Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Detroit/Pontiac Michigan
319 am EST sun Feb 14 2016
Another cold day can be expected today given the cold start. Current
temperatures range mainly between +5f and -5f across the area with
pockets of both milder and colder readings delineated mainly by sky
conditions...ie Saginaw near +10f under cloudy skies at 2 am while
Bad Axe sits near -10f under mainly clear skies. While Arctic high
pressure will be shifting east of the area this morning...southeast
flow back off this high...coupled with increasing clouds throughout
the afternoon...will maintain cold conditions area-wide today with
highs generally in the teens.
The increase in cloudiness is due to an area of isentropic upglide
that overspreads the area between the exiting high pressure and an
approaching surface trough which will extend south from low pressure
tracking to Hudson Bay. By later this evening into the overnight
hours...the gradual increase in Theta-E air within this regime with
provide sufficient moisture to promote an expanding area of light
snow. This area will be helped along with additional lift within
left exit region of jet streak shifting eastward across the Ohio
Valley overnight tonight. This area of light snow/flurries will
increase in coverage from about 10 PM to midnight and persist into
Monday morning before drying southwest flow shifts into lower
Michigan in the wake of this passing trough. While snow will remain
light throughout this event...the persistence of occasional snow
showers for 12 hours or so will lead to a fairly widespread area of
around an inch of snow with a few pockets approaching two inches by
Milder air will be ushered eastward over the central Great Lakes
with the passage of this surface trough...so expect temperatures to
climb into the Lower/Middle 30s by late Monday as precipitation ends
and milder southwest flow ensues. This relatively mild air...in
comparison to the Arctic airmass that has held sway through the
weekend...persist into Tuesday as a clipper low pressure approaches
the area. There is a loose model consensus on the main lift from
this clipper focusing the best precipitation just south to the area
from Tuesday into Tuesday night. Still...it will bring the next
chance of light snow to the area with at least dusting to near one
inch of additional snow possible over portions of the forecast area.
A brief setback in the moderating trend will follow this clipper
with temperatures holding closer to 30f degrees from Wednesday into
Thursday as another modest shot of Arctic air brushes the area as
high pressure sinks through the Great Lakes. This return of colder
Canadian air will be short-lived as the upper pattern becomes much
more progressive through the end of the forecast period with a more
notable intrusion of Pacific air expected within strengthening
southern stream. While some connection between the northern and
southern streams will allow for several rather robust shortwaves
tracking through an increasingly zonal upper level flow
pattern...milder air will win out and bring temperatures into the
upper 30s to middle 40s across the area late this weekend and most
likely into the upcoming weekend.
High pressure exiting the central Great Lakes early this morning
will allow southerly winds to develop today...topping out around 20
knots tonight into Monday. The southerly winds will also bring
milder air into the region...along with light snow late tonight into
Monday. Winds will then become light and variable on Tuesday as high
pressure returns. A cold front tracking through on Wednesday will
allow for northwest winds to increase to at least 20 knots.
Aviation...issued 1158 PM EST Sat Feb 13 2016
Surface high pressure in control this morning...leading to calm
winds and mainly clear skies...exception being at mbs where patch of
clouds at 5000 feet is passing through. Winds will shift to the
southeast today as high pressure exits...this may allow for some
moisture to come off Lake Erie...supporting a borderline MVFR/VFR cumulus
up...with the higher confidence across the southern taf sites.
clear skies this morning...but winds shifting to southeast Sunday
morning and slowly increasing during the day will bring a good
chance of low clouds development (around 3 feet) this afternoon.
Attention tonight will then focus on arrival of light
snow...expected to develop by midnight...and persist overnight into
Monday morning...with an inch or two of accumulation expected.
//Dtw threshold probabilities...
* medium in ceilings below 5000 feet this afternoon...low this
evening...then high tonight.
* High confidence in snow being the precipitation type.
Lake St Clair...none.
Michigan waters of Lake Erie...none.
You can obtain your latest National Weather Service forecasts online
at www.Weather.Gov/Detroit (all lower case).