773 FXUS64 KFWD 051739 AFDFWD Area Forecast Discussion National Weather Service Fort Worth TX 1139 AM CST Tue Dec 5 2017 .UPDATE... The brisk winds of change are upon us as last night's strong cold front continues to plow southward towards the Gulf Coast. Breezy north winds will persist today, but will gradually diminish later this evening and overnight as the pressure gradient relaxes. Interestingly, lower-level cold advection isn't all that pronounced across the region in the wake of the front, with the core of the strongest CAA displaced to our north and east. Still, the stout north winds and dense cloud cover will help hold the diurnal temperature range in check across our northern and western counties. Bumped temperatures up a few degrees into the upper 50s across our Central Texas counties based on latest temperature trends. We'll leave a very low mention of a shower across the south and east where weak isentropic upglide will persist. This evening and overnight, isentropic upglide focused near 305-310 K will increase as a disturbance currently dropping through the Great Basin approaches the region. As this lift encounters moisture above 700 mb, light precipitation is expected to develop. Very dry air below this level will create an environment conducive for cooling due to diabatic effects as initial precipitation evaporates. While temperatures everywhere are expected to remain above to well above freezing tonight and into Wednesday, wet bulb zero heights are expected to fall to under 2 kft or so, and this could support a potential for some very light sleet mixing in with rain as far north as the I-20 corridor based on this morning's model guidance. This mention of very light sleet has been added to the forecast after midnight tonight west of I-45 and south of a Graham to Rockwall line. We'll stress again, however, that above-freezing temperatures mean any impacts from wintry precipitation will remain extremely minimal. Updated products have been sent. Carlaw && .AVIATION... /Issued 600 AM CST Tue Dec 5 2017/ 12 UTC TAF Cycle Concerns---Potential for rain showers at all TAF sites. Potential for turbulence beneath showers. Light rain showers will continue at Waco over the next couple of hours before dry air overspreads from the north. Farther north at the Metroplex TAFs, the threat for showers this morning will be low, but non-zero. Mid-level clouds between FL070 and FL120 will continue to overspread the area. Northerly winds of around 10 to 15 knots will continue. There is a risk that wind gusts may approach 25 knots later this afternoon. Winds will subside around and after 00 UTC Wednesday. Stronger lift will overspread from the southwest this evening and into early Wednesday increasing rain chances. There will be a potential for turbulence beneath rain showers at all TAF sites. With better low level moisture across Central TX, I've added a mention of VCSH during the mid-evening hours with -SHRA from midnight through 12 UTC at Waco. There's a potential for -RASN at Waco, but for now, the better risk for this appears just outside of the 12 UTC TAF cycle. For the Metroplex TAF sites, low levels will be slightly drier and warmer and rain showers should be more scattered in nature. Showers across D10 should diminish in areal coverage after 12 UTC for the D/FW extended TAF. 24-Bain && .SHORT TERM... /Issued 349 AM CST Tue Dec 5 2017/ /Today and Tonight/ A cold front continues to slice southward through Central and East TX as of 3 AM. This feature will likely continue to generate showers (though a rumble of thunder or two cannot be completely ruled out) across the aformentioned geographical area through at least noon today. There could be a few light rain showers or sprinkles farther back to the northwest, but widespread rain isn't expected today near the I-20 corridor. From mid-morning through noon, it appears that large scale lift shuts off for much of the afternoon hours which only supports a low chance for light rain showers across Central and East TX. After a day of record warmth for some areas, conditions will be noticeably cooler today! Mid-level cloud cover in tandem with northerly winds should keep most highs across most areas in the 50s. A few spots across western and northern zones may only climb into the upper 40s for high temperatures. For tonight, isentropic lift along the 310K theta surface should overspread from the west and southwest. While the lift is respectable in magnitude, low levels will remain parched, at least initially. This should mean that much of what falls should be in the form of virga early in the evening. As