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Displaying AFOS PIL: AFDFWD Received: 2018-08-20 09:06 UTC
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152 FXUS64 KFWD 200906 AFDFWD Area Forecast Discussion National Weather Service Fort Worth TX 406 AM CDT Mon Aug 20 2018 .SHORT TERM... /Today and Tonight/ The main concern in the short term forecast will revolve around rain chances and temperatures. It appears that Central Texas will have the best opportunity for showers and a few storms this morning and into the afternoon. While the temperature contrast across the front will remain low, north winds will usher in drier air--making it feel a bit more pleasant for North Texas. Central Texas will likely see another day of hot conditions. A couple of outflow boundaries were noted this morning across parts of North and Central Texas. Most of these boundaries remain in response to convection that occurred on Sunday and again early this morning. The main synoptic front was actually being sampled by the WSR-88D network and was located near the I-44 corridor as of 330 AM. While the temperature gradient along the front is quite weak, there is nearly a 7-8 degree change in the dewpoint temperature, with mid to upper 50s degree dewpoints across western Oklahoma. Through the day this drier air should spill southward as the surface pressure gradient upstream tightens on the backside of a low across the Missouri River Valley. As the front advances, there will theoretically be a threat for showers and a few thunderstorms along and ahead of the boundary where surface dewpoints remain in the upper 60s to low 70s. Additionally, pockets of better convergence may exist where the main front interacts with outflow boundaries. I've carried a 15 PoP with a mention of showers and an isolated thunderstorm or two for most areas to address this potential for rain/storms. Most areas within the 15 PoP will remain rain-free. The better risk for more concentrated rain/thunder activity, however, will actually be across Central Texas where a modest conveyor of isentropic ascent along the 300 K theta surface is forecast. The front should sweep through most areas by this afternoon, except for Central Texas. Rain/thunder chances will remain highest here (around 20 to 30 percent) in the afternoon. There will be a risk for strong to near-severe storms given the large DCAPE values and hot conditions. The veered low level flow ahead of the front will be the main culprit for these hot conditions and afternoon highs should climb into the upper 90s to near 100 degrees. Heat index values may climb to or just above 105 degrees across Central Texas. Despite these numbers, a Heat Advisory is not expected given that 1) Peak heat index values were just below 105 on Sunday afternoon and 2) Heat index values on Tuesday should be lower as drier air overspreads the region. Regardless, individuals across Central Texas should remain vigilant and continue to exercise their heat safety rules. Elsewhere, a light northwesterly breeze is forecast behind the front which should result in continued warmth (due to slight downsloping), but slightly more pleasant conditions due to the drier air. High temperatures behind the front will still manage to climb into the low to mid 90s. By this evening, the front should have cleared most of Central Texas with clearing skies. The low moisture content and light winds overnight should promote modest radiational cooling and allow temperatures to fall into the 60s and low 70s. Bain && .LONG TERM... /Tuesday through Sunday/ Postfrontal daytime temperatures have been 10 to 20 degrees below normal across the Central Plains, but the main thrust of cold advection will chase the departing upper low into the eastern U.S. Deep northerly flow will continue across North and Central Texas on Tuesday, but the weak surface winds will provide negligible cold advection. However, dew points will fall by 10 degrees or more. With abundant sunshine, the light winds and the reduction in humidity will only help buoy daytime temperatures. Highs will be near normal along and north of the I-20 where the postfrontal advection will be maximized, but portions of Central Texas may flirt with the century mark Tuesday afternoon. Despite the warm temperatures, the lower humidity will take the edge off the heat. In addition, evening temperatures will fall more readily, and daybreak temperatures Tuesday through Thursday will be quite pleasant for August. Our frontal boundary will begin to retreat/erode during the middle of the week, with the onset of return flow across the Big Country as early as Wednesday. While this might suggest the potential for some warm-frontal isentropic lift, with intensifying ridging aloft, this should be limited to a few clouds. Southerly winds will ensue regionwide by Thursday, with a steady increase in Gulf moisture thereafter. The humidity may slow the warming trend, but with ridging anchored over the Lone Star State, triple digits should pepper the region late in the week. Even with tropical moisture in place, the increasing length of night should allow most areas to fall into the mid 70s for morning lows (though inner-urban areas in the Dallas/Fort Worth Metroplex may see lows near 80F). Extended guidance is hinting that the ridge may shift to the east this weekend, which would tap the brakes on the temperatures while opening the possibility for coastal convection to approach from the southeast. For now, will maintain a dry forecast for the final weekend of August. 25 && .AVIATION... /Issued 1147 PM CDT Sun Aug 19 2018/ A weak cold front extends along a line from Bonham to Breckenridge while moving slowly southward this evening. Interaction between the front and outflow from earlier convection is currently generating additional thunderstorms west of area TAF sites. There is a low chance that isolated convection may occur near the Dallas-Fort Worth area airports during the overnight hours as the front approaches, but with such a low probability, will stick with VCSH in the 06Z TAFs at this time. The primary impact will be the wind shift as the front pushes through the Metroplex around daybreak. Wind speeds will not be all that impressive, but should be enough to affect DFW departures and arrivals due to the northwesterly direction. The front will continue to work its way south, making it through KACT late Monday morning along with a few showers and perhaps an isolated storm possible. Otherwise, VFR conditions will rule through the end of the forecast period. 30 && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 95 73 96 72 95 / 20 5 0 0 5 Waco 100 73 99 73 98 / 20 5 5 5 5 Paris 91 67 92 67 90 / 20 5 0 0 5 Denton 94 67 95 70 93 / 5 5 0 0 5 McKinney 94 68 94 69 93 / 20 5 0 0 5 Dallas 96 74 96 72 95 / 20 5 0 0 5 Terrell 95 70 95 71 94 / 20 5 0 0 0 Corsicana 99 74 97 70 96 / 20 5 5 0 0 Temple 99 74 99 73 99 / 30 10 10 5 5 Mineral Wells 94 68 96 70 95 / 5 5 0 5 5 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$ 24/25