UPDATE
Issued at 656 AM CDT Sat Jul 27 2024

There are still a few pockets of light showers, with the only lightning activity over the Northwest Angle. Any flash flood impacts have diminished and while there is lingering ponding most warnings will likely be able to be expired on time barring new information. Otherwise, forecast for thunderstorms isn't any clearer today with CAMs continuing to show high variation in scenarios as forcing is less obvious. Frontal zone should still be the main focus during the afternoon, but coverage/impacts are uncertain and no changes are currently planned to messaging at this time.

DISCUSSION
Issued at 333 AM CDT Sat Jul 27 2024

Synopsis

The large scale pattern features strong ridging extending from the southwestern CONUS across the Great Lakes. SW flow aloft is currently in place on the northwest side of this feature ahead of a mid/upper low over Saskatchewan. The ridge is shown to flatten Sunday into Monday in response to the trough passing to the north in Canada with a more organized synoptic mid/upper level trough passing to our south. This gives us a reprieve from above normal temperatures, but keeps the active pattern in place. As the ridge slowly rebuilds/amplifies through late week/next weekend we remain along the northern fringe keeping us in line for progressive/less organized waves that aren't well resolved at this range. This also allows for rising heights and trends back towards above average temperatures (though not as hot as west and southwest of our region).
Evapotranspiration continues to aide in higher Td's pooling in our region, so instability can be assumed to be present as these waves pass keeping at least conditional threat for severe beyond the initial 3 day period.

Heavy rain and flash flooding early this morning

a stalled/slow moving frontal zone has remain aligns southwest to northeast, with LLJ/deep moist advection overriding this within SW flow aloft. High PWATs for our region (1.5-1.8") and higher freezing levels have supported efficient rain processes and clusters of thunderstorms have tended to train over similar areas along this axis. Impacts haven't been widespread, however due to the high rain rates MRMS Flash products have supported issuance of flash flood warnings for the immediate urban/Grand Forks area and parts of northwest MN. The trend is already for this activity to decrease in intensity upstream aligning with latest CAMs/timing and eventually most of the heavier rain should be northeast of our region by mid morning. There is still a window for additional localized flash flood impacts over the next 3-6hr.

Severe thunderstorm threat today

The frontal zone will tend to linger from southeast ND across northwest MN through midday, and while there will be a trend towards a lull in shower/thunderstorm coverage/intensity by late morning, BL moisture pooling/higher Tds with steep mid level lapse rates will support additional destabilization in the 12-3pm period, then more organized severe convection developing by the evening as the LLJ strengthens. As this happens models are showing an subtle mid level wave arriving and helping to initialized new activity near this frontal zone. Increasing shear with veering hodographs east of the front support a window for supercells to develop (mainly in north central MN) where CAMs are showing some strong/brief UH tracks closer to Lake of the Woods/Beltrami counties. Even if discrete supercells fail to initiate there would be a tendency for stronger updrafts and possible clusters/smaller MCS. Too much leftover cloud over from the morning convection may delay initiation or limit the severe threat to elevated les organized cores. These possibilities are reflected in CAMs, and impacts could range from isolated/marginal severe to scattered severe and larger hail to around golf ball. Tornado threat isn't zero, but could be limited due to the tendency for activity to cluster/for cold pools.

Severe thunderstorm threat Sunday

There is more uncertainty on the potential impacts/coverage in our area Sunday as synoptically there may be a trend towards the most organized forcing splitting around our area. Good should still be in place, with more linear shear profile's CAMs at this range show the potential for MCS development toward sour southeast, though broad areas of higher Tds and at least some forcing support the potential for an isolated severe threat across a larger part of our area.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/
Issued at 656 AM CDT Sat Jul 27 2024

There are some pockets of MVFR stratus in central MN, otherwise aviation impacts are minimal with only a few pockets of showers over parts of eastern ND and northwest MN. The question will be coverage/impacts of thunderstorms when they redevelop this afternoon/evening and confidence at this point is too low to include in TAFs this cycle. Winds should shift to the south and increase today 12-15kt, gusting higher before decreasing again with sunset as low pressure pushed east.

FGF WATCHES/WARNINGS/ADVISORIES
ND...None.
MN...None.