644 FXUS64 KSHV 072022 AFDSHV Area Forecast Discussion National Weather Service Shreveport LA 222 PM CST Sun Nov 7 2021 .SHORT TERM.../Tonight through Monday Night/ The axis of a shortwave ridge will slowly move east of the area tonight and early Monday morning. At the same time, the center of a surface high will also move into the Southeast CONUS. This will allow low-level southerly flow to finally return to the area, but moisture return will be very slow. Winds should decouple again after sunset this evening, and the light winds and clear skies should allow for another night of prime conditions for radiational cooling. The biggest question and main weather impact tonight surrounds the potential for fog. Surface dewpoints this afternoon are currently in the mid to upper 40s and have held fairly steady today in most locations. Overnight low temperatures should fall below these minimum dewpoint values nearly areawide, but especially across the eastern half of the forecast area in Louisiana and Southern Arkansas, where the coldest overnight lows are expected. If we apply the Crossover Temperature technique for fog formation, this would suggest the potential for more fog areawide tonight. The best chances for fog, including the possibility of dense fog, will be across Louisiana and Southern Arkansas closer to the axis of the surface ridge, where winds will be calm, and where the difference between overnight lows and the Crossover Temperature will be the greatest. The overall synoptic conditions are quite similar to last night when dense fog was widespread, and this gives increased confidence for fog tonight. Uncertainty still remains as to the potential for dense fog and its extent, so fog headlines will not be issued with this package. Any fog that develops early Monday morning should quickly begin to mix out after sunrise. Another day of abundant sunshine is expected. Low-level southerly winds and warm air advection should increase slightly as the center of the surface ridge continues to move east. Therefore, I trended temps are few degrees above the NBM for highs Monday as they seemed too cool. More patchy fog is possible Monday night and into Tuesday morning as the southerly winds begin to advect moisture northward from the Gulf of Mexico. CN .LONG TERM.../Tuesday through Sunday/ The 1025mb surface high will be parked over the SE U.S. early in the week and continuing to slowly warm and moisten on our back end of the circulation. The upper level ridge axis will be drifting eastward into the SE U.S. during Tuesday with another warm day, but just a touch cooler with some additional clouds. The southerly winds will start to veer a bit to SW ahead of the approaching storm system, especially into Wednesday with mid to upper 70s really all through midweek. Lows will continue to run above average with moist flow and additional cloudiness and a range of 50s on Wednesday and even some lower 60s early Thursday ahead of the next front. Rain areas are modeled well on GFS and the ECMWF to progress through our area during Thursday for the most part. The event will be characterized by another deep cyclone, (remember the windy day under the deep upper low), but this one will be farther to our north. However, we are essentially still waiting on the air mass so to speak. Both models bring a little bubble 1017mb high in with a cloudy short wave for the most part early on Friday which will be proceeding the larger air mass of 1026mb arriving for the weekend. Areas of heavier precipitation may overrun the tiny airmass, but most of the QPF remain on our Eastern and Southern fringe early Friday. Then our skies will clear out with more chilly mornings this weekend in the 30s. Highs will be below average with Saturdays mid to upper 50s north and low 60s south the coolest "day" and then warming back toward average on Sunday. /24/ && .PREV DISCUSSION... /issued 1158 AM CST Sun Nov 7 2021/ AVIATION... For the 07/18z TAFs, SKC and VFR conditions should prevail areawide through midnight tonight. However, another round of fog, some of which may be dense at times, is expected to develop and affect most TAF sites after 08/08z. This will likely result in more IFR/LIFR visibilities. Flight conditions should gradually improve back into the VFR range by 08/15z-08/16z as abundant sunshine in increasing southerly winds help to mix out of the fog. Wind speeds should remain below 10 kts for the duration of this TAF period. CN && .PRELIMINARY POINT TEMPS/POPS... SHV 43 76 47 74 / 0 0 0 0 MLU 39 75 42 74 / 0 0 0 0 DEQ 39 74 45 71 / 0 0 0 0 TXK 43 74 48 72 / 0 0 0 0 ELD 39 73 42 71 / 0 0 0 0 TYR 47 76 52 75 / 0 0 0 0 GGG 42 77 47 74 / 0 0 0 0 LFK 42 77 47 74 / 0 0 0 0 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 09/24