044 FXUS64 KSHV 020459 AFDSHV Area Forecast Discussion National Weather Service Shreveport LA 1059 PM CST Tue Dec 1 2020 .AVIATION... A front will approach from the west, bringing showers and ceilings lowering to MVFR in the 09-12z window at Tyler, Lufkin, and Longview. Showers will reach Texarkana and Shreveport in the 12z-15z window. VFR will continue to prevail through the morning hours at Monroe and El Dorado. Showers will increase in coverage through the day as they shift eastward and ceilings will lower to IFR everywhere except Monroe and El Dorado in the afternoon hours on Wednesday. Thunderstorms embedded with rain cannot be ruled out Wednesday afternoon at Lufkin, Tyler, Longview, and Shreveport with showers lingering across much of the area into Wednesday evening. /04-Woodrum/ && .PREV DISCUSSION... /issued 926 PM CST Tue Dec 1 2020/ UPDATE... The latest mid-level analysis indicates a 500mb ridge axis centered over the ArkLaMiss with a trough digging southward from the Colorado Front Range into the Texas Panhandle. At the surface, a 1009mb low is located over North Texas with a cold front extending southwest of this feature into West Texas. Locally, well ahead of the front, a southeasterly low-level flow is in place, aiding slowly warming dew points in the 20s and 30s after bottoming out in the teens and single digits in portions of the area earlier today. Some high cirrus is passing across the area this evening. Overnight, the trough will continue to move into North Texas while the surface low slowly slides eastward into Central Texas and the front occludes. An area of isentropic uplift will develop in warm air advection ahead of the occluded front, providing forcing for some showers to develop in East Texas and southeastern Oklahoma during the pre-dawn hours. This is supported by all 9 members of the SPC HREF with scattered showers developing. Rainfall amounts by dawn will be mostly light and less than a quarter of an inch. Temperatures cooling overnight will be countered by the southerly flow and increasing cloud coverage. The forecast is fairly close to the NBM with lows ranging from the mid 40s in East Texas and Deep East Texas to the lower 30s in the ArkLaMiss. /04-Woodrum/ PREV DISCUSSION... /issued 310 PM CST Tue Dec 1 2020/ SHORT TERM.../Tonight through Wednesday Night/ The increasing large scale ascent and cooling aloft associated with the upper trough will allow for showers and possibly a few embedded thunderstorms to gradually develop and expand across our western half through Wednesday morning. Convection will continue to expand farther east to encompass the remainder of the region through the afternoon hours with any threat of thunder primarily confined south of I-20 with the sfc low tracking closer to the coast. With all the cloud cover and convection, high temperatures will generally range from the mid and upper 40s north through the 50s farther south. Convection should gradually begin to diminish in coverage and intensity from west to east through the overnight hours on Wednesday night as the trough lifts farther north and east. However, some lingering light rain or drizzle will likely continue beyond that into early Thursday morning, especially across our NE half. Even with clouds and some lingering precipitation, overnight low temperatures will still drop into the mid to upper 30s to lower 40s by daybreak on Thursday as cold air advection increases. /19/ LONG TERM.../Thursday through Tuesday/ The closed low will drift NE into NE OK and the Ozarks Thursday and Thursday evening, with the attendant trough SW of the low expected to slide SE through Wrn and NCntrl TX. As this low lifts NE, a sfc trough/dryline will shift E through Srn AR/Ncntrl LA, exiting the region into the Lower MS Valley during the afternoon. Dry air entrainment beneath the low early Thursday morning should shift the majority of the early morning convection E of the area to start the period, although weak convergence along and just ahead of the sfc trough may yield isolated -SHRA over SCntrl AR/Ern sections of NCntrl LA during the morning before diminishing in the afternoon with the trough's departure. Have continued slight chance/low chance pops mention for these areas Thursday, with dry conditions returning Thursday night as drier air continues to advect farther NE of the H850 trough over the Ern zones. A stratocu field is progged to drop SE behind the H925-850 trough over E TX/Srn AR/much of N LA Thursday afternoon/evening, likely keeping a lid on temps falling to/below freezing Thursday night/Friday morning. The stratocu will likely linger through much of Friday, resulting in another day of below normal temps, but should clear from NW to SE during the late afternoon/evening with the upper trough's departure, allowing temps to settle down to near or below freezing areawide. A dry NW flow aloft will become established over the region through at least the first half of the weekend, with strong insolation and light W sfc winds resulting in a return to more seasonable temps areawide. Given the NBM's cool bias under such insolation, have trended max temps this weekend some 2-3 degrees above the NBM (but not as warm as the MEXMOS), before sfc ridging builds back SE into the area Sunday night/Monday. Although the ECMWF/Canadian have flip- flopped in regards to the overall synoptic pattern early next week than the more consistent GFS, all progs suggest dry conditions will continue through the end of the long term period (and possibly through the end of next week), as any Gulf inflow will remain cut off given the persistence of the sfc ridge over the region. Mild days and cold nights will continue, with temps near or slightly above the seasonal norms. 15 && .PRELIMINARY POINT TEMPS/POPS... SHV 41 52 38 52 / 10 90 70 10 MLU 32 58 42 55 / 0 40 80 30 DEQ 38 46 36 48 / 20 90 60 10 TXK 39 48 37 48 / 10 90 70 10 ELD 33 53 38 51 / 0 70 80 20 TYR 47 54 36 51 / 20 90 30 10 GGG 44 53 35 51 / 20 90 40 10 LFK 47 58 36 55 / 20 90 50 10 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 04/15/19