Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 160513

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
113 AM EDT Fri Mar 16 2018


Thickest strato-cu will be pivoting southeast of the area with the
passage of cold front early in the forecast. Subsidence in the wake
of this front has already eroded a great deal of this cloud deck
save for lake effect plumes feeding from Lake Superior/northern Lake
Michigan. So, any bkn clouds early will trend to few-sct overnight
and persist for the remainder of the forecast as surface ridging
builds into the region. Northwest winds will hold in the 10-15 kt
range overnight and then weaken and back to the west/southwest on

For DTW...Remaining cigs aob 5kft will scatter out overnight with
few-sct clouds, at most, expected the remainder of the forecast.
Northwest winds (320-330) will remain elevated overnight with even
some gusts to 20 knots early. Winds then back to the southwest and
weaken Friday.


* Medium in ceilings at or below 5000 ft through 08z or so.

* Moderate in crosswind thresholds being exceeded overnight.


Issued at 328 PM EDT Thu Mar 15 2018



As of 325 PM EDT...The region continues to sit under a northwest
flow regime as broad longwave troughing encompasses the eastern third
of the CONUS. Within this flow, a weak embedded piece of midlevel
energy continues to rotate through lower Michigan, and will exit east
by this evening. Lake aggregate moisture plume has resulted in
dreary stratus/stratocu blanketing much of the region, with enough
boundary layer moisture and dynamic lift/daytime heating to squeeze
out occasional flurries from time to time. Steepening low- level
lapse rates has resulted in some more intense snow showers to develop
as well within this flow, with brief reductions in visibility noted
by regional observations. A quick coating is possible with these snow
showers, with up to a half an inch of accumulation possible over the
Thumb where a few possible snow squalls may develop later this
afternoon. Confidence in snow squall potential remains low, but
something to keep an eye on with the very steep low-level lapse rates
heading into the evening hours. High temperatures will top out in
the 30s across the region, with a few upper 30s readings possible
near the Ohio border.

Any remnant snow shower/flurry activity will wane after sunset as
the flow becomes increasingly anticyclonic through the column as
upstream high pressure begins to build into the region. The
exception to this will again be across portions of the Thumb where a
few snow showers may linger into the early overnight especially
along the Lake Huron coastline. As is typical during the winter
months, however, low-level clouds will be tough to erode despite
increasingly drier air advecting in. It will likely take until after
midnight for clouds to clear out as another embedded shortwave
currently located north of the Straits swings through. Despite these
factors, a slackening pressure gradient leading to decreased winds
will help low temperatures tonight fall into the upper teens for
most areas, with potential for colder readings if clouds manage to
scour out earlier than expected.


Surface high pressure will continue to build across the region
Friday along with slowly rising upper-level heights. Drier air will
also continue to filter across the region with plentiful sunshine
and dry weather expected. High temperatures will be a few degrees
warmer with more sunshine, but still limited to the 30s, albeit more
mid to upper 30s than Thursday. Model guidance continues to be in
good agreement with an area of low pressure tracking south of the
region late Friday night and into Saturday on the southern edge of
confluent upper-level flow. The northern extent of the precip shield
will feature a sharp cutoff virtually riding the
Michigan/Ohio/Indiana border, and with the antecedent dry low-levels
in place, it will be hard pressed to see any precip reach into
southeast Michigan so will just go with an increase in cloud cover
for southern areas. Weak warm air advection accompanying the low
passage, however, will allow high temperatures Saturday to reach
into the lower 40s for most locations. Another ridge of high
pressure will build across the region beginning Saturday night with
continued tranquil conditions.


The extended period of quiet weather is expected to continue for
both Sunday and Monday as high pressure travels east from the Ohio
Valley into the Atlantic. Fairly good convergence is now seen
between long range models runs regarding an upper-level closed low
that travels from southern MO/IL into southern OH throughout
Tuesday. Mid-level flow will then weaken across the Ohio Valley late
Tuesday which will cause a surface low to stall across the region
into southern Michigan, bringing precipitation chances late Tuesday
into Wednesday. Precipitation seen throughout the morning hours
would likely fall as snow or a rain/snow mix, before transitioning
to rain during the daylight hours as daytime highs peak in the upper-
30s to lower 40s for Wednesday. Otherwise, a second high pressure
system is forecasted to build across the state Thursday into Friday,
bringing another period of dry conditions.


A push of colder air under northwest winds will advance across lake
Huron this evening. Although over-lake mixing depths will not be too
terribly high, there remains high probabilities of wind gusts around
30 knots across the open waters of Lake Huron. A ridge of high
pressure will extend across Lower Mi on Friday. This will result in a
steady weakening of the winds as they back toward the west. A broad
region of high pressure will linger over the region through the
weekend, leading to generally light winds.


Lake Huron...Small Craft Advisory until 4 PM EDT this afternoon for LHZ421-

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



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