397 FXUS64 KFWD 151044 AAA AFDFWD Area Forecast Discussion...UPDATED National Weather Service Fort Worth TX 544 AM CDT Fri May 15 2020 .SHORT TERM... /NEW/ Update: No significant changes to the earlier short term discussion below outside of raising highs a degree or two across the areas along/west of I-35/35W. Think there could be a little more insolation than previously expected across those areas. Linear MCS across the Ozarks well north-northeast of the area is already becoming outflow dominated, so have my doubts if it doesn't mix and wash out as it approaches the Red River Valley around midday or early afternoon. Hard to say, but an elevated cap across North Texas, not sure how much coverage of convection develops before late afternoon or early evening. 05/ Previous Discussion: /Overnight Through Friday Night/ We will continue with our unsettled, mid-May pattern as we move through the weekend. The pre-dawn hours through this afternoon should be relatively quiet with breezy, warm, and humid conditions continuing. A strong 30-40 knot LLJ early this morning will help draw up widespread stratus and maintain the muggy conditions we saw yesterday morning as well. As we warm and begin mixing late this morning, ceilings should rise and become broken by midday, before scattering late today with additional mid-high clouds aloft as a relatively strong capping inversion keeps the area dry. Despite breezy conditions, highs will warm to between 85 to 90 degrees across much of the area. In addition, an MCS is forecast to drop south-southwest out of Southeast KS and The Ozarks right around sunrise as it follows the better instability. However, this activity will weaken through the day as it runs into said capping farther south and the loss of good low level inflow after prime mixing late this morning. I can't rule out isolated to scattered strong to severe storms along the immediate Red River Valley along a possible outflow boundary later this afternoon with instability being the main driver for localized downburst winds and large hail. The dryline across the Texas Panhandle and Western Oklahoma then becomes active late in the afternoon and continue into the evening hours, as a mid-level impulse lifts out across far West Texas during peak heating. As these storms propagate along the eastern edge of the extreme instability into our northwest counties just before sunset, we can expect the potential for damaging downburst winds and large hail to be a threat. By sunset and after, another strong southerly 35-45 knot low level jet will feed into these storms across Northwest and West-Central Texas. This feature will help to congeal convective activity likely into a broken line of severe storms, or possibly a couple of severe line segments as it moves into western North and Central Texas after dark. As this occurs, damaging winds to 70 mph will become the primary hazard along with locally heavy rainfall (totals between 1-2 inches) and minor flooding. Any embedded supercells within the line will still be able to produce some good size hail as well considering the steep mid level lapse rates between 7-8 Deg C within the hail growth zone. As this activity pushes east or southeast into the I-35 and I-20 corridors by midnight and after, it will eventually weaken as it moves into a more stable and capped airmass during the pre-dawn hours Saturday. Another factor will be the relatively weak deep layer northwest shear 25 knots or less. Another factor that will likely cause some demise in storm intensity and strength will be a linear storm complex exploding across South-Central and the Texas Coastal bend in response to a secondary shortwave lifting out from Mexico and across the Upper Rio Grand Valley and Hill Country. This more southern complex of strong to severe storms will likely intercept/interrupt the better moisture flux and southeasterly inflow within the 925mb-800mb layer. Despite the expected weakening trend of thunderstorms across much of our CWA, my feeling is strong to severe convection may continue along and south of the I-14 corridor all the way into daybreak Saturday due to this area and it's environment still be unstable and available for convection to feed off of. 05/ && .LONG TERM... /Issued 323 AM CDT Fri May 15 2020/ /The Weekend through Next Thursday/ The main weather headline in the long term forecast period will be the potential for widespread rain and thunderstorms...particularly on Saturday. Showers and a few storms may linger some into Sunday. Thereafter, generally rain/storm-free weather is anticipated. Ongoing showers and thunderstorms are expected at the start of the long term period as a slowly decaying Mesoscale Convective System (MCS) overspreads the region. A severe weather threat may persist as CAPE values may still be in the 1000-1500 J/kg range. The primary hazard would be damaging winds. Accompanying the damaging wind threat will be the potential for heavy rain. I'll discuss this a bit more later. Current thinking is that the complex will take on an increasingly north-south orientation and move toward the east and southeast. While weakening, this line should be expansive enough to induce a Mesoscale Convective Vortex or MCV...somewhere across Central TX. The MCV will be the impetus for heavy rain and a possible flood event somewhere between I-35 and the U.S. HWY 75/I-45 corridors. PWATs on Saturday will likely climb into the 1.4-1.6" range which is roughly 150-175% of normal. 