lakeville weather journal

Over and over I say how spoiled we have been this summer. It only continues! This last week I took a hiatus from the journal with some other projects and distractions needing attention...and the weather was seasonal and tame to boot. As we enter one of the last weekends of summer for many, my eye turns again to a pretty textbook setup for convection. The pattern has shifted a bit more prospectively, as the GFS and NAM models both swung precip chances ahead in the calendar.

Currently, low level moisture is already in place throughout the region as cloud remnants from a Dakota MCS last night breezed in overnight and simmered in the dirunal sun. With dewpoints steady throughout the region in the low-mid 60's, and some pushing 70 out west, this will be the most attributable factor in atmospheric instability preceeding the cold front that is progged to sweep through early Monday AM. Indeed precipitable H2O values push over 2" in two pools according to the model ensemble - Northcentral through western MN late saturday PM and over the Sioux Empire for Sunday. Theta-E is on par with other dyn's, including a strengthening LLJ nosing up over the Sioux Empire. Upglide and advection promoted by the LLJ will tap the p-wat from FAR east towards the central lakes of MN, forcing convection Sat night.

One slight "anomoly" I spotted in the 12Z NAM run...3500 J/kg of CAPE plotted over the Couteau des Prairies at 00Z Sunday. CAPE values elsewhere were non-factors...The model favors the Couteau for convection genesis, so I have to wonder if this is just preferential treatment, or if an MCS will fire there as well as Central MN Sat night? One thing seems certain...should a well organized MCS fire over the Couteau, the cloud debris on Sunday may inhibit heavier pre-frontal convection later on Sunday, when the Twin Cities and Lakeville have the best shot at storms. The forthcoming model runs will have to revisit this. So my Lakeville Forecast for now...

FRIDAY NIGHT....scattered clouds, low 65. Fog possible in low areas after midnight. Light S wind to calm conditions.

SUNDAY....Muggy and warm, Partly Cloudy with high of 88. Thunderstorms develop after suppertime, move in towards sunset. Low 62. South wind 10-15 shifting to W and calming after dark.