FXUS63 KBIS 131131 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 631 AM CDT Sun Oct 13 2024 .KEY MESSAGES... - Freezing temperatures this morning across north central and western north Dakota. Widespread freezing temperatures again Monday morning. - Patchy fog is possible over portions of western North Dakota through the mid morning hours. - Gusty north-northwest winds are expected in the southern James River Valley through the afternoon. - Generally warming temperatures and dry conditions will be found through at least mid next week. Some breezy winds may be found at times. && .UPDATE... Issued at 630 AM CDT Sun Oct 13 2024 Quiet conditions are found across the forecast area this morning. Low temperatures have to around or below freezing across much of the west and portions of north central North Dakota, while temperatures in south central North Dakota are from the mid 30s to around 40. Winds are generally light and variable, though the southern James River Valley remains somewhat breezy, with sustained speeds around 12 to 15 mph. A deck of high level clouds have moved in across the forecast area a little earlier than anticipated, so have adjusted the sky grids accordingly. Otherwise, the forecast remains on track. && .DISCUSSION... Issued at 400 AM CDT Sun Oct 13 2024 Near meridional flow is found over the forecast area this morning as an upper level ridge struggles to displace a low center found to moving over northern Minnesota. At the surface, high pressure is building in across our northwest, promoting a generally clearing sky and a stilling of winds across much of the forecast area. A slightly tighter pressure gradient can be found across the James River Valley, which has allow for gusty winds, with speeds generally from 15 to 20 knots and gusts up to 30 knots, linger overnight. With the cooler air mass accompanying the high pressure center, the very light winds, and the generally clearing skies, low temperatures across the west and the north are expected to dip to around or below freezing. We have continued the previous shifts' 50/50 blend of NBM/NBM50 to account for slightly cooler temperatures that deterministic ensemble has settled on. Due to these temperatures, a Freeze Warning is in effect through 10 AM CDT / 9 AM MDT across much of northern and western North Dakota. Also of note is that this new, cooler airmass over the west has also aided in moisture recovery across this area which, along with the very light winds, could promote the formation of patchy fog through the mid morning hours over portions of western North Dakota. Otherwise for today, much cooler temperatures around or slightly below seasonable normals are expected, with highs forecast broadly in the 50s. Gusty north-northwest winds up to 30 MPH are anticipated across the southern James River Valley through the afternoon today, though winds will remain generally light elsewhere. With high pressure settling over the forecast area this afternoon and overnight, widespread low temperatures at or below freezing are expected across most of the forecast area again tonight into Monday morning. Similarly to this morning, we have continue the NBM/NBM50 blend for low temperatures. Another headline for this widespread freeze will likely be needed, but in collaboration with our neighbors we have held off during this update to prevent mixed messaging with the Freeze Warning that is already in place. By Monday afternoon, the upper level ridge building in from the western CONUS is anticipated to begin to intrude into our western counties. With the deeper penetration of the terminal axis associated with this ridge, slightly warmer high temperatures from the lower 50s east to the mid 60s southwest are forecast. As the ridge lingers over the forecast area through the mid week, a general warming trend is expected to bring high temperatures back into the 60s and 70s for Wednesday and Thursday. With another surface high progged to move over northern Minnesota on Tuesday, a tightening pressure gradient and modest CAA is expected to promote gusty winds across western and central North Dakota Tuesday afternoon, then more broadly across most of central and portions of western North Dakota on Wednesday. With these winds and warming temperatures allowing for lower minimum RHs in the upper teens and 20s across the west, there may be near critical fire weather conditions on Tuesday and Wednesday, though this will depend on how well these ingredients align. Late in the workweek, there is some agreement between ensemble members in a change into a slightly more active pattern as a the ridge is displaced to the east and a upper level trough dips into the northern Plains. The exact timing and strength and timing of this trough is a source of discourse between the ensemble members, and of the uncertainty in the forecast at this time. At this time, the NBM has placed chances (30-50%) for showers late Thursday through Friday. In any case, there is good agreement that a return to more seasonable temperatures, with highs generally in the 50s and 60s will accompany this pattern shift through the end of the week. && .AVIATION /12Z TAFS THROUGH 12Z MONDAY/... Issued at 630 AM CDT Sun Oct 13 2024 VRF ceilings and visibility is expected at all terminals throughout the 06Z TAF period. Shallow, patchy fog is possible across the west this morning, though the confidence in this impacting visibility at any terminal is too low to add to the TAFs at this time. Light winds this morning will somewhat strengthen and organize out of the north northeast through the afternoon, will sustained speeds general up to around 12 knots. The exception to this is the south central, including the terminal of KJMS, which is expected to observed gusty north northwest winds with speeds from 15 to 20 knots and gusts up to 30 knots this morning through this afternoon. Winds will then generally diminish this evening, becoming very light and variable through the end of the TAF period. && .BIS WATCHES/WARNINGS/ADVISORIES... Freeze Warning until 10 AM CDT /9 AM MDT/ this morning for NDZ001>005-009>013-017>021-031>034-040>044. && $$ UPDATE...Adam DISCUSSION...Adam AVIATION...Adam