Good morning and happy Thursday! Focus today will be centered around the arrival of a cold front in conjunction with a strong low pressure system which will spark chances for severe thunderstorms across parts of northern Texas this afternoon and into northeastern and southern parts of north Texas this evening. Models are still showing some differences in the timing of the cold front, so when storms arrive will be heavily influenced by the location of the front this afternoon. So, keep that in mind when viewing any of the graphics presented as you scroll down. The NWS office in Ft. Worth is anticipating the greatest chances for severe weather to arrive in the Dallas/Ft Worth metroplex between 3pm and 8pm. Of course…that’s encompasses about all of rush hour for the cities, so keep that in mind as you plan your homeward bound activities this afternoon. It could definitely be a messy commute for parts of the city and surrounding communities.
Here’s a look at the current severe weather outlook from the Storm Prediction Center which an enhanced risk of severe weather encompassing all of the Dallas/Ft. Worth Metroplex, Sherman, Paris and down towards Waxahachie, Hillsboro, Corsicana and over towards Granbury. Supercell thunderstorms with damaging winds and golf ball size hail are possible if storms remain somewhat scattered and isolated this afternoon as they begin developing west of I-35. The general consensus at this time is that the more scattered and isolated storms that have formed will begin to fill in and develop squall line characteristics by the time they reach the I-35 corridor. Once they do that, the straight-line wind threat increases. Straight-line winds can be just as damaging as tornadoes, so keep that in mind if you have outdoor activities or athletic games or practice sessions planned this afternoon and evening. The squall line of strong storms is expected to continue moving south/southeast into central and southeast Texas during the late evening hours. Have a way to receive weather warnings this afternoon and into the nighttime hours either from a smartphone weather App or your NOAA Weather Radio.
Here’s an updated look at the possible track and timing of the storms this afternoon and into the evening hours. As mentioned above, some of the models are still showing a couple of hours differences in the arrival of the front, so the times provided below are just a generalization and best guess for now. We’ll keep an eye on things this afternoon as the radar beings to light up. I’m planning to be out chasing this afternoon, and David may make the drive down as well and provide some live streaming coverage. Stay safe everyone!
Severe Thunderstorm WATCH issued for northern Panhandle
A severe thunderstorm WATCH has been issued for parts of the northern panhandle until 10pm this evening. Strong storms have already developed across the OK panhandle and are expected to clip the northeastern panhandle; however, additional isolated thunderstorm development across this area is possible this afternoon and evening…hence the watch. The most likely time-frame for a squall line of strong to severe storms still seems likely late tonight and early tomorrow morning across parts of the northern panhandle, western OK and eventually impacting the Red River area and north Texas by daybreak tomorrow morning. See below the graphic for the nerd version of this Watch discussion from the Storm Prediction Center.
SEVERE THUNDERSTORM WATCH NUMBER 347
NWS STORM PREDICTION CENTER NORMAN OK
350 PM CDT SUN JUN 22 2014
THE NWS STORM PREDICTION CENTER HAS ISSUED A
* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
WESTERN AND CENTRAL KANSAS
NORTHWEST OKLAHOMA AND THE OKLAHOMA PANHANDLE
* EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 350 PM UNTIL
1000 PM CDT.
* PRIMARY THREATS INCLUDE...
WIDESPREAD DAMAGING WIND GUSTS TO 70 MPH LIKELY
SCATTERED LARGE HAIL LIKELY WITH ISOLATED VERY LARGE HAIL EVENTS
TO 2 INCHES IN DIAMETER POSSIBLE
A TORNADO OR TWO POSSIBLE
DISCUSSION...STRONG STORMS ARE DEVELOPING FROM SWRN KS AND THE TX/OK
PANHANDLES NEWD INTO CENTRAL KS WITHIN A VERY UNSTABLE ENVIRONMENT
WITH CAPE OF 2000-3000 J/KG. 25-30 KT WEST/NORTHWEST MID-LEVEL
WINDS ARE CONTRIBUTING TO EFFECTIVE SHEAR OF 30-35 KT WHICH WILL
PROMOTE ORGANIZED MULTICELL AND OCCASIONAL SUPERCELL STRUCTURES.
ACTIVITY IS EXPECTED TO CONTINUE INCREASING WITH POTENTIAL FOR LARGE
HAIL AND DAMAGING WIND GUSTS. IN ADDITION...UPSTREAM SEVERE STORMS
OVER ERN CO ARE EXPECTED TO GROW UPSCALE AND MOVE EWD/SEWD AS A
FORWARD PROPAGATING QLCS BY LATE THIS AFTERNOON AND EVENING...MOVING
INTO WRN PARTS OF THE WATCH DURING THE EVENING WITH A MORE
WIDESPREAD THREAT FOR DAMAGING WIND GUSTS.
