165 FXUS64 KLZK 100027 AAA AFDLZK Area Forecast Discussion...Updated for Aviation National Weather Service Little Rock AR 720 PM CDT Tue Oct 9 2018 .AVIATION... Showers/scattered thunderstorms in western Arkansas will gradually build into central/eastern sections of the state overnight and Wednesday. While there will be a lot of clouds, mainly VFR conditions are expected overnight, with some MVFR conditions in places. MVFR conditions will become more widespread toward dawn Wednesday as low clouds increase. A cold front will sweep through the region from the west on Wednesday, with conditions returning to VFR. Winds will be south/southeast at 6 to 12 mph overnight, and west/northwest at 10 to 20 mph Wednesday. (46) && .SHORT TERM...Tonight Through Wednesday Night A negatively tilted shortwave trough centered roughly over portions of southern Colorado and Kansas will continue pushing northeastward into the Central Plains and Midwest portions of the US through Wednesday night. As the upper level trough pushes northeast of Arkansas, a cold front will sweep through the state, leaving behind noticeably cooler temperatures for Wednesday afternoon/evening. This potent storm system was responsible for several severe thunderstorms and tornadoes across Oklahoma this morning, as a pre- frontal line of thunderstorms pushed northeastward through the state. Remnants of the QLCS are currently pushing eastward into portions of western Arkansas, but have weakened considerably as the better energy pulls northward. Additional convection has initiated across western Arkansas, but has yet to show any signs of significant growth or severe trends. However, before the short term period ends and the aforementioned front moves through, we will likely see several rounds of thunderstorms, some of which could be severe. Despite the upper level forcing pushing northward away from Arkansas, the LZK 18z upper air sounding shows over 3000 J/kg SBCAPE with effective SRH of 152 m2/s2. Therefore, severe weather should be possible with any thunderstorms that form. The western half of the state has the best chance of seeing strong to severe thunderstorms through the early morning hours on Wednesday. The main hazards continue to be strong and damaging winds, although given the CAPE profile from the LZK 18z sounding would not be surprised if we see some hail from the stronger thunderstorms. Additionally, there remains an isolated tornado threat, mainly across the northwestern portions of the state where there are better 0-1 km SRH values (around 200 m2/s2). Another threat will be localized heavy rainfall. The 18z LZK sounding shows PWAT values of 1.68 inches, which has increased from the 1.54 inches that was measured in the 12z LZK sounding this morning. This is mainly due to strong, southerly flow advecting warm and moist air up from the Gulf. Finally, the cold front should push east of the state by Wednesday evening, leaving behind drier and colder temperatures. Highs on Wednesday will range from the mid 60s across the north, to lower 80s across the south. Low temperatures overnight Wednesday will have a wide spread as well, with lower to mid 40s across the far north, and mid to upper 50s across the far south. && .LONG TERM...Thursday Through Tuesday A highly amplified upper pattern remains for the duration of the long term period. Not many changes made this update from the previous discussion. Model agreement among long term models is fairly decent through late Friday. Saturday, timing issues arise to overall evolution and timing of the upper trough, translating down to the position of the surface low. In the long term, will go with a blend of models to account for this, slightly in favor of ECMWF, until confidence levels increase. In summary, the coolest air of the season should overtake the state early in the period with a new storm system approaching by the weekend followed by possibly even cooler temperatures afterwards. Beginning the period on Thursday, in the upper levels, broad troughing is expected be situated across the Northern Plains with ridging over the Western Atlantic. Between these systems, SW to NE flow dominates much of the central and eastern CONUS. Tropical Cyclone Michael should traverse the flow between the trough to the west and the high to the east. Therefore, Michael's impacts as regards to rainfall or moisture will have no impacts here locally in our CWA. At the surface, a strong low pressure center will be located near the Great lakes region with a well defined frontal boundary extending southward through the TN valley towards the MS Gulf Coast. Ahead of the front, Tropical Cyclone Michael will be affecting the GA/SC/NC region. Behind the front, surface high pressure will be diving south out of Canada bringing much cooler and drier air to the region. Locally, temperatures and moisture levels begin to drop off nicely through late Friday. Highs during this time are expected to top out in the 60s and 70s with lows in the 40s and 50s. Heading into Saturday, the brief duration of zonal flow aloft from previous days begins to transition as an upper level trough digs S near the four corners region. Cyclogenesis begins to develop in lee of the Rockies. As the low deepens and moves E on Saturday, return flow of rich moist air overtakes the drier/cooler air that has been in place across AR. By Saturday evening, surface low approaches AR from the W, showers and thunderstorms are expected to develop as upper level vort max passes through the base of the trough supplying sufficient atmospheric lift in addition to lift from the deepening surface low over AR. Widespread severe weather is not anticipated at this time due to limited moisture return as evident on theta E map. PWATS should increase from around half an inch to around an inch and a half during this period. Trends will have to be monitored closely. On Monday into Tuesday, in the upper levels, the trough becomes positively tilted and quickly progresses into the nations mid- section. At the surface, rainfall will come to an end early on Monday as a cold front moves W to E across the AR. Surface high pressure is expected build into the region behind the front, possibly advecting some of the coldest and driest air of the season thus far into AR. && .PRELIMINARY POINT TEMPS/POPS... Batesville AR 81 69 79 51 / 40 70 80 0 Camden AR 84 72 83 55 / 50 80 60 0 Harrison AR 76 66 70 46 / 70 90 60 0 Hot Springs AR 80 71 78 53 / 60 80 60 0 Little Rock AR 82 72 80 53 / 50 80 80 0 Monticello AR 84 73 82 56 / 30 60 70 10 Mount Ida AR 78 68 76 50 / 70 90 50 0 Mountain Home AR 79 67 74 48 / 60 90 80 0 Newport AR 83 70 80 53 / 30 60 80 10 Pine Bluff AR 85 72 81 55 / 40 70 70 0 Russellville AR 80 70 77 51 / 70 90 60 0 Searcy AR 81 71 79 51 / 40 80 80 0 Stuttgart AR 84 72 81 54 / 30 70 80 0 && .LZK Watches/Warnings/Advisories...NONE. && $$ Short Term...CROSS / Long Term...JONES