FXUS63 KDTX 060157

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
957 PM EDT Fri Jun 5 2020


Waning instability coupled with intrusion of dry air and subsidence
behind the cold frontal boundary will end all rain chances over the
next hour, with the exception of portions of the northern Thumb where
an area of residual moisture holds on. Any shower activity observed
will be light in nature with no thunderstorm activity expected. This
will lead into a mostly clear and calm night with a secondary weak cold
front expected to pass through SE MI by the late morning/early
afternoon hours. Dry air and weak frontal forcing will preclude any
rain chances tied to secondary front.


Issued at 731 PM EDT Fri Jun 5 2020


Ongoing passage of a cold front combined with a subtle low-level
boundary located just north of the Metro terminals have produced
weak isolated showers confined mainly just north of the Metro area,
with secondary showers wedged between KMBS to KFNT. This subtle
forcing combined with a slight uptick in instability will continue
to produce a low-end rain shower or short-lived thunderstorm through
01Z. Given the isolated coverage and low-confidence for development,
rain and thunderstorms will be left out of this TAF issuance with
the exception of KDET, where two convective cells reside. Broadscale
subsidence has and will continue to fill in behind the front which
will effectively end all rain chances and will produce VFR cigs
through the overnight hours. Gradually wind shift from west to
northwest will take place tonight and overnight, with northwesterly
flow expected to hold through the bulk of TAF issuance.

For DTW...

Low-end chance for showers or an isolated thunderstorm through 01Z,
tied to a subtle northerly boundary, otherwise, dry weather and VFR
cigs overnight.


* Low for an isolated thunderstorm through 01Z

Issued at 526 PM EDT Fri Jun 5 2020


Forecast reasoning provided in the Update Discussion Issued at 1103
AM EDT regarding the severe weather potential this afternoon and
early evening hours remains valid.

Low level thetaE warm sector will remain in place across all of
Southeast Michigan through 00Z as 6 hr 1000-500mb geopotential
height falls remain centered over the area. Depth of antecedent dry
air with rapid onset to lower level thetae continues to wreak havoc
in the forecast soundings. The latest HRRR solutions are somewhat
puzzling not giving any credit to the lower to middle 60 dewpoints
that are surging across western Lower Michigan in tow of this
initial shower and thunderstorm activity. The potential still exists
for an isolated strong to possibly severe wind gust with deep
convection through 35.0-40.0 kft agl. However, relatively slow cell
movement of 25 mph and weak environmental wind field less than 25
knots through 10.0 kft agl will be a significant negative on
convective environment/potential. Latest CAM signal suggests
thunderstorm potential through approximately 23Z.

Low level thetae scours out rapidly 03-06Z as a cold front pushes
across the area. Low to midlevel wind trajectories will then
transition to anticyclonic, supporting very efficient isentropic
downglide on the 310-307Ke surfaces. Forecast soundings do show a
clear signal for aggressive subsidence centered at 650mb by 06Z

Strong support within the models for surface based ridging this
weekend. Models showing very strong stability from 3.0 through 15.0
kft agl. Very quiet and ideal summer weather for Southeast Michigan.
Highs this weekend are expected to reach middle 70s to around 80
degrees both Saturday and Sunday. Little cloud cover is anticipated.

High amplitude upper level ridge is then forecasted to develop over
the Central Great Lakes for the beginning of next week. Models
indicate H5 heights potential exceeding 588 dam. Current forecast
information suggests highs reaching the low 90s will be possible on
Tuesday. Main item to be monitoring will be the forecast trends
regarding Cristobal remnants as its forecasted to lift due northward
into the Midwest. Uncertainty exists with timing of interaction
between tropical moisture and strong upper level trough/PV over
western United States. Important, because eventual track of
Cristobal will bring with it a heavy rainfall and flooding risk.


Areas of gusty showers and thunderstorms are advancing across Lake
Erie this evening which may lead to locally higher waves. A cold
front moves through late this evening bringing about additional
showers and thunderstorms followed by northwesterly flow. Wind
speeds will increase on Saturday as the surface gradient strengthens
due to stronger high pressure building to the northwest and a
deepening low over the Northeast. High pressure over northern
Ontario shifts eastward on Sunday with a secondary high over
northern Lake Huron causing winds to veer toward the northeast
drawing slightly cooler and drier air into the central Great Lakes.
A warming trend begins on Monday as high pressure influence keeps
conditions dry with lighter winds veering southeasterly. The
remnants of TS Cristobal arrive mid-week presenting timing and
precipitation uncertainty.


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



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