Early Afternoon Update on Severe Weather Potential
We continue to keep an eye to the sky early this afternoon. The atmosphere across Central Texas has become extremely unstable and supportive of explosive thunderstorm development. However the cap is still putting a lid on things for now. I do expect that we’ll likely start seeing a few discrete storms developing by 5 PM in the eastern Hill Country and into parts of Central Texas. Determining exactly where the first storms will fire is difficult until we start seeing signs of agitated cumulus on visible satellite. An outflow boundary from storms earlier today has set up shop south of the D/FW Metroplex and can easily be seen on visible satellite as a line of clouds from Stephenville east to Hillsboro and Corsicana. This outflow boundary could play a role in storm behavior later today as it may locally enhance the severe weather parameters with any storms that approach it.
The strongest storms today will be capable of producing destructive hail up to the size of baseballs along with damaging wind gusts over up to 70 MPH. One or two tornadoes are possible with the most intense supercells. Later this evening at least one cluster of storms may impact portions of Central Texas into the Brazos Valley and Southeast Texas. The cluster of storms would have less of a hail threat but an enhanced damaging wind threat should it develop. Today is a nowcast type of day where we have to wait until storms actually begin to develop to see how things will play out today. For the moment the clouds across the D/FW Metroplex and North Texas are keeping the severe weather threat lower compared to further south where temperatures are approaching 90 degrees in spots. Should the outflow boundary south of D/FW start to move north (retreat) there could be rapid airmass modification and an associated increase in the severe weather threat in areas where it’s cool and cloudy at the moment. We’ll keep an eye on that possibility.
Once the first thunderstorms develop this afternoon they will likely do so explosively. Extreme instability and adequate wind shear will promote rapid development and organization of storms. Storms will slowly move east/southeast with the most intense storms producing destructive hail, damaging wind gusts, and perhaps even a tornado or two. With such extreme instability in place we have to keep an eye out for storm rotation even with the weaker low level wind shear. In some cases the extreme instability values can compensate some for weaker wind shear when it comes to low level rotation. We’ll see how trends play out over the next 90-120 minutes. I expect the Storm Prediction Center will issue a discussion sometime in the next hour or two describing when they plan on issuing the first watches of the day. I’ll plan on posting another update in the 3 to 4 PM timeframe or sooner if necessary. For the severe weather outlook graphics I posted a bit earlier before the server had a hiccup head to my noon update here.
Let me start out this noon update by saying we currently have no severe weather in the state this morning. We did have a potent severe thunderstorm set up over Van Zandt county between 9 and 10 AM with gusty winds and brief rotation. As of 12 PM we have a large area of light to moderate precipitation across East Texas. The strongest cores in this precipitation shield are producing cloud to ground lightning and heavier rain. Isolated heavy shows continue across parts of the D/FW Metroplex where temperatures have remained in the low to mid 70s after precipitation earlier this morning.
I’ll also say today is NOT expected to be a big tornado day. Low level winds are simply too weak to support a high-end tornado threat. The two primary severe weather hazards will be large hail and damaging wind gusts. While a few tornadoes are certainly possible I want to emphasis there is no reason to be worried or scared.
So how does the rain earlier this morning impact the severe weather setup later this afternoon? Well there have been a couple changes that we’ll talk about. The primary implication from this morning’s storms is an outflow boundary that has pushed south of the D/FW Metroplex to between Hillsboro and Waco. On the north side of this boundary surface temperatures are about five to ten degrees cooler than to the south of the boundary where temperatures have climbed into the 80s. Overall this results in the most significant severe weather threat shifting a bit south. As such the severe weather outlooks have been adjusted accordingly from the Storm Prediction Center.
Speaking of severe weather outlooks let’s take a look at the brand new one just issued! I’m doing something different now in that I’ve created graphics for each specific severe weather hazard including the potential for tornadoes, large hail, and damaging wind gusts. The result is three different graphics depicting each severe weather hazard versus just the overall risk today. This means you may have an enhanced risk for damaging wind gusts this evening but a low tornado threat for example.
Overall there is an enhanced risk of severe weather across Central Texas, parts of North Texas, and East Texas later today. As rain continues to move out early this afternoon the atmosphere should begin to quickly destabilize. South of the outflow boundary where temperatures have warmed into the 80s the atmosphere is already priming itself. The most significant severe weather threat today could evolve in Central Texas along and south of this outflow boundary where the atmosphere will be extremely unstable. Initial thunderstorms may develop as soon as 3 PM (or in the 4-5 PM timeframe). These discrete storms will likely be supercellular with a threat of very large hail, damaging wind gusts and even the possibility of a tornado or two.
As thunderstorms congeal later this evening into one or more complexes or clusters the threat for damaging wind gusts will increase while the threat for very large hail will decrease. Storms will likely move in an eastward fashion with dominant storms turning to the east/southeast. We’re continuing to monitor trends early this afternoon for signs of mesoscale factors such as small outflow boundaries or other atmospheric phenomena that could locally enhance any severe weather threat. For now I’ll leave you with the meteorological discussion from the Storm Prediction Center regarding the latest severe weather threat for today. I’ll have another update out around 2 PM which will be more specific regarding short-term trends. For now we’re in a waiting game.
