


Area Forecast Discussion
Issued by NWS Bismarck, ND
Issued by NWS Bismarck, ND
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111 FXUS63 KBIS 121207 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 707 AM CDT Sun Oct 12 2025 .KEY MESSAGES... - Very windy today, with west to northwest winds around 30 to 35 mph and gusts as high as 55 mph. - Periods of rain expected in northwest North Dakota this morning through early evening. A few thunderstorms are possible in the morning, and snow could briefly mix in with the rain during the late afternoon and early evening. - Much cooler to start the work week, then warming back up to near or slightly above average mid to late week. - Widespread below freezing temperatures likely across western North Dakota tonight and northern North Dakota Monday night. - Medium to high chances for rain Wednesday through Friday. && .UPDATE... Issued at 707 AM CDT Sun Oct 12 2025 The cold front has begun surging into western North Dakota, producing gusts as high as 45 mph. Isolated thunderstorms are tracking north-northeast across Williams and Divide Counties. The main cell, which passed just to the east of Williston around 630 AM CDT, has shown signs of pulsing intensity, and earlier in its life span had some weak rotation aloft. Radar analysis has not supported hail any larger than pea size, and wind gusts stronger than those caused by the cold front have not been observed directly with the storms. The chance of thunderstorms will continue in this part of the state until around 9 AM CDT. Patchy dense fog has also developed in northwest parts of the state, mainly impacting the Tioga area. Conditions should improve either after the passage of the cold front or perhaps sooner from thunderstorms passing by. && .DISCUSSION... Issued at 504 AM CDT Sun Oct 12 2025 The base of a potent upper level trough is swinging across the Continental Divide of the Northern Rockies early this morning. A lead shortwave that is responsible for widespread rain showers across the eastern Dakotas and western Minnesota is lifting northeast into southeast Manitoba and western Ontario. Trailing the lead shortwave, low level warm air and moisture advection has maintained a broad area of widely scattered showers from the Turtle Mountains to near Lake Sakakawea. This activity may continue to percolate into the mid morning hours. Farther west, rain more closely associated with the intense DCVA in tandem with a left exit region of a strong upper jet is approaching the North Dakota/Montana border. An initial concern through the mid morning hours will be the potential for a few thunderstorms. This signal has been showing up in CAMs since this morning entered their forecast time ranges. As of 330 AM MDT, there were 2 separate but decaying thunderstorms between Sidney and Baker. But some CAMs do suggest a possible re-flaring of this convection as it moves into far northwest North Dakota from around 7 to 10 AM CDT. MUCAPE as high as 500 J/kg, steep mid level lapse rates, and increasing effective bulk shear to around 50 kts could promote a stronger storm or two. A surface trough is analyzed along the ND/MT border early this morning. The rapidly lowering mid level heights upstream will force the surface trough into a cold front that surges across the state from west to east this morning and early afternoon. While this is occurring, the northern end of the surface trough is forecast to undergo rapid cyclogenesis over the southeast corner of Saskatchewan this morning, lift into southwest Manitoba this afternoon as a sub- 990 mb low, and occlude this evening as the parent trough catches up to it. The main concern from the deepening surface low pressure system is the potential for strong winds. Strong magnitudes of cold air advection and pressure rises look to produce an initial surge of gusts as high as 45 mph with the frontal passage this morning, strongest in the southwest and tapering off slightly over time and space. As the low continues to deepen and lift northeastward this afternoon, all of western and central North Dakota will fall under the strong pressure gradient with sustained cold air advection, rising surface pressure, and steep low level lapse rates. Mean BL winds are forecast around 30 to 35 kts around midday, but should steadily rise to as high as 40 to 50 kts by early evening. The strongest corridor of winds is expected across northern North Dakota this evening as an 850 mb jet wraps around the southwest flank of the low. There is still forecast uncertainty on the magnitude of these winds in both the HREF and among global ensembles. Given the expected strong dynamics of this system, we are leaning our forecast toward the higher end outcome of mean mixing potential closer to 50 kts. Due to the forecast consistency on the timing and location of the strongest winds, we have preemptively extended roughly the northern half of the Wind Advisory until midnight CDT tonight, and also increased the forecast maximum gusts to 55 mph. The timing and strength of the frontal passage will create a unique diurnal temperature trend that varies across the state. The James River Valley could see midday temperatures spike to near 70, aided by compressional heating, before cooling back into the 50s by late afternoon. Central North