Area Forecast Discussion
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
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972 FXUS63 KBIS 081935 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 235 PM CDT Sat Jun 8 2024 .KEY MESSAGES... - Isolated showers possible today with the highest chances (20 percent) over the northwest and west-central (Crosby, Williston, Watford City, Killdeer, Beach, Medora). - High temperatures the next few days normal to just below for early June (normal is mid 70s). Above normal temperatures are expected with increasing confidence for Wednesday (80-85 degrees). - Widespread showers and thunderstorms (80 percent chance) expected Monday afternoon and Monday night, with an isolated stronger storm possible over the southwest and south central. Then stronger thunderstorms possible again on Wednesday. && .DISCUSSION... Issued at 235 PM CDT Sat Jun 8 2024 An upper level low that has stalled over the Canadian Prairies will slightly retrograde to the southwest through the afternoon while beginning to open. Weak cyclonic flow is briefly dipping into the northwest, allowing for a period where isolated showers will be possible over the northwest and north central through the early evening. With ample dry air near and above the surface, much of the rain that does fall out of these showers will likely become virga. Where these showers or virga do fall, some slightly enhanced gusts up to 25 mph will be possible. Otherwise, winds are anticipated to remain fairly light out of the northwest this afternoon, from 5 to 10 mph, then beginning to turn northerly and diminishing overnight. High temperatures today remain at or slightly below seasonable normals, forecast from the upper 60s northwest to the mid 70s southeast. Overnight low temperatures are forecast from around 40 in the northwest to the upper 40s in the southern James River Valley. The upper level low will continue to diminish overnight into Sunday, and will eventually be absorbed by an incoming shortwave trough that is slated to push into the northern Plains by early Monday. As such, conditions on Sunday are anticipated to remain mainly dry with slightly lower temperatures compared to today, from the mid to upper 60s across the International Border to the lower 70s over the south. A surface low center associated with the upper level trough will dig into the northern Plains on Monday, pushing chances (60 to 80%) for showers across North Dakota through the day. As the surface low pushes into western South Dakota Monday afternoon, some modest instability will develop along a N-S orientated boundary across our west. With model SBCAPE forecast from 500-1000 J/KG and bulk shear from 30-40 knots, there will be some potential for conditionally strong storms to develop over the southwest and south central Monday afternoon and evening. CSU Machine Learning has begun to paint portions of the far southwest and south central with a 15% probability for severe hail in this timeframe. The better instability is currently expected to remain further to our south, however, and the SPC has place a Marginal (level 1 of 5) just over the border in South Dakota. WPC is painting an area of Marginal potential for Excessive Rainfall over much of central North Dakota for this system, with this area slated for a 40-50% chance of exceeding 0.50" of rainfall by Tuesday morning. Highs on Monday are expected to remain seasonably cool, forecast from the mid 60s north to the lower 70s south. Conditions behind this system will rapidly dry out Tuesday morning as upper level ridging builds into the northern Plains, promoting warming temperatures with highs broadly peaking into upper 70s and mid 80s by Wednesday. By Wednesday afternoon, the ridge will begin to erode as another progressive pacific shortwave travels up the ridge. As another associate surface low system pushes eastward across North Dakota, there will be a brief period Wednesday afternoon where stronger storms will be possible across the Southern James River Valley. SPC has already begun to advertise a 15% chance for severe thunderstorms across eastern North Dakota on its Day 4 Outlook. Timing will make or break this system, however, with a majority of ensemble members (~80%) championing a very progressive system that exits the forecast area by the early afternoon period, which would greatly limit the chance for us to see much of anything on Wednesday. We will have to continue monitoring forecast trends with this system over the next few days. Through the later half of next week, flow aloft will become increasing northwesterly as longwave ridging begins to push in from the west. Temperatures will return remain fairly seasonable, with highs forecast in the mid 70s to low 80s through the end of the workweek. Conditions will remain dry through the early Friday, when a few ridge riders will promote chances for precipitation each day through the end of the week. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 235 PM CDT Sat Jun 8 2024 VRF ceilings and visibility are anticipated at all sites through the 18Z TAF period. Some isolated showers falling primarily as virga will be possible across the northwest and north central through this afternoon. Winds will remain generally light out of the northwest, with KXWA and KJMS experiencing some gusts up to around 20-25 knots through the early afternoon. Winds then turn northerly and diminish overnight and remain light through the end of the TAF period. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Adam AVIATION...Adam