173
FXUS63 KDTX 021657
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1257 PM EDT Sun Jun 2 2024

.KEY MESSAGES...

- A chance of showers lingers this afternoon for much of Southeast
  Michigan.

- A warming trend continues Monday with highs in the lower 80s
  expected Monday afternoon.

- Unsettled weather returns Tuesday and lasts through mid-week with
  periods of showers and thunderstorms.

&&

.AVIATION...

A small center of low pressure and weak cold front exit SE Mi while
supporting clusters of showers this afternoon. A general transition
from IFR to MVFR ceiling underway during the morning also continues
with afternoon heating and as the pressure systems exit. Light
northerly cloud layer wind has weak high pressure/diverging
directional influence to help with a decreasing cloud trend as
daytime heating/instability diminish this evening. The clear sky and
light wind keep a widespread fog scenario in play late tonight and
Monday morning. Northerly flow this afternoon and evening is not
quite enough to scour out boundary layer moisture and surface Td
holds in the 50s as ideal radiational cooling conditions develop.
Model soundings capture trends affecting all of the terminal sites
and there are convincing fog signals in typically more stubborn GFS
MOS/LAMP guidance supporting IFR/LIFR restriction leading into
sunrise. Model RH and forecast soundings then suggest fog follows a
typical morning dissipation to VFR by late morning through Monday
afternoon.

For DTW/D21 Convection...Thunderstorms are not expected through this
forecast period.

DTW THRESHOLD PROBABILITIES...

* High for ceiling at or below 5,000 feet this afternoon, low by
  this evening.

* Moderate for cigs/vsby falling below 200 ft and/or 1/2 SM Monday
  morning.

&&

.PREV DISCUSSION...
Issued at 345 AM EDT Sun Jun 2 2024

DISCUSSION...

The back edge of a meridional plume of deep moisture is currently
working eastward across Lower Michigan this morning. System relative
isentropic ascent was fairly upright windily in the 00-06Z time
window, but the most focused of warm advection lift has since moved
off to the eastern Great Lakes. Currently, a fairly
homogenized/barotropic air mass remains in place with forcing for
lift relegated to weak deformation. The expectation is that while
midlevel dry air will encroach from the west, low level moisture
will hang around Southeast Michigan at least through mid morning
hours. Regional mosaic radar shows a loss of returns, but the
lingering saturation in the lowest 5.0 kft agl is expected to result
in continued drizzle chances this morning.

The influx of midlevel dry air brings some question as to how
widespread the coverage of opaque cloud will be today. A few breaks
will allow diurnal heating to result in warm and humid conditions.
Surface dewpoints are forecasted to hold in the lower 60s today.
Forecast data is sending mixed signals as CAMS are resolving
explicit convective activity but forecast soundings are convincing
in static stability above 6.0 ft agl.Differential heating and lake
boundary convergence boundaries are expected to be crisp enough to
function as trigger mechanisms for shallow/low topped showers. The
most likely time period for showers will be with a mature boundary
layer in the 20-03Z window. Best focus may begin in the Thumb and
along the I 69 corridor before moving southward as a lake breeze
boundary backdoor into portions of northern Metro Detroit. Left the
afternoon shower chances/rumble of thunder alone.

Much of Monday is expected to be quiet as a fairly pervasive
anticyclonic influence holds over Lower Michigan and the warm
advection response remains fairly disjointed. This changes for
Monday night as the center of the main upper level ridge axis pushes
east of Lower Michigan. Westerly return flow sets up and allows for
remnant MCS activity to approach the state. There is varying
agreement on the amount of QPF over the cwa, with the nam
unquestionably the most bearish. The current forecast has a chance
of showers and thunderstorms Monday night which is sufficient. No
strong thunderstorm activity is anticipated with poor lapse rates in
the lowest 10.0 kft agl.

Relatively quiet conditions for Tuesday and downstream ridge
amplification occurs over Southeast Michigan ahead of dynamic upper
level jet packet digging through the northern Plains. Warm and humid
conditions are expected Tuesday afternoon with heat indices well
into the middle 80s. A total pattern overhaul is then in store for
the middle and end of the week. Models have been very consistent in
an abnormally strong low geopotential height anomaly becoming
established over the Great Lakes. Timing the arrival of the main
height fall response and absolute vorticity advection will be
important in forecasting the strength of convection Wednesday.
Current data favors midday Wednesday. Cold advection will then surge
build into the state. The current forecast reads lower to middle 70s
for daytime highs at the end of the week, but appears ripe for
future revisions.

MARINE...

A slow moving low pressure system will weaken as it advances toward
southern Lake Huron today. The associated region of light rain will
diminish as it exits east this morning. As the low pressure system
weakens, high pressure will develop across the region tonight into
Monday. Winds will generally remain light given the weak gradient
across the eastern lakes. An approaching warm front will bring a
chance of showers and thunderstorms to the region on Tuesday.
Southeast wind gusts approaching 20 knots are possible as the
gradient increases ahead of this front. The warm front will then be
followed by a strong cold front on Wednesday, sustaining the chances
for thunderstorms.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

AVIATION.....BT
DISCUSSION...CB
MARINE.......SC


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