Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 221701
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
101 PM EDT Wed Mar 22 2017

.AVIATION...

Essentially no weather to speak of for the next 18-24 hours.  Two
short term issues are rapidly resolving themselves this afternoon.
First, lake effect cloudiness off Lake Huron extended down into
northern metro Detroit area briefly resulted in sub 4KFT cigs, but
drier air mixing through the convective boundary layer has eroded all
but shorteline adjacent clouds. Second, mixing over the thumb region
has temporarily resulted in northerly winds gusting to 20 knots. As
high pressure footprint gets more established this afternoon expect
gradient and wind speeds to weaken substantially. Only other issue
will be advance of mid and high cloud in warm advection ahead of next
advancing short wave in the DTW area in the last 6 hours of the TAF
on Thursday.

For DTW...Lake effect cloud and weakening pressure gradient to
result in mostly clear skies and lessening winds this afternoon and
tonight over the DTW airspace. Some mid and high cloud expected
Thursday afternoon but bases likely to be at or above 10KFT.

//DTW THRESHOLD PROBABILITIES...

* None

&&

.PREV DISCUSSION...
Issued at 308 AM EDT Wed Mar 22 2017

DISCUSSION...
A large arctic high pressure centered just north of Lake Superior
will drift across the state today and off to the east on Thursday.
Northerly winds will decrease somewhat from Tuesday but still remain
around 10 mph putting a bit of a chill in the air. Plenty of
sunshine today as airmass is extremely dry. Lake band of clouds right
along the Lake Huron shoreline will dissipate this morning as
surface flow become more offshore. Highs today will struggle into
the 30s even with a late March sun as 850mb will be around -12c.
Another cold night tonight with strong radiational cooling as skies
will remain clear and winds will go near calm from decoupling under
weak gradient. Will see teens again all locations with pockets of
single digits in colder prone locations. Thursday will see decent
waa above the surface as temps will rise about 10c at 925mb and 850mb
though surface flow will be from a cooler southeast direction.
Mixing during the first part of the day from plenty of sunshine will
help temps rebound into the 40s before increasing high clouds from
approaching storm system spread across the area in the afternoon.

A warm front ahead of a large developing low pressure over the
central plains will lift north through the area Thursday night.
Isentropic ascent ahead of the warm front will spread light
rain, possibly mix with snow at the onset as wet bulbing in very dry
low levels may bring profile below freezing at first.  Models still
progged the warm front to lift to central lower Michigan Friday then
stalling. This would bring an end to rain in the south but still
keep showers going across the Saginaw Valley and Thumb. Very warm air
south of the front will produce highs in the low 60s most locations
and possibly mid 60s near the Ohio border as long as the front lifts
far enough north.

The developing low pressure system will quickly close and drift
towards Michigan while gradually filling and weakening.  Strong High
pressure across Canada will suppress the front across central lower
Michigan back down to the Ohio border.  This will keep the shower
chances going all weekend and into the beginning of next week.
Temperatures will remain mild with highs mostly in the 50s and lows
30s north to 40s south.

MARINE...

Stable arctic high pressure will become parked over the central
Great Lakes today and Thursday. Northerly surface winds will remain
seasonably subdued with a stable near surface environment. Southerly
flow will emerge and then increase late Thursday in response to the
center of surface high pressure building into the Mid Atlantic
Region. Strengthening southwesterly gradient flow will support the
increase in winds particularly for the Lake Huron Basin. Latest
signal from model consensus suggests a high confidence in wind gusts
reaching the 25 to 33 knot range particularly after 00Z-Friday. The
wind forecast becomes more tricky for the weekend as a warm front
will lift into the Great Lakes region before stalling. Specific
forecast becomes low confidence for any one location as the details
remain high dependent on the exact frontal placement. Will say the
pattern appears conducive for a long duration easterly flow event.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory until 4 PM EDT this afternoon for LHZ421-
     441>443.

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

$$

AVIATION.....05
DISCUSSION...DRC
MARINE.......CB


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