Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 201707
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
107 PM EDT Mon Mar 20 2017
Weak ascent working along an elevated warm front will maintain a
window for showers /mainly Detroit corridor/ late today, while
perpetuating a combination of VFR diurnal cu and a lower coverage of
MVFR stratus. There remains a low probability for thunderstorms
with any activity, but confidence on occurrance remains too low to
include. This moisture will exit to the east early tonight, with
developing light northerly flow encouraging a clearing sky across
the lowest 5000 ft overnight.
For DTW...Low probability for thunderstorms remains through late
afternoon. Current radar trends suggest ongoing development
upstream will remain just south of DTW, potentially affecting
southern sections of the airspace. Probability of occurrance at
DTW remains too low to include attm.
//DTW THRESHOLD PROBABILITIES...
* High in ceilings below 5000 ft through the evening. Low
* Low for thunderstorm occurrance through late afternoon.
Issued at 325 AM EDT Mon Mar 20 2017
A band of showers and thunderstorm with a wintry mix developed over
northeastern Wisconsin and Lake Michigan early tonight as a
shortwave tracking eastward interacted with a narrow band of deeper
moisture and steep mid level lapse rates. The shortwave is now
tracking through southeast Michigan where it is encountering much
more drier air and stable lapse rates as evident by the decreased
lightning and decreasing high radar reflectivity. Surface obs
indicated light snow falling from about 9k ft ceilings. Expected this
band of light snow or rain mix to exit to the southeast by around 6am.
For today, expect mainly quiet weather for the first part of the day
as any forcing will be lacking. For this afternoon, cold front to
the west will be moving east with no real solid upper level forcing
for the northern two thirds of the cwa. For the southern counties,
a warm front will remain nearly stationary along or just south of
the border. A small mid level wave with a weak surface low
reflection currently over Iowa will track eastward along the warm
front and effect the southern counties up to about the I96
corridor in the 18-00z time frame with showers and a few
thunderstorms as instability along and south of the warm front will
be great enough for elevated convection. No severe weather is
expected. North of the I96 corridor will have just a chance for
showers with cold frontal passage as again moisture will not be as
deep and forcing confined mainly to frontal convergence. Highs today
mainly upper 40s.
Some light showers may still linger far southeast corner this
evening otherwise large strong area of high pressure in central
Canada will begin building into the Great Lakes through the week
with the center reaching overhead Wednesday then slowly sliding to
the east Thursday. Temperatures for mid week will be below average
with lows Wednesday and Thursday morning in the teens.
The next weather maker will be from a warm front that will lift
through Thursday night as a large low pressure system develops over
the central plains and begins moving eastward for the weekend.
Relatively large scale high pressure will hold over the region today
and tonight. This will keep marine weather concerns at a minimum.
The potential does exist for some weak thunderstorm activity over
Lake Erie and Lake St Clair late this afternoon and early evening.
A strong backdoor cold front will push down Lake Huron late Tuesday
afternoon and Tuesday evening. Cold air advection in the wake of
this cold front will be very strong resulting in steep lapse rates
and deep mixing. Models are suggesting that wind gusts will exceed
34 knots over much of the northern two thirds of Lake Huron Tuesday
20-08Z. A gale watch has been issued for portions of the lake. Small
craft advisories will likely for much of the nearshore zones
including Saginaw Bay.
Lake Huron...Gale Watch from Tuesday afternoon through late Tuesday night for
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
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