885 FXUS63 KFGF 281802 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 102 PM CDT Tue May 28 2019 .UPDATE... Issued at 1258 PM CDT Tue May 28 2019 Cirrus spreading into SE ND and WC MN as high level moisture moves north ahead of the 500 mb low in Colorado. Thin enough to avoid too much temp impacts. Sunny north. Did raise highs a tad north a couple degrees as HRRR has far northern RRV 77-78. Did lower dew pts a bit as very dry air with the west-southwest advecting in and also some mixing of drier air to the sfc. Dew pts in the 27-35 range. && .SHORT TERM...(Today and tonight) Issued at 406 AM CDT Tue May 28 2019 Surface observing sites indicate areas of early morning fog across much of MN lakes country and along and east of the James River Valley in ND, under a sfc high pressure-induced nocturnal radiational cooling. A few sites have fallen into the 30s under this regime, but expect fog to dissipate after sunrise as daytime heating of the boundary layer commences. Early this morning, water vapor imagery shows the forecast area positioned in split flow between a Hudson Bay closed low and high anvil clouds advecting northward into the Dakotas from ongoing Central Plains convection ahead of a Colorado Low. As this Colorado Low ejects into the Plains, strong upper level ridging over the West builds into the Northern Plains through Wednesday. Pre-dawn surface observations show a much drier airmass with dew points in the mid 20s to mid 30s across the southern Canadian prairie, poised to advect south into northeast ND and northwest MN with westerly winds developing north of lingering surface high pressure. This set up will support a dry atmospheric column, yielding mostly sunny skies today across much of ND and northwest and west central MN today. Additionally potential for afternoon cumulus develops in this area as moderate low level lapse rates develop under strong daytime heating. The exception to this would be for portions of the far southern valley where remnant convective anvil will linger well into the day. Ultimately, this setup will yield quiet, dry weather with afternoon high temperatures in the upper 60s to upper 70s today. Afternoon minimum humidities will drop into the 20s to lower 30s for most spots along and north of US Hwy 2 with fairly light west winds and higher humidity values in the 30s and 40s for locations further south. As warm air advection and ridging develop heading into Wednesday, there is potential for many sites to approach or surpass the 80 degree mark. However northwest flow aloft looks to advect smoke from the Alberta wildfires over portions of the region and could cap potential for warmer weather Wednesday. Large scale pattern dominated by split flow across the CONUS, with northwest flow over the Northern Plains transitioning to more of a progressive westerly flow late in the extended forecast period. High temps will tend to be above normal near 80 Thursday and Friday, and closer to normal beyond Friday (70s). .LONG TERM...(Wednesday through Monday) Issued at 406 AM CDT Tue May 28 2019 Large scale pattern dominated by split flow across the CONUS, with northwest flow over the Northern Plains transitioning to more of a progressive westerly flow late in the extended forecast period. High temps will tend to be above normal near 80 Thursday and Friday, and closer to normal beyond Friday (70s). Thursday-Thursday night: Ridge migrates from the northwest to southeast over our CWA out of Canada with general trend towards synoptic scale height rises/subsidence over our CWA. WAA increases and by midday Thursday a surface trough (behaving more like warm front) sets up near the Red River with region of increasing convergence. There is some question whether this area of increasing convergence/mesoscale forcing can overcome the deeper synoptic level subsidence and limited moisture. NAM/GFS/GEM are showing weak/convective QPF signal along this north-south orientated boundary, though they vary somewhat on orientation, coverage, and amounts. If a thunderstorm were to initiate Thursday afternoon/evening during peak heating, there may be adequate instability/shear for a few strong or even marginally severe storms. Confidence is just not high on initiation. Friday-Friday night: A shortwave trough is still shown to drop south out of Canada along with an associated cold front by Friday night. Increasing low level moisture ahead of this front and steepening mid level lapse rates should allow for increasing CAPE and potential for stronger updrafts. There is a stronger QPF signal Friday afternoon through Friday night night raising confidence in thunderstorm coverage. Strong/deep shear and ML CAPE possibly in excess of 2000 J/KG are shown by GFS ahead of this cold front and, as would be expected, severe parameters are lining up (Craven sig severe in excess of 20,000 m3/s3). Due to the progressive nature of the pattern and low level flow favoring more of a westerly direction ahead of fropa, I'm a little skeptical of advertised surface Tds which may be resulting in CAPE a little higher than may be realized. Still, severe potential is there even if CAPE is lower than advertised. Saturday-Tuesday: Trend is towards drier conditions Saturday afternoon through Sunday with return to upper level shortwave ridging. Progressive westerly flow Sunday night through Tuesday will allow for a series of shortwave troughs to bring showers and possible thunderstorms back to our region. Even with reasonable consensus in model height patterns aloft, there is enough variance on evolution of these systems and related surface fields to lower confidence in coverage/impacts at this range. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1258 PM CDT Tue May 28 2019 VFR thru the pd with some cirrus in the south and clear sky north. Winds rather light thru tonight...more west-southwest NE ND/far NW MN and more E-NE SE ND and WC MN....under 10 kts...though brief 15 kt gusts far northern areas near Canadian border this aftn. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...Riddle SHORT TERM...BP LONG TERM...DJR AVIATION...Riddle