Area Forecast Discussion
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
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885 FXUS63 KBIS 171609 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 1109 AM CDT Tue Sep 17 2024 .KEY MESSAGES... - Isolated to scattered severe thunderstorms are possible across western into central North Dakota this evening and tonight. - An active pattern continues through the week, with low to medium chances for showers and thunderstorms most days. - Temperatures will trend cooler through the week after today, with forecast highs in the lower 60s to lower 70s by this weekend. && .UPDATE... Issued at 1108 AM CDT Tue Sep 17 2024 Just a quick update to add that we have cancelled the Dense Fog Advisory, as visibilities have improved across the area. .UPDATE... Issued at 942 AM CDT Tue Sep 17 2024 Patchy dense fog continues to linger across the northwest, with some areas still not seeing any improvement in visibilities. NDDOT webcams also indicate plenty of dense fog in that area. As a result, we`ve extended the Dense Fog Advisory until noon CDT. Otherwise, the forecast remains on track, with low stratus still present in the north, clear skies in the south, and continued light winds across the entire area. Winds are still forecast to increase with continued surface heating through the day. .UPDATE... Issued at 642 AM CDT Tue Sep 17 2024 Dense fog and low stratus extends from Crosby, to Maxbass, to Minot, to Hazen, covering most of the area across northern North Dakota. The expectation, from the general pattern and from high-res guidance, is for gradual improvement through the morning, although low clouds could linger in far northern North Dakota into the afternoon. Dense Fog Advisory is in effect until 10 AM CDT. Made some minor adjustments to PoPs and sky cover with this update, otherwise going forecast looks good for most of the day, before we get to more severe weather potential. .UPDATE... Issued at 439 AM CDT Tue Sep 17 2024 Update for the issuance of a Dense Fog Advisory for northwest and portions of central North Dakota. Many locations under the low stratus deck are reporting visibilities of one quarter mile or less, with NDDOT webcams adding to the certainty of areas of dense fog. && .DISCUSSION... Issued at 317 AM CDT Tue Sep 17 2024 This morning, the synoptic pattern was dominated by a deep upper low over Nevada, with southwest flow aloft across the Dakotas. At the surface, a low was analyzed in southeast Montana, with a stationary front extending east from the center of the low across North Dakota. Some isolated convection was ongoing just north of the surface low, moving north. Although there are still some high clouds left over from evening convection, nighttime satellite imagery is showing the edge of a low stratus deck that extends across much of northern North Dakota, expanding into the northwest. There are some reduced visibilities being reported underneath this stratus, although it does seem to be a bit isolated for the moment, with NDDOT cameras in these areas showing clear conditions. Regardless, will be something to keep an eye on into the morning. Southeasterly low-level flow will continue today on the east side of the surface low, leading to another warm, humid day for mid September. Forecast highs range from the lower 80s to lower 90s across western and central North Dakota, and dew points will be mainly in the 60s. Precipitation chances ramp up this evening into the overnight hours as a secondary front from the surface low pushes northeast across the forecast area, with falling heights spreading across the area as the upper low approaches. Organized storms will be possible across eastern Montana into western North Dakota, with high-res guidance pretty consistent in convection developing in Montana late this afternoon before moving into North Dakota this evening. A moderate axis of instability is progged to be in place from the warm and humid airmass, as the 00 UTC HREF shows a plume of 1500-2500 J/kg of MUCAPE across northwest into central North Dakota, along and ahead of the warm front lifting north. 0-6km shear will be very marginal until the main upper forcing gets closer, staying around 20-30 knots before increasing to around 40 knots tonight. A low-level jet is expected which will likely keep convection going through the night as the entire system progresses east, and the latest NBM PoPs do keep a 30-50% chance of showers and thunderstorms across much of the forecast area through the night, with the highest chances in the northwest. With not the most favorable overlap of environmental parameters, and some uncertainty in storm mode, will keep messaging of wind gusts up to 60 mph and hail up to the size of half dollars. The most likely timing of any severe storms in western North Dakota is after sunset. The active pattern continues through the rest of the work week as general troughing persists across the western CONUS, keeping us under broad southwest flow aloft. Blended PoPs keep near- daily low to medium chances for showers and thunderstorms across the area through the end of the extended period. Cooler air will be allowed to filter in across the region, with NBM temperature probabilities continuing to show a cooling trend into the weekend. Expect highs to be much closer to normal this weekend heading into the next work week, generally in the lower 60s to lower 70s. && .AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/... Issued at 642 AM CDT Tue Sep 17 2024 Low stratus and areas of dense fog are leading to IFR/LIFR conditions across northern North Dakota, including KXWA/KMOT. Conditions are expected to slowly improve through the morning, while VFR conditions should continue across southern terminals. Southeast winds will be breezy ahead of an approaching system that will bring chances for showers and thunderstorms this evening into tonight. Highest likelihood of impact is at KDIK/KXWA, with lesser chances to the east. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Besson DISCUSSION...Jones AVIATION...Jones