FXUS63 KFGF 030312 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 1012 PM CDT Wed Apr 2 2025 .KEY MESSAGES... - Heavy snowfall rates between 1-2 inches per hour will continue in northwest Minnesota through the afternoon and early evening. - Another wave sweeps through Friday with a chance for 2-4 inches of snow. && .UPDATE... Issued at 1012 PM CDT Wed Apr 2 2025 The main 700 MB low pressure center is now east of our region, however large scale synoptic ascent within cyclonic flow on the back side of the trough is maintaining a larger area of light (to locally moderate) snowfall across eastern ND and northwest/west central MN. Ground temperatures are dropping and locations where melting was occurring previously are accumulating and slick roads are being reported across a larger portion of our area. Latest CAMs (particularly the HRRR) are doing a better job of handling the slower exit of light accumulating snow, and support this continuing through 06Z (1 AM) in ND and potentially lingering in northwest MN through 9-11Z. Considering these trends I went ahead and extended the ND advisories and warnings through 1 AM matching the expiration of the MN counties. Some consideration may eventually be given to extending the MN counties, however there should be drier/stable air eventually spreading in at that point and the chance for more than flurries or a light dusting may have decreased. We'll monitor trends and see if this is finally breaking up at that time. UPDATE Issued at 718 PM CDT Wed Apr 2 2025 Widespread light snow continues across the region, with pockets of moderate to locally heavy snow slowly weakening. While ground temperatures continue to play a role in limiting accumulations additional light accumulations can still be expected through mid evening in ND, with a better chance for 1-3" in northwest MN as light accumulations may linger longer into the evening (thorugh 1am) as the 700 MB low transitions east. This is reflected in latest trends in CAMs and the decision was made to exerted the advisory and warning in ND through 03Z (10 PM) and in northwest MN through 06Z (1 AM). && .DISCUSSION... Issued at 253 PM CDT Wed Apr 2 2025 ...Synopsis... The very large scale extratropical cyclone continues to spin around Iowa. A broad swath along an inverted trough continues to bring bouts of snow across much of northwest Minnesota and portions of southeast North Dakota. As the low continues to progress northeastward through the evening and overnight, snow will diminish in intensity with light snow lingering after midnight. Snow should come to an end by noon tomorrow at the latest, but the warnings will likely expire at 7 PM CDT. As we progress later into the week, a brief quiet day on Thursday will be replaced by a clipper system Friday. Warm air advection ahead of the clipper is fairly weak, but frontogenesis on the backside of the clipper is stout. Lack of moisture return inhibits QPF totals, but 2-4 inches are a reasonable worst case scenario for what ends up on the ground. As we progress through the remainder of the period, modulating 850mb temperatures and upper ridging should keep us fairly quiet with signals for impacts at a minimum. Temperatures will rebound, but the question mainly will be how quickly as snowpack may linger for a day or so after accumulation. ...HEAVY SNOW THIS AFTERNOON... A broad swath of synoptic ascent continues across northwest Minnesota with embedded frontogenesis along an inverted upper trough. This has contributed to strong organized banding in northwest Minnesota, where 1 inch per hour rates may be occurring but has not been confirmed yet. Radar estimates are pushing 2+ inches, and given the surrounding environment with instability, this does appear reasonable. The main question at this point is how long will it last at given points. Right now, the reasonable upper end for prolonged banding appears to be an additional 3-5 inches, but for the most part you should expect generally 1-2 additional inches of snow. As the low progresses eastward through the evening, synoptic ascent will diminish and disorganize any banding, it's just a matter of when at this point in time. Given lingering uncertainties in end time and duration of banding, the headlines will remain the same as the current band lines up well with the Winter Storm Warning. ...ADDITIONAL SNOW FRIDAY... A clipper will sweep through the region from west to east Friday. Warm air advection ahead of this clipper is very weak, so not much in the way of additional accumulating snowfall is likely from the first portion of this system. Still, at least some ascent will contribute to light snow showers. As the cold front pushes through, this one possesses the greatest lift and thus provides for the strongest precipitation signal. Forward propagation of a line of snow is expected, and will likely remain perpendicular to the long axis. For this reason, significant snowfall accumulations are not expected to arise. Even if we see the reasonable worst case, which is 4 inches of snow, it is very likely that not all 4 inches will make it to the surface once again. At least expect some travel impacts as the cold front sweeps through. Winds associated with this are very weak so blizzard conditions will likely not develop. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 718 PM CDT Wed Apr 2 2025 IFR to MVFR conditions continue across eastern ND and northwest MN due to widespread light to moderate snow, and a few lingering pockets of LIFR conditions where heavy snow is tracking. General trend should be for improvement in vis as snow dissipates this evening, and eventually ends west to east through the early morning hours tonight. MVFR (and a few pockets of IFR) ceilings linger after the snow ends and VFR chances do not return until the afternoon Thursday over northeast ND and far northwest MN. Northerly winds 12-16kt will shift to the northwest then west- northwest as this system passes, decreasing below 12kt Thursday as surface high pressure builds east. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Winter Weather Advisory until 1 AM CDT Thursday for NDZ016- 026>030-054. Winter Storm Warning until 1 AM CDT Thursday for NDZ038-039- 049-052-053. MN...Winter Weather Advisory until 1 AM CDT Thursday for MNZ001-002- 005-007-008-013>015. Winter Storm Warning until 1 AM CDT Thursday for MNZ003-006- 009-016-017-022>024-027>032-040. && $$ UPDATE...DJR DISCUSSION...Perroux AVIATION...DJR