Area Forecast Discussion
Issued by NWS Grand Forks, ND
Issued by NWS Grand Forks, ND
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577 FXUS63 KFGF 211736 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 1236 PM CDT Tue May 21 2024 .KEY MESSAGES... - Northerly winds gusting to 50 mph are expected across the southern Red River Valley this afternoon and evening. There is a 20 percent chance for gusts around 60 mph. - Heavy rainfall may lead to localized overland flooding this afternoon into Wednesday for the Southern Red River Valley into Minnesota. - Depending on the extent of heavy rain, river flooding could start as early as Thursday for some areas along the southern Red River basin. && .UPDATE... Issued at 1236 PM CDT Tue May 21 2024 With the guidance of the RFC issued a few river flood watches for the southern Red River Valley and a river flood warning for Fargo with the expected rises in levels from the rain that is falling today into tomorrow with crests not expected until later this week. See MPD 296 for further details on short term rain potential in the area. Wind is still on track to increase this afternoon with rain overspread the Aberdeen to Fargo to International falls line. UPDATE Issued at 911 AM CDT Tue May 21 2024 Only change to the forecast was expanding the wind advisory into north central Minnesota based off the latest RAP and a strong low level jet along the northern edge of the deformation axis this afternoon. Set west central Minnesota segment to expire around midnight while areas towards Lake of the Woods will see high winds continue through the night as the pressure gradient lingers longer in those areas. Monitoring for the need of a short fused wind warning if these high winds aloft start making it to the ground this afternoon. UPDATE Issued at 652 AM CDT Tue May 21 2024 The initial areas of rain associated with the approaching system is spreading into our south matching up with timing from earlier. Lighting activity is minimal and most reports so far for the activity aliened with our region are in the light to moderate range (again within expectations). So far forecast appears to be on track. && .DISCUSSION... Issued at 416 AM CDT Tue May 21 2024 A strong Colorado low type system is developing currently over eastern Colorado with SW flow increasing deep moisture advection into the Northern Plains this morning. This system will be responsible for wind, rain, and potential excessive rain impacts today into Wednesday. As this system transitions east an active quasi-zonal pattern with additional organized mid/upper lows moving out of the Pacific NW or Canadian Prairies will remain in place over the next 7 days with additional rain events possible but lower confidence/predictability regarding impacts at this time. Regarding Winds today: As the surface low deepens and moves north, strong gradient will support increased winds and while mix layers are deep, model mixed layer winds show maximum values in the 40- 47kt range in the southern Red River Valley this afternoon into the early evening and this is a consistent signal between current deterministic models. A little better mixing 50kt (warning impact) winds may develop and NBM probs highlight around a 20% probability for this in the far southern Red River Valley. Regarding rain/flooding potential: There is strong consensus for the 700 MB low track to support a prolonged period of deformation lining up from the southern Red River Valley into west central MN. Main instability axis is well to the south (MUCAPE may only be around 100- 200 J/KG at the most) and HREF shows any signal for higher rates (1"+/hr) to the southeast. Still, forcing and instability (as it is) will be enough for periods of light to moderate rain and occasional convective pocket of brief heavier rain to track over a lot of our area. Heaviest rain axis is more likely to linger longer in MN than in the southern RRV, and probs from NBM and HREF support this trend. HREF PMM would indicate the heaviest rain axis supporting 2-4" over 6hr periods, though higher amounts are still possible especially if considering the length of the event. Adjusted FFG would require almost double those values for more than localized runoff and as rates are not favorable for actual flash flooding. Localized overland/areal type flooding would be favored (ponding/more gradual runoff). Depending on the extent of the higher totals riverine flooding is possible with a delay in responses (responses on rivers by Thursday from this rain event). River probabilities relayed from RFC coordination on Mon day shift: Minor Flooding: 20-40% Moderate Flooding: 10-30% Major Flooding: Less than 10% For the Red River at Fargo (FGON8) specifically, one can add 10-30% to Minor and Moderate values, with chance for Major around 10%. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1236 PM CDT Tue May 21 2024 Rain will continue through the night with little spatial change aside from a slight pivot as the low track northeast through Minnesota. Ceilings in areas of rain area widely expect to be VFR to MVFR though in heavier rain could dip into IFR for areas such as Bemidji. Strong northerly winds around 2000ft will create LLWS despite sfc winds near 20-30 kts as well. VIS generally 3-5 miles in rain though periodically lower. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Wind Advisory until 1 AM CDT Wednesday for NDZ039-049-052-053. MN...Wind Advisory until 1 AM CDT Wednesday for MNZ002-003-022-023- 027>032-040. Wind Advisory until 7 AM CDT Wednesday for MNZ006-009-015>017- 024. && $$ UPDATE...TT DISCUSSION...DJR AVIATION...TT