FXUS63 KDTX 202330
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
730 PM EDT Tue Mar 20 2018
Prevailing northeast flow will sustain dry low level conditions
through the TAF period. While a thickening canopy of high cloud
will lift into the region tonight, this will ensure skies remain
clear across the lowest 7-8k ft. Evidence of a narrow strip of
stratus lifting from Saginaw Bay into MBS is waning now, so will
lean toward simply a scattered coverage moving forward. Gusty
northeast winds will ease early tonight as diurnal support fades,
but with the occasional gust near 20 knots still likely through the
For DTW...Winds hold from the north-northeast /010-030 direction/
tonight, gradually easing in both magnitude and gust frequency.
Gradual backing of winds to north and north-northwest throughout
Wednesday. Skies to remain clear across the lowest 5000 ft through
/DTW THRESHOLD PROBABILITIES...
Issued at 309 PM EDT Tue Mar 20 2018
Strong Canadian high pressure (1030+ MB) will remain anchored
along/near Ontario/Quebec border over the next several days.
12Z DTX indicated a very dry airmass in place over southeast
Michigan today, as 850 MB dew pt depression checked in at 32 C, with
a PW value of 0.14 inches.
Brisk northeast winds will continue through tonight (holding min
temperatures in the low/mid 20s), shifting to the North-Northeast
early tomorrow morning. Strengthening low-mid level circulation
tracking through southern Ohio will send 850-700 MB Theta-E gradient
over Lenawee/Monroe counties overnight. But with continued low level
feed of dry air, still looking at the snow shield holding near the
southern Michigan border. 12z Regional Gem would even argue for
light accumulations south of I-94 as 700 MB specific humidity rises
to 2.5 G/KG. Preference is more toward the slightly drier RAP
solution, but low chance pops for light snow late tonight still
seems warranted south of I-94, especially if that flow becomes a bit
more easterly off Lake Erie.
Upper level shortwave ridging to become established on Wednesday.
With northerly flow off cold waters of Lake Huron, looks like good
temp gradient setting up during the day, as 925 mb temps advertised
to range from -8 C over northern tip of the Thumb to -2 C along the
southern Michigan border, translating to highs in lower 30s to lower
Dry airmass and skies becoming clear Wednesday night will lead to a
favorable radiating night, sending temps into the lower 20s. Could
even see mins sneak into the teens in the normally colder locations
if winds fully decouple.
Thursday and beyond...
Confluent NW flow still forcing all meaningful precip south of the
area while ensuring mostly sunny skies with dominant high pressure
at the surface. The third week of spring will see temperatures
creeping ever-closer to average values as ridging builds over the
central CONUS for the remainder of the forecast period.
Large High pressure to the north and a low pressure system moving up
the Ohio Valley will continue a prolonged period of moderate
northeast wind which will continue this afternoon through Wednesday
before gradually diminishing Wednesday night. Occasional gusts to
30 kts are likely through Wednesday. The long northeast fetch over
open water will build high waves through the period and small craft
advisories remain in effect through Wednesday for all marine areas
except Lake St Clair which is through tonight. Advisories will
continue into Wednesday night for outer Saginaw Bay and Lake Huron
near shore. The wind will weaken and back north by Wednesday night
as the low exits the mid Atlantic coast and as the Ontario high
builds over the western Great Lakes. This will allow waves to
gradually diminish below advisory levels all areas by Thursday and
last through Friday.
MI...Lakeshore Flood Advisory until 10 AM EDT Wednesday for MIZ083.
Lake Huron...Small Craft Advisory until 2 AM EDT Thursday for LHZ421-441>443.
Small Craft Advisory until 4 PM EDT Wednesday for LHZ422.
Lake St Clair...Small Craft Advisory until 8 AM EDT Wednesday for LCZ460.
Michigan waters of Lake Erie...Small Craft Advisory until 8 AM EDT Wednesday for LEZ444.
You can obtain your latest National Weather Service forecasts online
Back to Main Forecast Discussion Page