Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 130850
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
350 AM EST Wed Nov 13 2019

.DISCUSSION...

High pressure sliding through the region overnight with clear skies
and calm winds atop a fresh snowpack has resulted in efficient
radiative cooling conditions. Temperatures are mainly hovering in
the mid single digits with our typical cold spots at or even below
zero. The coldest air within this current thermal trough is behind
us now as the airmass will moderate through the day with southerly
flow and waa ahead of the next system targeting the region tonight.
The effects of the waa won`t really be felt at the surface today as
highs are limited to the mid/upper 20s. Air is too cold to start,
clouds will prevent much help from the sun, and initially waa will
be felt in the mid levels. There is a chance that a wedge of warmer
air will lift up through the southern few counties late in the day
which could boost temps up closer to 30.

A long wave trough will swing through the region tonight bringing
the next chance of snow. After 00Z this evening, a cold front will
drop into Mid MI as a mid level wave tracks along it. Isentropic
ascent ahead of it will saturate mid levels but very dry boundary
layer will be tough to overcome for most of SE MI initially.
Moisture quality is low as PWATs only rise from about 0.3" up to
0.5" during peak forcing, and soundings show the dry low levels
struggle to ever truly become saturated. Narrow corridor of FGEN
aided by left exit region of a 90kt jet will pair with the weak
front to help showers develop though. Best chances will be along and
north of I69 where up to an inch can be expected. As the front
continues south toward morning, the shortwave will be exiting
eastward leading to lower totals as one heads south. Snow should
start falling later this evening ending by Thursday morning.

There is a chance that weak cold advection on the backside of the
cold front will advect some lake effect showers off Lake MI through
the morning Thursday. A slight SW wind component will keep the bulk
of this cloud band and light showers along and north of M59. High
pressure will reduce inversion heights and bring in drier air
helping to shut if off for the afternoon.

High pressure will hold Friday through the weekend resulting in a
precip free forecast. Though the airmass will slowly moderate
through this time, 850mb temps look to hover in the low single
digits keeping the stretch of below average temps going (highs
mainly below 40F). The next longwave trough looks to swing through
Monday bringing the next chance of precip.

&&

.MARINE...

Relatively calm boating conditions will be short-lived as high
pressure departs to the east and causes a stronger pressure gradient
to build over the open waters on Wednesday, bringing the return of
20-25 knot wind gusts with at least a small potential for low-end
gales over northern Lake Huron. While funneling up Saginaw Bay may
enhance winds enough to support occasional 25 knot gusts, scenario
appears marginal and transient enough to forgo headlines. The same
goes for an gale potential as there is a better chance that gusts
remain closer to 30 knots or northern Lake Huron.

Winds will then settle back down tonight into Thursday before
increasing again from Thursday night into Friday as another cold
front clips the area. Once again, expect gusts to generally top out
near 30 knots over northern portions of the lake. However, with the
wind direction veering from westerly to northerly on Friday, wave
action will build from north to south and may eventually reach Small
Craft Advisory criterion late Friday into Friday.

&&

.CLIMATE...

Record low maximum temperatures for November 13

Detroit Area....21 (1911)
Flint Area......19 (1986)
Saginaw Area....21 (1986)

Record lows for November 13/14

Detroit Area...12/13 (1911/1986)
Flint Area.....12/12 (1986/1986)
Saginaw Area...12/11 (1986/1933)

&&

.PREV DISCUSSION...
Issued at 1203 AM EST Wed Nov 13 2019

AVIATION...

Combo of diurnal loss in mixing depths to 3.0-5.0 kft agl and axis
of composite H5-H3 trof pushing east of Southeast Michigan longitude
has resulted in very strong synoptic scale support for subsidence
and clearing skies overnight. Midlevel warm advection begins to
increase the latter half of tonight but vertical theta e profiles
show very little moisture advection until later Wednesday as cold
drainage flow out of the southeast remains dominant. Forecast
soundings show very efficient drying sub 5000 ft to limit any chance
of boundary layer cloud through much of the afternoon Wednesday with
any initial forcing used in moistening the column. Warm front aloft
forcing/system relative isentropic ascent shows to bring
precipitation potential for northern terminals after 00Z Thursday.
Introduced a prevailing MVFR light snow group at KMBS after 03Z.

For DTW...VFR tonight and Wednesday.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling aob 5000 ft tonight and Wednesday.


&&

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

$$

DISCUSSION...DRK
MARINE.......DG
CLIMATE......DG
AVIATION.....CB


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