Expert Forecast Opinion

000
FXUS63 KDTX 021101
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
601 AM EST Thu Feb 2 2023


.AVIATION...

A strong cold front will progress from northwest to southeast across
the area this afternoon. The front will be marked by a gradual
veering of the winds from SW to WNW. A deepening mixed layer ahead
of and in the wake of the front will support wind gusts of 20 to 25
knots. Low level moisture convergence and some enhanced lake
moisture will result in low end VFR and MVFR based clouds along and
in the wake of this front this afternoon and evening and will
support a chance for snow showers/flurries.

For DTW...There will be a veering of the winds to the west,
generally in the 21Z to 23Z time frame as the cold front moves
across metro. Winds will then turn more northwesterly thereafter.

DTW THRESHOLD PROBABILITIES...

* Medium for ceilings aob 5kft this evening and tonight.

* Low for crosswind thresholds to be reached this evening.

&&

.PREV DISCUSSION...
Issued at 359 AM EST Thu Feb 2 2023

DISCUSSION...

The return of bitter cold conditions is on its way for tonight
through Friday night as the next round of arctic air surges into the
region. A fast moving shortwave marking the leading edge of the
inbound arctic air mass pivots around the base of the mid-level
Hudson Bay low this morning, causing an expanding area of PV
advection and height falls to release southeastward and across the
Great Lakes and New England today and tonight. The surface front is
currently stationary over Lake Superior, but this will be quickly
ushered southward as that arctic air gains momentum this morning.
For the first half of today, expect southwest winds to strengthen to
around 20-30 mph as a surface low rapidly develops along the front
and increases the pressure gradient. Temps will rise from the teens
this morning to around 30 thanks to weak warm advection, but the
wind does look to offset much in the way of tangible warming as wind
chills peak in the teens.

The arctic front drops southward across lower Michigan through the
day, reaching the Tri-Cities and Thumb by mid-afternoon and Metro
Detroit by the evening hours. Some moisture pooling ahead of the
front and steepening lapse rates intersecting the DGZ will bring
scattered snow showers with fropa. Heavier snow shower potential
continues to look unlikely locally despite some weak instability
advertised by hi-res progs. Boundary layer moisture recovery will be
weak this morning as the Lake Michigan plume will mainly be directed
over northern Lower, and a good deal of mid-level dry/stable air
will be surging in just behind the front to keep convective depths
shallow and forcing brief. The best chance for some more organized
snow showers to hold together will be over the Thumb where the
remnants of the Lake Superior/northern Lake Michigan moisture plume
will be directed as the flow veers from southwest to northwest.
Minor accumulations will be possible there.

Arctic air will quickly fill into the region on gusty northwest
winds this evening and overnight. 850mb temps bottom out near
-25C by Friday morning, near the 1st climatological percentile. With
the snowpack still largely intact, temps should fall to near 0 by
sunrise Friday. Winds will let up a bit overnight, but a persistent
northwest breeze around 15-20 mph will hold wind chills in the -10
to -15 range with the the lowest values across the northern CWA.
Wind Chill Advisory headlines may be needed tonight and tomorrow
morning as a result.

Very cold conditions persist through Friday with northwest wind
continuing to provide a feed of moisture from the lakes upstream,
resulting in mostly cloudy skies and occasional flurries as the
boundary layer sits within the DGZ. Wind chills are likely to stay
near or just below 0 through the afternoon before falling again
Friday night. Lower confidence in Wind Chill Advisory conditions
Friday night/Saturday morning as winds will be slightly weaker with
high pressure passing just south of us.

The longwave trough moves out on Saturday and gusty south flow sets
up as the high pressure moves into the Mid-Atlantic. This ushers in
a much milder air mass through the day. There will be a chance of
light snow across the northern counties as the elevated warm front
lifts through. Another opportunity for some light snow and possibly
some rain mixing in across the south occurs on Sunday with a weak
low working across the Great Lakes. Overall mild conditions are then
favored to stick around through the middle of next week.

MARINE...

The Great Lakes starts the day still wedged in between high pressure
stretched along the Ohio Valley and large low pressure system up
over Hudson Bay. Cold front associated with the low is now over lake
Superior with a secondary low spinning up along which will track
into Ontario this morning. The cold front will proceed south through
the area this afternoon. A tight gradient in advance of the front
has kept a moderate southwesterly flow going through the night in
the 20 to 30 knot range. In the wake of the front, the gradient
remains tight and and a reinforcing surge of colder air will spread
across the region. This will support northwest gales (35-40kts)
through latter half of the day and into early Friday as well as
periods of heavy freezing spray. A Gale Warning and Heavy Freezing
Spray Warning have been issued for all open waters of Lake Huron for
this period. In addition Small Craft Advisory is in effect for all
nearshore waters of Lake Huron and Outer Saginaw Bay to account for
the winds around 30 knots closer to shore and elevated waves.
Unsettled pattern persists into the weekend as the Great Lakes
continue to reside under an arctic airmass/upper level troughing.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Gale Warning from 10 AM this morning to 4 AM EST Friday for LHZ361-
362.

Heavy Freezing Spray Warning from 10 AM this morning to 4 AM EST
Friday for LHZ361-362.

Gale Warning from 4 PM this afternoon to 4 AM EST Friday for LHZ363-
462>464.

Heavy Freezing Spray Warning from 4 PM this afternoon to 1 PM EST
Friday for LHZ363-462>464.

Small Craft Advisory until 4 AM EST Friday for LHZ421-441>443.

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

$$

AVIATION.....SC
DISCUSSION...TF
MARINE.......DRK


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