…SUMMARY… SEVERE THUNDERSTORMS ARE EXPECTED ACROSS PORTIONS OF TEXAS EASTWARD INTO THE LOWER MISSISSIPPI VALLEY. VERY LARGE HAIL AND DAMAGING WINDS WILL BE THE MAIN THREATS…BUT A FEW TORNADOES ARE POSSIBLE. ADDITIONAL…BUT MORE ISOLATED…STRONG TO SEVERE STORMS WILL BE POSSIBLE IN THE NORTHERN AND CENTRAL ROCKIES…THE HIGH PLAINS…AND ACROSS PARTS OF MID-ATLANTIC STATES TO LOWER GREAT LAKES REGION.
…SOUTHERN PLAINS TO LOWER MS RIVER VALLEY… THE DECAYING REMNANTS OF AN MCS/TRAILING COLD POOL CONTINUE TO SPREAD SOUTHEASTWARD ACROSS PARTS OF NORTH TX/FAR SOUTHERN OK LATE THIS MORNING. INITIAL SEVERE THREAT THIS AFTERNOON WILL BE IN ASSOCIATION WITH WHAT MAY BE AN UPSCALE DEVELOPING QUASI-LINEAR COMPLEX AND/OR AN MCV ACROSS PARTS OF EAST TX INTO LA AND PERHAPS OTHER PARTS OF THE MID-SOUTH/LOWER MS RIVER VALLEY. THE PRECEDING AIR MASS ACROSS THE CORRIDOR WILL CONTINUE TO STEADILY WARM/DESTABILIZE COINCIDENT WITH AMPLE HEATING AND LOWER TO MIDDLE 70S F SURFACE DEWPOINTS. DAMAGING WINDS/BOUTS OF SEVERE HAIL WILL BE POSSIBLE.
FARTHER WEST…ADDITIONAL INTENSE STORM DEVELOPMENT IS ANTICIPATED ESPECIALLY ACROSS PARTS OF CENTRAL/WEST-CENTRAL TX INTO LATE AFTERNOON/EARLY EVENING. THIS WILL BE VICINITY OF THE SYNOPTIC FRONT IN CONJUNCTION WITH RESIDUAL INFLUENCES OF EARLY DAY OUTFLOW/DIFFERENTIAL HEATING. THIS SCENARIO WILL LIKELY BE AIDED BY THE APPROACH OF A SHORTWAVE TROUGH/SPEED MAX…WITH ATTENDANT STRONGER MID/HIGH-LEVEL WESTERLIES…NOTED TO BE MOVING EASTWARD OVER NM AT MID-MORNING. SUPERCELLS CAPABLE OF LARGE HAIL AND POSSIBLY A COUPLE OF TORNADOES WILL INITIALLY BE POSSIBLE…WITH STORMS LIKELY GROWING UPSCALE AND ADDITIONALLY POSING A DAMAGING WIND RISK AS THEY SPREAD GENERALLY SOUTHEASTWARD TONIGHT. PENDING EARLY AFTERNOON TRENDS AND GREATER CONFIDENCE IN A PEAK RISK CORRIDOR…AREAS SUCH AS WEST-CENTRAL/CENTRAL TX COULD WARRANT AN UPGRADE TO MODERATE RISK /MAINLY FOR VERY LARGE HAIL/ WITH THE 20Z DAY 1 UPDATE.
Well at least that is the plan. Let me start out by saying this is a new feature we’re going to be doing that details the upcoming chase day’s expected events and basic plan. Since it looks like we could have a few days of chasing coming up over the next week I’m hoping this helps please some of our storm lovers and followers. These won’t usually be very long but I will include some more nerdy material. In this case I’ll keep it short and sweet since I need to get ready to hit the road.
Here is the latest severe weather outlook from the Storm Prediction Center for Tuesday. They’ve issued a moderate risk of severe weather including the potential for more significant severe weather across parts of Nebraska, Kansas, Iowa, and Missouri. Most of the purple zone on the graphic above is where severe weather is likely on Tuesday in the form of large hail, damaging winds, and the possibility of tornadoes. The most widespread severe weather threat will likely be in the form of widespread damaging straight-line winds perhaps developing into a derecho (long-lived wind event that moves several hundred miles east). While data later today/tonight and Tuesday morning will give us our final target we’re currently planning to head to Salina, Kansas for tonight. Paige and I will be chasing with Stephen Jones of WeatherStorm.net.
I’ll leave you with a little storm-porn from one of our more nerdy sources. The supercell composite takes into account several atmospheric variables and puts them all in one algorithm. This doesn’t mean severe weather is expected nor does it mean storms will even occur inside the zone. In fact many of the times this graphic shows very high numbers is when the cap is thermonuclear and all that happens is a blue sky bust (no storms). Tuesday looks to be an exception where there will be just enough forcing to cause storms to develop in a very unstable, strongly sheared environment. We could very well end up in parts of Nebraska on Tuesday but the plan is to head to Salina, Kansas tonight. My plan is to stream tomorrow using YouTube Live (technically a Google hangout). I’ll share more information on that later tonight along with my latest thoughts regarding tomorrow’s chase once we arrive in Salina.