Tag Archives: RAIN

What happened to our El Nino Winter?

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Our weather of late across the state has many of us asking what happened to the predictions of a cooler than average and wetter than average Winter for Texas due to the strong El Nino pattern.  And with Spring storm season right around the corner, it also has us wondering if this lackluster El Nino will have an impact on tornadoes and other forms of severe weather this coming Spring.  Our precipitation in December ended up ranking slightly above average across the state..especially for areas along and east of I-35.  For January, we ended up slightly below average, and so far this month, we’re trending below average in precipitation once again.  That’s not exactly what was projected back when we began talking about the onset of a strong El Nino pattern.  We expected the above average precipitation chances to continue on through the entire winter.  However, data for January…and now into the first of February…is hinting that may not happen.

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This past weekend, The National Weather Service office in Ft. Worth took a look at the data collected so far on this Winter’s strong El Nino pattern and compared it data on past strong El Nino events.  They took a look at analogs from these past events, compared it to the data we have leading up to this event, and concluded that we may be seeing a similar pattern to what we saw back in the winter of 1957-58.  As you can see on the plots below…we ended up drier than average across the northern half of the state and wetter than average across the southern half of the state. 

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The El Niño is now past its peak, and sea surface temperatures in the equatorial Pacific are cooling. However, the current sea surface temperature anomalies are still among the warmest on record, thus, strong El Niño conditions are still in place. But so far in 2016, there have been very few rainmaking systems from the Pacific that have impacted Texas, and precipitation totals for the year to date are below normal throughout North and Central Texas.

How unusual is this, particularly with strong El Niño conditions in place? Although El Niño winters tend to favor above normal precipitation, this is not always the case. The driest among the strong El Niño events (1957-1958) has been a remarkably good analog for 2015-2016:

-Very wet spring ends a multi-year drought (1957 and 2015)
-July and August are very dry (1957 and 2015)
-Wet autumn (1957 and 2015)
-Winter with near to below normal precipitation (1957-1958 and 2015-2016)

So naturally the next question is what impact this will have on our Spring rain and storm season?  The NWS office in Ft Worth goes on to say that Spring of 1958 was pretty wet for us…and it also featured below average numbers of tornadoes.  More on that further down the in the blog.  The images below from the Palmer Drought Index for the months of March, April and May of 1958 attest to the fact that we did transition into a wet spring that year.  And we have the current precipitation outlook from the Climate Prediction Center which still supports the probability of above normal rainfall through Spring.  

  195803 195804 195805

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Does this mean we will begin to see more rainfall by early next month and potentially a wetter than average spring?  Maybe.  The Climate Prediction Center Outlook keeps us within a higher probability of rain during the months of March, April and May.  But we have to remember, El Nino is not the only factor which impacts the weather.  All we can say for sure at this point is yes, we will get rain this Spring…we always do…but we cannot discount the possibility that we may not get the rain we expect, much like what we’ve seen so far this winter.  

What about storms and tornadoes?  For that, we have to dig back into historical data for the spring of 1958 once again…as that appears to be the past El Nino event we are most aligned with currently.  On average during the months of March, April and May, Texas sees an average of 11, 29 and 43 tornadoes respectively. During the Spring of 1958, it was noted that we had fewer than average tornadoes reported across the state.  A total of 7 were reported in March, 12 in April and only 15 in May.  Now, keep in mind that current technology has allowed us to record tornado sightings with greater accuracy than we had back in 1958, so there could be a few missing…but that’s still a notably small number of reports.  

March April May

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The natural assumption based on the data above would be that Spring weather patterns coming out of an El Nino winter do a lower than average number of tornadoes.  This assumption is supported based on recent scientific research as well.  A paper published in Nature Geoscience in April of 2015 by climate scientists/researchers John Allen, Michael Tippett and Adam Sobel, draws the conclusion that there tends to be a decrease in the amount of severe storms producing tornadoes and hail during El Nino springs.  The reason for this is tied to the position of the subtropical jetstream typically identified with each type of pattern.  Typical El Nino patterns for the spring season tend to alter and weaken the surface winds that bring Gulf moisture up over our state.  This is more of a setup for just general rain showers than severe weather.  On the other hand, a typical La Nina pattern would tend to concentrate more hot and humid air over our region which is generally more favorable for storm formation.  Should we expect to see fewer tornadoes and severe weather this coming spring?  Since this is relatively new research, more time and study is needed to determine if there really is a clear-cut answer to that question.  

