Good morning and happy Sunday! Just a quick update for everyone on the outlook for today, plus a first look at the Enhanced Risk of severe weather for late Monday into early Tuesday. Light rain showers continue in a band stretching from west Texas into western north texas this morning. We expect this will be the trend today with additional showers and a few isolated thundershowers to develop and traverse this region of the state today and into tonight. For today, here’s an overview of the rain chances and a peek at the simulated radar of how things may look over the next 15 hours. Why 15? That’s as far out as this particular model reaches… 😀
The severe weather threat for tomorrow is increasing. The Storm Prediction Center upgraded the outlook to an Enhanced Risk for the period from Monday afternoon into early Tuesday. Very strong dynamics will be in place by Monday afternoon with a strong system overhead, plenty of moisture, a crashing cold front and sufficient instability and shear to produce a chance for isolated supercell thunderstorms to develop across parts of the eastern panhandle, northwest Texas and west central Texas by Monday evening. During the late afternoon/early evening timeframe, when the storms are more isolated, there will be a threat for a few tornadoes. As we get into the 7 to 9pm timeframe, these storms are expected to quickly evolve into a squall line of strong storms along the leading edge of the cold front and blast east across the northern half of the state and towards the I-35 corridor within the midnight to 2am timeframe. Greatest threats with this line of storms will be the potential for very strong winds and damaging hail. Crazy as I may be, I’ll be chasing this Monday evening, but David will be manning the weather desk and will provide updates for everyone throughout the night.
What a year this has been for the drought in Texas. It was obliterated back in May and June but rapidly returned for the summer months. We were getting slammed by questions about El Nino and why it hadn’t shown up. I believe the past few weeks have clearly shown that El Nino is present. With the rains over the past couple of weeks the drought has once again been all but obliterated from Texas. The brand new drought monitor has 99.39 percent of Texas out of an official drought designation! An intense storm system is expected to bring a widespread precipitation event to Texas early next week so we’re not done yet!
The following statement accompanied the updated drought monitor from the National Drought Mitigation Center.
The Southeastern Great Plains, Lower Mississippi Valley, and Adjacent Southeast
Moderate to heavy precipitation fell on most of this region. Most areas from the Mississippi/Ohio Confluence southward through the Lower Mississippi Valley, southeastern Oklahoma, and eastern Texas reported at least an inch of precipitation, with 2 to locally over 5 inches measured in a swath from southern Missouri into northwestern Arkansas, plus an area farther south extending from southeast Oklahoma and northeastern Texas eastward through southern Arkansas, much of Louisiana, and some parts of Mississippi outside the areas of abnormal dryness and moderate drought. Large areas of improvement were introduced in the wetter areas, and most other areas were unchanged; however, D0 was expanded into parts of eastern Arkansas, southwestern Tennessee, and northwestern Mississippi that missed most of the precipitation. The eastern half of this area received only 50% to 75% of normal rainfall in the last 30 days, and deficits of 4 to locally 6 inches have accumulated since early September.
During November 12-16, the heaviest precipitation should fall on windward slopes in western Washington and northern Idaho. Peak values of 12 to nearly 18 inches are anticipated in the northwesternmost reaches of Washington while totals may top 6 inches in northernmost Idaho. Substantial totals are also expected in western Oregon and far northwestern California, with amounts topping out in the 2 to 4 inch range along the Oregon Coast. Relatively heavy precipitation is also anticipated across the northern half of the Great Lakes, with 2 to 3 inches forecast in northwestern Wisconsin and adjacent areas. Meanwhile, moderate precipitation (with amounts above 2 inches only in a few isolated locations) is expected across the northern half of New England and New York, far southern Florida, the southeastern Great Plains and western Lower Mississippi Valley, and parts of the northern Sierra Nevada and southern Cascades. Temperatures should average well above normal (5 to 10 degrees) in the northern half of the Plains and much of the Great Lakes Region. In contrast, temperatures should average around 3 degrees below normal in the Great Basin and central Intermountain West.
For the ensuing 5 days (November 17-21), the odds at least slightly favor wetter than normal conditions nationwide, except in a small part of the northern Plains and in a swath across the Big Bend of Texas, southern sections of Arizona and New Mexico, and central and southern California. All of Alaska has enhanced chances for above normal precipitation as well. The best chances for wetness are in the southern half of the Mississippi Valley. We should see warmer than normal temperatures on average in the central and eastern parts of the country and cooler than typical conditions from the Rockies westward.
Another Multi-Day Heavy Rain Event Starting Friday
The weather across Texas is going to be much calmer tonight and for the first half of this work week. However the calm weather isn’t going to last for more than a few days. It now appears likely that an upper level low pressure will move into the Southwest United States this week. By Friday its possible this cutoff upper low could be sitting on the Arizona/New Mexico border. A cutoff low means its disconnected from the jetstream and not being influenced by the strong steering currents. These pesky upper level lows can be a pain to forecast due to their unpredictable nature. All of that is a fancy way of saying we’re still several days out from the event and you can most definitely expect forecast changes. Nothing is written in stone yet.
While confidence is low in the eventual placement of the low it does look likely that we’ll see a return of rain and storms across parts of Texas by Friday. At this time those rain/storm chances look to continue into Saturday which just so happens to be Halloween. We’re six days away and I won’t even waste your time by trying to give you more specific rain/timing chances. Just know that it looks like another multi-day potentially heavy rain event is possible beginning Thursday Friday and continuing into Saturday, possibly Sunday. The timing aspect of the forecast is expected to change as we get closer to the event and forecast confidence increases.
One of the main reasons I’m talking to you about a potential precipitation event five days out is the chance of another significant rain event. Moisture levels look to be quite high again and both the American and European weather models are showing some locations receiving several inches of rain. At this time the Weather Prediction Center is indicating the potential for 3-5+ inches of new rain on Friday through Sunday across North Texas, Central Texas, and Southeast Texas. That kind of rain on already saturated soil would result in another episode of flooding. Rivers are running high but should at least be on the decline by the end of the work week.
The forecast will certainly change between now and later this week. Strength of the upper level low along with its location will determine where the heaviest rains set up and how much rain those locations may see. Based on the latest weather model data there is the possibility of another flash flood/heavy rain event in the Friday-Sunday timeframe. Check back for forecast updates this week.
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.
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.
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.
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.
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.
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.
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).
Tropical Mischief Upcoming? An Initial Look at the Potential
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.
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.
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.