093 FXUS63 KFGF 131235 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 635 AM CST Wed Feb 13 2019 .UPDATE... Issued at 625 AM CST Wed Feb 13 2019 Light snow has diminished in place of increasing fog across northwest and west central MN under the low stratus deck. Visibilities down to 1/2 mile have become common with occasional drops to 1/4 mile. Visibilities have been fluctuating up and down over the past hour, but web cams showed enough fog to warrant an SPS. This fog should linger through sunrise before gradually diminishing by 9 AM. No other forecast changes needed. && .SHORT TERM...(Today and tonight) Issued at 332 AM CST Wed Feb 13 2019 Surface observations across much of northwest MN have been reporting light snow for the past few hours under a persistent low level stratus deck. This stratus deck is likely the result of broad low level convergence between a ridge axis to the west and an exiting low to the east. Hi-res guidance suggests this feature will persist through sunrise, so a dusting to a tenth of an inch of new snow accumulation can't be ruled out for a few spots if the light snow activity continues. To the west across ND... dry westerly low level winds and broad subsidence in the wake of an upper level low are keeping skies clear and allowing temperatures to drop down into the teens to twenties below zero via strong radiative cooling. Although a few places may have wind chills briefly drop down below -25, weak winds are expected as the surface ridge remains over the region through morning. With the current stratus deck expected to gradually erode after sunrise, partly cloudy conditions are expected for today across the region with highs only reaching into the single digits and teens. An upper level low is expected to move into south central Canada by this evening and will bring light snow chances along the International border and possibly as far south as the Highway 200 corridor by this evening and into tonight. Snow accumulations of one half to two inches will be possible over this broad area, but are most likely north of Highway 2. Surface observations from southwest Canada show an arctic airmass in place that is expected to move into the Dakotas behind a cold front/surface trough overnight tonight. This will help keep overnight temperatures in the single digits (above and below zero) for much of the region. .LONG TERM...(Thursday through Tuesday) Issued at 332 AM CST Wed Feb 13 2019 Thursday: Trough shifts east, with subsidence building in from the west any lingering snow ending in our northeast my midday. A strong surge of CAA moves across our CWA through the day Thursday coinciding, with increasing surface gradient (highlighted by 6-8MB 6HR pressure rises). Even if depth of mixed layer is limited until midday/afternoon we should see winds at least around 20kt, with 925MB winds by the afternoon around 30kt in our southeast. Temps may hold steady or fall below zero from the west, and with these winds/temps we could expect at least patchy blowing snow with travel impacts possible in open country. These increasing winds and falling temps will also lead to lower WC values (-25 to -35) at least in the morning period Thursday and again Thursday night. Friday-Wednesday: Shortwave ridge aloft should lead to relatively quiet weather Friday/Friday night regarding measurable snow potential, however over the weekend there is increasing spread in ensembles and determinist models as split troughs migrate eastward and there is very little consistency on evolution/track of potential forcing/moisture. I couldn't rule out snowfall during these periods, but there is not a strong enough dry or wet signal for any individual period to adjust from mean/consensus which paints some slight chance or chances PoPs for parts of our CWA Saturday night through Sunday night. By the middle of next week models indicate troughing with a split flow around our region favoring dry conditions. Regarding temperatures: Persistent large scale troughing/lowered heights through the extended period across the Northern Plains, resulting in persistently cold/below normal air mass through the extended period. Expect highs to remain in the single digits (or a little lower) for much of our CWA, with overnight lows below zero through all extended periods (many overnight periods in the 10s to teens below). && .AVIATION...(For the 12Z TAFS through 12Z Thursday morning) Issued at 521 AM CST Wed Feb 13 2019 Main impacts this morning are light snow, fog, and low ceilings over much of northwest/west central Minnesota and the Red River Valley. All TAF sites except KDVL are currently under a persistent low stratus deck with LIFR/IFR ceilings between 2 to 7 hundred feet. Light snow and fog have both been reported via surface observations and web cams under this deck and have reduced visibility below one mile at times. This feature has not been handled well by short term guidance and is expected to linger through at least sunrise, and possibly through 18Z for KBJI. General clearing is expected over northwest MN during the early afternoon hours. High clouds are already starting to move in across northern ND and will continue to spread eastward through the day. Lower ceilings between 1-3 kft will move in later this evening and tonight in association with a cold frontal passage and increasing snow chances. Snow is most likely for locations and TAF sites along and north of Highway 2 with a dusting to two inches of accumulation possible by Thursday morning. Although it is outside of the current TAF forecast period, strong northwest winds are expected for central and eastern ND during the day on Thursday. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...AM SHORT TERM...AM LONG TERM...DJR AVIATION...AM