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In conclusion, the fact that we’ve been relatively dry this winter does not preclude a chance for transitioning into a wetter than average pattern this spring.  And while past research indicates a lower frequency of tornadoes and severe weather during El Nino springs, there is insufficient evidence that we definitely will see a less active Spring this year.

Links to source data:

http://www.ncdc.noaa.gov/temp-and-precip/us-maps/1/201601?products[]=statewidepcpnrank

http://www.srh.noaa.gov/fwd/?n=climateoutlook

https://www.ncdc.noaa.gov/temp-and-precip/drought/historical-palmers/psi/195801-195805

http://www.spc.noaa.gov/wcm/permonth_by_state/May.png

http://www.tornadohistoryproject.com/tornado/Texas/1958/May/map

https://www.climate.gov/news-features/featured-images/el-ni%C3%B1o-and-la-ni%C3%B1a-affect-spring-tornadoes-and-hailstorms

 

 

 

Major Weather Impacts Anticipated Today through Sunday for eastern 2/3rd of Texas

An incredibly complex forecast is in store for Texas over the coming three days. In the five years we’ve run a weather blog at Texas Storm Chasers the next few days are probably some of the most complex in terms of a forecast. It only becomes more complex because Hurricane Patricia – now the strongest hurricane on record in the eastern Pacific (or Atlantic). We have a lot to talk about and with the potential for significant impacts I’ll try to do my best at explaining it all.

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Since late yesterday afternoon and overnight we’ve seen widespread rain and thunderstorms over the Big Country, Northwest Texas, and North Texas. Overnight the heaviest rain has fallen in a corridor from Hamilton northeast through the D/FW Metroplex to Sherman, Bonham, and Paris. Relatively widespread rain accumulations of 1 to 3 inches have been recorded with isolated totals up to 5 inches. The rain last night and this morning was the first of several rounds were expecting. We’re no where near done and frankly this event is just beginning. I would prefer there not be dozens of messages in my inbox saying the forecast was a bust until Sunday (at the earliest).

Let me preface the forecast discussion with a couple of notes. We cannot accurately tell you where 10-12+ inch rain totals will fall. Where we do see those extremely heavy rain totals is where we’re going to be most concerned about the threat of widespread/potentially significant flash flooding. Most folks will fall into the bracket of 3 to 7 inches of additional rain on top of what we’ve already seen fall overnight. I know most of you have seen little to no rain (I’m talking to you in Central Texas, South Texas, and Southeast Texas). It also won’t be raining all the time over the coming days. We’ll see activity come in waves with breaks in between.

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For the short-term forecast through the early afternoon we’re using the High Resolution Rapid Refresh (HRRR) weather model. It did fairly well overnight with the placement of rain and thus we’ll continue to use it for this afternoon. A marked increase in precipitation coverage and intensity is anticipated by lunchtime across South-Central Texas, Central Texas, and Northeast Texas including the Austin and San Antonio areas. By mid to late afternoon thunderstorms should be ongoing across Central Texas, the Hill Country, North Texas, and potentially Northeast Texas. Showers and storms are also possible across East Texas and the Brazos Valley. The heaviest storms will be capable of producing rainfall rates of 2 inches per hour. A few storms may also become strong with the possibility of hail up to the size of quarters, 55 MPH wind gusts, and a very low tornado threat.

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The threat for heavy rain increases tonight across North Texas, Central Texas, the Hill Country, and parts of South Texas. The flooding threat looks to increase as some locations may pick up 3 to 7 inches of rain tonight. I can’t tell you with any accuracy where the localized heavy bands of rain will set up since those are dictated by mesoscale processes which can’t be forecast more than a few hours in advance.

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The forecast from Saturday onward has changed due to the latest forecast for Hurricane Patricia. Now the strongest hurricane on record for either the eastern Pacific or Atlantic basins this storm has created a forecast mess. Patricia will make landfall this afternoon near Puerto Vallarta, Mexico as a devastating category 5 hurricane. Maximum sustained winds are at 200 MPH with gusts closer to 250 MPH. Those winds are comparable to what you would see with an EF5 tornado. There will be utter destruction where the eyewall makes landfall and the surge is going to be incredible. Even with all that Patricia will not be a hurricane when it reaches Texas. The circulation will rapidly weaken and possibly even dissipate.

