438 FXUS63 KFGF 100448 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 1148 PM CDT Tue Oct 9 2018 .UPDATE... Issued at 1146 PM CDT Tue Oct 9 2018 No additional updates. UPDATE Issued at 1004 PM CDT Tue Oct 9 2018 No big changes needed. Updating grids to show advance north of the rain area. Just arrived in Fargo between 2-3z and timing would bring it to Grand Forks 07z or so. HRRR cools 925 mb layer to snow levels 09z-12z period. Incoming NAM shows about the same ideas as past runs with snow band near mid level def zone with higher rates of snow in NW MN later Wed into Wed eve vs more Wed morning-midday in Jamestown/Valley City area. UPDATE Issued at 630 PM CDT Tue Oct 9 2018 Rain area on its way northward and updated timing of rain arrival as it spreads north. Timing of rain to snow changeover is the main fcst issue with the idea of it doing so in the 09z-13z period across the area for most. Snow amounts of 3-6 inches look good for the advisory area...though as usual some slight differences in exact heavy snow placement. NAM and RAP are more JMS-GFK-ROX vs GFS seems to target more FAR-TVF-BDE. && .SHORT TERM...(This evening through Wednesday) Issued at 300 PM CDT Tue Oct 9 2018 Snow totals and winter headlines will be the main headaches for the period. Water vapor loop shows the main upper trough over CO/NM, with a kicker system digging down through OR/ID that will help push the more southeasterly trough into the Northern Plains by Wednesday afternoon. The surface low is still well to our south over KS, but will move quickly northeastward tonight into IA/southern MN and then into the Great Lake for tomorrow. There will be plenty of synoptic lift from the trough as it lifts into our area, and the models continue to indicate strong 700mb frontogenesis setting up over our area tonight into tomorrow. Rain currently moving through eastern SD will enter our southern counties this evening, pushing northward throughout the night. The main deformation band will continue over the central CWA for much of the day tomorrow, before weakening and pushing eastward during the late afternoon and evening. The biggest question is not if we will get rain and snow, which is yes, but how much snow will accumulate and what the impacts will be. GEFS plumes are still all over the place with snow amounts, ranging from less than an inch of accumulation to near 10 inches at KBDE. There will be a decent amount of cold air coming down the backside of the low pressure system, along with strong northwest winds. However, quite a bit of the QPF will be falling during the daytime hours, and there should be at least some melting as snow falls. With the melting and compaction of wet snow, think that even with 0.5 to 1.5 inch of QPF there will be a pretty broad area of 3 to 6 inches. The exception of this will be where any mesoscale banding sets up, the exact location still unknown. Could see more than 6 inches to even warning level snow amounts in that band, but again, do not know the exact location at this point. Thus, will put out a broad winter weather advisory, and highlight in the wording there will be a narrow band of heavier snow. Visibilities will also be reduced within that narrow band, although with the wet snow it will be more splattering on north facing surfaces vs blowing. .LONG TERM...(Wednesday night through Tuesday) Issued at 300 PM CDT Tue Oct 9 2018 Potent storm affecting the forecast area on Wed will see snow gradually taper off from southwest to northeast during Wed night into Thu morning, ending over north central MN by early Thu morning. Cool and breezy, but drier weather will move back into the region for Thu as temperatures remain solidly in the 30s. Zonal flow and modest warm air advection will result in some warming into the 40s on Sat as a clipper system moving out of Canada brings rain and snow chances to northeast ND and northwest MN. Overall winter weather impacts are expected to be minimal at this time. Any residual pcpn will move east during Sun with temps dipping well below average once again. Another clipper offering chances for mixed pcpn is scheduled for Tue with some hope for moderation in temps maybe to near normal by the end of next week or next weekend. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1146 PM CDT Tue Oct 9 2018 Conditions will go downhill thru 12z as rain continues to spread north and begins to turn to snow in many areas. The exact timeline of changeover is in question as usual but should be within the 09z and 15z period at the TAF sites and most other areas except parts of west central MN. Winds will continue to increase with north- northeast winds of 15 to 30 kts some gusts to 35 kts in the RRV. Vsbys variable in snow...but likely IFR or LIFR once the snow begins with ceilings mostly IFR or low end MVFR. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Winter Weather Advisory until 1 AM CDT Thursday for NDZ008-016- 024-026>030-038-039-049-052>054. MN...Winter Weather Advisory until 1 AM CDT Thursday for MNZ001>009- 013>017-022-023-027-028. && $$ UPDATE...Riddle SHORT TERM...JR LONG TERM...WJB AVIATION...Riddle