Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 231941
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
341 PM EDT THU JUN 23 2016
Satellite/radar trends supports rapid clearing from north to south
as post wave subsidence/drier air takes hold early this evening,
setting us up for a cool night under clear skies with most
locations falling back into the 50s Tonight. With surface dew pts
already established in the 40s, Thumb region stands reasonable
shot to fall back into the upper 40s.
A warm up will then take place tomorrow through sunday, with a
fairly straight-forward synoptic pattern setup. An upper level ridge
will build into the Great Lakes Region, ahead of the strong upper
level wave/low currently centered near Vancouver. 500 MB heights to
build to around 590 dam on Saturday over southern lower Michigan,
and expecting temperatures to push into the upper 80s to near 90
degrees underneath the ridge axis. Relatively low humidity levels as
surface dew pts reside in the 50s before we get into return flow
over the second half of the weekend.
The large upper level low over the Pacific Northwest looks to be
tracking into Ontario on Sunday. There looks to be good surge of low
level moisture/850 mb theta-e sliding east into southeast Michigan
during Sunday, with surface dew pts progged to reach around 70
degrees. High temperatures are expected to end up around 90 degrees
with 850 mb temps advertised around 20 c, which would lead to
moderately unstable airmass (MLCAPES around 2000 J/kg). Adequate 0-6
km shear of 25 to 30 knots supports a severe risk. On the flip side,
prefrontal trough is getting far removed from any upper level
support, and there still chance we may be end up capped, as 700 mb
temps flirt with 10 C. 12Z euro shows chance for activity ending by
00z, but will maintain low pop in the evening for possible timing
adjustment. Keeping with timing uncertainty, potential earlier
convection time could short circuit the max forecast a few degrees.
MONDAY THROUGH FRIDAY:
Trough of low pressure remains over the Great Lakes region early
Monday morning. This will allow for chances of showers/thunderstorms
overnight Sunday through early Monday morning. Surface high pressure
begins building over southeast Michigan by Monday afternoon/evening;
however, upper level trough lingers through at least Tuesday. There
will be a slight chance of showers persisting in the forecast into
Tuesday...mainly over the Northern Thumb and northeastern coastal
areas. High pressure takes a better hold over the area by Wednesday
with dry conditions anticipated through Friday. Monday`s high temps
will be in the mid 80`s north to near 90 south...with high dew point
temperatures...so expect a hot and muggy day to start the workweek.
Cooler temperatures in the mid to upper 70`s with lower dew points
to follow for the remainder of the extended period.
Surface high pressure will build into the central Great Lakes
tonight and Friday. Very pleasant early summer weather is
anticipated over area waterways throughout much of the upcoming
weekend. Light easterly flow at 10 knots or less will be in place on
Friday before veering to southeasterly on Saturday. The next chance
of showers and thunderstorms will be Sunday afternoon as a cold
front advances through the region.
Issued at 217 PM EDT Thu Jun 23 2016
A very weak impulse tied to the entrance region of a jetstreak aloft
is responsible for the scattered coverage of light showers over
southeastern Michigan this afternoon. This forcing will strip out of
the area during the late afternoon lowering the chances for any
additional tempo to vicinity showers after 20z. Forecast soundings
show less saturation at the top of the mixed layer this evening
supporting lessening sky fraction due to loss of daytime heating.
Quiet conditions are anticipated tonight with a debate warranted for
the amount of mid to high cloud that will be around overnight. The
forecast soundings are dry, but forecasted isentropic rh analyses
along with satellite represenation of upstream cloud suggests a more
pessismistic all tonight for high cloud. Went with SCT coverage at
15 kft agl, but very well could be overcast of down to 9 or 10 kft
AT DTW. Tempo group for light showers is valid through 20 UTC before
shortwave impulse support pushes to the east. Varying amount of high
cloud is expected through tonight as upstream cloud and saturation
funnels across the area within a shearing deformation axis. Light
easterly flow will remain in place throughout the period. Looking at
wind speeds to become light this evening with the loss of the mixed
layer, only to increase modestly again Friday morning.
//DTW Threshold Probabilities...
* High in ceilings below 5000 ft this afternoon. Low tonight and
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
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