Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 232306
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
706 PM EDT Mon Apr 23 2018


.AVIATION...

CLouds will thicken from the south this evening with sprinkles
moving into area as low level moisture increases with time. Expect a
drop to MVFR conditions late tonight into Tuesday morning with a
continued lowering of cigs/vsbys during the course of the day as
better deformation forcing leads to an expanding (although likely
disorganized/patchy) field of light rain and fog. Best rainfall may
actually hold off until after forecast period as northern stream
shortwave digs into area and provides better upper level support.

For DTW...Sprinkles will work into the area in the 04z-06z time
frame with eventual MVFR cigs late tonight (possibly dropping to IFR
Tuesday afternoon). Intermittent light showers can be expected thru
much of Tuesday with patches of fog lending itself to IFR/lower MVFR
vsbys.

.DTW THRESHOLD PROBABILITIES...

* High for ceilings aob 5000 ft after 08z Tuesday.

* High for rain as precipitation type.

&&

.PREV DISCUSSION...
Issued at 335 PM EDT Mon Apr 23 2018

DISCUSSION...

A mild day across southeast Michigan, as temperatures top out around
70 degrees. Unfortunately, going to be shaving close to 10 degrees
Tomorrow, and close to another 10 degrees on Wednesday.

Large upper level low over the central Mississippi River Valley this
afternoon will slowly slide east into the Central Appalachians
Tomorrow night, and begin to merge with the northern stream upper
level wave currently tracking through Central Canada.

Modest height falls and enough moisture transport expected tonight
(PW Values rising to near 1 inch) into Tuesday to support light
showers with low level troughing/inverted surface trough becoming
established, along with some modest mid level fgen/upper level
divergence. Although the forecast will feature showers likely, good
chance the bulk of daylight hours will be dry at any given point.

Stronger upper wave/height falls to arrive Wednesday morning, with
the mid level cold pool (-25 C at 500 MB) tracking across the
Central Great Lakes during the day. Deeper moisture looks to be
shunted off to the East Tuesday night, so may be able to get away
with most of Wednesday being dry, as the 12z NAM/GFS remain more
progressive with the northern stream trough axis. However, the 12z
Euro is remaining consistent with a slower/closing off 700-500 MB
low developing over southern Lower Michigan, and with support from
UKMET, prefer to keep a chance of showers in the forecast for
Wednesday. Temperatures should be holding in the lower 50s as 850 mb
mb temps lower to between -2 C to zero.

Although the Euro even wants to hold onto showers Wednesday evening,
will allow for the post frontal drying/subsidence to kick in, with
skies clearing out Wednesday night as anticyclone builds in.
Assuming this is a case, good chance for many sites to drop at or
below freezing with favorable radiating conditions.

Fairly quiet weather for the latter half of the week into the
weekend. A shortwave ridge will slide through the region on Thursday
resulting in another sunny day with temps reaching into the 60s as
southwest flow returns ahead of the next trough. This trough will
sweep through lower MI on Friday bringing a narrow band of showers
across the area along a cold front. Surface high pressure quickly
filling in behind this front with upper level ridge building east
into the region as well. Northwesterly flow will prevent better
heating across the Great Lakes but temps will still hover in the mid
50s through the weekend.

MARINE...

The ridge of high pressure over Lake Huron will slowly exit to the
east while moisture moves in from the south overnight via the
Tennessee Valley low pressure system. Scattered rain showers will
persist over the area Tuesday into Wednesday. A weak cold front
moving in early on Wednesday will shift light and variable winds to
moderate and northerly with gusts above 25 kt by midday. This will
result in wave heights likely above 4 ft and therefore above the
threshold for Small Craft Advisories. Winds will weaken Wednesday
evening and back to westerly then southwesterly by Thursday evening
as high pressure slides through the Great Lakes. The next cold front
is still on track to arrive Thursday night into Friday.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&

$$

AVIATION.....DG
DISCUSSION...SF/DK
MARINE.......TF


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