30-60 day percent of normal rainfall for locations south of I-20 and east of I-35 reveal that above normal rainfall has been received across this region---though some short term drying has been noted over the last two weeks. The QPF remains tricky, but model guidance is starting to converge on a solution that places the axis of greatest rainfall likely near and east/southeast of a Cameron to Dallas to Sulphur Springs line. GEFS mean QPF shakeout to a 3" to 5" swath of rainfall Saturday into Sunday across the Brazos Valley and parts of East Texas with the deterministic ECMWF not being too far behind with its QPF. The NAM remains the excessively wet outlier with rainfall total (in the 4" to 6" range). While the NAM was largely disregarded, if the MCV evolves as suggested by this model, the deep easterly fetch through the 500mb layer, PWATs close to 175% above normal and skinny CAPE profile would foster convective cells supportive of rainfall amounts offered by the NAM in some capacity. HREF probability match mean QPF appears to offer a decent solution for PoPs/QPF and I've tailored the official forecast to mimic these trends. While it has been dry recently for parts of East Texas and the Brazos valley, the longer term rainfall analysis suggests that rainfall rates needed for efficient runoff processes may not need to be overly high. Given that the official QPF is closer to 2" to 3" across this area, we'll forgo any Flash Flood/Flood Watches, but we'll need to closely monitor this potential over the next couple of shifts---especially if the NAM solution appears more correct. That being said, I expect at least some minor to possibly moderate flooding along parts of the Trinity and Brazos River basins across parts of East and Central Texas. Rain and storm chances may linger into the day on Sunday near and ahead of a front. The best rain chances will reside across East Texas and Central Texas where an additional 1/4" to 1/2" of rain will be possible. After the weekend, it appears that the weather pattern across the Southern Plains will become less active, outside of perhaps diurnal showers/storms across the Caprock/Panhandles as an omega pattern should set up. With ridging overhead, high temperatures will climb closer to seasonal normals. At this time, it appears that the ridge will be strong enough to ward off any nocturnal MCSs that can sometimes sneak in underneath the upper ridge during this time of year. Bain && .AVIATION... /NEW/ /12z TAFs/ Concerns and challenges: MVFR cigs this morning becoming VFR before 18z. Exact timing of VCTS later this evening and best window for TEMPO TSRA. MVFR cigs BLO FL015 already has been at Waco Regional Airport a few hours and has surged north toward the Red River just E of DAL/GKY. I expect these cigs to expand west across most, if not all of DFW D10 airports through 15z-16z. All airports should rise into low VFR AOB FL050 by 18z, then eventually scatter in the lower levels with SCT-BKN150-300. I have maintained VCTS arriving between 03z-05z at all airports. Across DFW Metro airports, decided there was too much uncertainty to take a stab at a window for likely TSRA with so many scenarios possible. 18z TAFs and beyond will be able to better assess the more categorical TS impacts at all terminals. S/SE surface winds 10-15 knots with occasional gusts in excess of 20 knots will prevail through 02z- 03z, but a few models showing potential outflow boundary with a shift to E/NE at 10 knots possible. With uncertainty on evolution of any TS outflow this evening, will keep south flow prevailing at DFW. 05/ && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 89 68 80 66 83 / 20 80 90 30 10 Waco 89 68 79 65 82 / 20 80 90 30 20 Paris 83 67 77 64 78 / 40 60 70 70 30 Denton 88 68 80 65 83 / 30 80 80 30 10 McKinney 87 68 79 65 82 / 30 80 90 40 10 Dallas 88 70 80 67 83 / 20 80 90 30 10 Terrell 86 67 78 66 81 / 20 70 90 50 20 Corsicana 87 69 77 66 80 / 20 70 90 40 30 Temple 90 68 79 65 82 / 20 80 90 20 20 Mineral Wells 90 66 79 65 83 / 20 70 60 20 5 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$ 05/24