DFW FORECAST DISCUSSION
000 FXUS64 KFWD 242342 AFDFWD Area Forecast Discussion National Weather Service Fort Worth TX 642 PM CDT Sun May 24 2020 .SHORT TERM... /NEW/ /Through Monday evening/ Convection from earlier today has left a large cold pool across North and Central Texas. A few thunderstorms are still ongoing along a Stephenville to Waco line, but these storms have been on a weakening trend. Furthermore, an early look at the just-released 00Z RAOB shows that capping has built back into the region. These observations suggest that the atmosphere is thoroughly turned over, which introduces a bit of uncertainty into the overnight forecast. Thunderstorms are ongoing well to our west across the Llano Estacado and into the Concho River Valley and Big Bend Region. These thunderstorms should continue a eastward trek through the evening hours. These storms could begin to weaken as they enter our western counties and encounter the more stable air. Still, confidence is high enough on at least some convective coverage to maintain Likely PoPs. That being said, the severe weather potential looks quite low. Where thunderstorms do occur however, large precipitable water values and near saturated profiles will mean thunderstorms will be capable of heavy rainfall rates. Heading into Memorial Day, some thunderstorms will likely be ongoing in the morning, but should start to exit the area by later in the morning. Afternoon heating will likely be limited with lingering cloud cover, with highs only forecast to get into the low 80s. A few showers and thunderstorms could develop in the humid environment across North and Central Texas, but with the lack of any significant surface boundaries, will keep PoPs in the Chance range for Monday afternoon. Shower and thunderstorm chances will increase into Monday night however as another upper-level shortwave trough passes through the region. Shear and instability look limited, but with precipitable water values remaining at or above 1.50 inches, heavy rain will be the primary concern. Godwin && .LONG TERM... /Issued 311 PM CDT Sun May 24 2020/ /Tuesday through Next Weekend/ Unfortunately, the challenges continue in the long term forecast period as it pertains to the placement of the greatest PoPs. What appears certain is that most areas across the region will receive some rain. Temperatures will be below normal by 5 to 10 degrees through the entirety of the long term forecast period. The synoptic picture is becoming a little clearer as we start the period and a diffuse frontal boundary is expected to ooze south of the Red River. Deep troughing across the Permian Basin will result in largely southwest flow aloft. Synoptic scale shortwave troughs and mesoscale convective vortices will convoy toward toward the Ozarks as a result. It appears probable that a good cluster of convection will already be ongoing across the Concho Valley late Monday evening. At present time, the most likely area to be impacted will be locations along and west of the US HWY 281 corridor between 00-06Z Tuesday (Monday evening). There will be a modest severe weather risk given that deep layer shear values will be near 30 knots...700-500mb lapse rates approach 7 C/km and MLCAPE values will top out in the 1500-2000 J/kg range. Convective modes will likely be in the form of line segments/bows thus facilitating a damaging wind risk. The multicellular nature of activity will also support a marginally severe hail risk. Through the pre-dawn hours on Tuesday, storm activity should track eastward but may begin to slow as mean flow starts to become more meridional. In fact, both upshear and downshear Corfidi Vectors become increasing orthogonal to the line of convection and this may suggest that the activity will slow, thereby increasing the flooding risk. Exactly where this occurs is a little hard to say and model QPF varies significantly spatially. Moreover, this batch of convection that moves out of the Concho Valley could impact what happens farther upstream along the surface frontal boundary. There should be enough large scale ascent, however, to overcome any subsidence induced on the northern fringe (the Big Country and North Texas) of the Concho Valley complex. 0-6km flow along the front suggest that any convective type activity will likely train across areas near and northwest of an Eastland to Mineral Wells to Sherman/Denison line. The exact coverage of the heaviest precipitation, however, remains unknown. Given this uncertainty and after coordination with WFOs Norman and Tulsa, we`ve elected to hold off on any Flash Flood/Flood Watches. If higher resolution guidance can focus QPF totals a bit better over the next few model iterations, we`ll need to consider one, especially given the antecedent conditions. Showers and thunderstorms should continue to push eastward through the day on Tuesday with the greatest rain/storm threat shifting into East Texas. The severe weather threat does not look overly favorable, given the very narrow CAPE profile and largely unidirectional wind profile. However, a severe wet downburst threat may materialize in some of the more robust convective elements. The skinny CAPE profile combined with the unidirectional wind profile coupled with PWATs in excess of 1.5" will support very efficient warm-rain processes and thus a persistent flood/flash flood risk...especially for locations along the Red River. Mid-week through the end of the weekend looks to remain unsettled as the main upper low remains across the area. PoPs are largely broad-brushed given that there is some model disagreement with the positioning of the upper low. The latest ECMWF remains the farthest to the east and southeast with the position of the upper low (across the Brazos Valley) with the rest of the model consensus lagging back towards the northwest across the northern Big Country. What is certain is that the best chance for rain during the calendar day should be during the daylight hours with a relative lull in rain/storms during the nocturnal periods Wednesday through next weekend. Bain && .AVIATION... /NEW/ /00Z TAFs/ Convection has dissipated within the D10 TRACON, with VFR and south flow prevailing. Another round of TS should approach from the west late tonight, reaching the TRACON area by 06Z. Some uncertainty exists with regards to timing/coverage, but 06Z-09Z appears to be the most likely time for impacts. CIGs may drop to MVFR within TS, but should generally remain VFR outside of TS. At KACT, MVFR CIGs even outside of TS appear more certain during the overnight and morning hours. TS should exit by late morning, giving way to VFR at all terminals by 18Z. Godwin && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 67 80 67 74 63 / 70 40 80 80 30 Waco 67 82 65 77 61 / 80 40 90 80 20 Paris 66 77 65 75 64 / 60 40 80 80 40 Denton 64 79 65 73 61 / 70 40 80 70 30 McKinney 66 80 65 75 62 / 60 40 80 80 30 Dallas 68 82 68 76 64 / 60 40 80 80 30 Terrell 68 81 66 78 63 / 70 40 70 80 30 Corsicana 66 81 67 75 63 / 80 40 60 90 30 Temple 66 82 65 76 61 / 80 40 90 90 20 Mineral Wells 65 78 62 71 60 / 70 40 80 70 30 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$ 37/26