Area Forecast Discussion
Issued by NWS Dallas/Fort Worth, TX

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000 FXUS64 KFWD 271755 AAC AFDFWD Area Forecast Discussion...UPDATED National Weather Service Fort Worth TX 1255 PM CDT WED JUL 27 2016 .AVIATION...
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/18Z TAFS/ As expected, two areas of convection are being monitored. Both the HRRR and TTU WRF have been good with initiation of isolated- scattered showers and storms developing within an are of mid level deformation and high moisture content west-northeast from DFW currently. The other area I`m watching is outflow coming up into central TX. Highest concentration of activity is currently between Gainesville and Bonham, which should eventually push an outflow boundary southward toward the DFW terminals between now and 4 pm. Have carried a 3-hr TEMPO group for MVFR -TSRA and variable gusty winds to 30 kts or so. We should see outflow come through before 22Z and push better convective chances south of DFW with better chances focusing on central TX and Waco from 22Z through sunset. Confidence is good on some convection around, but timing or length of time of persistence of convection is not high. Environmentally, south- southeast winds will prevail 5-10 kts, with the exception of a brief outflow surge by 20Z-21Z that should wash out by 00Z over DFW airports. AWW has been issued current for lightning through 20Z/3 pm cdt. Beyond nightfall into tonight, deformation area shifts south and could see latent heat release redevelop pre-dawn convection along and south of I-20 by sunrise. Confidence here is very iffy, but have a mention of VCTS at Waco where probabilities are higher for TSRA with just VCSH at DFW airports for now. 05/
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&& .UPDATE... Main update this morning was to adjust PoPs/Wx based on current observations and recent analysis/model output. Upper air analysis in conjunction with water vapor imagery revealed a mid-level deformation zone extended from the Concho Valley back up towards the Ark-La-Tex. Similar to yesterday, this feature in combination with daytime heating should be enough to encourage scattered convection late this morning and into the afternoon hours. The better threat for rain and thus highest PoPs are confined to an area along the aformentioned deformation axis. I have nudged PoPs upwards into the likely category for most areas along the Red River with lower rain chances further south towards Central TX where WV imagery indicates drier mid-level air. Despite this mid-level dry air, diurnal sea-breeze activity and subsequent convective outflows may still support some scattered convection and I will keep a mention of showers and storms here. With regards to hazards...the 12 UTC FWD RAOB sampled an environment characterized by 2" PW values. This combined with the weak deep layer shear and thus minimal dry air entrainment and given expected slow storm motions---a heavy rain and a minor flood threat will likely develop. Given the moist environment, there does remain some potential for a strong downburst or two due mainly to precipitation loading. If storms can survive the hostile environment across the southeastern zones, a slightly higher risk for downbursts will exist here. Otherwise, heavy rain will be the main headline for today. I have cautiously lowered temperatures along the Red River where cloud cover and rain should keep temperatures in the low to mid 90s here. Given the time of year, however, it will only take a few hours of sunshine to send temperatures soaring into the mid 90s. The remainder of the forecast appears to be in great shape and updated products have been sent. 24-Bain && .PREV DISCUSSION... /ISSUED 347 AM CDT WED JUL 27 2016/ Hot and humid conditions along with scattered showers and thunderstorms will continue for a couple more days across North Texas before upper ridging builds back in across the Southern Plains. Water vapor imagery shows a weak upper trough centered over Louisiana this morning. This feature is expected to continue to slowly move north today. To the northwest of the upper trough...there is a band of moisture associated with a mid level deformation axis which extends from southwest Missouri into central Oklahoma and into North Texas. 00Z upper air analysis at 700mb indicated the presence of rich moisture from near Midland into North Texas and extending into the Ozarks. Latest RAP analysis indicates PW values in excess of 2 inches along this axis and across a good chunk of North Texas. At the surface...there is some weak troughing noted from south of Lubbock to near Wichita Falls and into southern Oklahoma. Given these features...think a good portion of North Texas...especially across the northern half of the CWA...will see convection develop later this morning into the afternoon hours...so we have raised PoPs to 40-50%. South of the I-20 corridor there may be a relative minimum in convective coverage with the exception of our far southern counties. This area may see some activity spread north from southeast Texas. All of this activity should again be diurnally driven with a peak in coverage late this afternoon and diminishing after sunset. Conditions will be favorable for isolated strong downburst winds and locally heavy rainfall. Later tonight...a second shortwave trough will swing through the Central Plains and into northern Oklahoma with northerly flow at 500 and 700mb increasing. There is some potential for a complex of thunderstorms to develop and move south late overnight although the latest high resolution guidance is less bullish on this scenario. Nonetheless...will have some 20% PoPs late tonight mainly along and north of I-20. The more likely scenario is that this passing shortwave sends a weak boundary down into North Texas for Thursday. With rich moisture still in the region...scattered showers and thunderstorms would likely develop along this boundary during the day Thursday. Will continue with 30-40% PoPs during this time across much of North Texas. Beyond Thursday...upper ridging begins to nudge back eastward into the area. This will confine PoPs on Friday mainly to the eastern half of the CWA and only across the far northeast by Saturday. Temperatures will slowly nudge upwards back to near 100 degrees during this time with rain chances diminishing to near zero by the latter half of the weekend. A pair of strong shortwave troughs will move through the northwest U.S. Sunday and Monday which should help deepen a surface low east of the Rockies. This will keep wind speeds up a bit across North Texas so it won`t feel too oppressive across the region. Dunn && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 96 77 96 77 97 / 50 50 30 10 20 Waco 96 77 97 75 99 / 20 20 30 10 20 Paris 96 74 93 73 94 / 50 50 40 20 30 Denton 93 73 94 74 96 / 60 60 30 10 20 McKinney 93 75 94 75 95 / 60 60 30 20 20 Dallas 96 78 96 76 98 / 50 50 30 10 20 Terrell 95 75 94 75 96 / 40 40 40 20 20 Corsicana 95 76 96 76 96 / 20 20 40 20 20 Temple 94 75 96 75 97 / 20 20 30 10 20 Mineral Wells 95 72 95 72 97 / 50 50 30 5 10 && .FWD Watches/Warnings/Advisories... None. && $$ 05/24

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