446 FXUS64 KSHV 021539 AFDSHV Area Forecast Discussion National Weather Service Shreveport LA 939 AM CST Sat Mar 2 2019 .UPDATE... Removed morning fog out of a large portions of the area, although left fog in for remainder of the mrng for portions of ne TX, mainly west of hwy 59. Have made no other changes attm./07/. && .PREV DISCUSSION... /issued 628 AM CST Sat Mar 2 2019/ AVIATION... IFR cigs areawide with patchy mostly mvfr vsbys in drizzle/fog. Expect slow improvements to mvfr cigs by 02/18z. NE-E winds will continue around 5 kts thru most of the 03/12z fcst cycle. Cigs will begin to lower to low mvfr to ifr by around 03/03z. Expect widespread rain with ifr cigs and vsbys to begin btwn 02-06/-09z across the area from the nw. Some embedded tstms possible but aside from klfk, not mentioned in TAF's attm./07./ PREV DISCUSSION... /issued 424 AM CST Sat Mar 2 2019/ SHORT TERM.../Today through Sunday/ Low level moisture continues to hang across the region this morning which has resulted in patchy fog across the region along with some patchy drizzle. A bit of a range in temperatures this morning with low 40s north of Interstate 30, where the drier air has been in place, and lower 50s across Deep East TX and Central Louisiana, where the moisture is a little deeper. Patchy fog and drizzle will continue through mid morning, with some possible light rain south of Interstate 20, where the deeper moisture is located. Models suggest there will be a break in the rain today from Noon through the late afternoon, however clouds and below normal afternoon temperatures will hang around the region. Highs today will run from the low 50s north of Interstate 30 to low 60s across Deep East TX and Central Louisiana. As we move into the late evening and overnight hours, a weak disturbance will move across the region resulting in showers and isolated thunderstorm development across the region. Effective bulk shear will approach 40 kts along with some marginal lapse rates and low freezing heights which could result in some marginal severe hail in some isolated locations. SPC has issued a Marginal Risk to highlight this possibility. Widespread showers/t-storms will return again on Sunday as weak surface low will move across East TX/North Louisiana dragging a strong arctic front across the region. Winds will shift to the NW behind the front and temperatures will fall throughout the day. With moderate instability (SB CAPE 1000-1500 J/kg) along with strong shear (50-60kt 0-6km) across central Louisiana, some strong to severe storms will be possible Sunday morning into the early afternoon across a corridor between Natchitoches-Grant-Caldwell- LaSalle parishes. The primary threat will be damaging winds, but an isolated tornado threat could also be possible. The front will clear the region by the late afternoon hours, and drier arctic air will continue to push into the region. /20/ LONG TERM.../Sunday Night through Friday/ Cold, arctic air will continue to spill S into the region Sunday night in wake of the fropa earlier in the day, with the short term progs in good agreement this morning with the shortwave trough exiting the area to the E, and the H850 trough quickly shifting E into SE TX/S LA. Although cold advection will follow the front, the progs depict considerable post-frontal cloud cover which will linger through the overnight hours Sunday night. In addition, this air mass will initially be shallow, with cold air damming around the higher terrain of the Ouachitas delaying the onset of the coldest air until later in the day Monday. Thus, have trended a bit warmer than the Blended guidance and closer to the MOS numbers for min temps Sunday night, with additional elevated cloud cover expected to increase from the W Monday once the lower level moisture erodes. The GFS is suggesting this morning that weak isentropic lift within this elevated moisture lyr might result in some areas of IP across the region, but sfc temps are expected to remain well above freezing, this no accumulation is expected. The GFS/ECMWF are in good agreement with another shortwave trough rounding the broad longwave trough over the Plains/MS Valley Tuesday, which will reinforce much drier air Swd Monday night/Tuesday morning, with the coldest (subfreezing) nights in the forecast period expected Monday and Tuesday nights with the arctic ridge settling S into the region. Temps should begin to gradually moderate by midweek as the sfc ridge begins to shift E of the region. In fact, the GFS/ECMWF remain consistent with earlier runs with low level moisture quickly advecting NE into E TX Wednesday evening, and across the remainder of the region Thursday morning. The low level moisture profile is progged to continue deepening Thursday along a SWrly LLJ, such that isolated warm advection SHRA will be possible over the Wrn half of the region, before expanding across the remainder of the area Thursday night. Have continued the trend with the previous forecast in maintaining slight chance pops Thursday, before raising pops to low chance Thursday night areawide. However, the models diverge significantly thereafter with the ECMWF the outlier in developing/expanding the warm sector N to near the Red River Valley of Srn OK/N TX into the Nrn sections of SW AR Friday, whereas the GFS/Canadian continue to suggest a weak cold front sliding SE through the area Friday/Friday before pulling up stationary over Deep E or SE TX/Cntrl or Srn LA. Have trended the end of the extended closer to the GFS/Canadian blend given its run to run consistency, thus maintaining chance pops Friday before diminishing with the fropa Friday night. However, with the very low amplitude noted in the mostly zonal flow over the Srn Plains/Lower MS Valley, it remains to be seen whether this front will have enough of a push from the attendant shortwave troughing over the Plains/Midwest by the end of the week. && .PRELIMINARY POINT TEMPS/POPS... SHV 59 50 50 33 / 20 70 70 10 MLU 59 51 53 32 / 20 70 70 10 DEQ 53 45 46 25 / 30 70 70 10 TXK 53 45 46 28 / 30 70 70 10 ELD 57 46 47 28 / 20 70 70 10 TYR 55 47 48 30 / 30 70 70 10 GGG 57 49 50 33 / 20 70 70 10 LFK 61 56 57 38 / 20 70 70 10 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$