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On Saturday an area of low pressure, possibly the remnants of Patricia, will move into the Rio Grande Valley from Mexico. Moisture from Patricia along with southeast winds across the western Gulf of Mexico, the Rio Grande Valley, South Texas, and Southeast Texas will create an incredibly moist environment. Precipitable water values, a way to measure how much water/moisture is in the atmosphere, will be 500 to 600 percent above norman. The stage will be set for prolific rainfall rates. This has required a forecast adjustment compared to two days ago when the heaviest rains were forecast to be across North and Central Texas. Its not that the heaviest rains have moved south because this is a completely different system from what is causing rains across North Texas today. By Saturday evening most weather models have a non-tropical area of low pressure moving northeast up the Texas coastline from the Rio Grande Valley into Southeast Texas. This low pressure is expected to continue its northeast move on Sunday and be near Lake Charles near dinner time on Sunday.

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Due to the amount of moisture available to the low along with expect dynamics a significant and widespread rain event is forecast for the Rio Grande Valley into Southeast Texas. Widespread 2 to 5 inch rain amounts are probable with located accumulations up to 12 inches. Much of that rain could fall in a matter of 6 to 12 hours. The eventual location of the heaviest rain along with rain totals will be determined on where the low passes. We’ll have to closely monitor the track because if it moves over the warm waters of the Gulf instead of just inland it could try and become a tropical cyclone versus a non-tropical low. In terms of the rain forecast it doesn’t really matter as much if its a tropical or nontropical low. The ridiculous amount of moisture will still be present.

Another forecast adjustment thanks to Patricia is the introduction of a severe weather risk. Locations to the east and northeast of the low will be in an area of enhanced wind shear. Low-level instablity values are expected to be at least marginally favorable for rotating/low-topped thunderstorms. The amount of available instablity will determine the significance of the severe weather threat. At this time we are concerned about a tornado risk in the Rio Grande Valley and South-Central Texas on Saturday with the tornado risk spreading into Southeast Texas Saturday Night and Sunday.

As you can see we’ve got a lot to deal with over the next few days. Two storm systems both with an almost endless supply of rich moisture. Some locations will likely receive 10-12+ inches of rain but those totals will be isolated. Most folks will receive 2 to 6 inches of rain. Obviously the flood risk will be highest where the most rain falls – but we also need to watch for how much rain falls in a short period of time. If you get 2 inches of rain in 30 minutes that’ll cause big problems just like 8 inches in 3 hours. Cities and urban areas will be particularly susceptible to flash flooding. We’ll be doing a periscope video chat at 10 AM CT to talk about the setup and answer a few of your questions. You don’t need a twitter/periscope account to watch. The link will be posted on our social media platforms and twitter feed (which you can access on the right sidebar on our desktop side or just below this post on your mobile devices).

Statewide Heavy Rain Event Wednesday-Saturday

After months of expectation and anticipation we can finally say the rain is on the way. An active period of weather across all of Texas is making for busy times. Since all of Texas is expecting rain at some point this week I’ve broken down this blog into rain chances, severe weather potential, flood risk, and the overall temperature trends. As always there is some uncertainty in the forecast so you can expect refinements during the event. All of that said lets get down to it!

Day by Day breakdown on Rain Chances

Chance of rain/storms Today

Chance of rain/storms Today

Chance of rain/storms Tonight

Chance of rain/storms Tonight

A few coastal showers are possible in Southeast Texas this afternoon. Otherwise we’ll be looking out west for the beginning of our rain event across Texas. Scattered showers and thunderstorms are expected across Far West Texas, the Permian Basin, the South Plains, and the western two-thirds of the Texas Panhandle. By tonight activity will become widespread across the far western Texas and the New Mexico/Texas border in the South Plains into the Texas Panhandle.