Dakota could see late morning high temperatures near 60, followed by near-steady temperatures south central and falling temperatures north central. Western North Dakota could see a trend similar to that of central North Dakota, but around 10 degrees cooler and with a more rapid fall in the northwest through the afternoon. After the initial round of rain with potential thunderstorms in the northwest this morning, there may or may not be a brief break before the wrap-around deformation band of precipitation consolidates this afternoon. There is uncertainty in the southern extent of the deformation band, from as far north as McKenzie County to as far south as Highway 12. Regardless, the duration of precipitation will be much longer in the northwest where there are medium to high chances for at least a quarter of an inch of liquid. There is still a potential for enough cooling to allow snow to mix in before the precipitation ends during the late afternoon or early evening. This would be most likely to occur along the higher terrain from Divide to northern Mountrail Counties. The NBM derived probability of measurable snow is only around 10 to 20 percent, and snowfall rates are no longer expected to be high enough to overcome melting on contact with the warmer ground. Aside from the deformation band, there is low chance that a narrow band of showers could develop along the leading edge of the vort max as it pivots through central North Dakota this afternoon. But much of the day should remain dry outside of the northwest. A surface ridge axis is forecast to expand from southern Alberta into South Dakota tonight, cutting through southwest North Dakota. The southwest therefore has the highest odds of a hard freeze tonight, with projected lows in the mid 20s. Upper 20s to lower 30s are in the forecast for the rest of the western half of the state, with mid 30s in the James River Valley. The surface ridge axis is forecast to lift northward on Monday, leading to a dry but much cooler day with high temperatures only in the lower and mid 40s northwest to mid 50s southeast. By Monday night, shortwave energy will begin to eject from the base of another deep western CONUS trough. The northern half of the state is more likely to remain under the influence of Canadian surface high pressure through Monday night, which could allow for a widespread hard freeze there. The southern half of the state may see increasing clouds and a light easterly breeze Monday night, but there is still a 50 to 75 percent chance of sub-freezing lows across the south. The aforementioned lead shortwave could bring some light rain showers to western and southern parts of the state on Tuesday. Then after a brief period of upper level ridging Tuesday night, the western CONUS trough is forecast to migrate into the Northern and Central Plains and Upper Midwest mid to late week. Cluster analysis reveals an even split among each of the GEFS and ECMWF ensemble members between a more progressive and open wave and one that is deeper and slower. Regardless of these timing discrepancies, this pattern places medium to high chances for rain across the state from Wednesday into Friday. There is very high ensemble confidence that surface temperatures will not fall below freezing while precipitation is falling. In fact, the NBM shows a distinct mid week warming trend that brings high temperatures back to near or slightly above average (50s and 60s) and low temperatures safely above average (mid 30s to upper 40s). Another aspect of this part of the forecast that may need monitoring is a low chance for thunderstorms on Wednesday, as clusters representing the more progressive solution bring 500-1000 J/kg CAPE along with 30-40 kts of deep layer shear into the state. && .AVIATION /12Z TAFS THROUGH 12Z MONDAY/... Issued at 707 AM CDT Sun Oct 12 2025 Widespread low ceilings, primarily MVFR but with some IFR, are expected across much of western and central North Dakota this morning. South central into eastern North Dakota should improve to VFR this afternoon, with the southwest following suit this evening. But northwest and north central parts of the state are more likely to maintain an MVFR ceiling through much of the night. Periods of rain are expected in northwest North Dakota through early this evening. Isolated thunderstorms will also impact the area until around 14Z. There is a low chance that rain could mix with snow during the late afternoon and early evening, but this would be more likely to occur north of KXWA. A cold front will surge across the state from west to east this morning and early afternoon, shifting winds to the west-northwest. Gusts as high as 35-40 kts are possible with and behind the front this morning. Then expecting westerly winds sustained around 30 kts with gusts to 45 kts across most of western and central North Dakota this afternoon. Winds should taper off from south to north this evening, but north central parts of the state could see even stronger gusts closer to 50 kts early in the evening. && .BIS WATCHES/WARNINGS/ADVISORIES... Wind Advisory until midnight CDT tonight for NDZ001>005- 009>013-021>023-025. Wind Advisory until 8 PM CDT /7 PM MDT/ this evening for NDZ017>020-031>037-040>047-050. && $$ UPDATE...Hollan DISCUSSION...Hollan AVIATION...Hollan