Bumpy Start to Father's Day Weekend?
I have been caught up with studies for recurrent training this week, so I have not dedicated much time to the ol' forecasting, however...I am relatively pleased with the longer-term shot at a forecast in my last post. The most significant deviation from my forecast was the temps, and some different precip chances here and there. Otherwise, we are on track.
Nice weekend setup for convection potential (once again) for the area. Deep-trough system from the Pac-NW came off the Rockies yesterday with some hardcore supercells in parts of Eastern MT. These "elevated" storms rolled off the Bighorn Mtn range and gulped up warm advection fuel from the LLJ as they propogated NE across the eastern MT high plains. Baseball and larger-sized hail, along with 85 mph winds were reported in Miles City, MT from the storms.
The same system has now moved east and has settled in overnight on the shores of Lake Oahe (MO River Valley) through the Dakotas. Sfc low centered near Mitchell, SD per mesonet readings at this time, with warm front a little more pronounced per the 00Z radiosonde plots...700MB analysis of the data shows the warm sector has surged a little further north, with current warm front extending thru a steep arc roughly ATY-FAR-FFM-AXN-HCD-FBL-LSE. From the sfc low, front has technically occluded along the trough boundary, running retro up through ABR-DVL- just west of Lake Winnepeg, and then stretching back to Medicine Hat, AB, where closed low spins the top end.
Not much movement of the front is expected overnight from model outputs, and to boot the strong S-SW flow of warm tex-mex air has now started to sip Gulf Moisture. Strong capping in place overnight per soundings, which show a decent mid-level inversion between 9000-13000 feet. ETA has a vorticity max progged near the ABR-ATY area for 18Z, and this should begin the breaking of the cap. The GFS painted the v-max same local, but later (00Z), and this is where the two models begin to stray from each other.
GFS pushed precip maxes out of the Sioux Empire overnight Fri into mid-AM Sat. The Sioux Empire is a favorite genesis location for the GFS this season, and I don't know why it has such a strong bias for it... for it has never held too true (yet). ETA has precip maxes painted off of its happy hunting ground this season - The Couteau des Praries and moving swiftly SSE, with higher chcs of soaking for southern MN. ETA has had better luck with this type of a setup, but with the strong LLJ from the SW ahead of the front, I don't see the overpronounced SE propogation as realistic.
Splitting the difference on timing and locality is my bet for now. I forsee storm genesis between the Couteau and the MN River Valley sometime between 21Z and 00Z. Propogation will be more easterly, and I think the MCS will form along the vort max line, which the GFS did a nice job painting SW-NE from the FSD area up through BRD around this time. This is a "classic" central MN setup for severe weather, and I will be shocked if we don't see WW's issued by by late afternoon, all things considered. I personally liked the MPX-WFO early PM discussion, outlining a similar outlook, but holding off on definitive severe threats. Their weekend outlook focused on the shortwaves emitting from the closed AB/SK low...but I think the 00Z model runs actually link up our weekend weather with the upper jet, now troughing in the intermountain west, soon to go zonal and bring a Tex-Mex low up to the mid-plains late Saturday. I call for precip chances rekindled on Fathers Day, with convection potential evident as well. More updates late tomorrow, hopefully, and thru the weekend!!
FRIDAY... Mostly Cloudy in AM, turning partly cloudy, hot, steamy by afternoon. High 87. 60% chc of strong thunderstorms after 6PM, low 70. S-SW winds 10-15 mph,
SATURDAY...Wake up to 30% chc of lingering thunder, then clearing through afternoon, high 82. Low 60. West winds 6-10 mph, calming and turning NW after midnight.
FATHERS DAY...Partly Cloudy, High 86. 40% chc of thunder approaching sundown thru overnight hours. Low 70.