Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 301108
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
708 AM EDT Sat May 30 2020

.AVIATION...

Cooler and less humid air continues moving into SE Michigan on
moderate NW today. A wide range of sky condition is expected during
the early morning, ranging from clear to patchy MVFR stratus as
daytime heating begins. This leads to a gradual transition to more
consistently broken ceiling but more firmly VFR above 5000 ft this
afternoon. There may be just enough instability for a pop-up shower
but not until after 18Z and mainly east of the terminal corridor.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling below 5000 feet today.

&&

.PREV DISCUSSION...
Issued at 259 AM EDT Sat May 30 2020

DISCUSSION...

Variable coverage of mid-level stratus extending from northern
Wisconsin into the Saginaw Valley a consequence of post-frontal
moisture trapped in the approaching H85-H7 thermal trough. The
seasonably cool and dry airmass already in place at the surface will
respond favorably to diurnal heating allowing stratus to transition
to a greater coverage of broken stratocu along with wind gusts
increasing to around 20 kts this afternoon. 120kt 250mb jet streak
translating toward the Great Lakes today will amplify the southern
periphery of the PV anomaly currently pivoting toward Lake Superior
and forcing another cold front through the CWA during peak heating.
Despite high static stability above 700mb, there will be potential
for mixing depths to overachieve on a localized basis, particularly
as rather active fgen processes along the upper jet axis support
steady top-down deepening of the incoming dry slot. Juxtaposition of
the lead edge of this dry slot with low-level cold front during peak
heating may allow stratocu to bubble into a some sporadic light
showers in the 21-00z time frame - worth introducing a 15 pop. Went
a couple degrees below consensus for highs along/north of the
glacial ridge given noted NWP undersimulation of existing mid-level
moisture this morning.

Cold advection commences in the wake of the front allowing H85 temps
to around -1C by early Sunday morning. Deep dry air, confluent
northwest flow aloft, and aggressively building 1028mb high pressure
anchored near Chicago will ensure cloud-free skies, light wind, and
high temperatures in the mid 60s. Monday basically a modified
persistence forecast from Sunday - airmass modification allows highs
to rebound to around 70 degrees.

NWP consensus remains in tact Monday night into the midweek period.
Northern periphery of the high amplitude ridge established over the
central CONUS deamplifies in response to a series of synoptic scale
height falls over central and southern Canada. Resultant transition
to broad W/WNW flow extending from the High Plains into the Great
Lakes will advect warmer and more unstable air into the region, the
lead edge of which will be marked by a transient period of
showers/chc thunder Monday night. By Tues-Wed, T/Tds already back
into the 80s/60s. 00z ECMWF maintains strong continuity in its
depictions of a favorable thermodynamic environment establishing
over Lower Michigan during the first half of Tuesday becoming moreso
late Tuesday night as a healthy EML is advected east. Signal for
potential severe wx is clear but the window of opportunity appears
limited as a northern wave digging into eastern Ontario shunts the
instability gradient south as early as Wednesday morning.

MARINE...

Moderate northwest flow continues through the day today. A small
craft advisory may be needed late this evening for Lake Huron as
higher waves clip the Thumb. Strong high pressure builds over the
region early Sunday and remains overhead through the day Monday
bringing quiet marine conditions for the period. Shower and
thunderstorm chances increase again late Monday into Tuesday as the
next low pressure system begins to move into the central Great Lakes.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

AVIATION.....BT
DISCUSSION...JVC
MARINE.......KDK


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