Chance of rain/storms Wednesday

Chance of rain/storms Wednesday

Chance of rain/storms Wednesday Night

Chance of rain/storms Wednesday Night

Scattered showers and storm chances will spread east on Wednesday to include the Concho Valley, Big Country, South-Central Texas, South Texas, and the Rio Grande Valley. Numerous showers and storm chances will continue for the Texas Panhandle and Far West Texas. Widespread activity will continue Wednesday Night across the Texas Panhandle, South Plains, Northwest Texas, Permian Basin, Far West Texas, and Southwest Texas.

Chance of rain/storms Thursday

Chance of rain/storms Thursday

Chance of rain/storms Thursday Night

Chance of rain/storms Thursday Night

Widespread/numerous showers and storms will continue on Thursday across the Texas Panhandle, Northwest Texas, Big Country, Concho Valley, Permian Basin, South PLains, Southwest Texas, and South Texas. Scattered activity is forecast across North Texas, Central Texas, Southeast Texas, and the Rio Grande Valley. Numerous showers/storms will spread east into North Texas, Central Texas, and Southeast Texas in addition to previously mentioned areas Thursday Night.

Chance of rain/storms Friday

Chance of rain/storms Friday

Chance of rain/storms Friday Night

Chance of rain/storms Friday Night

Friday is going to be very wet across North Texas, Northeast Texas, East Texas, Southeast Texas, Central Texas, South-Central Texas, the bIg Country, Concho Valley, South Texas, and the Rio Grande Valley. Those rain chances will continue into Friday Night. By Saturday we should start to see activity diminish in coverage west of Interstate 35 – but it does look wet for some of the football games. We’ll detail the rain chances for the weekend once we get closer.

Forecast Rain Totals

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The latest rain total forecast through Saturday from the Weather Prediction Center continues to show a statewide precipitation event. Widespread rain accumulations of 1 to 4 inches are expected across all of Texas. The only exception may be far Southwest Texas where lighter totals are forecast. Localized rain totals over 5 inches are possible but those exact spots cannot be accurately forecast until we’re within 24 hours (at best). This is going to be our best/most widespread rain event since Tropical Storm Bill back in June and I expect everyone in Texas to get rain by the time this event concludes this weekend.

Flash Flood Potential for Wednesday

Flash Flood Potential for Wednesday

Flash Flood Potential for Thursday

Flash Flood Potential for Thursday

Flash flooding is a possibility across the Texas Panhandle, South Plains, Permian Basin, Rolling Plains, Concho Valley, Big Country, Northwest Texas, and North Texas based on the current outlook from the Weather Prediction Center. Folks out in the Permian Basin and West Texas saw a good rain event about two weeks ago while locations further east haven’t seen diddly squat in weeks to months. The flood threat will continue to be evaluated but with very dry conditions its going to take quite a bit of rain to start up the flooding again. Obviously if we see very heavy rain in a short period of time the dry soils will only help so much.

Severe Weather Threat

Severe Weather Outlook for Today

Severe Weather Outlook for Today

An adequate combination of wind shear and instablity will be present today to support the possibility of a few severe thunderstorms across the South Plains, Permian Basin, and Far West Texas. The Storm Prediction Center has placed a level 2 severe weather risk for Southeast New Mexico, Far West Texas, and western parts of the South Plains. A level 1 marginal risk includes Southwest Texas, the Permian Basin, and the western half of the Texas Panhandle and South Plains. The strongest storms today could become supercellular with large hail and localized damaging wind gusts. One or two tornadoes cannot be ruled out but the tornado threat is on the low-end of the spectrum.

Severe Weather Outlook for Wednesday

Severe Weather Outlook for Wednesday

A marginal severe weather risk is in place for Wednesday across the Texas Panhandle, South Plains, Permian Basin, Far West Texas, and parts of the Big Country. Wind shear will be supportive of some organized thunderstorms but widespread cloud cover and precipitation are currently forecast to keep the atmosphere only marginally unstable. As we get closer and localized corridors of instablity become more clear we may see part of the risk area upgraded to a level 2/possible risk in later outlooks. Hail and localized damaging winds would again be the primary issue along with a low tornado threat.

Temperatures

Temperatures will be seasonal during the precipitation event. We likely won’t see much variation in day/night temperatures due to the widespread clouds and precipitation. High temperatures will top out in the upper 60s to mid 80s this week once we get rain going. Locations that are not receiving rain at times this week will be warmer with 80s.

