759 FXUS64 KFWD 021845 AAB AFDFWD Area Forecast Discussion...UPDATED National Weather Service Fort Worth TX 1245 PM CST Sun Feb 2 2020 .SHORT TERM... /NEW/ /Through Monday/ The day began with temperatures in the 40s, but this nocturnal boundary layer was paper-thin. The 12Z RAOB from KFWD showed 68F at 1200ft AGL, extraordinary for early February. This shallow cool layer has already been eliminated by the abundant sunshine, and temperatures have reached the 70s at midday. Deeper mixing will now ensue, which will slow the temperature climb the remainder of the afternoon. However, with 850mb temperatures as much as 10C above normal and downsloping southwesterly winds at the surface, the mercury may approach or even top 80F in some spots, particularly along and west of the I-35 corridor. Temperatures will rapidly cool this evening in the dry air, but a powerful low-level jet will keep the boundary layer well above normal early Monday morning. This southwesterly fetch will be largely a land breeze, with an anticyclone over the Gulf preventing onshore flow. But as the upper low off Baja taps into moisture from the tropical Pacific, mid and high clouds will steadily increase. A pair of impulses embedded in the flow will bring some low rain chances to the region during the daylight hours Monday. These precipitation processes will be occurring in mid-levels; and with very dry air in the 2-mile deep sub-cloud layer, measurable precipitation is unlikely. Thunder may accompany this activity across Central and East Texas; but even there, any rainfall should be scant. The increase in cloud cover will shave a few degrees off high temperatures, but gusty south winds and a head start to the day will still allow highs to top 70F once again on Monday. 25 && .LONG TERM... /Issued 254 AM CST Sun Feb 2 2020/ /Monday through Next Weekend/ An unsettled weather pattern is in store this week with increasing confidence of winter precipitation across a decent portion of the region Tuesday night-Wednesday, followed by much colder conditions area-wide through Thursday. An upper low currently located off the western Baja California coast will be kicked northeastward across Texas late Monday by a deepening trough over the Rockies. Increasing moisture and ascent associated with the system will result in scattered showers and a few thunderstorms Monday afternoon into Monday night, primarily for areas east of the I-35 corridor. Limited instability will keep the threat for any severe thunderstorms low, though a storm or two may be capable of small hail. Meanwhile, the deepening trough to the west will aid in the southward surge of a much colder, modified arctic airmass along the eastern flank of the Rockies. This frontal boundary is slated to push through North and Central Texas on Tuesday, dropping temperatures into the 40s and 50s Tuesday afternoon, then into the 30s Tuesday evening. Wind chills will plummet into the teens and 20s late evening and overnight as north winds increase to 15-25 MPH with higher gusts. Isolated convection is possible along the front, but the dense, shallow airmass will most likely outrun any storm which attempts to develop, mitigating the strong-severe potential. That said, a storm or two may be strong enough to generate small hail and gusty winds. The position of the trough to our west will place North and Central Texas in a region of strengthening isentropic lift Tuesday night. Scattered to numerous showers are expected area-wide, with precipitation transitioning briefly to freezing rain across the northwestern third of the area late evening as temperatures drop below 32. Cold air aloft should then spread in fairly quickly as the trough begins to shift eastward after midnight. The operational GFS continues to be the most aggressive with both cold air and moisture, and brings a swath of significant snowfall along and north of the I-20 corridor. The 00Z run of the NAM12 is similar with the thermal profiles to the GFS, but keeps the moisture farther north and west. Overall, confidence has increased that measurable snowfall is likely somewhere across the northern portions of the forecast area, but specific amounts and exact areas remain uncertain. In general, accumulations for Tuesday night-Wednesday have been nudged upward, but still remain below blended guidance values being that we are looking at days 3 and 4 of the forecast period. We have, however, introduced snow totals of a quarter inch or less in the DFW Metroplex, with any higher totals likely remaining to the north and/or west. Even if amounts remain light, the strong cold air advection in place may allow for some roads to still be affected, so travelers/commuters are urged to keep up with the latest forecast updates as we enter the work week. In general, accumulations and impacts become less likely the farther southeast you go. Precipitation will shift east of the area during the day Wednesday, with activity coming to an end overnight Wednesday night. Cold air will remain, however, with all zones likely falling below freezing by daybreak Thursday. The coldest air will occur across the northwest counties where lows should reach the lower 20s. Skies will become mostly sunny on Thursday as the upper trough axis moves east of the area and subsidence enters in its wake. It will still remain cold as the dense arctic lingers, and highs should stay mainly in the 40s. Zonal flow aloft and return flow at the surface will bring much warmer air Friday through next weekend, with rain chances returning late next weekend or early the following week. 30 && .AVIATION... /NEW/ /18Z TAFs/ Continued VFR with S/SW flow. Low rain chances mainly south and east of TAF sites. Mid and high clouds will steadily increase through Monday. A strong southwesterly low-level jet will be free of clouds, but winds in excess of 50kts may dip below FL020 early Monday morning. Some of this momentum will reach the surface by mid-morning, the initial gusts likely being the strongest, but gusty south winds will continue Monday afternoon. Rain from high-based showers are more likely to reach the ground south and east of our TAF sites, but virga may introduce sub-cloud turbulence FL050-100. Although still well beyond the scope of the TAFs, a strong cold front will arrive Tuesday afternoon, shifting the wind to the north. 25 && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 77 55 71 57 65 / 0 0 20 20 20 Waco 78 54 71 59 72 / 0 0 30 20 20 Paris 75 53 68 58 63 / 0 0 20 40 50 Denton 77 53 72 54 61 / 0 0 10 20 20 McKinney 76 54 70 57 64 / 0 0 20 30 40 Dallas 78 56 72 58 67 / 0 0 20 20 30 Terrell 76 56 71 59 67 / 0 0 30 30 40 Corsicana 76 56 71 61 71 / 0 0 40 30 40 Temple 78 54 70 60 74 / 0 0 30 20 10 Mineral Wells 79 53 73 52 59 / 0 0 20 10 10 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$ 25/24