Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 291911
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
311 PM EDT MON AUG 29 2016
Southeast Michigan remains firmly tucked immediately south of high
pressure heading into tonight...the effective weakly anti-cyclonic
low level flow maintaining a deeper layer of stability within a
generally dry profile. Near surface moisture content does remain
elevated, with a light/northeast flow again favoring some inland
penetration of Lake Huron moisture once nocturnal cooling sets in.
Areas of fog remain highlighted across the thumb, this corridor
certainly more favored for possible dense fog during the early
morning hours. Lows tonight upper 50s-lower 60s.
Area of weak height falls tied to a lead shortwave now lifting
across the upper MS Valley will ease a cold front into the lower
peninsula on Tuesday. Local area holds position south of the front
through the daylight period. Standard looking mixing profile capped
at the 850 level, but with the diurnal thermal response receiving a
subtle boost as the low level gradient becomes light southwesterly.
This will translate into highs of mid 80s areawide. Frontal zone
timed to enter the Tri-Cities/Thumb early Tuesday night,
subsequently working across the remainder of the area through early
Wednesday. No real component of moisture advection precedes or
accompanies this frontal passage, but the existing profile will
sustain a weakly unstable environment despite the increasingly
negative influence of the nocturnal cooling process. This will
present at least a chance for less organized convective development
through this time given sufficient frontal convergence working
beneath the ongoing weak height falls.
Lingering window for shower/thunderstorm development early Wednesday
across southern sections, before drying post-frontal northwest flow
takes a greater hold. Initial period of weak cold air advection
will be offset somewhat by daytime heating/mixing, with a greater
thermal advective response awaiting a stronger wave Wednesday night.
Moisture quality lacks to support anything more than an uptick in
clouds with this trailing wave, although growing overlake
instability may offer a glancing shot for shower development right
along the eastern thumb shoreline.
High pressure building into the region will bring cooler/drier
conditions into the area on Thursday, which will persist throughout
the weekend. High temperatures will peak in the low to mid 70`s on
Thursday and Friday, before warm air ushers back into the region,
allowing temperatures to return into the lower 80`s for a daytime
high. The chance for rain showers is expected to return on Monday
and Tuesday as a weak warm front pushes through the region.
Light to moderate southwest flow will transition to northwesterly
behind a cold front on Tuesday night. Northwest wind will be gusty
and will become fresh Wednesday evening into Thursday as additional
cool air spreads across the waters Wednesday evening. Small craft
advisories for the nearshore waters of Lake Huron will be likely
during this time as gusts hover around 25 kts and onshore flow
builds significant wave heights near the shoreline.
Issued at 1258 PM EDT Mon AUG 29 2016
Moisture in the process of mixing out over the area. Clear or nearly
clear skies in place in the Detroit area will hold save for some
passing patches of cirrus. Morning stratus is mixing into an MVFR cu
field from PTK north. This process will take another couple of hours
to complete, but a steady, predictable trend toward scattering and
clearing will be noted through the afternoon. Wind will tend to be
out of the southeasterly quadrant, but will likely be variable at
times through tonight due very weak gradient. Forecast soundings
suggest patchy shallow fog possible by sunrise Tuesday, but not
convincing enough to warrant inclusion of a vsby restriction in
the 18z forecast.
//DTW Threshold Probabilities...
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
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