Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 231057
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
657 AM EDT Mon Apr 23 2018

.AVIATION...

Mostly clear sky will start the day as high pressure maintains
control of conditions across SE Michigan while departing farther
east with time. Light NE wind during the morning shifts to SE at
most locations and as high clouds thicken during the afternoon.
These clouds will be the first sign of moisture arriving from the
Tennessee Valley system tonight. Scattered light rain showers are
possible overnight but VFR is expected to hold through sunrise
Tuesday.

.DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 339 AM EDT Mon Apr 23 2018

DISCUSSION...

Today will be the last of a nice stretch of dry days going back into
late last week. The 00Z DTX sounding last night came in with a PWAT
of 0.18 inches and shows a good amount of depth to the dry air that
has settled over southeast Michigan. Low level thermal ridge will
allow temperatures to climb even higher this afternoon with much of
the inland areas solidly in the upper 60s and lower 70s. However,
temperatures across the lakeshores of Lake Huron look to remain in
the 50s and maybe low 60s as east/northeasterly onshore flow from
the relatively cooler waters will hamper greater warming. Cloud
cover will begin to increase today from south to north emanating
from a closed low moving across the TN Valley. The increase in
clouds will arrive late enough in the day to not affect the warm up,
but it will signal the beginning of the moisture moving into the
region. Winds will veer to the south/southeast and surface dew
points into the 40s will be pulled into southeast Michigan this
afternoon. The resident dry airmass will likely hold off any light
precipitation that may try to lift into Michigan from south of the
state line during the day.

The closed low will meander across the TN Valley through tonight
while a shortwave begins to swing across south central Canada.
Theta-e advection and weak mid level isentropic lift on the north
side of the low will support low chances for rain across the far
south as soundings begin showing low to mid levels becoming
saturated. The saturation process will work north into Flint and
eventually the Tri-Cities. This will bring a slight increase in rain
chances for these areas into Tuesday morning.

By Tuesday afternoon, the northern stream shortwave will begin
digging through the upper Great Lakes and interact with the closed
low as it moves into the Ohio Valley and gets absorbed within the
northern stream westerlies. This interaction will increase rain
chances across all of southeast Michigan Tuesday afternoon and then
into Tuesday night as a surface cold front associated with the
shortwave moves through Michigan. These scattered rain showers from
Tuesday into Wednesday morning look to produce around a quarter of
an inch or less of QPF. Potential exists for lingering precipitation
chances through Wednesday as the Euro has this shortwave deepening
and becoming a closed low as it moves through lower Michigan and
northern IN/OH. Models still differ with how this evolution. If it
does pan out, expect an additional tenth of an inch of rainfall
mainly across the Thumb and eastern portions of the CWA.
Temperatures will drop behind the aforementioned cold front, but
remaining in the 50s and upper 40s for most locations.

Precipitation may still be lingering into early Thursday morning
across the eastern portions of the area if that closed low develops
and pivots northeast. A shortwave ridge looks to eventually move
over the area on Thursday bringing a brief break in precipitation
before the next wave diving out of Canada brings another round of
precipitation to close out the work week. The good news is high
temperatures look to at least hold in the 50s on Friday and into the
weekend.

MARINE...

High pressure will be in firm control of marine conditions for one
more day and provide a general light east wind and nearly calm waves
through tonight. Moisture from low pressure over the Tennessee
Valley will then spread northward over the central Great Lakes later
tonight and merge with that from a weak cold front during Tuesday
producing rain showers across the area into Wednesday. A light and
variable wind pattern will become moderate from the north Tuesday
night and Wednesday after the front moves through Lake Huron and
Lower Michigan and likely produce wave growth exceeding the 4 ft
threshold for Small Craft Advisories. High pressure moves in
Wednesday night and Thursday but not for long as the next front is
projected to move in from the west Thursday night into Friday.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

AVIATION.....BT
DISCUSSION...AA
MARINE.......BT


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