textproduct: Twin Cities

KEY MESSAGES

- Stratus and areas of fog continue this morning and for much of today. Sunshine remains absent through the weekend, finally returning behind our rain system into next week.

- Widespread rain likely Friday into Saturday. Little if any frozen precipitation types are expected with temperatures above freezing throughout.

DISCUSSION

Issued at 321 AM CST Thu Dec 26 2024

Compared to yesterday at this time, we are looking at similar amounts of fog but far less density with the lowest visibility in far southern MN around 1 mile and again around Alexandria in western MN around 1 mile. Widespread low stratus continues to produce areas of mist which is enough to begin to deposit on cold surfaces such as vehicles, with could produce a few slick spots on the typical trouble spots like bridges and overpasses. 24 hours from now we would expect to see fog still present but once again less dense than now as we start to see a few showers squeezed out of the stratus setting up our rain event arriving Friday into Saturday. Satellite imagery shows a swath of both stratus and upper level clouds stemming from the leading edge of a weakening trough slinging through the region today which will also bring a bit of extra moisture to our south helping set up Friday's event. Much like the last few days, we are unlikely to see the sun with 2 solid layers of clouds to fight through, with sunshine remaining absent until at least Sunday as the incoming rain system moves out.

Speaking of which, the forecast has not changed significantly since the last update in regards to the Friday into Saturday rain system. PWATS continue to be forecast within the upper echelons of climatology, with an amount that would make any kind of frozen precipitation type extremely unlikely given the thermodynamics required to produce them. Despite the PWATs, ensembles remain grounded in a solid 0.25-0.5 inches of rainfall total with the higher amounts favoring western Wisconsin and the lowest in western Minnesota. The forcing stems from enhanced CVA ahead of an incoming trough that begins to negatively tilt to the point the better forcing surges northwards from the central plains before developing a surface low as the trough apex reaches the intersection of eastern Iowa, southwestern Wisconsin, and northwestern Illinois. A broad shield of precipitation within the northwest quadrant of the surface low will give us persistent rainfall into early Saturday before wrapping up later in the day as the system drives further northeast towards the northern Great Lakes. Because the surface low is dynamically forced stemming from the upper level feature, the key thing to track to hone in the finer forecast details will continue to be the positioning of the trough as it tilts with some wobble in the best precipitation axis likely until the surface low forms. For now, there is medium to high confidence in the forecast favoring western Wisconsin for the highest amount of rainfall with reduced amounts to the west, with CAM guidance coming into play within the forecast process by this afternoon or later tonight.

Temperatures will remain on the warm side ahead of the rain bearing system due to the longwave radiation trapping from the widespread cloud cover keeping us warmer overnight, in addition to southerly surface winds bringing enough warm air advection to drive highs into the upper 30s today and low 40s through Sunday. It isn't until winds turn westerly at the surface and aloft before temperatures cool down, which looks to take place gradually throughout next week. By New Years Day, Highs look to range from the low to mid 20s with lows in the low teens, beginning January fairly close to normal. A low confidence forecast in yet another trough swinging through the northern plains by late Monday could give us a shot at some snow as we cool down, but for now guidance is extremely split between snow and nothing at all. It won't be until the rain system moves out and we get a bit closer before the details of our next potential snow system become clearer.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1100 PM CST Wed Dec 25 2024

MVFR to LIFR ceilings will remain through this period. Quite a range I know, but the higher MVFR ceilings will remain across mainly western Wisconsin and into parts of eastern and southern Minnesota. Central to western Minnesota will be IFR to LIFR. Still expecting these lower ceilings to spread east as we head into Thursday as the low level moisture moves. Near the end of the period as Friday approaches, rain shower chances will slowly increase. The best chance for rain come after the end of this TAF period on Friday. Winds will continue to come from a southeast direction with gustier winds in west central Minnesota.

KMSP...Persistent IFR ceilings eventually falling into LIFR later on Thursday. Should see some mist overnight, but not likely to be heavy enough for much to accumulate on surfaces. However temperatures will hover right around freezing, so some slick areas could be possible.

/OUTLOOK FOR KMSP/ FRI...MVFR/IFR, -RA likely. Wind SE 5-10 kts. SAT...MVFR/IFR, chc -RA. Wind SW 5-10 kts. SUN...VFR. Wind W 5-10 kts.

MPX WATCHES/WARNINGS/ADVISORIES

MN...None. WI...None.