####018006606#### FXUS63 KBIS 030310 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 1010 PM CDT Thu May 2 2024 .KEY MESSAGES... - Scattered showers and a few isolated thunderstorms will continue across northern North Dakota tonight and through most of Friday. Some light snow could mix in with the rain in parts of western North Dakota. - Temperatures will warm through the weekend, with windy conditions Sunday. - Chances for rain return late Sunday night, becoming likely by Monday (60 to 80 percent). Monday may also bring a higher chance for some thunderstorms. Low to medium rain chances (20 to 60 percent) continue into mid week. && .UPDATE... Issued at 1010 PM CDT Thu May 2 2024 Main low has progressed into northeast North Dakota late this evening, with the primary area of rain still directly around the low. Some scattered showers continue across mainly north central North Dakota, but activity has been diminishing over the past hour or so. A secondary low is centered in far southeast Saskatchewan, with low clouds in northwest North Dakota wrapping around the low. Additional rain showers are visible on radar across much of northern Montana, generally moving southeast in cyclonic flow. The main change with this update was to freshen up POPs through Friday morning with the latest blended guidance. We now have a mention of snow potentially mixing in with rain in parts of western North Dakota on Friday morning, with overnight lows in the upper 20s to lower 30s. No accumulation is expected at this time. UPDATE Issued at 659 PM CDT Thu May 2 2024 Surface analysis shows the center of a low in east central North Dakota, with widespread, more stratiform rain wrapping around the center of the low across the eastern part of state. A line of thunderstorms has developed on a narrow low-level warm nose, extending from the Bowbells area to just east of the Bismarck/Mandan area. Directly behind this is an additional line of primarily showers, with winds shifting to westerly and increasing behind this second line. Ceilings are still modestly high enough to where there is some virga present with these radar returns, seen both from our office and on NDAWN cameras across the area. We did get a report of small hail from a cell that passed through Strasburg. Low freezing levels do tend to drive small hail, and the RAP-estimated 50dbz height for severe hail is only around 13-15k feet, so would not be surprised if we got additional reports of small hail as these thunderstorms move through. As the upper low exits to the northeast, expecting showery activity to diminish across most of the area. There is additional development upstream in eastern Montana so will have to keep an eye on this to see if it persists over the next couple of hours and expands into western North Dakota. && .DISCUSSION... Issued at 343 PM CDT Thu May 2 2024 Satellite observations show an upper level low located over the northwest that will continue to push eastward this evening. Wrap around showers will persist across the western and northern half of the state. There is enough instability over the west and south central for thunderstorms. Thunderstorms will decrease later this evening as instability decreases. Overcast skies have resulted in below normal temperatures in the lower 50s this afternoon. The upper low will continue to push eastward Friday and cold air advection on the backside of the low will mix stronger winds down to the surface. In addition a surface pressure gradient will lead to breezy winds across the state in the afternoon. Temperatures will remain on the cooler side Friday as overcast skies will linger for much of the day limiting warming. Overnight lows could drop into the upper 20s across the southwest as surface high pressure passes over Friday night. Saturday temperatures will begin to trend upward to near normal as surface high pressure clears out the clouds across region and ridging begins to build out west over the Northern Rockies. Sunday temperatures are forecast to climb into the 60 to 70s out west as the upper level ridge pushes quickly through the region. A strong surface pressure gradient will lead to windy conditions across the western and south central North Dakota in the afternoon. This short term warm up will be short lived as another broad trough pushes across Western CONUS. A strong upper level low pressure system will move up from the Rocky Mountains Monday leading to widespread precipitation across the Northern Plains. The NBM has 50 percent chance of 1 inch rain across the Northern half of the state. Thunderstorms are possible as the system first moves into the region and there is some instability around 500-1000 j/kg. CSU Machine Learning Program has backed off on severe weather parameters due to the ensembles having decreased instability, but there still is low chance for severe weather Monday. In addition to rain, windy conditions are expected Monday as a strong surface low with a tight pressure gradient moves through the region. Wrap around precipitation will continue through Wednesday leading to showers and cooler conditions. Temperatures are forecast to sit in the 50s through the middle of the week. After this system there is a ton of model uncertainty as ensembles want to wash the upper low out over the plains while some solutions try to move it eastward. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 659 PM CDT Thu May 2 2024 VFR ceilings to start the TAF period, with intermittent MVFR visibilities in any showers and thunderstorms. Lower ceilings will be quickly moving into northwest North Dakota this evening, expanding across western and northern North Dakota into Friday. After a line of showers and thunderstorms moves through central and eastern North Dakota this evening, scattered showers will expand across the north through tonight and through the day Friday, primarily impacting KXWA/KMOT. Breezy west to northwest winds will continue across the area through the period. KBIS and KJMS are expected to stay VFR through the TAF period outside of any areas of precipitation. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Jones DISCUSSION...Johnson AVIATION...Jones