492 FXUS63 KFGF 181259 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 659 AM CST Mon Nov 18 2019 .UPDATE... Issued at 654 AM CST Mon Nov 18 2019 Some brief freezing rain was reported in Pembina county this morning. Otherwise expect rain from central ND into SASK will move southeast across the valley today. Most of the precip will be rain. && .SHORT TERM...(Today and tonight) Issued at 342 AM CST Mon Nov 18 2019 Water vapor loop indicated short waves over the southern MAN and along the far western Dakotas. Radar showed weak returns south and east of the radar but nothing appears to be reaching the ground. The Dakotas short wave was moving to the southeast and will spread light precip south and west of the area. Relatively deep moisture in western ND will move east today. Another area of precip over SASK will move southeast across the area later this morning and this evening. Some weak instabilities were noted for this afternoon. Mostly light rain is expected today. A wintry mix will be possible over the western part of the Devils Lake basin this morning before temps rise above freezing. A pre-frontal trough was located over central ND with a cold front over western ND. Both features will pair up by this evening. Another short wave will move through tonight and produce light precip over the eastern zones into Tue. .LONG TERM...(Tuesday through Sunday) Issued at 342 AM CST Mon Nov 18 2019 Main period of concern in the mid to long range periods will be Tuesday night through Wednesday night when accumulating snow may be possible across the region, which could result in some travel impacts. Strong ensemble agreement at 500/300 MB that positively tilted shortwave trough slides east along the International border and very slowly across North Dakota into northern Minnesota through Thursday morning, with southwest flow immediately ahead of this. Further south a stronger negatively titled shortwave trough ejects northeastward across the central Plains into South Dakota and southern Minnesota by Wednesday night and eventually merges just southeast of our CWA. Very good agreement in the timing and evolution of these features aloft. Mean position of frontal zone is stalled over southern ND Wed night, which eventually slides south with good consensus of CAA increasing Wednesday night over our CWA (850MB temp mean near -9C by Thursday morning). Initially, forcing will be tied to WAA along or overriding this frontal zone and there are indications in deterministic models that a strong lobe of positive 700MB frontogenesis will set up over western and central ND late Wednesday night and slide eastward. As CAA increases, this lobe of frontogenesis would weaken as shown by models. As this happens synoptic ascent will become dominant. A secondary well organized lobe of positive frontogensis develops near our southeast CWA as deformation increases along the northwest side of the 2nd shortwave trough. Between these features large scale synoptic ascent will still support potential for light precip, while the two regions of organized banding could support moderate snowfall rates. Ensemble spread is high regarding snow amounts due to the variability and narrow nature of this type of banding. Widespread totals based on 25th/75th percentiles generally ranging from 0.2 to 1.5", and higher totals based on 90th percentile of 3"+ possible where the banding sets up and holds together. We are not confident in the higher totals due to variances in the mesoscale features, but still feel these periods should be monitored for travel impacts. Regarding precipitation types Tuesday night-Thursday morning: Initially there is a deep dry layer that saturates top-down and during this transition Tuesday night-Wednesday. There isn't currently an indication of moisture advection within the lower levels until deep saturation occurs and ice would be present within the column (basically when it would actually be precipitating). This type of situation generally favors snow as a predominant type, though we can't rule out pockets of fzdz near the frontal zone or during the transition. On the back side of the system there is also some indication on 00Z NAM profiles of a saturated moist adiabatic layer lingering as precip winds down. If this actually happened, it would also support possible fzdz development late Wednesday night/Thursday AM. There isn't a lot of consensus in these fzdz signals, so expecting main impacts to be tied to snow accumulations and will monitor for any fzdz ugliness during the periods of transition. Thursday-Monday: Large scale trend will favor split-flow pattern over the Northern Plains through next weekend, however there is low consensus and very large spread in ensembles at 500/300 MB Friday into early next week regarding smaller scale features. General ensemble trends and mean/consensus favor moderating temperatures and generally dry or very low measurable precip chances (if any clippers were to pass near our region). Not a lot of confidence in sensible weather at these ranges beyond the general trends and they are reflected in forecast by NBM of near seasonal highs in the middle 30s Fri-Mon and slight chance/low end chance PoPs Sat night- Mon. && .AVIATION...(For the 12Z TAFS through 12Z Tuesday morning) Issued at 654 AM CST Mon Nov 18 2019 Mostly IFR conditions were mainly across the MN side of the Red River. The rest of the area was VFR. Expect IFR conditions to remain over the MN side for today and tonight. MVFR conditions will develop over eastern ND this afternoon and tonight. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...JH SHORT TERM...JH LONG TERM...DJR AVIATION...JH