Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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222
FXUS63 KDTX 230358
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1158 PM EDT Tue May 22 2018


.AVIATION...

High pressure will bring generally clear skies and light winds this
forecast period. These conditions will also lead to a period of
patchy fog overnight into early Wednesday morning given the amount
of residual low level moisture left over from recent rains.

For DTW...Clear skies and light winds overnight may support vsby
restrictions in fog. Otherwise, VFR conditions will prevail.

.DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 345 PM EDT Tue May 22 2018

DISCUSSION...

Mid level trough axis is currently swinging through lower MI and
should be east of the area by 00Z this evening. A surface reflection
of this feature, a secondary cold front, over extreme SE MI should
exit the area by 21Z this afternoon. This front has a good wind
shift with it from SW to NW and will also usher in a drier airmass
through the evening as well. Convection remains a possibility ahead
of this boundary as unstable air spread northward with surface
dewpoints in the mid 60s and clear slot ahead of the front enhancing
low level lapse rates. The primary surface cold front is to our
south advancing across Ohio which is blocking the better moisture
and instability with severe convection ongoing. Window is quickly
closing though as mentioned, and the front will be through in the
next couple hours.

High pressure building into the western Great Lakes behind the mid
level trough will bring in drier air which looks to quickly scour
out any residual cloud cover this evening. Visible satellite this
afternoon shows nearly clear skies across northern MI advancing
southward behind the exiting trough. Question for the overnight is
does the high enhance the nocturnal low level inversion and set us
up for fog? With dewpoints lingering in the 40s to near 50, and
decent radiational cooling with light winds under the high, looks
favorable for at least patchy fog around. A look through all the
hires models shows a favoritism for fog around the Thumb including
Saginaw Bay and southern Lake Huron. Current obs don`t offer much
help in diagnosing this, thus will keep with patchy mention and see
how the obs trend later this evening as clear skies work south.

High pressure will then center itself over lower MI on Wednesday
with a weak cold pool aloft left over to moderate as mid level flow
becomes weakly westerly. Good deal of sun with the exception of
potential diurnal cu field, and deep mixing to 800mb should allow
temps to rise into the upper 70s to near 80. The high slides a bit
east for Thursday which will allow southern return flow to advect
warmer air into the area. The mid level ridge will also slide east
with more influence over the Great Lakes, but indications are for
the ridge to slowly flatten as northern stream energy works into the
Midwest. 850mb temps will jump from around 9C Wednesday up to 14C
Thursday. Combined with full sun, this should result in highs in the
low to mid 80s.

Main story in the extended will be the much warmer temperatures to
round out the week and into the weekend.  Southerly flow will help
to bring temps up into the mid 80s those days with temps holding in
the low 80s through Monday.  There remains the possibility for some
showers in the extended with the best chance Saturday afternoon as a
wave moves across the northern Great Lakes region.

MARINE...

Modest northwest winds will grip all marine areas this evening and
tonight in the wake of low pressure slowly lifting east of the
region. High pressure takes control Wednesday and Wednesday night.
This will lead to a stretch of favorable boating conditions, with
generally light winds and low waves. Winds become southerly during
the late week period, with persistent high pressure maintaining
generally fair weather conditions during this time.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&

$$

AVIATION.....DG
DISCUSSION...DRK/SP
MARINE.......MR


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at www.weather.gov/detroit.



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