combined with Andy's answers.

Just one more question, for now.

In this "dry slot", what's the difference between it and what happens in spring storms when a "dry line" which comes through could mean tornadic activity and severe thunderstorms? Is it because there's not enough moisture to the east, or the "slot" is actually preventing the dryline from hitting the moist air? (Hope that made sense).

Yes, I've watched "Twister" one too many times.

Here in Temple, they offer storm watcher/chaser classes. Every spring I say I'm going to sign up, then get busy. I really need to do that.

Thank you SO much for taking the time to answer my questions. My local meteorologists probably DO on tv, but I get all of my news and weather online.

Again, I'm very grateful to both of you.

Here's to staying fire-free this weekend during our Red Flag Warning New Years.

[This message has been edited by janag81 (edited 12/29/2005 6:45p).]