We are coming into a more active pattern the next couple days. Below are the SPC predictions for today and Saturday. My concern for tomorrow is the enhance risk nosing its way towards south Michigan . We have the slight risk for severe storms tomorrow with the enhanced risk just to our south west.
A few areas may get wet today and tonight with some storms popping up across the area, but many areas will stay dry. Currently (7 am) there are some pockets of heavier rain around the Lansing Area The better chance for thunderstorms comes later Saturday when some severe weather is possible. Early next week looks cooler with occasional chances for showers and perhaps some thunderstorms, but with many dry periods as well.
HRRR and Futurecast models runs are for 18 hours beginning at 7am – a second model run begins at 3pm
Day and Week Planner
This feature has auto location.
(click images to enlarge)
The main focus is on thunderstorm coverage today into tonight and the threat for severe weather on Saturday into Saturday night. Overall, the coverage of thunderstorms today will be low and the threat for severe weather Saturday into Saturday night is increasing but not certain as of yet.
There are some favorable factors both early this morning and into the rest of the day for a few storms to pop up. A modest LLJ core will develop this morning (25-30 kts) over the lake and spread east. This occurs as some upper level divergence moves through. Deep layer shear looks better today than yesterday, with 35-40 kts expected. H1000-H700 wind convergence is noted on the GFS as we move throughout the afternoon, possibly helping some convection grow.
PW values are respectable, in the 1.25″-1.50″ range. However, high res CAMs are yawning at the prospect for convection today, leading to some speculation about coverage of storms. Kept POPs conservative today, mainly focusing on both early morning and then late day storm chances.
As was the case the last several afternoons, many locations won`t get a drop of rain while some may get occasionally heavy downpours. Storm chances persist tonight as the LLJ holds up over the area but again not expecting widespread activity at this point. The prospect for widespread showers and thunderstorms goes up considerably Saturday, particularly late in the day.
Surface based CAPE across southern Lower MI will likely reach 1000 J/Kg or more, coincident with increasing deep layer shear to 40 kts by 00z and possibly 50 kts by 06z Sunday. The GFS and GEM have pretty vigorous H1000-H700 convergence overhead during the evening and late night hours Saturday. This occurs as H1000-H500 RH increases to 90%.
With a 40 kt LLJ moving in and solid upper level divergence, convection may very well blossom over the region and it could be quite heavy. PW (precipitable water) values off the ECMWF are around 2.00″ as this occurs. The question becomes where will the convection fire and then where will it propagate?
The best instability may end up being near and south of I-96. This is where the convection may be strongest and it may tend to sink a bit south as it heads eastward with the mean wind. The exact region is subject to change as there will be areas of convection preceding the main show Saturday night, which will influence mesoscale boundaries.
Both strong wind gusts and hail would be the primary hazards. While we certainly need some rain and the ground will soak up quite a bit of what is coming, there may be localized flooding (ie. nuisance street flooding) in the heaviest storms.
Chances for rain are not very high during the long term. By Sunday night the cold front will have already moved through the cwa and cooler and drier air will be advecting south from Canada. We should see 2-3 days of highs in the 70s and lows in the 50s.
We`ll see some sunshine too, but the upper trough that will be moving across the Great Lakes will generate moderately steep lapse rates that will result in quite a bit of cu (cumulus clouds) and perhaps scattered showers early in the week. A stronger wave rotating through the flow Tuesday may produce a thunderstorm; Tuesday looks like the best chance of rain. High pressure then builds back into the cwa. As the upper flow transitions to zonal, we`ll see heights and temperatures rise toward the end of the week.