Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 151055
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
555 AM EST Sun Jan 15 2017


.AVIATION...

Any light fog around before sunrise dissipating, with clear skies
(below 25 kft) expected to hold right into tonight as the surface
high and dry airmass is slow to exit east. Winds look to be very
light and variable, 5 knots or less.

//DTW Threshold Probabilities...

* None.

&&

.PREV DISCUSSION...
Issued at 322 AM EST Sun Jan 15 2017

DISCUSSION...

Sfc high pressure will continue to dominate the region today with
persistent mid level confluent flow overhead. Regional satellite
data suggest some lake strato cu may brush the thumb region as the
low level flow veers northerly this morning (before weakening by
afternoon). There will also be some periodic high clouds across the
southern sections of the forecast area today. Otherwise, expect
ample insolation today with a similar low level thermal profile as
yesterday, boosting high temps into the low 30s over most of the
area. A period of good radiational cooling tonight, prior to an
increase in high clouds, will warrant min temps down into teens and
low 20s.

The upper low now churning across northwest Mexico is forecast to
lift into the central plains on Monday before lifting across Lower
Mi on Tuesday. This system will accelerate toward the Great Lakes
as northern stream short wave energy dives across the northern high
plains Mon/Mon night. Although the upper wave will dampen as it
lifts into the Great Lakes, there will be an expanding region of
strongly divergent flow aloft across Lower Mi late Mon through Tues
morning courtesy of good upper jet coupling. Deep layer moisture
transport, aided by 40-50 knot low level inflow, will increase
precip water values toward an inch by late Mon night. This moist
isentropic inflow coupled with good mid level positive vorticity
advection will support widespread precip Mon night into Tues
morning. The passage of the upper wave early Tues will also lead to
steepening mid level lapse rates, so some convective elements
(possibly even some thunder) seems likely Tues morning. Total QPF of
a quarter to half inch seem reasonable with this system. There are
indication in the 00Z model suite of more persistent mid level
deformation setting up across Central Michigan, suggesting higher
QPF totals possible across the Saginaw Valley and thumb regions.

As this moisture advects into the resident dry air across Se Mi
Monday and Monday night, there will be some precip type concerns due
to wet bulb cooling, especially at the surface. The initial surge in
mid level moisture Mon afternoon will warrant a chance of mixed
precip. The chance Mon afternoon looks to be quite low due to the
extensive low level dry air and weakening mid level frontal
circulation under enhanced mid level ridging on Monday. The better
chances for precip will occur from south to north Mon night with
the influx of deep layer moisture. While wet bulb cooling may lead
to a brief period of snow/sleet at the onset, rapid mid level
warming will support a quick change over to liquid. The actual sfc
low will not lift into lower Mi until late Tues morning. The
sustained east-southeast sfc winds and lingering low level dry
air indicates sfc temps will struggle to respond. The bulk of the
00Z model solutions suggest sfc temps holding between 30 and 33
deg for several hours Mon night, especially along/north of the
Irish Hills, where a glazing of icing looks possible. The approach
of the sfc low Tues morning should drive enough low level warm air
into the area to transition precip over to all rain, again from
south to north. The passage of the sfc low Tues afternoon and loss
of mid level moisture will then lead to drizzle and fog, possibly
into Tues evening.

Model solutions continue to struggle in their handling of the
northern stream energy dropping down from the northern plains/upper
midwest on Tues. This leads to a low confidence forecast with
respect to additional precip chances Tues night into Wed as model
solutions diverge. The Tues system will not be able to draw much
cold air into the area in its wake, so temps will remain relatively
mild. Much advertised long wave trough amplification across NOAM
still looks to support very mild air across the forecast area during
the latter half of next week into next weekend as heights build
across the ern US.

MARINE...

Light winds today as high pressure slides through the Central Great
Lakes. Southwest winds increasing some tonight, but topping out
mainly around 20 knots as milder air takes hold on Monday. Evening
warmer air to reach Lake Huron on Tuesday, resulting in
precipitation type falling as all rain. Surface low tracking through
the Western Great Lakes early next week, resulting in southeast
winds up around 20 knots over Lake Huron on Tuesday.

HYDROLOGY...

Low pressure coming out of the Southern Plains will spread rain into
southeast Michigan Monday Night into Tuesday. This system will have
a good deal of moisture to work with, but at this point, rainfall
totals are expected to end up around half an inch. Heavier
convective showers or even a slight chance of thunderstorms could
produce localized higher totals, but no flooding is anticipated.

&&

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

$$

AVIATION.....SF
DISCUSSION...SC
MARINE.......SF
HYDROLOGY....SF


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