NWS Forecast Discussion

FXUS63 KDTX 060350

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1150 PM EDT Sun Apr 5 2020


Expecting prevailing SKC tonight. A very dry air mass with efficient
mixing this afternoon will preclude much risk of fog. Entrance
region to upper level jetlet will migrate east of due north from
Michigan Monday. This will allow warm advection to approach from the
west late in the day. Center of coherent midlevel anticyclone will
pass through Southeast Michigan 15-18Z. Gradient of midlevel theta e
will eventually push into Southeast Michigan between 21-00Z which
will result in a midcloud deck at 6.0 ft agl. The low level will be
slow to saturate with cloud below 6.0 ft agl possibly waiting until
after 06Z Tuesday. Low confidence in location of initial
precipitation push Monday night as some signal suggests south of the


* None.


Issued at 324 PM EDT Sun Apr 5 2020

Aggressively building surface high pressure effectively eroded early
day grunge and is providing Southeast Michigan a delayed rise in
temperatures well into the 50s courtesy of full insolation for the
remainder of the afternoon. High pressure will reside directly
overhead for the balance of the night allowing effective radiational
cooling to commence immediately upon loss of diurnal heating. Lows
will easily fall into the 20s given current dewpoint readings, which
is in line with all MOS guidance. The extent of stratus and fog over
Lake Huron through midday has posed some concern for an intrusion of
the marine layer overnight, but the last couple of hours have seen a
rapid transition to clear skies over the lake which greatly reduces
the probability of redevelopment.

Clear skies continue into Monday. Temperatures likely to top out a
couple degrees warmer than today as another day of strong insolation
further modifies the existing airmass in the absence of meaningful
advection. This also begins the time of year when lake shadows can
expect to be notably colder than all other locations. Advancing
moisture reservoir and low-level baroclinic zone clearly evident on
channel 2 imagery this afternoon in the form of expanding stratus
over the southern Plains extending northeast along the front into
the Lower Great Lakes. This low-level moisture will pivot into the
area from the southwest as isentropic ascent increases Monday
afternoon into Monday night. A modest nocturnal low-level jet will
support showers and a few thunderstorms along the moisture gradient,
most likely south of M59, but both moisture and instability will be
marginal. Position of this boundary near the southern state border
thunder - if any - over SE Michigan during this time will be

Weak height falls approaching from the west on Tuesday will result
in a considerable diminishing of the surface gradient as surface low
becomes fairly expansive/diffuse over the region. Forecast soundings
indicate mid-level moisture will be poor throughout the day due to
developing subsidence. This in all likelihood leaves Southeast
Michigan socked in beneath a strengthening frontal inversion with
extensive low clouds and periods of fog/drizzle. Modest elevated
instability is noted but will be inaccessible in the absence of
larger scale forcing. Highs will range from the upper 40s to low 50s
within the extensive clouds to potentially the 60s near the Ohio
border. Strong model consensus that a shortwave embedded within a
transient period of WNW flow aloft will usher this airmass east on
Tuesday night. Release of aforementioned mid-level instability will
be possible during this time, though mid-level moisture will
continue to be lacking, so the mention of thunder has been carried


High pressure centered over the Wisconsin sector of Lake Michigan
continues to advect drier air over the central Great Lakes this
afternoon. The expansion of this dry airmass is well illustrated via
satellite imagery as residual marine stratus over southern Lake
Huron quickly erodes eastward. Expect entrainment to lead to final
clearing over US waters by 20Z. Thereafter, benign maritime
conditions will continue into the overnight period with light
prevailing winds gradually veering S/SE, holding below 10 knots into
Monday morning. Dry conditions persist early on Monday as the center
of the high treks through the Thumb before the low-level ridge
begins to compress over southern Ontario Monday evening. Focus then
shifts toward an inbound low Monday night as current model consensus
suggests a glancing shot of isentropic showers preceding more
dynamic showers/thunderstorms Tuesday afternoon/evening after the
low makes further inroads. Still some uncertainty as to the exact
track of the low at this time. High pressure then lifts out of the
eastern Plains making a brief appearance on Wednesday before wet
conditions ramp-up Wednesday night.

Issued at 323 PM EDT Sun Apr 5 2020


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



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NWS DTX Office Area Forecast Discussion