the low levels slowly saturate through the late evening and into the nighttime hours, the chances for more widespread measurable precipitation increases. I've reflected this thinking in the grids and at this time it appears as if areas south of I-20 will have the better probability of measurable rain. Forecast soundings, particularly for locations near and west of highway 281, do suggest that a few snowflakes or sleet pellets could mix in with the light rain as evaporative effects help to cool the column sufficiently. Currently, no impacts are expected due to recent warmth and surface temperatures remaining in the mid to upper 30s. 24-Bain && .LONG TERM... /Issued 349 AM CST Tue Dec 5 2017/ /Wednesday through Tuesday/ Wednesday is likely to be the coldest day this week across North and Central Texas and could feature some mixed wintry precipitation across parts of Central Texas through the afternoon. The cold front that came through last night will be well south of the area at the start of the day, but extensive cloud cover will be present with temperatures generally in the mid to upper 30s to start the day. A broad area of moderate to strong mid level isentropic ascent will be ongoing from deep south Texas well into North Texas Wednesday morning. This will result in extensive northward moisture transport atop the cool air already in place. A large area of light to moderate precipitation is expected to be ongoing or in the process of rapidly developing around 12Z Wednesday across much of Central Texas. Precipitation should eventually become focused along and east-west oriented band of strong 700mb frontogenesis by midday. The coarser resolution models have this band set up generally from Lampasas to Temple/Killeen and eastward with most of the precipitation extending from the Waco area southward into Central Texas. The higher resolution guidance is a little farther north with the precipitation, however, it is a safe bet that most of the precipitation will be focused across our southern counties. As we go through the day Wednesday, an upstream shortwave will dig through the Central Plains amplifying an already large trough over all of the eastern CONUS. As it does, a broad area of stronger forcing for ascent will spread into Central Texas. This area will also be in a favorable quadrant of an 130 kt upper jet located across north and northeast Texas. Through the day, thermal profiles will continue to cool. Initial precipitation during the morning hours may initially fall into relatively dry air below 800mb but this is expected to saturate fairly quickly by mid to late morning. Forecast soundings from the Waco area southward through Bell county and westward to Lampasas and Mills counties become cold enough by midday to support snowfall production with a deep saturated layer above 900mb. Surface temperatures are expected to remain above freezing through the day across the entire region, and there are some questions as to how cold the lowest 100mb or so above the surface get, but overall it looks like a good bet that some areas will see at least a little snow or sleet mix in with light rain during the day Wednesday. This favored area would again be from Goldthwaite to Waco and south to Temple/Killeen and Lampasas. As far as impacts are concerned...temperatures at the surface are expected to remain in the mid/upper 30s which will support melting of any frozen precipitation. At this time, it appears that no significant impacts would be expected other than some minor accumulations on grassy surfaces in the coldest areas. Temperatures are expected to remain in the mid/upper 30s across our southwest counties on Wednesday and will warm into the 40s and lower 50s farther north. Areas near the Red River may be the warmest, especially if the clouds clear faster than currently forecast. Temperatures Thursday through the upcoming weekend will be near or slightly below climatological normals as a large trough remains in place across much of the central and eastern U.S. Clouds are expected to clear Wednesday night and it should remain clear through the end of the week. Dunn && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 55 40 49 35 53 / 5 30 10 0 0 Waco 59 36 37 33 51 / 40 40 60 30 10 Paris 50 37 52 33 47 / 10 10 5 0 0 Denton 52 36 47 32 49 / 5 20 5 0 0 McKinney 52 36 51 33 50 / 5 20 5 0 0 Dallas 55 41 51 35 51 / 5 30 10 0 0 Terrell 54 38 49 34 53 / 10 30 10 5 0 Corsicana 57 40 40 34 54 / 50 40 40 20 5 Temple 58 39 39 34 52 / 40 40 80 40 20 Mineral Wells 51 36 44 30 48 / 5 30 20 5 0 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$ 90/82