Scientific Forecaster Discussion
000 FXUS64 KMEG 180539 AAA AFDMEG Area Forecast Discussion...UPDATED National Weather Service Memphis TN 1139 PM CST Sat Feb 17 2018 .UPDATE... Updated for 06Z Aviation Forecast Discussion below. && .PREV DISCUSSION... /issued 1041 PM CST Sat Feb 17 2018/ UPDATE... Clearing skies, light to calm winds, and saturated grounds have combined to create dense fog conditions across the northern third of the forecast area. A few stations have already reported 1/4 mile or less visibility at times. Latest GOES-east satellite also supports fog formation across areas that have seen clearing skies over the past hour or so. As skies continue to clear to the south, expansion of the advisory may be needed. Elsewhere, patchy fog is anticipated through the morning hours. Updated sky grids, nudged temperatures a bit, and issued the dense fog advisory. The rest of the forecast is on track. AC3 PREV DISCUSSION... /issued 548 PM CST Sat Feb 17 2018/ UPDATE... Updated for 00Z Aviation Forecast Discussion below. PREV DISCUSSION... /issued 307 PM CST Sat Feb 17 2018/ DISCUSSION...Surface analysis this afternoon places a cold front over portions of Central/Southern Mississippi and Northern Alabama. Regional WSR-88D radar trends indicate the back edge of a band of rain was located east of a line from Decaturville to Bolivar Tennessee to Clarksdale, Mississippi. As of 2 PM CST, temperatures across the Mid-South are in the 40s at most locations with the exception of Monroe County, Mississippi where temperatures are still in the lower to middle 50s. Rain will gradually taper off across the Mid-South for the remainder of this afternoon into this evening. A combination of residual low level moisture and temperatures falling back into the upper 30s to lower 40s may result in the development of patchy fog overnight. Highs on Sunday will remain cool in the 50s. Short term models indicate the downstream cold front will begin to return back north as a warm front on Sunday with rain chances increasing especially Sunday afternoon into Sunday night. It appears there may be some potential for relatively rain free conditions across portions of the Mid-South with the exception of Northeast Arkansas Monday into Monday night. Highs on Monday are expected to rise back into the lower to middle 70s. Long term models indicate chances for showers and a few thunderstorms will return to the Mid-South for Tuesday into Wednesday as a cold front approaches the Lower Mississippi Valley. Mild temperatures are expected to persist into Tuesday but gradually cool for the middle of next week north of I-40. Temperatures will moderate slightly for the remainder of next week along with continued rain chances each day. CJC && .AVIATION... 06Z TAFs Ground fog had developed around JBR late Saturday evening, behind departing MVFR stratus and in an area of calm winds. Similar conditions prevailed further east near and north of MKL. It's probable that MEM will not escape at least some fog overnight. LAMP guidance winds showed 3 to 5 KT winds prevailing at MEM Saturday evening, when winds were actually 0 to 3 KT through the evening. The trend of less than 3 KT winds will likely continue through the predawn hours, potentially leaving the urban heat island and scattered high clouds the only limiters on dense fog formation. Few changes for the Sunday afternoon and evening periods. MVFR deck should arrive late afternoon. Ceilings should lower Sunday evening, with the approach of tropical maritime warm front lifting north through MS. PWB && .MEG WATCHES/WARNINGS/ADVISORIES... AR...Dense Fog Advisory until 8 AM CST Sunday for Clay-Craighead- Greene-Lawrence-Mississippi-Poinsett-Randolph. MO...Dense Fog Advisory until 8 AM CST Sunday for Dunklin-Pemiscot. MS...None. TN...Dense Fog Advisory until 8 AM CST Sunday for Carroll-Crockett- Dyer-Gibson-Henry-Lake-Lauderdale-Obion-Weakley.