Scientific Forecaster Discussion
000 FXUS64 KFWD 122325 AFDFWD Area Forecast Discussion National Weather Service Fort Worth TX 525 PM CST Tue Dec 12 2017 .AVIATION... Northwest winds are beginning to subside this evening as a broad surface high builds into the region. By 9-10 PM, winds will return to the WSW where they will remain through Wednesday morning. SW winds will increase by midday Wednesday to 12-17 kts in advance of another dry cold frontal passage Wednesday evening. Have introduced the front's northwest wind shift in the extended DFW TAF. Otherwise, VFR conditions will prevail with only FEW/SCT high cirrus. -Stalley && .SHORT TERM... /Issued 322 PM CST Tue Dec 12 2017/ /Tonight/ Calm weather is in store tonight, with northerly winds subsiding to around 5 mph across North and Central Texas. Southwesterly winds will return after midnight, still remaining around 5 mph. The low wind speeds, clear skies and relatively dry air will allow for temperatures to drop from the 30s to around 40 degrees across the region. Slightly higher elevated moisture will stream into Central Texas during the pre-dawn hours on Wednesday, leading to a few clouds to start out the day. Hernandez && .LONG TERM... /Issued 322 PM CST Tue Dec 12 2017/ /Wednesday through Monday/ A split flow pattern will continue across the region through the end of the work week with an upper ridge along the West Coast, an upper low over Baja California and a progressive but dry northwest flow regime over the Southern Plains. A shortwave (currently located over Alberta) will race southeastward through the Plains Wednesday, which will send a cold front through North and Central Texas Wednesday night. After a chilly day today, a return to west winds and compressional warming ahead of the front will lead to a rapid warm-up Wednesday afternoon, and we have sided with the warmer end of guidance as a result (similar to Monday). West winds and good mixing means that we have also gone with the drier side of guidance, and another elevated fire danger day is expected as minimum RH values fall into the teens Wednesday afternoon. Conditions will improve by sunset Wednesday as winds slacken and temperatures fall. The front will move quietly southward through the area Wednesday night, and another cool and breezy day can be expected on Thursday. A second and stronger shortwave will swing southeast through the Plains late Thursday into early Friday, sending a reinforcing shot of cool air southward and keeping Friday's temperatures a few degrees below Thursday's readings. The dry and breezy weather will keep fire danger elevated on Thursday and Friday, but the cooler airmass should hopefully help to mitigate the overall threat. A slight westward shift in the upper level pattern this weekend will send a third and yet stronger shortwave southeast from the Great Basin into the Four-Corners area on Saturday. The system will be far enough west to grab the Baja low and sling it quickly northeast across Mexico and Texas Saturday and Saturday night, then into the Tennessee Valley on Sunday. Models are in better agreement now and are indicating a faster and more moist system than previous runs. We haven't jumped on board with the likely and categorical POPs (across the eastern counties) as advertised by the ECMWF, but an upward adjustment to the POPs have been made for the Saturday / Saturday night timeframe based on model trends. The increase in low level moisture will also help to reduce fire danger, though the western counties will still experience an elevated fire threat where moisture return will be limited and the warmest air will exist. Yet another cold front will push through on Sunday, bringing a return to cool and dry conditions during the early part of next week. 30 && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 40 73 40 59 37 / 0 0 0 0 0 Waco 32 69 39 60 36 / 0 0 0 0 0 Paris 34 69 37 55 32 / 0 0 0 0 0 Denton 33 74 37 58 34 / 0 0 0 0 0 McKinney 34 72 37 57 34 / 0 0 0 0 0 Dallas 40 72 41 59 38 / 0 0 0 0 0 Terrell 32 70 38 59 34 / 0 0 0 0 0 Corsicana 34 67 40 59 35 / 0 0 0 0 0 Temple 33 67 40 61 36 / 0 0 0 0 0 Mineral Wells 33 76 36 58 33 / 0 0 0 0 0 && .FWD WATCHES/WARNINGS/ADVISORIES... None.