Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 140453
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1153 PM EST Mon Feb 13 2017


.AVIATION...

An ongoing increase in the southerly gradient will support light
winds through the morning. A shallow nocturnal stable layer should
inhibit much in the way of gusts until late in the morning or early
afternoon when daytime mixing supports gusts topping 20 knots at
times. Dry air will inhibit lower cloud development across Se Mi
through Tues morning. Increasing chances for lower clouds will then
occur Tues afternoon from north to south with the approach of a cold
front from the north. Snow showers are expected along/behind this
frontal system Tues evening.

For DTW...Winds will generally remain south-southwest through early
afternoon before veering toward the west-southwest this afternoon.
Additional veering of the winds toward the west will occur Tues
evening with the passage of the cold front.


//DTW THRESHOLD PROBABILITIES...

* Moderate in ceilings below 5000 ft Tuesday night.

* Low in crosswind thresholds being exceeded Tuesday evening.

&&

.PREV DISCUSSION...
Issued at 353 PM EST Mon Feb 13 2017

DISCUSSION...

Tightening pressure gradient between a deepening low pressure system
dropping southeast from the western shore of Hudson Bay and surface
riding settling south of the area will lead to steady southwest flow
overnight tonight promoting warm air advection into Tuesday morning.
With clear skies and relatively light winds early, expect the low
temperatures to occur by midnight with steady to slowly rising
temperatures overnight. Guidance envelop suggests lows in the upper
20s to around 30 which seems reasonable given the relatively decent
radiative cooling potential during the evening hours.

While a brief period of weak cold air advection will begin Tuesday
morning with lead surface troughing, expect neutral temperature
advection to be the rule in west/northeast flow in advance of the
main cold front that will surge through the area Tuesday evening as
aforementioned low pressure near Hudson Bay swings southeast just
north of Georgian Bay by late Tuesday. This will lead to another
relatively mild day in the 40s with southern parts of the forecast
area reaching the middle 40s.

Much colder readings overspread the region Tuesday night and then
persist into Wednesday as the vigorous shortwave trough driving the
surface low sweeps into the eastern Great Lakes and leads to a
amplification of the eastern CONUS longwave trough. Another rather
significant shortwave disturbance, noted on water vapor imagery this
afternoon, will drop quickly into the base of the developing upper
low to the east and lead to further amplification of this feature as
well as instigate another rather strong winter storm system over the
New England states. The net result for the central Great Lakes will
be temperatures at or slightly below average temperatures for the
middle of February (highs around 30/lows in the teens/20s).

Given the source region of these waves well north of the area, do
not expect any notable moisture return into the area before the
resultant system takes shape Tuesday night into Wednesday. So, the
chance of snow showers will remain rather low with little to no
accumulations expected into the middle of the week.

High pressure moving over the Great Lakes on Thursday will bring
a decrease in cloud cover with highs remaining in the low 30s before
850-mb temps begin a warming trend through the end of the week. As
upper level ridging moves into the Great Lakes warmer air will enter
the region with low level southwest flow moderating temperatures
into the 50s by Saturday. The upper level ridge then remains in
place through early next week keeping dry conditions in place with
temperatures around 10-20 deg F above normal for SE Michigan (highs
well into the 50s and lows in the 30s) through next Monday.

MARINE...

Winds shift to southwesterly and strengthen tonight in response to
low pressure forecast to track southeast across Ontario over the
next 36 to 48 hours.   Neutral stability conditions will exist for a
brief time this evening with solid 25 knot flow over much of Lake
Huron.  Winds will ease by Tuesday as stability increases. Attention
then turns to the late Tuesday night and Wednesday periods, as cold
air wraps back across the lakes in the wake of this low pressure
system.  Strong potential for a period of northwest gales over a
good portion of lake Huron during this time, conditions certaintly
warranting a gale watch.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Gale Watch from late Tuesday night through Wednesday afternoon for
     LHZ361>363-421-441-442-462-463.

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

$$

AVIATION.....SC
DISCUSSION...DG/JD
MARINE.......MR


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at www.weather.gov/detroit.



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