773 FXUS63 KFGF 022123 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 423 PM CDT Mon Sep 2 2019 .MESOSCALE DISCUSSION... Issued at 422 PM CDT Mon Sep 2 2019 The threat for severe weather this afternoon into evening remains in place for portions of eastern North Dakota into northwest and west- central Minnesota. Main hazards will be damaging wind gusts to 75 mph with a continued but lesser threat for hail to the size of golf balls and a tornado or two. Timing looks to start near 3 PM in the Devils Lake Basin ending around Midnight in west-central Minnesota. Highest threat area remains in southeastern North Dakota into west- central Minnesota, including the Fargo metro. A vigorous short wave trough readily apparent on water vapor is moving through southern Canada with an upper jet max ahead. In the lower levels, warm air advection resultant of a strong LLJ is feeding a severe but elevated MCS currently in central North Dakota. These elevated storms are northeast of a warm front and thin warm sector ahead of a cold front lingering behind in western North Dakota. Strong winds throughout the column are resulting in 50+ kt shear and MCS storm mode gives confidence in the potential for winds gusting to 75 mph. This MCS is starting to take on bow-like characteristics as it matures just upstream of the CWA. However, a limiting factor on transferring these higher winds to the surface is a large shallow stable layer noted by 18Z BIS RAOB and visually seen as extensive stratus within the warm sector ahead of convection. However, additional warm air and moisture advection may help erode this stable layer as the afternoon progresses. Still looking for best chance for highest winds on the southwestern portion of this MCS closest to the area of higher DCAPE within the warm sector. While not as likely, hail is still a threat due to the strong EML noted by very steep mid level lapse rates will aid in a tongue of MUCAPE values exceeding 2000 J/kg, despite meager surface based moisture noted by dew points in the low to mid 60s advecting into western, central, and now southeastern North Dakota. This combined with very strong wind shear will continue the threat of large hail, possibly up to 2 inches. Another issue may be wind driven hail. Again, strongest convection on the southern/western edge of the MCS and any additional discrete storms hold best chance for large hail. The reservoir of higher surface moisture content in central South Dakota is looking more likely to advect into southeastern North Dakota into west-central Minnesota, at least partially. As the trough moves east, the passage of the warm frontal boundary will aid in strong low level shear along with strengthening of the a LLJ towards this evening. This brings the chance of QLCS tornadoes within the MCS given strength of low level shear, particularly due to the observation of mid level development along the leading edge of the MCS. Models currently are maintaining a strong cap in place over southeast ND and west-central MN, but I wouldn't rule out cap erosion on the western periphery of the MCS. && .SHORT TERM...(This afternoon through Tuesday night) Issued at 353 PM CDT Mon Sep 2 2019 This afternoon-tonight: Showers/storms should continue to overspread our CWA as negatively titled trough progresses eastward, with main severe threat tending to be tied to MCS (hugging instability axis/theta-E gradient). Tendency in guidance is for most activity to move east through the evening transitioning east of our CWA after midnight. Window for severe seems to be through the evening (probably wrapping up by midnight). Widespread moderate to heavy rain is expected with most lighting activity where more intense thunderstorm activity tracks (mainly in our southwestern 2/3). Tuesday-Tuesday night: Cold pool lingering in our eastern CWA (mainly MN) could support a few showers redeveloping through the day Tuesday before sunset, with dry conditions generally favored further west in ND. Unidirectional flow and LLJ behind departing upper trough should support windy conditions, with clearing/mixing heights determining how high winds actually get. Could see near advisory winds depending on mixing. Complications of sky cover on wind and temps through the day. Due to strong CAA we may see highs struggle to warm above 60-62 for some areas (dependent on clearing). .LONG TERM...(Wednesday through Monday) Issued at 353 PM CDT Mon Sep 2 2019 The extended period will be unsettled with waves crossing the area every few days...particularly on Thursday and Saturday...in northwest flow aloft. Otherwise...expect cooler Canadian high pressure to settle in between the systems as the upper trof shifts over the area. Thus...overall expecting temperatures to be a bit on the cool side and increasingly moist as the pattern resembles more of a typical fall season regime. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) Issued at 118 PM CDT Mon Sep 2 2019 LIFR conditions due to low stratus lingering over BJI should begin to improve during the early afternoon with system approaching from our west. Showers and thunderstorms will impact all terminals during the TAF period, with best chances in ND in the 22-03 period and 00Z-06Z period in MN. Severe thunderstorms capable of strong winds in excess of 60 mph, large hail, and the possibility of tornadoes may develop, but severe impacts at terminals still uncertain enough I held back on introducing more significant impacts during this issuance. MVFR or even lower conditions may occur as a result of moderate to heavy rain in thunderstorms, with stratus possibly lingering as system transitions east and southeast of the region late this evening. While winds would shift to the west-northwest and diminish at the surface as thunderstorms move east, a period of low level wind shear is still possible behind thunderstorm activity. Northwest winds are expected to increase late Tuesday morning with gusts 25-35kt possible (mainly in the Red River Valley). && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ MESOSCALE...CJ SHORT TERM...DJR LONG TERM...Hopkins AVIATION...DJR