Area Forecast Discussion (AFD)
Issued by Huntsville, AL (HUN)
729 FXUS64 KHUN 202050 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 350 PM CDT Tue Mar 20 2018 .NEAR TERM...(Tonight) Issued at 350 PM CDT Tue Mar 20 2018 A storm system that in part brought a plethora of severe weather across parts of this region yesterday has exited well to the east of this region. A cold front extending south of a complex of low pressure over the Mid Atlantic, continued to produce scattered severe weather from eastern North Carolina to Florida. Warmer conditions that were across most of the Tennessee Valley on Monday have shifted well to our east of the region, with mid afternoon temperatures ranging from the mid 40s in southern middle Tennessee, to the lower 50s across northern Alabama. Post system moisture and upglide in the 290-300K region has resulted in more clouds than sun across the region, and periods of light rain. The colder air further to our north has resulted in a rain/snow changeover near Clarksville TN and across southern Kentucky. The colder air filtering southward this evening and in the overnight, will cause some of the light rains to become a mix of rain/snow, then possibly all snow for a brief period, before ending around daybreak Wednesday morning. Given the warm temperatures as of late, no accumulations are expected at this time. Moisture and associated clouds will also clear out from NW to SE as the drier and colder air build across the Valley. Night time lows should cool into the lower 30s (just above freezing), however a gusty at times northwest winds of 10-20 mph will produce wind chill values into the lower and mid 20s. .SHORT TERM...(Wednesday through Thursday) Issued at 350 PM CDT Tue Mar 20 2018 Generally sunny skies, but colder than normal conditions are forecast for Wednesday, or the first full day of Spring, as cold high pressure builds in from the west. High temperatures will only warm into the upper 40s to lower 50s with NW winds of 5-15 mph. Somewhat colder conditions are expected Wed night as winds become light/variable under the high as it moves across the region. Night time lows for most if not all of the area should fall below freezing. We will probably issue a Freeze Warning to cover this in a later shift, if this trend continues, with forecast lows in the upper 20s to around 30. A slightly warming trend on Thursday is forecast with highs recovering into the mid 50s to around 60. Normal highs this time of year are around 67 degrees. .LONG TERM...(Thursday night through Monday) Issued at 350 PM CDT Tue Mar 20 2018 A return southerly flow will return more lower level moisture and instability to the region. This will bring increased clouds, as well as a slight chance of rain late Thursday night. An unsettled pattern appears to be setting up again - for another weekend, as a series of lows move along a frontal boundary that will set up in a west-east manner across the eastern CONUS. Inter-model comparison between the GFS/ECMWF/Canadian were in reasonably good agreement into early next week. The models do indicate a frontal boundary draped mainly north of the area in the Saturday into Monday time frame. This placing the area in the warmer, more unstable sector warrants a mention of thunder within generally more widespread showers. The approach of a low and the front close enough made for scattered showers/storms on Sunday. Showers should continue into the first part of the next work week. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1230 PM CDT Tue Mar 20 2018 MVFR conditions will prevail through at least 02Z at the KMSL and KHSV terminals. An upper low will swing through the region this afternoon, bringing isolated to scattered light rain across the region. Confidence is low on if this activity will reach the area, however if it does, visibilities may be reduced as low as 4SM. Given the lower confidence, have not included these lower visibilities in the TAF. Otherwise, cigs around 1500 feet will persist through 02Z and then lift to around 2500 feet between 02Z and 06Z. By 06Z, cigs will lift and VFR conditions will return. Winds will generally remain from the northwest and gust up to 18 to 20 kts this afternoon before diminishing after 02Z. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...RSB SHORT TERM...RSB LONG TERM...RSB AVIATION...73 For more information please visit our website at weather.gov/huntsville.