Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 170456

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1256 AM EDT Sat Mar 17 2018


Surface ridge will maintain vfr conditions and light winds across
the area through Saturday. The only clouds expected will be varying
degrees of cirrus as system passes to the south of the area. Winds
will be light westerly overnight (near calm late) and then become
northerly on Saturday in the 6-8 knot range.

For DTW...Light and variable winds overnight with surface high
pressure becoming northerly around 6 knots on Saturday. A bulk of
moisture/clouds will remain south of DTW on Saturday with just a
veil of cirrus.


* None.


Issued at 315 PM EDT Fri Mar 16 2018


Cold airmass remains in place, as 12z DTX sounding indicated an 850
mb temp of -13 C. Thus, despite nearly full mid March insolation
today, temps still were only able to make it into the 30s (as of 3
PM), with the northern Thumb region still holding in the mid/upper
20s with the snowpack.

Upper level northwest confluent flow allowing high pressure to hold
over Lower Michigan tonight will lead to another good radiating
night with the current surface dew pts residing in the lower teens
and winds going calm overnight. Mid/high clouds look to be the main
hindrance for preventing mins from dipping into the teens, and clouds
look to be mainly south of M-59, where lows in the 20s will be

The upper level low currently over the Central Plains will be
shearing off to the east and tracking through the Ohio Valley on
Saturday. Tight 850-700 MB Theta-E gradient fails to reach southern
Michigan border, thus no concerns for precip, with the dry airmass
and PW values around 0.25 inches holding through the Weekend.

Airmass modifying over the weekend as 850 mb temps reach toward
-3 C on Saturday and toward 0 C on Sunday. This is expected to
result in highs reaching the lower 40s on Saturday, to near 50
degrees on Sunday. The exception will be the Thumb region with the
snow cover and colder easterly flow off Lake Huron. With the dry
airmass, favorable radiating nights will continue, allowing for
increased diurnal swings, as mins still dip into the 20s both
Saturday and Sunday night.

Forecast confidence weakens considerably early next week as ejecting
upper-level energy out of the Rockies in an overall stagnant larger
hemispheric wave pattern will result in the formation of a closed
upper-level low and corresponding surface low pressure. Long range
guidance is in good agreement that this will occur, but still
diverges rather significantly regarding the track of these features.
The GFS is much farther north than the ECMWF, bringing the precip
shield near the Ohio border, while the ECMWF is much further south
as it tracks across the Tennessee River Valley (bulk of latest GEFS
supports this track as well). If this system were to impact the
region, with chances seeming low at this time given confluent upper
jet pattern across the Great Lakes suppressing subtropical energy to
the south, the best timing for precip chances would be Monday into
Tuesday. Will go with a largely dry forecast during this timeframe,
however, with only a mention of precip near the Ohio border. Dry
Canadian high pressure then ridges southward into the Great Lakes
for the midweek period.

With a generally northwesterly flow regime dominating through much
of the long term, colder continental airmass air will continually
filter across the region leading to a return of below normal
temperatures running roughly 5-10 degrees below normal.

MARINE...High pressure building into Michigan has led to a dry air
mass and relatively cloudfree conditions over the region. Winds will
continue to decrease while backing more westerly in response to the
high sliding in west of Lake Huron. A broad region of high pressure
will linger over the region through the weekend, leading to
generally light winds.


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



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