997 FXUS64 KJAN 271036 AFDJAN Area Forecast Discussion National Weather Service Jackson MS 436 AM CST Sun Jan 27 2019 .DISCUSSION... Today and tonight... Longwave troughing will remain situated across much of the eastern part of the CONUS through tonight. A mid-level shortwave trough will move through today, which will bring some additional cloud cover but no rain is expected. Temperatures across the region today and tonight will be about average for this time of year, if not just a tad above average. Highs will be in the mid to upper 50s and some lower 60s with overnight lows dropping into the upper 30s tonight. /28/ Monday through Tuesday: Quite the change in airmass is in store for us over the beginning of the week, with the potential for impactful winter weather as well. During the day Monday a surface low will track eastward toward the southern Great Lakes with an attendant sharp cold front extending southwestward into the ArkLaTex by midday. Ahead of this front, rather mild conditions can be expected here. The daytime hours will be dry across the vast majority of the forecast area, though showers ahead of the front will approach the Delta by sunset. Monday night the front will track southeastward across the area, likely clearing the Pine Belt by daybreak. A somewhat narrow band of rain showers will accompany the front, with a broader corridor of post frontal precipitation following. The change in temperature behind the front will be drastic given the polar nature of the airmass accompanying it. This should lead to a quick transition to wintry precipitation (primarily snow) behind the front, beginning across the Delta around or slightly before midnight, then during the overnight hours across much of the remainder of the area. The transition near the Pine Belt may occur closer to daybreak Tuesday. Any scenario involving a colder airmass chasing the back edge of precipitation in our area is tricky at best. Given the lack of any notable frontal wave/mesolow expected to move along the front, it doesn't appear likely for wintry precip to last more than 2-3 hours. In addition, antecedent ground temperatures will be quite warm. Nevertheless, SREF mean snowfall totals have been trending upward in many locations, and these were used as a base for this forecast's amounts. We still anticipate the highest amounts will be roughly over the northern 2/3 of the area, but accumulating snow is possible areawide. The very sharp drop in air temps should help make up somewhat for warm ground temps. Some individual guidance does suggest locally higher totals mainly in the northeast/eastern portions of the CWA, but given the inherent uncertainty with this particular setup, I feel it would be most prudent to use a more conservative starting point, then hone details as confidence increases closer to the event. There has been a trend in recent model runs to show more of a gradient in amounts over the far western portions of the CWA, so some slight downward adjustments were made in that area to reflect that. We are now within the time window we could consider posting a watch, but confidence is not high enough in a specific area for us to proceed with one quite yet. With respect to impacts, we could see snow covered roads, particularly on elevated surfaces, in many areas by sunrise Tuesday. I felt the previous shift was very astute in recognizing there could be a flash freeze of sorts, even in areas that don't see greater snow amounts, given the abrupt fall in temperature. We will only make minor adjustments to the elevated/limited areas in the HWO/graphics to continue to highlight the potential for travel impacts. Tuesday will be a rather cold day as strong cold advection persists through the morning. Any snow cover that exists will help hold down temperatures. Wind chills in the teens will be possible, especially north of I-20, throughout the morning hours. Winds will calm considerably by Tuesday night with mostly clear conditions setting the stage for a hard freeze in many areas. Wednesday through Saturday: We'll finally see a large scale pattern transition over the latter half of the week as the longwave upper trough shifts eastward off the Atlantic coast and is replaced by upper ridging in the northern stream of the jet. The southern stream will remain oriented more zonally from northern Mexico through the northern Gulf. Wednesday should be dry and cool as a surface ridge moves across the region, though there could be an uptick in clouds accompanying a weak reinforcing front. Heading into Thursday, a surface cyclone is expected to develop over the NW Gulf and track eastward across the Gulf through Friday. There's some model disagreement with respect to how far north precip will develop with this system, as the Euro remains more suppressed keeping things drier over our area. For now, we'll maintain isolated to scattered POPs Thursday into Friday, then tweak as the system gets closer. /DL/ && .AVIATION... 06Z TAF discussion: VFR conditions are expected through the period. Winds will be light to calm overnight but resume a westerly to northwesterly direction around 5kts on Sunday. /28/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 59 38 64 27 / 10 0 2 85 Meridian 59 37 63 31 / 10 0 2 85 Vicksburg 59 39 65 27 / 9 0 5 85 Hattiesburg 61 38 67 34 / 5 0 2 79 Natchez 59 40 66 30 / 10 0 4 85 Greenville 56 38 61 25 / 6 0 19 85 Greenwood 57 39 63 23 / 6 0 9 83 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ DL/28