Tropical Mischief Upcoming? An Initial Look at the Potential

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The weather forecast for this upcoming week has become quite a bit more interesting. There is unusually good weather model support that a low pressure will move into the Southwest Gulf of Mexico in a few days. This low then expected to move north towards the Texas coast. From there there are a few different possibilities that would result in drastically different forecasts. Before we dive into all that let’s start off with what we have right now.

An area of low pressure is located just inland near Chetumal, Mexico. This low is expected to move west/northwest over the Yucatan Peninsula this weekend. By Monday it is possible that this system will into the warm waters of the Bay of Campeche, or the extreme southwest Gulf of Mexico. From there we’ll have to take a look at what weather models propose.

For the sake of keeping things simple and not over-analyzing weather model data I won’t go into the timing detail of each model’s output. I’ve put together a graphic showing what three main weather models suggest track-wise for the low pressure. Should impacts to Texas occur they would start off late Wednesday in the Rio Grande Valley and continue into next weekend.

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The european weather model takes the low pressure into the western Gulf of Mexico on a northeast trajectory before turning it north with a landfall in far western Louisiana. From there the European model has the low moving north across far western Louisiana. Out of the three weather models the European is the most aggressive making this system a moderate to strong tropical storm at landfall. The American and Canadian models show a weaker system that either remains a tropical depression or does not become tropical at all. They have it moving across or along the coastline of the Rio Grande Valley northeast into Southeast Texas. Both models then turn our system north into East Texas and Northeast Texas.

Those tracks take into account that the storm actually does develop. If it does not than we’re just talking about a hypothetical event. However many of the weather models are in fairly good agreement that a tropical low will develop. Once it develops we’ll have to figure out where its going to move. Regardless of it being a tropical storm, tropical depression, or just a regular low it would have very rich moisture to work with. Like Bill in June the system would likely produce prolific rainfall along and just east of its path. Depending on the amount of organization folks within about a hundred miles west of where the low tracks could also receive quite a bit of rain. This is all assuming the low develops and makes landfall in Texas. If it passes too far to our east we’re going to be left relatively dry with north winds. The rain forecast shown for the Texas Panhandle and West Texas is from a separate system unrelated to our potential tropical low.

Forecast rain totals through next weekend. These are subject to drastic changes based on future forecast adjustments.

Forecast rain totals through next weekend. These are subject to drastic changes based on future forecast adjustments.

At this point it’s a waiting game to see if the tropical low develops as weather models depict over the next few days. If it does develop then our next concern will be the path of the low and who could get slammed by heavy rains. We’ll also have to watch for organization and it to become a tropical depression or storm. If that occurs than strong winds and coastal concerns would also come into play. Again all hypothetical until we actually have a storm.

September 9 Texas Weather Roundup

Good Wednesday Morning! A line of showers with embedded storms is impacting parts of Central, North, and Northeast Texas. The leading edge extends from San Saba northeast to Hillsboro, Mineola, to Texarkana. Some parts of the line are more potent than others with frequent lightning and heavy rain.

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The area of precipitation will continue to make southward progress today. We do expect weakening with mostly non-thunderstorm activity anticipated across Central and East Texas later this morning. We may seen an uptick of activity across the Big Country and South-Central Texas this afternoon. Severe weather is not expected today.

Rain accumulation forecast through Friday

Rain accumulation forecast through Friday

The weak cold front responsible for the ongoing precipitation will continue to move south today. It will become stationary on Thursday with additional precipitation chances. Severe thunderstorms are not expected with the upcoming activity. Overall rain accumulations will average a quarter of an inch up to an inch. The few lucky folks may receive up to two inches of rain through Friday.

While by definition we are dealing with a cold front its not an impressive one. Cloud cover and the rain chances will help knock temperatures back down to seasonal averages with upper 80s to mid 90s. For tonight we’ll see temperatures drop back into the 60s and 70s. Dewpoint values won’t drop off much with the cold front so it will continue to be humid.

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North winds will help keep temperatures steady-state through Saturday with seasonally average high and low temperatures. By Sunday and into next week south winds will push temperatures back up with dry weather once again. As we continue into mid-September the cold front intrusions should start to become more frequent along with active weather.

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