570 FXUS64 KFWD 191251 AFDFWD Area Forecast Discussion National Weather Service Fort Worth TX 751 AM CDT Sat Oct 19 2019 .UPDATE... The vigorous shortwave that gave parts of the area some widely scattered, brief, elevated showers and storms this morning is quickly exiting the area. Meanwhile, a cold front continues to enter the far western CWA as of sunrise. I am removing the slight chances for storms in the far eastern counties and adding some patchy-areas of fog across our far southeast counties. South winds 5-10 mph winds in advance of the cold front has helped to advect rich low level surface dew points temperatures in the upper 50s to lower 60s across this area with stratus and some fog. Though isolated areas of dense fog are possible, I don't believe it will be widespread enough for any advisories this morning. This fog should be short-lived and begin dissipating readily after mid-morning, as strong insolation heats up surface temperatures rapidly. 05/ && .AVIATION... /Issued 655 AM CDT Sat Oct 19 2019/ /12z TAFs/ Concerns and challenges: FROPA 15z-18z will shift south winds around 10 mph to the west, then northwest 10-15 knots by 18z. Otherwise, VFR with no precipitation expected. A vigorous mid level impulse continues moving east of the airports this morning with just scattered mid-high level clouds in it's wake. Eventually, SKC conditions will prevail as a cold front arrives later this morning...putting DFW and DAL into north flow. Waco will likely see the wind shift a few hours later; or between 18z-21z. NW winds 10-15 mph behind the cold front later today are expected to become light N or calm after sunset tonight, as the dry boundary layer decouples rapidly and high pressure at the surface slides into the area. 05/ && .SHORT TERM... /Issued 350 AM CDT Sat Oct 19 2019/ /Today Through Tonight/ A vigorous mid level impulse is moving east across the CWA early this pre-dawn, Saturday morning. Low level southerly flow on area VWPs from local radars was impressive and currently southerly at 40-45 knots, which shows the influence this strong shortwave is having even on the dry, lower levels. GOES satellite imagery was even indicating a gravity wave shooting out well in advance of the elevated convection across Central Texas. Widely scattered, high- based and elevated showers and tstorms continue racing east across mostly the area from I-35 and to the east, where strong vertical motions are saturating and destabilizing the mid levels quite impressively considering the initial dry environment this system arrived into. Central Texas areas are a bit more displaced south, but isolated storms were occurring as far south as Cleburne and Italy in Johnson/Ellis counties per latest regional radar. I can't rule out isolated, short-lived elevated convection through mid- morning across the far eastern counties per the real-time data. In addition, pooling of relatively higher dew points > 60 degrees across parts of Milam, Robertson, and Leon counties may result in brief fog development from the Highway 6 corridor east toward I-45 around sunrise. I do not expect any impacts from any fog development with fog dissipating quickly by mid morning in response to rapidly warming temperatures and increasing surface wind speeds. Beyond mid-morning and in wake of this morning's shortwave disturbance exiting the area, we should see the cold front sweep readily southeast through the area through this afternoon. This front will mainly drawn in slightly drier air into the region with any thermal advection being negligible. Plentiful sunshine will prevail with highs warming into the upper 70s northwest to near 90 degrees across parts of Central Texas. It will be breezy from the I-35 corridor and points west where northwest winds 10 to 15 mph will contain occasional gusts to around 20 mph as momentum transfer with the boundary layer is easily achieved. A mostly clear and seasonably cool night is expected for your Saturday night as surface high pressure settles across the area. A good radiational cooling set up will occur as wind speeds come down quickly after sunset with decoupling of the dry boundary layer. Lows by Sunday morning are expected to be mostly in the 50s with near calm winds to start a day that will become much more active later on. 05/ && .LONG TERM... /Issued 350 AM CDT Sat Oct 19 2019/ /Sunday through Friday/ The cold front will stall out across South Central and Southeast Texas Sunday morning but as a longwave trough deepens over the Central part of the country, southerly flow will intensify over the region. The southerly flow and sunshine will certainly result in very warm temperatures as highs will reach the low 90s in the west to the mid 80s in the east. Elevated grass fire danger will occur across the western zones as RH drops to near 25% and surface winds increase to 10 to 20 mph. Moisture pooled on the south side of the front will return northward during the day but the primary forecast uncertainty is how much, how fast, and how deep will the moisture layer be by the early evening hours when synoptic forcing for ascent begins to impinge upon the region. The moisture quality will control whether the atmosphere can convect while temperatures are still warm enough from daytime heating to support surface based convection and a more substantial severe weather risk. This moisture layer looks to be very shallow west of I-35, but have more depth east of I-35. At this time most of the guidance does not show the moisture arriving fast enough for storms anywhere in the CWA Sunday evening, but a couple of the CAMs and the ECMWF do show it making it into the northeast zones where it juxtaposes with forcing for a risk of supercells and severe weather. Should this occur, all modes of severe weather would be possible with this activity between 6 pm and 10 pm Sunday evening mainly across the northeast zones. SPC has outlooked a part of the CWA in slight risk, but given the uncertain and highly conditional nature of this threat, that forecast may be a bit aggressive. With the loss of daytime heating temperatures will cool after sunset and CINH will increase over the entire area. However increasing forcing for ascent will attempt to remove the capping inversion and it is likely that once a cold front begins to plow into the CWA around midnight that we will see a line of storms develop along it. The line may initially be broken across the NW zones, but should fill in as it reaches the DFW Metroplex around 2 am. Have increased PoPs into the likely and categorical range for the entire CWA except for the NW zones. While deep layer shear and instability values are both squarely in the severe weather parameter space, the mode of the convection (a line parallel to the shear vector) should mitigate the severe weather threat. Still, some marginally severe hail or wind may occur with this line as it progresses through the CWA. Rainfall will average 1/10 of an inch in the northwest to over 1 inch in the east. Drier northwesterly winds on Monday will bring some cooler air into the region with highs topping out in the 70s in what should be a pretty nice day after any lingering morning rain/clouds exit to the southeast. Excellent radiational cooling is expected Monday night and temps will drop into the 40s for most locations. Gradually warming temperatures will occur Tuesday and Wednesday with pleasant weather prevailing in dry northwesterly flow aloft. The next system will noticeably impact our sensible weather on Thursday as a longwave trough amplifies and deepens over the Central US. There is a bit of uncertainty on whether this system will be progressive (ECMWF) or slower with a closed low at the base of it (GFS/GEFS). Either way it looks like a front will arrive on Thursday afternoon with a chance of showers and storms. Either the trough will be progressive and send colder air in here faster, or be slower and result in overrunning clouds/rain continuing into Friday. Both scenarios warrant lowering high temperatures Friday with temps possibly struggling to reach 60. Fear not, another pleasant Autumn weekend should follow. TR.92 && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 83 55 88 56 74 / 0 0 10 80 10 Waco 88 56 90 58 76 / 0 0 10 80 20 Paris 80 55 80 57 71 / 5 0 10 90 20 Denton 81 53 87 53 74 / 0 0 10 60 10 McKinney 82 54 86 56 73 / 0 0 10 80 10 Dallas 84 58 88 57 74 / 0 0 10 80 10 Terrell 84 55 88 59 74 / 0 0 10 90 20 Corsicana 86 57 86 59 73 / 5 0 20 90 30 Temple 88 58 89 59 76 / 0 0 20 70 30 Mineral Wells 81 52 89 53 74 / 0 0 10 50 5 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$ 05/92