971
fxus63 kdtx 181029
afddtx
area forecast discussion
national weather service detroit/pontiac mi
529 am est mon nov 18 2024
.key messages...
- milder through wednesday with highs in the 50s. some 60s possible
in the south tuesday.
- widespread showers return early tuesday as a warm front lifts into
the area.
- breezy and colder for the end of the work week as strong low
pressure develops over the eastern conus. this system brings the
potential for rain and snow during the late week period.
&&
.aviation...
drier air attempting to slowly move in from north to south, but
struggling with the very lights winds in place. thus, shallow
ifr/lifr fog remains possible at the start of the taf period before
mixing out mid morning, with then mostly clear/partly cloudy skies
for much of today. southeast winds increasing to around 10 knots
toward the end of the day will allow moisture and low to mid clouds
to return this evening, helped out by the trajectory off lake erie.
the southern tafs will likely see borderline mvfr/vfr cigs toward
midnight, which should expand northward tonight.
dtw threshold probabilities...
* low for ceiling at or below 5000 ft through mid morning, then
meduim this evening and tonight with high confidence for tuesday.
&&
.prev discussion...
issued at 337 am est mon nov 18 2024
discussion...
the upper level jet axis overhead of the great lakes is undergoing a
rapid transformation from anticyclonic to cyclonic curvature as the
speed max pushes east of southeast michigan by 12z this morning.
locally, this will place southeast michigan in a very favorable
location for confluence aloft today and will cause the 950-925mb
extension of the cold front to stall over portions of lenawee county
and northern ohio. surface ridging will pass through the area and
any ascent along the boundary to the south is forecasted to be
extremely shallow. a substantial amount of dry air will be in place
over the forecast area, leading to sunshine today for a majority of
southeast michigan. daytime temperatures will be in the middle to
upper 50s some 10 degrees above normal with winds generally light.
warm advection will ramp up quickly this evening as meridional low
level jet (40-50 knots) is directed into portions of western lower
michigan. plan view perspective shows best lift occurs between 700-
500mb but propagates rapidly through southeast michigan between 03-
08z. forecast soundings support residual dry air staying in place
particularly south of i 69. low chance pops are adequate and not
expecting much qpf.
the edge wave low pressure deepening over the great plains today
will lead to a shorter wavelength upper level ridge that will build
across southeast michigan early tuesday morning. very poor synoptic
scale forcing for ascent then carries through during the late
morning and early afternoon hours as significant weakening of the
absolute vorticity maximum occurs and an extremely unfavorable jet
configuration aloft takes shape. the occluded front tracks across
midday tuesday favoring the stretching deformation but really
looking at lackluster dynamics. 60-80% rain chances are fine for a
time on tuesday because of very high saturation in the lowest 7.0
kft (small raindrops or drizzle).
forecast attention remains centered on the wednesday and thursday
periods as strong potential vorticity energy and jet forcing aloft
moves into the central united states. the mass adjustments are
expected to result in additional cyclogenesis in vicinity of the
great lakes. a high variance in potential outcomes remains on the
table as some fairly substantial outliers exist. one of these
outliers is the 18.00z nam12 solution which suggests a fairly long
duration of accumulating snow. still a long ways off from any
answers as the latest cluster analysis of eps/geps/gefs datasets
places the deepest surface troughing north of southeast michigan
over the lake huron basin and a tertiary low pressure center
deepening off of long island by 12z 11/21. virtually all of the
clusters support some east coast transfer with the northeast united
states development. the key to the sensible weather forecast and
potential for accumulating snow for southeast michigan will be what
sort of lake induced mesolow will lock onto and persist over the
great lakes. there are a significant number of eps solutions that
suggests it will occur over the lake erie basin, while the gfs runs
since the 16th have shown a preference for the straits. the issue of
very warm lake temperatures is a real one and could lead to thermal
profiles too warm for snow outside of the strongest rates. less than
10% of the solutions in the 18.00z eps bring significant
accumulations to the area. the outgoing forecast will read for a
rain/snow mix wednesday night and thursday with no accumulations.
the best potential for snow may be to the south across ohio with a
better shot at colder unmodified air undercutting the great lakes.
given the projected low stability/potential instability and
likelihood for very strong forcing and mass adjustments, it is
important to stress again that we remain a long ways from an answer.
the forecast for the end of the week and next weekend is highly
dependent on how progressive the cold air aloft remains. latest
ecmwf solution carries the cutoff rapidly out of the area by early
friday allowing for deep column warming. lake effect precipitation
will remain likely fri-sat in the immediate downwind vicinity of the
lakes, but precipitation type may remain a cold rain.
marine...
a cold front has cleared the great lakes this morning as wind
direction continues to veer to the west-northwest in the wake of the
front. elevated wind speeds will linger across northern lake huron
through around daybreak, tied to the elevated mixing depths that
have set up as a result of the cooler air temperatures. the late
morning and early afternoon hours will see winds dwindle as high
pressure briefly fills in across the region. high pressure will then
wash out over the ontario-quebec border late tonight into early
tomorrow morning.
a low pressure system then moves from the plains into minnesota,
strengthening the pressure gradient over the great lakes as winds
then veer to the east-southeast. this will bring sustained winds
around 20 to 25 knots for portions of lake huron starting tomorrow
morning, with gust potential around 30 knots given shallow mixing
depths tapping into a shallow yet energetic wind field aloft.
favorable fetch over northern lake huron could bring some isolated
gusts to gales. otherwise, small craft advisories will be likely for
portions of the nearshore zones for both winds and waves given the
favorable fetch.
&&
.dtx watches/warnings/advisories...
mi...none.
lake huron...none.
lake st clair...none.
michigan waters of lake erie...none.
&&
$$
aviation.....sf
discussion...cb
marine.......am
you can obtain your latest national weather service forecasts online
at www.weather.gov/detroit.