Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 152313

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
713 PM EDT Tue May 15 2018


A textbook evening release of northeast flow from Lake Huron is in
progress during early evening. This will be followed by greater
influence of surface high pressure settling into Lower Michigan
tonight through Wednesday morning. A clearing trend results during
the evening with some lower dewpoint air making it down through FNT.
There is some lingering uncertainty at PTK and especially DTW where
surface dewpoint could remain in the lower 50s through sunrise. Fog
potential is greatest there even if the surface wind remains
northeast while an east to southeast component will provide added
boundary layer cooling and moistening from Lake Erie. Based on the
most recent RAP/HRRR soundings, the plan is to maintain MVFR
restriction in the forecast for late tonight through early Wednesday

For DTW... Potential remains for MVFR fog and scattered low stratocu
late tonight through early Wednesday morning. A light east to
northeast surface wind is also expected through Wednesday morning.


* Low for ceiling 5000 ft or less during the evening.


Issued at 316 PM EDT Tue May 15 2018


Dissipation of most of this morning`s cloud cover has paved the way
for healthy diurnal boundary layer growth this afternoon. Surface-
based moisture field indicated by dewpoints in the upper 50s and
steeper lapse rates in the lowest 8kft courtesy of a glancing blow
by the thermal trough traversing Ontario has allowed for some
shallow convection invof the Saginaw Valley this aftn where some
added lift is provided by the edge of the marine layer. As heating
is lost a strong inland push of the marine layer, aided by high
pressure northeast of the Great Lakes region, will provide a focus
for a few more isolated showers over interior locations before
sundown. Despite lingering cirrus and a light gradient, marine
influence will allow temps to fall into the upper 40s and low 50s.
Easterly overlake fetch over Lake Erie will support a very shallow
inversion in the Detroit and Downriver areas late tonight into early
Wednesday suggesting for or stratus potential mainly east of the
glacial ridge, burning off quickly Wed morning. Upper ridge
gradually translating east will support modest warming of the column
Wed into Thurs with highs nearing 80 outside of lake shadows.
Renewed confluent flow over the Canadian Prairie will support
another surge of high pressure north of the area Thursday. Inland
locations still approaching 80 once again, but likely hovering in
the low 70s and upper 60s in the Thumb and Saginaw Valley courtesy
of marine influence. Mostly sunny skies throughout this time with
modest diurnal cu and passing cirrus peeling off a weak cutoff
circulation over the Mississippi Valley.

Pleasant, dry conditions will continue on Friday before shower and
thunderstorm chances return for the weekend. A slow-moving
disturbance lifting through the Ohio Valley will bring a slight
chance for showers as it clips the southeast corner of Michigan on
Saturday. A better chance for more widespread showers and
thunderstorms will then arrive on Sunday as a mid-level wave and
associated cold front drops through the Great Lakes region. High
pressure then looks to return early next week bringing a return to
dry, pleasant conditions. Temperatures will be near average Friday
through Monday with highs in the low to mid 70s and lows in the 50s.


Front has dropped south and winds have flipped to northerly. Weak
gradient has kept winds on the light side with a clearing cloud
trend from north to south over the lakes as high pressure begins to
build over the central Great Lakes. As the high pressure moves
through the region, winds will shift back out of the south tomorrow
and remain light. Expect fairly calm conditions much of this week
resulting in low wave action and light winds across much of the
lakes through the end of the week.



Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.




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