Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 250356
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1156 PM EDT Sun Mar 24 2019


.AVIATION...

A narrow region of post frontal (low end) MVFR stratus may briefly
impact the terminals prior to the arrival of much drier air from the
north. This dry air is associated with strong high pressure that
will expand into northern Minnesota tonight and will support clear
skies late tonight through the day Monday. The position of the sfc
high will support north-northeast winds around 10 knots through the
day Monday.

.DTW THRESHOLD PROBABILITIES...

* Low in ceilings at or below 5000 ft tonight.

&&

.PREV DISCUSSION...
Issued at 909 PM EDT Sun Mar 24 2019

UPDATE...

The region of mid level frontal forcing causing the light rain
along/south of the I-94 corridor in SW Lower Mi will track across the
Ohio/Michigan border through the rest of the evening/early overnight.
This mid level forcing will continue to contract/weaken over the next
several hours. This and the rather poor moisture quality across Se
Mi will remain supportive of just chance type pops for measurable
rain this evening (mainly south of I-94 corridor). Meanwhile the cold
front continues to push south across the forecast this evening, with
post frontal temps already in the 30s across the Saginaw Valley and
thumb region. Overall the current forecast looks reasonable, so no
major evening update will be warranted this evening.

PREV DISCUSSION...
Issued at 338 PM EDT Sun Mar 24 2019

DISCUSSION...

Mostly cloudy day across southern MI today as mid and upper level
moisture streams in from the south from a shortwave tracking east
through the Ohio Valley. This wave ejected out of the stacked low
farther west, currently over the IA/MO border which will itself
drift east-southeast through tonight. Question for southern MI is to
what degree does the moisture/forcing tied to the low lift into the
area?  Model trends continue to keep the bulk of the moisture to
south due in part to a few factors. First is a jet streak entering
the base of the mid level low pressure trough will shoot due east
producing pressure falls southeast of the surface low pulling it in
that direction. Secondly there is strengthening confluent flow over
lower MI as northern stream trough sinks south through the Great
Lakes. This is adding stability to the region making it hard for any
lead energy to survive. Lastly there is a wealth of dry air from the
surface to 15kft as noted in the 12Z DTX sounding. Though it`s been
slowly moistening through the day, that amount of dry air will be
tough to overcome with the longwave pattern in place. There does
remain a chance for showers along the MI/OH border this evening as
the deepest moisture pairs up with a cold front dropping south
through the straits that will reach the Detroit Metro around 00Z.
This shallow front may add enough forcing down low to pull the
better forcing from 600mb down to a more favorable 700-850mb. If any
rain does fall it will be light and not last long so the chance pops
with low QPF will carry on with this package.

The cold front will quickly drop temperatures tonight noting temps
across northern MI ahead of the front near 50 and just behind the
front near freezing. Winds will flip from southwest to
north/northeast and become gusty tonight as temps drop. Lows tonight
will fall into the 20s for most locations as dry cold air surges in.
Dewpoints will dip into the teens but winds will not go calm under
the clear skies to allow further cooling.

High pressure then builds across the region for the first half of
the week. Even with nearly full sun in late March, temperatures will
struggle to get much into the 40s Monday as the thermal trough
swings through and 850mb temps decrease through the day.
Temperatures will then slowly moderate through mid week as heights
start climbing with weak westerly flow aloft.

Return flow from high pressure centered across New England/western
Atlantic will aid in increasing temperatures Wednesday into
Thursday, with forecasted highs peaking in the upper-40s to lower
50s Wednesday and eventually the mid to upper-50s by Thursday.
Western periphery of the aforementioned high pressure system will
keep conditions dry throughout Wednesday, with extended periods of
sunshine possible, at least throughout the morning and early part of
the day, as dry air holds across Michigan. There will, however, be a
slight chance to see rain showers develop throughout Thursday,
caused by the passage of a weak cold front that travels and stalls
out across central Michigan.

Otherwise, a baroclinic zone is forecasted to set up across Michigan
Friday through the weekend, which will bring an extended chance to
see rain showers throughout the weekend as warm air overruns across
a stalled frontal boundary. High uncertainty in regards to
forecasted highs and lows as temperatures will be a function of
where the frontal boundary sets up. Latest ECMWF trends are pointing
towards cooler air setting up across Michigan relative to previous
model runs, with temperature highs in the 40s looking more probable
by Saturday. An approaching low pressure system will travel
northeast across the Ohio Valley into Lake Ontario Saturday into
Sunday which will pull even cooler air across Michigan by Sunday,
marked by h850 temperatures at -11C in the latest ECMWF run. This
would suggest the possibility of seeing highs capped in the 30s and
even snow on Sunday as moisture wraps around to the northwest of the
low. Overall, extended periods of rain (with possible snow) expected
this weekend with below normal temperatures.

MARINE...

A cold front will push south across Lake Huron during the rest of
the afternoon and settle south of Lake Erie this evening. The front
will be marked with a sharp wind shift to the northeast. Solid post
cold air advection in the wake of this front will support wind gusts
of 20 knots or more this evening into tonight. Higher gusts between
20 and 30 knots will persist on Monday, mainly over northern Lake
Huron where the pressure gradient strengthens for a time between low
pressure east of Hudson Bay and high pressure building into the area
from the west. Small Craft Advisories will continue into tonight and
Monday morning for the waves generated by this onshore flow. The
high will then build into the region late Monday and persist into
Tuesday, supporting a gradual decrease in the winds and waves.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...Small Craft Advisory until 10 AM EDT Monday for LHZ422.

     Small Craft Advisory until 2 PM EDT Monday for LHZ421-441>443.

Lake St Clair...Small Craft Advisory until 10 AM EDT Monday for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 10 AM EDT Monday for LEZ444.

&&

$$

AVIATION.....SC
UPDATE.......SC
DISCUSSION...DRK/AM
MARINE.......DG


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