Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
FXUS63 KDTX 190814
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
314 AM EST Thu Jan 19 2017
Amplified upper level ridge axis west of the Appalachians extending
through the Central Great lakes Today. 00z DTX sounding revealed
stout low level inversion based around 2 KFT, and with back edge of
low clouds still over northern Indiana, going with more
pessimistic cloud forecast today, in line with the NAM 950 MB RH,
and thus will have to cut back on high temperatures, going with
highs predominately in the lower 40s but mid 40s possible as some
late day breaks in the clouds potentially occur, but high clouds
likely already in place.
Negative tilted upper level trough axis lifting north, allowing for
excellent moisture transport Tonight, as seen in 850-700 mb Theta-E
fields and PW values approaching 1 inch, with weakening surface low
lifting into the State Friday morning. Should be sufficient to
generate widespread showers with the stretched out trough/moisture
axis gradually diminishing/shriveling up as it lifts northward
during the day on Friday.
Mid clouds arriving this evening, limiting low temperatures to around
freezing (30-34), as surface dew pts also do not stray very far
from the freezing mark.
Good warm layer (7 C average temp from 925-850 MB) to start this
evening, but wet bulb cooling/lift will lower the column into the
low single numbers early Friday Morning, drawing some concern of
frozen precip. Overall, think we looking at all or mainly rain,
with just a low chance of a brief period freezing rain or sleet.
Local probabilistic SREF guidance also indicating just low chance
of icing in a few spots, with most locations having near zero
Potent Jet/Upper level energy tracking through Southern
California/Baja California expected to lift through the Midwest
(IOWA) Friday Night with the upper jet (250 mb) tracking through
Southeast Michigan on Saturday. Models not very active with the warm
front lifting through lower Michigan, and suspect we may end up with
good deal of light rain showers, more pessimistic than outgoing
forecast. This could also be the case Saturday night into Sunday
as well, as Gulf of Mexico moisture breaks off and advances into
Michigan (925-850 mb dew pt to 5-6 C per Euro).
Even more Pacific Energy to track through Baja California/Mexico
over the Weekend, leading to deepening storm system tracking
through the Gulf Coast States, and then reaching the Carolinas by
Monday Morning. This is a farther south and east trend, and thus
rain chances for Monday have decreased some, but 00Z Euro Still
clips us with precipitation Monday/Monday night, with potentially
enough cold air to support snow, as 850 mb fall into the -4 to -6
Southwest winds across Lake Huron will weaken during the course of
the morning as high pressure expands across the eastern Great Lakes.
A surface trough is forecast to lift from the Ohio Valley tonight
across Lower Mi on Friday. This trough is forecast to weaken,
sustaining an overall weak gradient across the lakes. This along
with strong over-lake instability due to warm air across the region
will support relatively light east-southeast winds on Friday. Light
easterly winds will persist through the weekend. The east winds will
increase Monday as deepening low pressure is forecast to lift up the
A narrow ribbon of deep layer moisture will lift from south to north
across the area late tonight into Fri afternoon, associated with a
mid level trough axis. There is a fairly high probability that total
rainfall amounts with this system will be around a quarter of an
inch. There will be no flooding concerns with this low of a rainfall
Issued at 1152 PM EST Wed Jan 18 2017
IFR ceilings will persist into Thursday, slowly eroding from south
to north during the afternoon. Some fog in the 3-5SM range will also
be possible overnight into Thursday morning. Main concern will be
how far north this clearing can work before southwest flow back to
the east/northeast in response to weak low pressure lifting into the
midwest. Would not be surprised to see at least MVFR cigs to hold at
KMBS/KFNT with perhaps 50/50 confidence in scattering out further
south. In any event, any clearing will be brief as stratus expands
over area late tomorrow night with the slow approach of this low
For DTW...Expect VFR ceilings into Thursday morning. Will maintain
transition to scattered about 18z-19Z, but am not overly confident
in that. If it doesn`t clear by 20z-22z, it probably won`t as low
level moisture increases with approach of weak low/warm front with
solid IFR conditions expected again by end of the forecast period
//DTW Threshold Probabilities...
* High for ceilings below 5000 ft into early Thursday afternoon, low
in degree of clearing 18z-22z.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
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